by dividing the lax capsule and synovial membrane on the medial side
of the patella, and overlapping the edges with a double line of catgut
sutures.

Lateral dislocation of the patella is met with in extreme forms of
_knock-knee_, and after correction of this deformity by osteotomy, and
its possible occurrence should be guarded against at the time of the
operation.

#Genu Recurvatum.#--In this deformity the knee is hyper-extended, the
thigh and leg forming an angle which is open forwards; the attitude
may be permanent or may only appear on walking. It is an extremely
disabling and unsightly deformity.

There are several varieties. In the _congenital form_, which is
apparently due to a faulty attitude of the lower extremities _in
utero_, the patella may be imperfectly developed or absent; the knee
is convex backwards, and attempts to flex the joint cause pain. Other
deformities frequently coexist. The treatment consists in flexing the
joint to a right angle under an anæsthetic, and maintaining this
attitude by means of plaster-of-Paris or splints until the growth of
parts overcomes any tendency to relapse.

_Acquired Forms._--The most common acquired form is the result of
anterior poliomyelitis, and is described in the next section.

The deformity may also be due to rickets which has caused a backward
bend of the tibia immediately below its upper epiphysis--sometimes
combined with an exaggerated forward curve of the femur. If there is
no prospect of spontaneous rectification, the upper end of the tibia
should be divided with the osteotome, and the limb straightened.

It may result also from fracture or from separation of one of the
epiphyses in the region of the knee, or from cicatricial contraction
of the quadriceps. As a result of bone and joint disease, it is met
with chiefly in neuro-arthropathies when the knee has become
disorganised and flail-like.

#Deformities of the Knee resulting from Anterior Poliomyelitis and
from Spastic Paralysis.#--When there is paralysis of all the muscles
acting on the knee, the joint may be so flail-like that the patient is
unable to stand without the aid of a crutch, or when weight is put on
the limb, it assumes the attitude of genu recurvatum. The usefulness
of the limb may be improved by the application of a rigid apparatus
with a lock at the joint so that it can be used in the extended
position for walking or in the flexed position for sitting. The rigid
knee produced by arthrodesis affords good support but is inconvenient
in sitting.

When the _quadriceps alone_ is paralysed, the patient is obliged to
maintain the joint in the position of extreme extension, because the
least degree of flexion results in the limb giving way under him. In
course of time the posterior ligament is stretched, and the joint
becomes hyper-extended, acquiring the attitude of _genu recurvatum_.
When it is bilateral the gait is seriously impaired. The treatment
consists in applying an apparatus which prevents hyper-extension, in
improving the condition of the thigh muscles, and in wearing a splint
at night which secures the flexed position. Recourse may be had to
operative measures, such as transplanting one of the hamstrings into
the patella, so as to compensate for the loss of power in the
quadriceps, arthrodesis, or supra-condylar osteotomy of the femur.

When the quadriceps is overcome by a _contraction of the hamstrings_,
as in spastic paraplegia, the knee is fixed in the flexed position and
the child is unable to walk. The flexion may be corrected by
lengthening the hamstring tendons, bringing the divided biceps tendon
through an opening in the vastus lateralis, and attaching it to the
rectus and to the patella. If there is a combination of flexion and
genu valgum, the knee-joint should be resected and ankylosed in the
straight position.

#Contracture and Ankylosis at the Knee.#--In addition to the different
paralytic forms above described, contracture may result from
ulceration and suppuration in the popliteal space, and from disease
(osteomyelitis) in one of the adjacent bones. The greater number of
contractures and ankyloses are the result of disease in the joint, and
have already been described.

GENU VALGUM AND GENU VARUM

In the normal limb, a line drawn from the centre of the head of the
femur to a point midway between the malleoli passes through the
centre of the knee-joint. If the line passes outside the centre of the
knee-joint, the condition is one of genu valgum; if inside, it is one
of genu varum (Fig. 135).

[Illustration: FIG. 135.]

#Genu Valgum--Knock-knee.#--In this deformity the leg joins the thigh
at an angle which is open outwards, and when the affection is
bilateral, the projecting knees tend to knock against each other in
walking; the term X-legs is sometimes applied to it.

_Etiology._--The observations of Macewen and of Mikulicz, and
information afforded by the Röntgen rays, have shown that the primary
cause of the deformity is an inequality of growth at the ossifying
junction of the femur or tibia or of both. This inequality of growth
is nearly always due to rickets, and its direction is determined by a
faulty attitude of the limbs in standing and walking. The legs being
abducted, the weight of the body falls unequally on the medial and
lateral parts of the ossifying junctions, and inequality of growth
results.

_Pathological Anatomy._--Examination of the femur usually shows that
the lower third of the diaphysis is lengthened on its medial side and
shortened on its lateral side, and that the epiphysis, itself
unaltered, is fitted on to the diaphysis obliquely, so that the medial
condyle appears to be increased in length and to occupy a level
distinctly below that of the lateral condyle. In many cases the tibia
shows corresponding alterations. On section of the bones, the
epiphysial cartilage and the zone of ossification are found to be
unduly broad and irregular.

[Illustration: FIG. 136.--Female child with right-sided Genu Valgum,
the result of Rickets. The pelvis is tilted, and the spine is curved.]

The neck of the femur is shortened and its angle diminished. The bones
of the leg are sometimes bent inwards in their lower thirds, and this
compensates partly for the valgus deformity at the knee. The articular
cartilage of the lateral condyle and the lateral meniscus are usually
thickened. In pronounced cases the quadriceps tendon and the patella
are displaced laterally, and this may be so pronounced that on flexion
of the joint the patella is dislocated on to the lateral condyle of
the femur. The biceps tendon and ilio-tibial band are shortened and
more prominent as a result of the approximation of their attachments,
and they are also displaced laterally. The sartorius and gracilis are
displaced backwards, so that they descend behind instead of on the
medial side of the knee. The popliteal artery lies on the back of the
lateral condyle instead of in the hollow between the condyles, and the
tibial (internal popliteal) nerve is displaced even farther outwards.
The capsular and other ligaments are slack, so that the joint is
unstable and easily hyper-extended. There is often some effusion into
the joint.

[Illustration: FIG. 137.--Female child with Rickety deformities of
upper and lower extremities.

(Mr. D. M. Greig's case.)]

_Radiograms_ reveal the changes in the bones (Fig. 138); the shaft of
the femur or tibia, or both, which may also be curved, is set
obliquely on its epiphysis; and the clear zone, corresponding to the
epiphysial cartilage, is uneven and broader than normal. There are
also less obvious changes in the density of the shadow and in the
arrangement of the trabecular structure of the bones.

[Illustration: FIG. 138.--Radiogram of case of Double Genu Valgum in a
child æt. 4.]

_Clinical Features._--In the infantile form (Fig. 139) the knock-knee
is commonly associated with rickets in other parts of the skeleton,
and especially with bending of the tibia and femur, and in extreme
cases the child may be unable to walk.

[Illustration: FIG. 139.--Genu Valgum in a child æt. 4. Patient
standing.]

The deformity is about as frequently bilateral as unilateral. There
may be knock-knee on the one side and bow-knee on the other. If, as is
usually the case, the deformity is due to obliquity of the femur, it
disappears on flexing the joint (Fig. 140), because in flexion the
tibia glides behind the projecting median condyle; if the deformity
affects the tibia only, the influence of flexion in disguising it is
not so marked. It is usually possible to hyper-extend the joint, and,
in the extended position, to rotate the leg outwards to a greater
extent than is normal. In unilateral knock-knee, the affected limb is
a little shorter than its fellow, but the patient compensates for this
by depressing the pelvis on the affected side.

[Illustration: FIG. 140.--Genu Valgum. Same patient as Fig. 139.
Sitting, to show disappearance of deformity on flexion of knee.]

_Prognosis._--In children below the age of six, the bones naturally
tend to straighten if the child is kept off its feet. After this age,
there is no such prospect.

The _treatment of knock-knee in children_ is directed towards curing
the rickets and preventing the child from putting its feet to the
ground. If it cannot have the services of a nurse and the use of a
perambulator, a light padded splint is applied on the lateral side of
the limb, extending from the iliac crest to 3 inches beyond the foot.
The splint is fixed above and below by bandages, and the projecting
knee is drawn towards it by a few turns of elastic webbing. A method
specially applicable to hospital out-patients, is to straighten the
limbs as far as possible under anæsthesia, and apply a plaster
bandage; the bandage is renewed at intervals of three weeks until the
deformity is corrected. Whatever plan is adopted, it must be
persevered with for at least six months, until the rickety changes in
the bones have been entirely recovered from.

If the child is approaching the age of five or six before it comes
under treatment, or if the deformity does not yield to treatment by
splints, it is better to straighten the limb by _osteotomy_.

In _adolescent knock-knee_ the patient seeks advice because of the
deformity or of pain after exertion, especially at the medial side of
the epiphysial junctions, of being easily tired, and of incapacity for
any occupation involving standing. The bones are coarse and badly
formed, and there is frequently a spinous process projecting downwards
from the medial side of the tibia about three finger-breadths below
the joint.

When the deformity is bilateral, the patient abducts the thigh and
rotates the limb outwards at the hip to disguise the deformity, and to
allow the projecting knees to pass each other. He usually supinates or
inverts the foot, with the object of bringing the whole length of the
lateral border of the sole into contact with the ground. Flat-foot is
exceptional. The boots are usually more worn along the lateral than
along the medial border of the sole and heel.

No apparatus that allows of the patient walking is of any value. If
the deformity is marked, there should be no hesitation in having
recourse to operation by one or other of the various methods of
osteotomy.

In severe cases it may be found that when the deformity is corrected
by osteotomy, the patella shows a tendency to be dislocated laterally
on flexion of the knee. This may be prevented by putting up the limb
in the attitude of slight genu varum.

The most difficult cases to treat are those in which, owing to curving
of the lower part of the shaft of the femur with the convexity
forwards, the knee is permanently flexed and cannot be completely
extended.

#Other forms of genu valgum# are relatively rare. There is a
congenital form arising from faulty position of the limbs _in utero_;
a traumatic form following fracture or epiphysial separation in the
region of the knee; and a paralytic form, usually combined with
flexion, in cases of spastic paralysis. Finally, genu valgum may be a
result of various forms of osteomyelitis of the lower end of the
femur, or of disease in the knee-joint, such as tuberculosis,
arthritis deformans, or Charcot's disease.

#Genu Varum--Bow-knee.#--In this deformity, which is the converse of
genu valgum, the leg joins the thigh at an angle which is open
medially. It is almost invariably bilateral, is of rachitic origin,
and is frequently associated with bow-legs (Fig. 141). The tibia takes
a greater share in its production than the femur. Although an ungainly
deformity, it is much less frequently the source of complaint than
knock-knee, because it scarcely interferes with locomotion--as a
matter of fact, the subjects of bow-knee, although short in stature,
are unusually sturdy on their legs. An extreme example of the
deformity is shown in Fig. 141.

[Illustration: FIG. 141.--Bow-knee in Rickety Child.]

Treatment is carried out on the same lines as in genu valgum.

#Rickety Deformities of the Bones of the Leg--Bow-leg.#--These
deformities are common in children; are nearly always bilateral and
symmetrical, and may be associated with knock-knee or bow-knee. They
may occur before the child is able to walk, the bones bending in the
attitude in which the limbs are habitually placed--over the nurse's
knee, for example, or as they are crossed underneath the child in
sitting. In children who are able to walk, the curve is due to the
weight of the body acting on the softened bones. In either case, the
bending may be increased by the traction of muscles, and sometimes by
the occurrence of greenstick fracture. The most common deformity is a
uniform curvature of the bones laterally and forwards, or a more
acute bend in the lower thirds of their shafts. In some cases the
chief curvature is forwards. The ungainliness in walking may be added
to by flat-foot. Backward curving of the upper end of the tibia has
been already described as one of the causes of genu recurvatum. The
most extreme deformities are met with in rickety dwarfs.

_Treatment._--Under the age of six, and particularly in children, who
are actively growing, the bones will probably straighten if the child
is treated for rickets and kept off his feet; well-padded lateral
splints are applied as recommended for knock-knee, and these should be
taken off at intervals for massage and douching. Above the age of six,
the choice lies between osteoclasis and osteotomy. In performing
osteotomy the bone is either simply divided or a segment is resected.
The fibula can usually be forcibly straightened, but may require to be
divided through a separate incision. In aggravated cases it may also
be necessary to lengthen the tendo Achillis.

The deformities of the bones of the leg in _inherited syphilis_,
_ostitis deformans_, and _osteomalacia_ have already been described.

#Congenital Deficiencies of the Bones of the Leg.#--The _tibia_ may be
absent completely or in part, more often on one side than on both
sides. In either case the leg is short and stunted, the knee is
flexed, the foot occupies the position of extreme equino-varus, and
the limb is useless. The extent of the defects is demonstrated by the
Röntgen rays. Among other defects with which it may be associated,
absence or deficient development of the patella is the most frequent.
When the upper end of the tibia is absent, the fibula articulates with
the lateral condyle of the femur. The operative treatment aims at
correcting the flexion at the knee, the equino-varus deformity of the
foot, and at substituting the fibula for the absent tibia. The
deficiency of the upper end may be compensated for by implanting the
head of the fibula between the condyles of the femur, and that at the
lower end by splitting the fibula so as to form a socket for the
talus. Amputation should be avoided, as even a dwarfed leg and foot
improves the service of an artificial limb. A modification of the
O'Connor extension boot may be employed.

The _fibula_ may be absent completely or in part. The clinical
appearances depend upon the condition of the tibia. When the tibia is
normal, the most notable feature is the absence of the lateral
malleolus, and the extreme valgus attitude of the foot. More commonly
the tibia makes a sharp forward bend just below its middle, and the
overlying skin presents a dimple or scar-like depression. This has
usually been regarded as an evidence of intra-uterine fracture, but
the observations of Hoffa suggest that both the bend of the bone and
the depression on the skin are due to pressure exercised upon the leg
from without by an amniotic band or adhesion. The leg fails to grow,
the deformity becomes more pronounced, and the toes become pointed. If
the tibia is markedly bent, it may be straightened by osteotomy; and
the tendons, Achillis and peronei, may require to be lengthened. If
the ankle is unstable as a result of the absence of the lateral
malleolus, it may be artificially ankylosed, or the lower end of the
tibia may be split vertically so as to make a socket for the talus. In
either case, the foot is placed in the equinus attitude to compensate
for the shortening of the leg. Deficiency of the tibia is frequently
associated with imperfect development of the great toe; deficiency of
the fibula with absence of the lateral toes and their metatarsal
bones.

_Volkmann's Supra-malleolar Deformity._--This condition, which is
closely allied to that just described, consists in a congenital
deficiency in the development of the bones of the leg, and especially
of the fibula, as a result of which the articular surface is oblique
and the foot deviates to one or other side. The foot usually occupies
a valgus position, the sole looking laterally, and only its medial
border coming into contact with the ground. It is treated by
supra-malleolar osteotomy.

THE FOOT

Various deformities are met with in the region of the ankle and
tarsus. The term "talipes" is commonly used to include all these, but
here it will be restricted to that form in which the heel is more or
less elevated, and the foot supinated so that it rests on its lateral
border--_talipes equino-varus_. In _pes equinus_ the foot is in the
position of plantar-flexion, and the patient walks on the toes. In
_pes calcaneus_ the foot is dorsiflexed so that the tip of the heel
comes in contact with the ground; this deformity may be combined with
eversion of the foot, _pes calcaneo-valgus_, or with inversion, _pes
calcaneo-varus_. When the instep is unduly arched, the terms _pes
cavus_, _pes arcuatus_ or _hollow claw-foot_ are employed; while loss
of the arch constitutes _flat-foot_, and eversion of the sole, _pes
valgus_.

CLUB-FOOT

#Talipes Equino-varus.#--This deformity may be congenital or
acquired.

#Congenital talipes equino-varus# (Fig. 142) is a common malformation
which is sometimes associated with other deformities, such as hare-lip
or spina bifida, and may be met with in several members of one family.
It is nearly twice as common in boys as in girls, and is slightly more
frequently bilateral than unilateral. Its etiology is obscure, and
various hypotheses have been put forward to account for it, but no one
is convincing. It may be pointed out, however, that the fœtal foot is
very easily moulded into abnormal attitudes by external pressure such
as might be exercised by the wall of the uterus when the liquor amnii
is deficient. In a number of cases there are indications of such
pressure over the bony prominences of the foot, in the shape of
circumscribed scar-like areas in which the skin is atrophied; and in
the infant, the intra-uterine position can be reproduced, thus
demonstrating its method of origin. The occurrence of club-foot in
several generations is alleged to support the Mendelian law.

[Illustration: FIG. 142.--Bilateral Congenital Club-foot in an
infant.]

_Pathological Anatomy._--In well-marked cases the foot presents a
concavity towards the medial side, the maximum point of the curve
being opposite the mid-tarsal joint. When the patient attempts to
stand, only the lateral border of the foot touches the ground, and the
weight is borne on the fifth metatarsal, the cuboid, and the greater
process of the calcaneus.

[Illustration: FIG. 143.--Radiogram of Bilateral Congenital Club-foot
in an infant.]

The individual tarsal bones, especially the talus and calcaneus, are
altered in shape as well as in their relations to one another and to
the tibio-fibular socket. The navicular and cuboid are rotated
medially around the anterior ends of the talus and calcaneus
respectively, and the tubercle of the navicular comes to lie close to
the medial malleolus. The lower third of the tibia is twisted medially
on its vertical axis.

The changes in the soft parts follow the general law that tissues
which are relaxed become shortened, while those that are put on the
stretch are lengthened. All the tissues on the medial, concave side of
the foot are shortened, the structures most affected being the medial
and the posterior ligaments of the ankle, and the inferior
calcaneo-navicular ligament. There is also shortening of the muscles
inserted into the tendo Achillis, and to a less extent of the tibiales
anterior and posterior. The extensor tendons on the dorsum are
displaced medially.

_Clinical Features._--_In children who have not walked_, the degree of
deformity varies, sometimes being very slight; in pronounced cases,
the foot is turned medially, and in that position forms a right angle
with the leg; the sole looks backwards and the medial border upwards.
The foot appears shortened because it is curved on itself, the heel is
narrower and more vertical than normal, the medial malleolus is
obscured by the approximation of the navicular, and the lateral
malleolus is unduly prominent.

In extreme cases, the supinated foot forms an acute angle with the
leg, and there is frequently a deep transverse depression across the
sole, the result of contraction of the plantar fascia--a feature which
is distinctive of the congenital form of club-foot.

_In children who have walked_, the deformity becomes aggravated. The
dorsum of the foot is markedly uneven, partly because of the
prominence of the individual tarsal bones, and especially of the head
of the talus and greater process of the calcaneus, and partly because
of a depression over the neck of the talus. Instead of resting on its
lateral border, the foot may finally rest on the dorsum, the sole
looking upwards and backwards. While the skin over the heel remains
comparatively thin and delicate, that covering the lateral border and
dorsum of the foot becomes the seat of callosities, beneath which
adventitious bursæ are formed. These bursæ are liable to become
inflamed, and are then a source of great suffering, and if they
suppurate may cause persistent sinuses. The muscles of the leg and
foot, although not paralysed, undergo atrophy from disuse. In walking,
the patient lifts one foot over the other in an ungainly and laborious
manner, without any spring, as if walking on stilts.

_In adults_, these features are further aggravated, and there are
permanent changes in the bones (Fig. 144).

[Illustration: FIG. 144.--Congenital Talipes Equino-varus in a man æt.
24; seen from behind.]

_Treatment._--This should be commenced as soon as the viability of the
infant is beyond question, as the younger the patient the more easily
and completely is the deformity rectified. Manipulations to correct
the deformity should be carried out twice or thrice daily, and the
limbs are also massaged and douched. At the end of two or three
months, assistance may be derived from the use of a simple lateral
poroplastic or aluminium splint with a foot-piece, or more simply by a
strip of rubber plaster. The foot is held in the over-corrected
attitude and the plaster is applied so as to maintain this attitude.
If this regime is systematically persevered with from within a few
days after birth, by the time the child begins to walk the sole can be
brought into contact with the ground, and the weight of the body will
aid in correcting the deformity. If the equinus element resists
correction, the tendo Achillis should be lengthened.

The turning in of the toes may be overcome by strapping the feet at
night to a wooden board with the whole lower limb rotated laterally so
that the toes of each foot point directly outwards. On account of the
tendency towards relapse, the manipulations and massage must be
persevered with for at least a year.

_Tenotomy and Forcible Correction under Anæsthesia._--In more severe
cases we have to deal not only with the contracted soft parts, but
with changes in the bones resulting from their having grown in
adaptation to the deformed attitude. The majority of surgeons defer
operative measures until the child is about a year old.

The soft parts to be divided are the tendo Achillis, the medial and
posterior ligaments of the ankle, the plantar fascia, the
calcaneo-navicular ligaments, and the tibialis posterior tendon. The
varus deformity may then be corrected by laying the foot on its
lateral side on a padded triangular wooden block, and pressing
forcibly on the anterior and posterior ends of the foot so as to undo
the curve on its medial side and allow of abduction of the foot; this
is usually attended with cracking as the shortened ligaments give way.
The equinus element is next dealt with by forcibly dorsiflexing the
foot until the deformity is over-corrected. If it is preferred to
correct the deformity in stages instead of at one sitting, the equinus
element is left to the last. In older children, the strength of the
hands is usually insufficient to stretch the tissues, and mechanical
wrenches may be employed, such as those devised by Thomas, Bradford,
or Lorenz.

_Resection of a wedge from the tarsus_ (Davies Colley, 1876) is
reserved for the most severe cases in which the shape and rigidity of
the bones prevent correction of the deformity by any other means. The
base of the wedge is on the lateral aspect, and the bone removed
includes parts of the calcaneus, cuboid, talus, and navicular.

_Removal of the talus_ is an alternative operation to resection of the
tarsus, and may yield equally good results.

In children, before the tarsal bones have become completely ossified,
Ogston's method yields good results; instead of removing a wedge from
the tarsus, the osseous nucleus of each bone is gouged out, leaving
the cartilaginous shell. In this way the intertarsal joints are not
interfered with, and the cartilaginous tarsus can be moulded so that
when ossification is completed the bones differ but little from the
normal.

After any of these operative procedures, manipulations, massage,
exercises, electrical stimulation of the muscles, and the wearing of
some apparatus must be persevered with for at least twelve months.
Failures are due to not sufficiently over-correcting the deformity in
the first instance, and to neglect of after-treatment; in hospital
practice it is difficult to ensure continuous supervision over long
periods.

Finally, _amputation_ may be called for when other methods have
failed, and the patient is unable to put the foot to the ground
because of suppurating bursæ and ulceration of the skin.

#Acquired Talipes Equino-varus.#--In the great majority of cases this
condition results from anterior poliomyelitis. It especially affects
the peronei and the extensors of the toes, and is unilateral. The
patient is unable to dorsiflex and abduct the foot, which hangs with
the toes pointed and the sole turned medially.

At first the joints are flaccid, and the attitude can easily be
corrected by manipulation. In course of time, however, the opposing
muscles--those inserted into the tendo Achillis, the tibialis
posterior, and the long flexors of the toes--become shortened, and
there is secondary contraction of the plantar fascia and of the
ligaments on the medial side of the foot, and the deformity is thus
rendered permanent. The bones also are altered in their shape and
mutual relations, the talus being rotated forwards so that a large
portion of its trochlear surface protrudes from the tibio-fibular
socket. The skin is cold and livid, and readily suffers from pressure
sores. The whole limb is ill-developed, and may be shorter than its
fellow, and the paralysed muscles are wasted and exhibit for a time
the reaction of degeneration.

A similar deformity may result from section of the peroneal (external
popliteal) nerve, from the peroneal form of progressive muscular
atrophy, and from peripheral neuritis.

The _treatment_ of paralytic equino-varus, short of operation, has
been referred to under anterior poliomyelitis (p. 242). If tendon
transplantation is indicated, the tendon of the tibialis anterior is
attached to the cuboid, and a strip of the tendo Achillis to the
dorsal aspect of the tarsus. Jones displaces the tibialis anterior
into the base of the fifth metatarsal.

If the paralysis is widely distributed, and the joints are flail-like,
it is better to ankylose the ankle and mid-tarsal joints. It may be
necessary to divide in several places the plantar fascia and other
structures that have undergone secondary shortening.

As using the limb hastens the restoration of function, the child
should be got on to his feet as soon as possible.

The spastic form of talipes equino-varus is comparatively rare. The
plantar flexors and invertors distort the foot into the equino-varus
attitude. The heel is drawn up, the anterior part of the foot is
adducted and inverted at the mid-tarsal joint. The muscles are tense
and rigid, and the reflexes exaggerated. The condition is frequently
bilateral, and is often associated with other deformities of the lower
limb and with a characteristic spastic gait. Considerable improvement
may be brought about by lengthening the tendons of the shortened
muscles. In severe cases it may be necessary to resect a portion of
the tarsus.

The occurrence of #varus without equinus# is so exceptional as not to
call for separate description.

#Pes Equinus.#--This deformity, in which the foot is in the position
of plantar-flexion with the heel drawn up and the toes pointed, is
nearly always acquired as a result either of poliomyelitis or of
spastic paralysis. In typical cases the patient walks on the balls of
the toes (Fig. 145). It is seldom met with as a congenital condition.
Occasionally it is due to nerve lesions such as peripheral neuritis,
or to injuries and diseases in the region of the ankle, when the foot
has been allowed to remain for long periods in the attitude of
plantar-flexion. In a limited number of cases the equinus attitude is
assumed to compensate for shortening of the limb.

[Illustration: FIG. 145.--Bilateral Pes Equinus in a boy æt. 7, the
result of Spastic Paralysis.]

In _poliomyelitis_ the deformity is most often unilateral (Fig. 146),
while in _spastic paralysis_ it is frequently bilateral (Fig. 145),
and is usually accompanied by excessive arching of the foot--pes
cavus--as a result of plantar-flexion at the mid-tarsal joint, and
hyper-extension of the first phalanges and plantar-flexion of the
second and third phalanges of the toes--"clawing of the toes."

[Illustration: FIG. 146.--Extreme form of Pes Equinus in a girl æt. 8,
the result of Anterior Poliomyelitis.]

_Clinical Features._--In the mildest cases the patient is able to
bring the foot to a right angle. In average cases the heel is raised
off the ground, and the foot rests on the balls of the toes. In
extreme cases, and especially when the extensors are completely
paralysed, the toes may be flexed towards the sole, and the weight is
borne on the dorsum of the foot (Fig. 146). The patient suffers from
painful corns and callosities, and from inflammation of bursæ which
form over the points of pressure. When unilateral, the patient
compensates for the lengthening of the limb by flexing the knee and
throwing the limb outwards in walking. In severe cases, especially
when both limbs are affected, the patient may be dependent on
crutches.

The talus projects on the dorsum, the anterior part of its trochlear
surface escapes from the tibio-fibular socket, and the calcaneus is
drawn up so that it comes into contact with the bones of the leg (Fig.
147).

[Illustration: FIG. 147.--Skeleton of Foot from case of Pes Equinus
due to Poliomyelitis.]

Shortening of the soft parts affects chiefly the muscles inserted into
the tendo Achillis, the posterior ligament, and posterior parts of the
lateral ligaments of the ankle. The fasciæ, ligaments, and muscles of
the sole of the foot are also shortened. The flexors of the toes, the
tibialis posterior, and the peroneus longus are shortened to a less
degree.

_Treatment._--Of all the deformities of the foot, pes equinus is that
most easily rectified. In recent cases a great deal may be done by
regular manipulations, and by the wearing of some corrective splint or
apparatus between times.

In well-marked cases it is necessary to lengthen the shortened
structures, and especially the tendo Achillis. When the equinus is
corrected, the excessive arching of the foot (pes cavus) and the
clawing of the toes usually disappear, but it may be necessary to
lengthen the flexor tendons, especially that of the great toe, and
also the plantar fascia.

Jones divides the tendo Achillis and the flexors of the toes
subcutaneously, and maintains the dorsiflexion by excising an oval
flap of skin from the front of the ankle.

In aggravated cases, the bones must be attacked, for example by
excising the talus. Arthrodesis of the ankle alone or along with the
mid-tarsal joint may be indicated when these joints are flail-like.
Amputation is reserved for cases which are otherwise hopeless, such as
that shown in Fig. 147.

When the deformity is compensatory to shortening of the limb, it is
usually said to be a mistake to correct the equinus. Experience shows,
however, that in young patients growth is stimulated by walking on the
limb after the deformity has been corrected; the sole of the boot is
then raised to the necessary extent.

#Pes Calcaneus.#--In this deformity the foot is dorsiflexed at the
ankle-joint. It is sometimes combined with eversion of the foot--_pes
calcaneo-valgus_, or with inversion--_pes calcaneo-varus_.

Pes calcaneus may be congenital or acquired. In the _congenital form_
the deformity is frequently bilateral. There is dorsiflexion at the
ankle-joint, and if an attempt is made to flex the foot towards the
sole, the extensor tendons stand out prominently. In marked cases the
long axis of the calcaneus is vertical, the tendo Achillis lies in
close contact with the tibia, and the hollows on either side of the
tendon are absent. The peronei are displaced from their grooves, and
may lie in front of the lateral malleolus.

Corrective manipulations are commenced within a few days after birth,
and a malleable splint is worn between times. When the child begins to
walk there is a natural tendency towards recovery. In severe cases it
may be necessary to lengthen the contracted tendons--the extensor
digitorum, the extensor hallucis, and, it may be also, the peroneus
tertius and tibialis anterior; the tendo Achillis may require to be
shortened.

In the _acquired form_, the appearances are different, because the
anterior part of the foot is usually flexed towards the sole, thus
disguising to a certain extent the dorsiflexion at the ankle. This
form is nearly always due to poliomyelitis, but it may also result
from accidental division of the tendo Achillis. The anterior part of
the foot is flexed towards the sole by the contraction of the plantar
fascia and short muscles of the sole, the balls of the toes are
approximated to the heel, and a deep transverse groove is formed in
the sole opposite the mid-tarsal joint. The deformity presents a
combination of the hollow foot--pes cavus--with pes calcaneus, and
resembles that of a Chinese lady's foot. The foot rests on the heel
and on the balls of the great and little toes, the sole of the foot
being so deeply hollowed that even the lateral border does not touch
the ground.

In paralysis of the calf muscles alone, the tendons of the peronei or
flexor digitorum longus may be divided and stitched to the calcaneus,
to take the place of the tendo Achillis. If the calf muscles are not
completely paralysed and the tendo Achillis is merely stretched, this
tendon may be shortened by splitting it longitudinally and making the
ends overlap, or its insertion may be displaced downwards. When the
ankle is flail-like, it may be necessary to perform arthrodesis.

Jones gets rid of the cavus deformity by resecting a wedge with its
base towards the dorsum from the middle of the tarsus; the foot is
then placed in a position of extreme calcaneus, the dorsum coming into
contact with the front of the leg. Four weeks later a wedge is taken
from the posterior part of the talus large enough to bring the foot
down to a right angle with the leg; the articular surfaces of the
tibia and fibula being denuded of cartilage, ankylosis takes place in
a good position.

#Pes Calcaneo-valgus.#--This deformity, which consists in a
combination of dorsiflexion at the ankle and eversion of the foot, is
as common as pure calcaneus (Figs. 148 and 149); the heel is
depressed, the sole looks laterally, and its medial border is convex.
Although it may be congenital, it is usually acquired as a result of
poliomyelitis. The calf muscles are paralysed while the peronei retain
their power, and, along with the tibialis anterior and the extensors
of the toes, become secondarily contracted. Treatment is conducted on
the same lines as in pes calcaneus, and the valgus may be controlled
by implanting the peroneus brevis into the navicular.

[Illustration: FIG. 148.--Pes Calcaneo-valgus with excessive arching
of foot.]

[Illustration: FIG. 149.--Pes Calcaneo-valgus, the result of
Poliomyelitis.]

#Pes Calcaneo-varus.#--In this rare deformity the heel is depressed
and the sole of the foot looks inwards.

#Pes Cavus.#--In this deformity, which is known also as _hollow
claw-foot_, _pes arcuatus_, or _pes excavatus_, the longitudinal arch
of the foot is exaggerated as a result of the approximation of the
balls of the toes to the heel (Fig. 150). It is most frequently met
with as an addition to pes equinus or pes calcaneus of paralytic
origin, and has already been described. There is a mild form which is
congenital, and which is quite independent of paralysis; another
variety occurs in diseases of the spinal cord, such as Friedreich's
ataxia.

The name hollow claw-foot appropriately indicates the clinical
appearances. The arch is exaggerated and the instep abnormally high;
there is hyper-extension of the toes at the metatarso-phalangeal
joints, and plantar-flexion at the inter-phalangeal joints; the
plantar fascia and muscles are shortened. The footprint shows that
neither border of the foot touches the ground. The patient complains
of pain in the instep, of painful corns over the heads of the
metatarsal bones, and of difficulty in getting properly fitting
boots.

_Treatment_ should first be directed towards the equinus or calcaneus
element of the deformity, for if these are corrected the cavus
condition tends to disappear. Exercises and massage should be
persevered with, and boots without heels should be worn. The
contracted structures in the sole may require to be divided, either
subcutaneously or by the open method, as a preliminary to forcible
correction, and the hallucis tendon may be brought through the head of
the first metatarsal. In aggravated cases the talus and the heads of
the metatarsal bones may be excised.

FLAT-FOOT--PES PLANUS AND PES VALGUS

Flat-foot or splay-foot is that deformity in which there is loss of
the arch, and the foot tends to be pronated and abducted. The term
_pes planus_ is applicable when there is merely loss of the arch; _pes
valgus_ when the foot is pronated and the sole looks laterally. Of all
deformities of the foot, flat-foot is the one for which advice is most
frequently sought; it is also a common complication of other
disabilities of the foot and of the lower extremity. It is usually
bilateral, and is about twice as common in the male as in the female.
Various types are met with; they are known according to their cause,
as static, congenital, traumatic, paralytic, rachitic, rheumatic,
arthritic, gonorrhœal, and tabetic.

[Illustration: FIG. 150.--Pes Cavus in association with Pes Equinus,
the result of Poliomyelitis.]

[Illustration: FIG. 151.--Radiogram of Foot of adult, showing the
changes in the bones in Pes Cavus.]

#Static or Adolescent Flat-foot.#--This, by far the most common and
important variety (Fig. 152), generally develops between the ages of
fourteen and twenty. It is called static because the essential factor
in its production is a disproportion between the weight of the body
and the supporting power of the arch of the foot.

[Illustration: FIG. 152.--Adolescent Flat-foot.]

It is met with in rapidly growing children or adolescents of feeble
muscular development and with long narrow feet, and those especially
who, after leaving school, begin some occupation which entails much
standing--such as that of a factory hand, message boy, or domestic
servant. To enable him to stand with the least effort for long
periods, the patient adopts an attitude which makes little demand on
the muscles, and throws nearly all the strain of the body weight on
the ligaments and bones of the feet. This, which has been called "the
attitude of rest," consists in standing with the limbs apart, the
knees slightly flexed, the legs slightly rotated laterally at the
knee, and the feet pronated, with the toes pointing laterally. The
most important local factors predisposing to flat-foot are weakness of
those muscles which normally support the ankle and the tarsal arches,
especially the tibiales; weakness of the ligaments of the foot; and
softness of the tarsal bones. When these conditions are present and a
faulty method of standing and walking is adopted, the undue strain to
which the tendons and ligaments are exposed results in their being
stretched; the bones are altered in position, and flat-foot results.
The head of the talus is displaced medially, and is protruded between
the calcaneus and navicular, tending to separate them from one
another, stretching the inferior calcaneo-navicular ligament and
causing the anterior part of the foot to be abducted. The plantar
ligaments--especially the inferior calcaneo-navicular--are stretched
and lengthened. In something like 80 per cent. there is the combined
deformity--pes plano-valgus--in those who apply for treatment.

[Illustration: FIG. 153.--Flat-foot, showing loss of arch.]

_Clinical Features._--The patient complains of being easily tired, and
of pain in the foot after walking or standing. There is generally more
pain before the appearance of the deformity than when it has
developed, and at this stage it is not so easily recognised, and is
apt to be called "rheumatism." The most common seat of pain is at the
medial border of the foot behind the tubercle of the navicular, and
this is due to stretching of the inferior calcaneo-navicular ligament.
Pain is also complained of in the middle of the dorsum across the
instep, from stretching of the interosseous ligaments. Later, there is
pain over the greater process of the calcaneus in front of the lateral
malleolus, from these bones coming into contact. There may be
nocturnal cramp in the muscles of the leg and foot.

The faulty attitude of the foot in standing and walking is usually
evident. The foot appears longer and broader than normal, and when the
body weight is put on it, it spreads out with the toes extended until
the entire sole is in contact with the ground. In advanced cases, the
medial border of the foot may be actually convex. Below and in front
of the prominent medial malleolus, the head of the talus forms a
rounded eminence, and a little farther forwards and lower still is the
projection of the tubercle of the navicular. The eversion of the foot
as a whole is best seen from behind; if the central axis of the leg is
prolonged downwards, it approaches the medial border of the heel
instead of passing through its centre; or, stated differently, instead
of the axis of the calcaneus being a continuation of that of the leg,
it deviates laterally and the medial malleolus is abnormally
prominent. When the eversion is more pronounced, the sole looks
laterally and the tendons of the peronei stand out in relief. The
anterior part of the foot is displaced laterally. Flat-foot is
frequently associated with stiff great toe; the patient having lost
the power of dorsiflexing the toe, the first phalanx and first
metatarsal are in a straight line, instead of forming an angle open
towards the dorsum.

The muscles of the leg are flabby and poorly developed. When the
patient is seated and asked to move the foot in different directions,
there is a characteristic stiffness, ungainliness, and restriction in
the range of movement. The feet are usually cold and sweat
excessively. The gait is slouching, and there is a want of spring and
elasticity. The lengthening of the foot results in the tendons,
especially the flexors, being too short, hence hammer-like contraction
of the toes may be brought about. The boots, after being worn, show a
bulging of the instep towards the sole, greater wearing away of the
sole along the medial border, and, when there is stiff great toe, an
absence of the transverse crease on the dorsum opposite the balls of
the toes. Footprints may be obtained by wetting the soles of the feet.
The print of a normal foot shows only the heel, the lateral border of
the foot, and the balls and tips of the toes. In flat-foot the medial
border appears in the print to a greater or less extent (Fig. 154). If
a record is wanted to estimate the progress of treatment, the sole of
the foot is painted with a 5 per cent. solution of ferro-cyanide of
potassium, and the patient stands on paper painted with the liquor of
the perchloride of iron diluted one-half; the print appears dark blue
on a yellow ground.

[Illustration: FIG. 154.--Imprint of Normal and of Flat Foot.]

_Skiagrams_ are useful for showing displacement of bones and
differences between sitting and standing, and for recording the
results of treatment.

_Prophylaxis of Flat-foot._--Stress is to be laid on a supervised
training of the whole muscular system, and especially of that of the
legs. In walking and standing, the feet should be kept parallel and
not pointed outwards, as was formally taught in schools of gymnastics
and insisted upon by drill instructors. Children should be taught to
walk properly, rising on the balls of the toes with each foot in
succession. Attention should also be directed to the boots, which
should be so fashioned that the medial side of the boot is kept
straight and the end of the boot is opposite the big toe.

_Treatment._--This is directed towards restoring and maintaining the
arch of the foot. As the measures adopted necessarily vary with the
extent to which the condition has progressed, it is convenient for
purposes of treatment to recognise the following four degrees. A first
degree, in which the arch reappears when the weight is taken off the
foot or the patient rises on the balls of the toes; a second, in which
the normal attitude can be restored by manipulation; a third, in which
this is only possible under anæsthesia; a fourth, in which the bones
are so displaced and altered in shape that correction is impossible
without operation.

_Cases of the First Degree._--If there is marked pain and tenderness,
the patient must lie up. The general health is improved by a
nourishing diet and by cod-liver oil and tonics; and the legs and feet
are douched and massaged thrice daily. When pain and tenderness have
disappeared, the patient is instructed how to walk and exercise the
feet. In walking, the medial edges of the feet should be parallel with
one another, first the heel should touch the ground and then the balls
of the toes. He should neither stand nor walk long enough to cause
fatigue, and in standing he should alter the attitude of the feet from
time to time, and occasionally rise on the balls of the toes. The
following exercises, devised by Ellis of Gloucester, should be
practised: (1) Rising on the balls of the toes, the toes being
directed straight forwards; (2) rising on the balls of the toes, with
the points of the great toes touching each other, and the heels
directed out, so that the medial borders of the feet meet in front at
a right angle; (3) in the same attitude, after rising on to the balls
of the toes, the knees are flexed and then extended before the heels
descend again; (4) while seated in a chair, one leg crossed over the
other, circumduction movements of the foot are carried out; (5) while
standing, the medial border of the foot is raised off the ground
several times, then the patient walks to and fro on the lateral border
of the foot, and in the same attitude lifts one foot over the other.
These exercises should be carried out slowly and deliberately, with
the feet bare, and they should be carefully supervised until the
patient thoroughly understands what is aimed at. The movements should
be performed a definite number of times at regular intervals, but
should not be pushed so as to cause pain or fatigue. The patient
should be fitted with well-made lacing boots, with the heel and sole
raised about half an inch on the medial side so that the foot rests
mainly on its lateral border. The additional leather, which can be
applied by any bootmaker, is in the form of a wedge, with its base to
the medial side, one on the sole and one on the heel. The wedge fades
away towards the lateral border, and also forwards towards the tip. In
time, the limbs are further strengthened by sea-bathing, cycling,
skipping, and other exercises.

In _cases of the second degree_, the patient should be provided with a
metal plate inside the boot. That known as Whitman's spring is the
most popular. A plaster cast is taken of the sole while the foot is
held in its proper position, and on this a metal plate, preferably of
aluminium bronze, is modelled. This is covered with leather and
inserted into the boot. We have found the supports devised by Scholl
simple and efficient. The treatment described for cases of the first
degree is carried out in addition.

In _cases of the third degree_, the deformity is corrected under an
anæsthetic. The foot is forcibly moved in all directions so as to
stretch the shortened ligaments and to break down adhesions, it is
then rotated into an extreme varus position, and fixed in
plaster-of-Paris or to a Dupuytren's splint. It may be necessary to
have recourse to the Thomas' wrench, employed in the correction of
club-foot. When the reaction consequent upon this procedure has
subsided, the question of shortening or of reinforcing the tendons
concerned in the support of the arch of the foot may be considered;
one of the peronei, for example, may be attached to the tubercle of
the navicular. We have not found it necessary to employ this
procedure.

In _cases of the fourth degree_, in which the displacement and
alterations in shape of the bones constitute an insuperable bar to
correction, operative treatment may be considered, either resection of
a wedge including the talo-navicular joint or forward displacement of
the tuberosity of the calcaneus.

#Spasmodic Flat-foot.#--There are cases of flat-foot in which pain and
spasm of the peronei muscles are the predominant features. If the
spasm is not allayed by rest in bed and hot fomentations, the foot
should be inverted under an anæsthetic; and in this position it is
encased in plaster-of-Paris. Jones resects an inch of each of the
peroneal tendons about 2-1/2 inches above the tip of the lateral
malleolus; Armour and Dunn claim to have obtained better results from
crushing the peroneal nerve in the substance of the peroneus longus.

#Paralytic Flat-foot# (Fig. 155).--In typical cases this results from
poliomyelitis affecting the tibial muscles. When other groups of
muscles are affected at the same time, compound deformities, such as
pes calcaneo-valgus, are more likely to result.

[Illustration: FIG. 155.--Bilateral Pes Valgus and Hallux Valgus in a
girl æt. 15, the result of Anterior Poliomyelitis.]

In paralytic valgus the medial border of the foot is depressed and
convex towards the sole, and although the foot can readily be restored
to the normal position by manipulation, it at once resumes the valgus
attitude. The leg is wasted, the skin is cold and livid, and the ankle
is flail-like. The treatment consists in reinforcing the paralysed
tibial muscles by attaching the peronei, or a strip of the tendo
Achillis, to the scaphoid, or in bringing about an ankylosis of the
joints above and in front of the talus.

#Traumatic flat-foot# is that form which results directly from injury.
It is most often due to a fall from a height on to the feet; the
ligaments supporting the arch are ruptured, and the bones are
displaced, either at the time of the injury or later when the patient
gets out of bed. The arch can only be restored by a wedge-resection of
the tarsus. Loss of the arch may follow as a result of walking on the
everted foot after injuries about the ankle, especially a badly united
Pott's fracture; the foot may be displaced laterally and pronated, the
sole looking laterally. This variety is very unsightly and disabling;
it is treated by supra-malleolar osteotomy of the tibia and fibula.

#Other Forms of Flat-foot.#--Flat-foot is sometimes met with in
rickety children, in association with knock-knee or curvature of the
bones of the leg, and is treated on the same lines as other rickety
deformities. It may follow upon an attack of acute rheumatism or upon
diseases in the region of the ankle and tarsus, such as gonorrhœa,
arthritis deformans, tuberculosis, and Charcot's disease; the
gonorrhœal flat-foot is extremely resistant to treatment. There is a
congenital form in which the sole is convex and the dorsum concave,
the result of the persistence of an abnormal attitude of the fœtus _in
utero_. Lastly, there is a racial variety, chiefly met with in the
negro and in Jews, which is inherited and developmental, and which,
although unsightly, is rarely a cause of disability.

#Pes Transverso-planus.#--Lange describes under this head a sinking or
flattening of the anterior arch formed by the heads of the metatarsal
bones, of which normally only the heads of the first and fifth rest on
the ground. In this condition all may be on the same level or the arch
is actually convex towards the sole. It may coexist along with the
common form of flat-foot, or it may be associated with the neuralgic
pain known as metatarsalgia.

#Painful Affections of the Heel.#--These include inflammation of the
bursa between the posterior aspect of the calcaneus and the lower end
of the tendo Achillis, inflammation of the tendon itself and its
sheath of cellular tissue, and the presence of a spur of bone
projecting from the plantar aspect of the tuberosity of the calcaneus.
The spur of bone is the source of considerable pain on standing and
walking, and tenderness is elicited on making pressure on the plantar
aspect of the heel; it is well demonstrated by the X-rays (Fig. 156).
The condition is usually bilateral. Complete relief is obtained by
removing the spur by operation.

Sever of Boston calls attention to a painful condition of the heel met
with in children, and associated with changes in the epiphysial
junction, allied to those met with in the epiphysis of the tubercle of
the tibia in Schlatter's disease. The changes in the epiphysial
junction can be demonstrated in skiagrams. Treatment is conducted on
the same lines as in teno-synovitis of the tendo Achillis.

#Metatarsalgia.#--This affection, which was first described by Morton
of Philadelphia (1876), is a neuralgia on the area of the anterior
metatarsal arch, specially located in the region of the heads of the
third and fourth metatarsal bones. It is most often met with in adults
between thirty and forty, is commoner in women than in men, and is
often combined with flat-foot. The patient complains of a dull aching
or of intense cramp-like pain in the anterior part of the foot. The
pain is usually relieved by rest and by taking off the boot. It may be
excited by pressing the heads of the metatarsals together or by
grasping the fourth metatarso-phalangeal joint between the finger and
thumb. In advanced cases the pain may be so severe as to cripple the
patient, so that she is obliged to use a crutch. On examination, the
sole may be found to be broadened across the balls of the toes, and
there may be corns over the heads of the third and fourth metatarsals.
Skiagrams may show a downward displacement of the head of one or other
of these bones, and prints of the foot may show an increased area of
contact in the region of the balls of the toes. The affection is of
insidious development, and is usually ascribed to sinking of the
transverse arch of the foot--pes transverso-planus--the result of
weakness or of wearing badly fitting boots. The intense pain is
believed to be due to stretching of, or pressure upon, the
interdigital nerves or the communicating branch between the medial and
lateral plantar nerves; Whitman believes it is due to abnormal side
pressure on the depressed articulations.

[Illustration: FIG. 156.--Radiogram of Spur on under aspect of
Calcaneus.]

_Treatment._--Great improvement usually results from treating
coexisting flat-foot, and pain is relieved by rest, massage, and
douching. A tight bandage or strip of plaster applied round the
instep before putting on the stocking may relieve pain. Boots should
be made from a plaster cast of the foot, high and narrow at the instep
so as to compress the bases of the metatarsals, and with the medial
edge of the sole and heel slightly raised; a support may be worn in
the sole, like that used for flat-foot, with both the longitudinal and
transverse arches exaggerated. Scholl has devised a support for the
anterior arch which we have used with benefit. When the head of one of
the metatarsals is displaced, it may be removed through a dorsal
incision running parallel with the tendon of the long extensor.

#Hallux Valgus and Bunion.#--_Hallux valgus_ is that deformity in
which the great toe deviates towards the middle line of the foot and
comes to lie on the top of, or beneath, the second toe (Figs. 155,
157). The head of the first metatarsal projects on the medial border
of the foot, and, as a result of the pressure of the boot, an
adventitious bursa is formed, which, when thickened by chronic
inflammation, constitutes a prominent swelling or _bunion_. It is a
common affection in civilised and especially in urban communities, and
reaches its acme of development in adult women. It may occur on one or
on both sides, and is sometimes associated with flat-foot.

[Illustration: FIG. 157.--Radiogram of Hallux Valgus. The sesamoid
bone is seen displaced towards middle line of the foot.]

The deformity develops slowly, and is usually attributed to the
wearing of stockings which are unduly tight at the toes, and of
improperly made boots. The boot that favours the occurrence of hallux
valgus is one which is too short and has pointed toes, with the apex
in the middle line of the foot instead of being in line with the great
toe. The pressure of the boot displaces the great toe into the valgus
position, especially if a high heel is worn, as the toes are then
driven forward into the apex of the boot. Once the great toe is
abducted by the pressure of the boot, the deformity is increased by
bearing unduly on the medial side of the ball of the great toe, and by
pointing the foot outwards in walking.

Arthritis deformans is rarely the cause of hallux valgus, but the
changes characteristic of that affection are commonly present in the
joint of the great toe. In pronounced cases, the base of the first
phalanx is displaced on to the lateral aspect of the head of the first
metatarsal, the exposed head of which frequently shows fibrillation
and wearing away of the cartilage, and is often surrounded by new
bone, sometimes amounting to an exostosis. There are also fringes from
the synovial membrane that may be caught between the articular
surfaces. The distal end of the first metatarsal is displaced
medially, broadening the tread of the foot, and in severe cases its
shaft is rotated on its long axis, so that its dorsal surface looks
medially; the great toe is then similarly rotated (Fig. 157). The
flexor and extensor tendons and the sesamoid bones are displaced
laterally. The ligaments and other soft parts on the medial side are
elongated, while those on the lateral side are contracted.

In women, the chief complaint may be of the disfigurement of the boot;
in others, of pain and disability resulting from the sensitiveness of
the joint and of the enlarged bursa over the head of the first
metatarsal. The inflamed bursa, which sometimes communicates with the
joint, may suppurate, and the infection may spread to the joint.

The _treatment_ varies with the severity of the deformity. In mild
cases, a great deal can be done by wearing properly made boots and
stockings with a separate compartment for the great toe, or a pad of
cotton wool or tent of rubber between the great and second toes. The
patient should practise manipulations and exercises of the toes and
feet, and putting the foot to the ground properly in walking. In
pronounced cases, the pain and tenderness must first be got rid of by
rest and soothing applications. At night, the attitude of the toe may
be corrected by a moulded splint fixed to the medial aspect of the
foot by strips of plaster; the toe is then bandaged to the distal end
of the splint. Scholl has devised a prop, made of rubber, to be worn
between the great and second toes. If there is flat-foot, this must
receive appropriate treatment.

In aggravated cases, the deformity can only be corrected by an
operation which consists in resecting the head of the metatarsal bone,
and the tendon of the long extensor may be detached from its
insertion and secured to the medial side of the first phalanx. A bar
may be placed across the sole just behind the balls of the toes, and
the boot should also comply with the anatomical shape of the foot.

#Hallux Varus or Pigeon-toe# (Fig. 158).--In this deformity, which is
extremely rare, the great toe deviates from the middle line of the
foot; it occurs chiefly in children in conjunction with other
deformities, and interferes with the wearing of boots. Treatment
consists in straightening the toe and retaining it in position by a
splint or plaster of Paris. The medial collateral ligament and the
tendon of the abductor hallucis may require to be divided.

[Illustration: FIG. 158.--Radiogram of Hallux Varus or Pigeon-toe.]

#Hallux Rigidus and Hallux Flexus# (Fig. 159).--These terms indicate
two stages of an affection of the metatarso-phalangeal joint of the
great toe, first described by Davies Colley. In the earlier
stage--_hallux rigidus_--the toe is stiff and incapable of being
dorsiflexed, although plantar-flexion is, as a rule, but little
restricted. When the joint, in addition to being stiff, is painful,
sensitive, and swollen, the term _hallux dolorosus_ is applied.

[Illustration: FIG. 159.--Hallux Rigidus and Flexus in a boy æt. 17.
There is a suppurating corn over the head of the first metatarsal
bone.]

As the disease progresses, the toe is drawn towards the sole and
becomes permanently flexed--_hallux flexus_--and any attempt at
dorsiflexion is attended with pain.

The condition is met with chiefly in adolescent males, is nearly
always associated with flat-foot, and is then usually bilateral. The
patient's gait, in addition to having the characteristic features
associated with flat-foot, is peculiarly wooden and inelastic, as
instead of rising on the balls of the toes with each step, he puts
down and lifts the sole as if it were a rigid plate. The pain is
increased by walking. The boot tends to become worn away at the point
of the toes and at the posterior edge of the heel, and the usual
crease across the dorsum is absent.

On dissection it is found, especially in hallux flexus, that the
inferior portions of the collateral ligaments are contracted, and that
the cartilage of that part of the head of the metatarsal which is
exposed on the dorsum is converted into fibrous tissue; there may also
be other changes characteristic of arthritis deformans. Bony ankylosis
has not been observed.

_Treatment._--In early cases, great benefit results from measures
directed towards the cure of the accompanying flat-foot, and
especially the wearing of the support of the anterior arch devised by
Scholl. If the joint of the big toe is painful and sensitive, absolute
rest should be enforced until these symptoms have disappeared. The
patient must wear a properly shaped boot with a pliable sole, and be
instructed how to manipulate and exercise the toe. Later, when the toe
is already rigid or flexed towards the sole, the above treatment is
not feasible. It is then best to correct the deformity either by
wrenching the toe into the dorsiflexed position, under anæsthesia, and
fixing it with a plaster-of-Paris bandage; or, when this is
impossible, by excising the articular end of the metatarsal bone and
interposing a layer of fatty or bursal tissue between the distal end
of the metatarsal and the base of the first phalanx. When these
measures are impracticable, the suffering may be relieved by inserting
in the boot a rigid metal plate which will prevent any attempt at
dorsiflexion in walking.

#Hammer-toe.#--This is a flexion-contracture which generally involves
the second, but sometimes also other toes. It may be congenital and
inherited, but usually develops about puberty, and is then, as a rule,
bilateral, and often associated with flat-foot.

The first phalanx is dorsiflexed, and the second is plantar-flexed,
while the third varies in its attitude, sometimes being in line with
the second (Fig. 160), sometimes even more plantar-flexed, and
sometimes dorsiflexed. When the second toe alone is affected, as is
commonly the case, it is partly buried by those on either side of it,
only the knuckle of the first inter-phalangeal joint projecting above
the level of the other toes (Fig. 160). The skin over the head of the
first phalanx being pressed upon by the boot usually presents a corn,
under which a bursa forms (Fig. 161). Both the corn and the bursa are
subject to attacks of inflammation, which cause suffering and
disability in walking. The soft parts at the distal extremity of the
toe are flattened out by contact with the sole of the boot--hence the
supposed resemblance to the head of a hammer.

[Illustration: FIG. 160.--Hammer-toe.]

On dissection, it is found that the contracture is maintained by
shortening of the plantar portions of the collateral ligaments of the
first inter-phalangeal joint and of the glenoid ligament upon which
the head of the first phalanx rests.

Hammer-toe is usually ascribed to the use of tight socks and of
ill-fitting boots, especially those which are median-pointed and are
too short for the feet, but in some persons there appears to be an
inherited predisposition to the deformity.

[Illustration: FIG. 161.--Section of Hammer-toe.

    _a_, Corn.
    _b_, Bursa over first inter-phalangeal joint.]

While corrective manipulations, strapping, and the use of splints may
be of service in slight cases, it is usually necessary to perform an
operation in order to extend the toe permanently. Before operating,
any infective condition, such as a suppurating corn or bursa, must be
corrected. The collateral and glenoid ligaments are divided
subcutaneously--Spitzy also divides the flexor tendons and
capsule--and if the toe can then be straightened, the foot is secured
to a metal splint moulded to the sole and provided with longitudinal
slots opposite the intervals on either side of the toe affected. The
toe is drawn down to the splint by passing a loop of cotton or elastic
bandage round the toe and through the slots. In many cases the
contraction of all the tissues on the plantar aspect, including the
skin, prevents the toe being straightened even after division of the
ligaments, and it is then necessary to remove the head and neck of the
first phalanx through a lateral incision. This is more satisfactory
than amputation of the affected toe at the metatarso-phalangeal
joint, as after this the adjacent toes tend to fall together and
favour hallux valgus. If amputation is performed, a pad of cotton wool
or rubber prop should be worn to fill up the vacant space.

The term _Gampsodactyly_ has been applied to a deformity in which all
the toes assume the position of hammer-toe, usually from a spastic
condition of the muscles controlling the toes.

#Hypertrophy of the Toes.#--One or more of the toes may be the seat of
hypertrophy or local giantism. This is usually present at birth or
appears in early childhood, and may form part of an overgrowth
involving the entire lower extremity (Fig. 162). The overgrowth may
involve all the tissues equally, or the subcutaneous fat may be
specially affected. The medial toes are those most commonly
hypertrophied. In addition to being enlarged, the toe may be displaced
from its normal axis. The hypertrophy may affect two or more toes
which are fused together or webbed (Fig. 162). The treatment consists
in amputating as much of the toe as will allow of an ordinary boot
being worn.

[Illustration: FIG. 162.--Congenital Hypertrophy of Left Lower
Extremity in a boy æt. 5. The second and third toes are fused.]

#Supernumerary Toes# (_Polydactylism_).--These vary from mere
appendages of skin to fully developed toes (Fig. 163); if they
interfere with the wearing of boots they should be removed.

#Webbing of the Toes# (_Syndactylism_).--This may affect two or more
toes, which may be united merely by a web of skin, or so completely
fused that the individual digits are only indicated by the nails; the
degree of fusion is shown by means of skiagrams. Unless associated
with congenital hypertrophy, no treatment is called for.

[Illustration: FIG. 163.--Supernumerary Great Toe.

(Photograph lent by Sir George T. Beatson.)]

THE UPPER EXTREMITY

#Congenital Absence of the Clavicle.#--Both clavicles may be absent,
and it is possible for the patient voluntarily to bring his shoulders
into contact with one another in front of the chest; there is little
or no impairment of function.

#Displacements of the Scapula.#--_Congenital Elevation of the Scapula_
(Sprengel's shoulder, 1891).--This abnormality is rare, and is not
usually recognised till several years after birth. In one variety
there is a bridge of bone or fibrous tissue connecting the superior
angle of the scapula with the spinous process of one of the cervical
vertebræ, and there may be a false joint at one end of the bridge
permitting a certain amount of movement of the scapula. Associated
abnormalities in the vertebræ and in the ribs are shown in skiagrams.
In the more common type, the scapula seems to be held in its elevated
position by shortening of the muscles attached to its body, and it is
often rotated so that its lower angle is close to the spine and its
axillary border nearly horizontal, or the axillary border may lie in
close to the ribs, and the vertebral border project from the chest
wall. The shoulder is generally higher and farther forward on the
affected side, and there is a moderate degree of scoliosis. There is a
want of purchase in the movements of the shoulder and upper arm.

[Illustration: FIG. 164.--Congenital elevation of Left Scapula in a
girl: also shows hairy mole over Sacrum.

(Mr. D. M. Greig's case.)]

When the deformity is bilateral, which is rare, the neck is short and
thick, the chin lies close to the sternum, and the arms can scarcely
be raised to the horizontal.

Gymnastic exercises and the wearing of a brace to hold the shoulders
back and down may be followed by some improvement, but, as a rule, it
is necessary to mobilise the scapula by operation. An X-ray photograph
should first be taken, because, when the scapula is connected with the
spine by a bridge of bone, this must be resected. The muscles attached
to the vertebral border and spine of the scapula are divided, the
bone is drawn down to its proper position, and the parts are fixed by
plaster bandages.

_Winged Scapula._--This condition consists in a marked displacement
backwards of the lower angle and vertebral border of the scapula, when
the patient attempts to raise the arm from the side (Fig. 165). Under
normal conditions, in making this movement the serratus and rhomboid
muscles pull forward the vertebral border and inferior angle of the
scapula, and so fix the bone firmly against the chest wall. When these
muscles are paralysed, as a result of anterior poliomyelitis,
neuritis, or injury of the long thoracic nerve of Bell, or of the
fifth and sixth cervical nerve-roots through which they receive their
supply, the patient is unable to abduct the arm, and the deltoid
having lost its _point d'appui_, its contraction merely results in
tilting the angle of the scapula backward (Fig. 165).

[Illustration: FIG. 165.--Winged Scapula; the patient is holding the
arms out in front.]

_Treatment._--In the majority of recent cases the condition yields to
the administration of strychnin and other muscle and nerve tonics, and
the use of massage and the faradic current. The application of a
carefully adjusted padded belt is sometimes useful. The method of
treatment by stitching the latissimus dorsi over the lower angle of
the scapula is based on the erroneous assumption that the displacement
is due to the slipping of that muscle off the bone; at the same time,
it must be admitted that the operation sometimes diminishes the
deformity and adds to the patient's comfort.

A more efficient method consists in detaching the clavicular portion
of the pectoralis major from its insertion, and stitching it to the
serratus anterior so as to make it take on the function of this
muscle, or stitching it to the axillary border of the scapula. Success
has also followed suture of the vertebral border of the scapula to the
subjacent ribs (Eiselsberg).

_Displacement of the scapula upwards and laterally_ has been observed
as a result of partial paralysis of the trapezius when the nerves
supplying it have been divided in removing tuberculous glands from the
neck. In these acquired displacements, treatment is directed towards
the nerve lesion and towards the improvement of the muscles by
electricity, massage, and exercises; when the paralysis of the
trapezius is permanent, the disability is gradually overcome by the
compensatory hypertrophy of the levator muscle.

#Congenital Dislocation of the Shoulder.#--This rare condition is
usually bilateral, and is associated with other congenital defects.
The glenoid cavity is deformed or absent, and the dislocation may be
sub-coracoid, sub-acromial, or sub-spinous. The movements of the arm
are restricted, and the development of the extremity as a whole is
imperfect. It is sometimes possible to reduce the dislocation by
manipulation, or, if this fails, by operation. Unilateral dislocation
is sometimes mistaken for dislocation that has occurred during
delivery and _vice versa_.

#Habitual Dislocation# is described on p. 65.

#Paralytic Deformities--Paralytic Dislocation of the Shoulder.#--The
muscles in the region of the shoulder may have their innervation
interfered with as a result of various conditions, of which
poliomyelitis and injuries of the brachial plexus at birth are the
most important. The capsular ligament of the shoulder-joint, being no
longer kept tense by the scapular muscles--especially the deltoid and
lateral rotators--becomes relaxed, and is gradually stretched by the
weight of the arm. The appearances are characteristic; the muscles of
the shoulder are wasted, the acromion is prominent, and between it and
the upper end of the humerus there is a marked hollow into which one
or more fingers may be inserted. The arm hangs flaccid by the side,
rotated medially and pronated, and moves in a flail-like fashion in
all directions, the patient having little control over it. The best
results are obtained by the transplantation of muscles, the trapezius
being detached from the clavicle and stitched to the surface of the
deltoid, and the upper arm fixed in the position of horizontal
abduction with the arm rotated laterally and supinated. Bradford
inserts a portion of the trapezius into the humeral insertion of the
deltoid. When these methods are impracticable, the upper arm may be
fixed to the trunk by some form of apparatus, or arthrodesis is
performed so that the movements of the scapula are communicated to the
upper arm; the best attitude for ankylosis is one of abduction with
medial rotation, so that the hand can be brought to the mouth.

In cases of poliomyelitis, when all the muscles governing the elbow
are paralysed while the muscles of the hand have escaped, it may be of
great service to fix this joint permanently at rather less than a
right angle. This may be effected by arthrodesis, or by removing an
extensive diamond-shaped portion of skin from the flexor aspect of the
joint and bringing the raw surfaces together, commencing the stitching
at the lateral apices of the gap.

[Illustration: FIG. 166.--Arrested Growth and Wasting of Tissues of
Right Upper Extremity, the result of Anterior Poliomyelitis in
childhood.]

#Congenital Dislocations at the Elbow.#--_The head of the radius_ may
be dislocated forwards, backwards, or laterally--usually in
association with imperfect development of the radius and of the
lateral condyle of the humerus. When the displaced head of the bone
interferes with supination, or with extension, it should be removed.
Congenital dislocation of both bones of the forearm is extremely rare.

#Cubitus Valgus# and #Cubitus Varus#.--When the normal arm hangs by
the side with the palm of the hand directed forward, the forearm and
upper arm form an angle which is open outwards--known as the "carrying
angle"; it is usually more marked in women in association with the
greater breadth of the pelvis and the relative narrowness of the
shoulders. When this angle is increased, the attitude is described as
one of _cubitus valgus_. This deformity may be acquired as a result of
rickets, but more commonly it is due to fracture of the lateral
condyle of the humerus, in which the separated fragment has been
displaced upwards.

_Cubitus varus_ is the reverse of cubitus valgus. It is more common,
is always pathological, and is nearly always a result of fracture of
the lower end of the humerus or separation of the lower humeral
epiphysis and subsequent interference with growth. These deformities
may be corrected by supra-condylar osteotomy of the humerus.

[Illustration: FIG. 167.--Lower end of Humerus from case of Cubitus
Varus.]

#Synostosis of the superior radio-ulnar joint# is a rare congenital
condition, in which the hinge movements at the elbow are free, but
supination is impossible; an attempt may be made by operation to form
a new joint.

#Volkmann's ischæmic contracture# of the muscles of the forearm,
resulting in the production of claw-hand, is described in Volume I.,
p. 415.

#Deformities of the Forearm and Hand.#--The _radius_ may be absent
completely or in part, frequently in combination with other
malformations. The most evident result is a deviation of the hand to
the radial side--one variety of _club-hand_. The forearm is
shortened, the ulna thickened and often bent, and the thumb and its
metacarpal bone are often absent, so that the usefulness of the hand
and arm is greatly impaired (Fig. 171). For this condition Bardenheuer
devised an operation which consists in splitting the lower end of the
ulna longitudinally and inserting the proximal bones of the carpus
into the cleft.

Congenital deficiency of the _ulna_ is extremely rare.

#Intra-uterine amputation# by constriction of amniotic bands sometimes
occurs (Figs. 168, 169).

[Illustration: FIG. 168.--Intra-uterine Amputation of Forearm.]

[Illustration: FIG. 169.--Radiogram of Arm of patient shown in Fig.
168.]

#Drop Wrist from Anterior Poliomyelitis.#--In this condition the
capacity of extending the fingers is deficient or absent. Recovery can
be confidently predicted if, on still further flexing the fingers,
they can be voluntarily extended towards the point from which they are
flexed (Tubby and Jones). Considerable improvement may result from
fixing the hand by means of a splint in the attitude of dorsal
flexion. The splint is removed at frequent intervals to allow of
massage and other treatment being carried out, and it has usually to
be worn for a period of one to two years. In some cases recourse
should be had to arthrodesis.

[Illustration: FIG. 170.--Congenital absence of Left Radius and Tibia
in a child æt. 8.

(Mr. D. M. Greig's case.)]

In _spastic paralysis_ the most pronounced deformity is flexion of the
forearm and pronation and flexion of the hand (Fig. 166). Gradual
extension at the wrist may be brought about by the use of a malleable
splint, in which the angle is gradually increased, over a period of at
least twelve months. Failing success by this method, operation may be
had recourse to, and this consists in lengthening of tendons, and
tendon transplantation. Tubby has devised an operation for converting
the pronator radii teres into a supinator, and Robert Jones another in
which the flexors of the carpus are made to take the place of the
extensors. "These operations, combined if necessary with elongation of
the flexors of the fingers, pave the way for diminution of the angle
of flexion at the elbow, lessening of the pronator spasm, increase of
the supinating power, reduction of the carpal flexion, and addition to
the extensor power at the wrist" (Tubby and Jones).

#Congenital Club-hand.#--This rare deformity corresponds to congenital
club-foot, and probably arises in the same way. The hand and fingers
are rigidly flexed to the ulnar or radial side, so that the patient is
incapable of moving them. Treatment is carried out on the same lines
as for club-foot.

A deformity resembling this, _acquired club-hand_, is brought about
when the growth of either of the bones of the forearm has been
arrested as a result of disease or of traumatic separation of its
lower epiphysis. The hand deviates to the side on which the growth has
been arrested--_manus valga_ or _vara_. The treatment consists in
resecting a portion of the longer bone.

[Illustration: FIG. 171.--Club-hand, the result of imperfect
development of radius. The thumb is absent.

(Photograph lent by Sir George T. Beatson.)]

#Madelung's Deformity of the Wrist.#--In 1878, Madelung called
attention to a deformity also called sub-luxation of the hand, in
which the lower articular surface of the radius is rotated so that it
looks towards the palm; there is palmar displacement of the carpus,
and the lower end of the ulna projects on the dorsum. The cause of the
condition is obscure, but it is met with chiefly in young women with
slack ligaments, whose laborious occupation or athletic pursuits
subject the hand and wrist to long-continued or repeated strain. It is
as frequently unilateral as bilateral and may recur in successive
generations. There is a good deal of pain, the grasping power of the
hand is impaired, and dorsiflexion is considerably restricted. The
deformity disappears on forcible traction, but at once reappears when
the traction is removed. A wristlet of poroplastic or leather
extending from the mid-forearm to the knuckles is moulded to the limb
in the corrected position, and is taken off at intervals for massage
and exercises.

When _operative treatment_ is called for, it takes the form of
osteotomy of the radius and ulna about an inch or more above their
articular surfaces.

#Congenital dislocation of the wrist# is rare.

#Deformities of the Fingers.#--Various forms of _congenital
dislocation_ of the fingers are met with, but they are of little
clinical importance, as they interfere but slightly with the
usefulness of the digit affected.

_Congenital lateral deviation of the phalanges_ is more unsightly than
disabling; it is met with chiefly in the thumb, in which the terminal
phalanx deviates to the radial or to the ulnar side in extension; the
deviation disappears on flexion.

_Congenital contraction of the fingers_ is comparatively common. It is
an inherited deformity, and is often met with in several members of
the same family. It most frequently affects the little or the ring and
little fingers (Fig. 172), and is usually bilateral. The second and
third phalanges are flexed towards the palm; the first phalanx is
dorsiflexed, this being the reverse of what is observed in Dupuytren's
contraction. Duncan Fitzwilliams suggests that it should be called
"hook-finger," and that it is probably due to imperfect development of
the anterior ligament of the first inter-phalangeal joint. He has
observed it in association with laxity of the ligaments of the other
joints of the body.

[Illustration: FIG. 172.--Congenital Contraction of Ring and Little
Fingers.]

The affection is usually disregarded in infancy and childhood as being
of no importance. In young children, the deformity is corrected by
wearing a light splint fixed with strips of plaster, or a piece of
whalebone or steel inside the finger of a glove. In older children,
the finger may be straightened by subcutaneous division of the
ligament over the palmar aspect of the base of the middle phalanx, or
failing this by lengthening the flexor tendons and resecting a wedge
from the dorsal aspect of the first phalanx close to the
inter-phalangeal joint.

#Dupuytren's Contraction.#--This is an acquired deformity resulting
from contraction of the palmar fascia and its digital prolongations
(Fig. 173). It is rare in childhood and youth, but is common after
middle life, especially in men. It is often hereditary, and is said to
occur in those who are liable to gout and to arthritis deformans.
While it is met with in the working-classes and attributed to the
pressure of some hard object on the palm of the hand--such as a hammer
or shovel or whip--its greater frequency in those who do no manual
work, and the fact that it is very often bilateral, indicate that the
constitutional factor is the more important in its causation.

[Illustration: FIG. 173.--Dupuytren's Contraction.]

In the initial stage there is a localised induration in the palm
opposite the metacarpo-phalangeal joint, and the skin over it is
puckered and closely adherent to the underlying fascia. After a
variable interval, the finger is gradually and progressively flexed at
the metacarpo-phalangeal joint. The ring finger is usually the first
to be affected, less often the fifth, although both are commonly
involved. It is rarest of all in the index. The flexion may be
confined to the metacarpo-phalangeal joint, or the middle and distal
phalanges may also be flexed; and as the deformity becomes more
pronounced, the nail of the affected finger may come into contact with
the skin of the palm. Dissections show that the flexion of the finger
is the result of a chronic interstitial overgrowth or fibrositis and
subsequent contraction of the palmar fascia and of its prolongations
on to the sides of the fingers. The digital processes of the fascia
are thickened and shortened, and come to stand out like the string of
a bow. The adipose tissue in the skin of the palm disappears, and the
skin and fascia thus brought into contact become fused. The tendons
and their sheaths are not implicated; they are found lying deeply in
the concavity of the curve of the flexed digit. There is no pain, but
the grasp of the hand is interfered with, the patient is unable to
wear an ordinary glove, and he may be incapacitated from following his
occupation.

The condition is easily diagnosed from congenital contraction by the
fact that in the latter the proximal phalanx is dorsiflexed.

_Treatment._--When seen in the initial stage, contraction may be
prevented by passive movements of the finger and by massage of the
indurated fascia; we have observed cases in which these measures have
held the malady in check for many years, but when flexion has already
occurred, they are useless, and according to the social position,
habits, or occupation of the patient, the condition is left alone or
the deformity is corrected by operation.

Adam's operation consists in multiple subcutaneous division of the
contracted fascia in the palm and of its prolongations on to the
finger; in addition to dividing the fascia, the tenotomy knife should
be used also to separate the skin from the fascia. The finger is then
forcibly extended, and a well-padded splint secured to the hand and
forearm. The skin on the palmar aspect opposite the first
inter-phalangeal joint may give way when the finger is extended;
should this occur, the resulting gap may be covered by a skin graft.

After healing has occurred, massage and movements must be persevered
with, and a splint (Fig. 174) worn at night, as there is an inveterate
tendency to recurrence of the contraction. In view of this tendency
there is much to be said in favour of the radical operation which
consists in removal of the fascia by open dissection. Owing to the
long time required for healing and the sensitiveness of the scar, the
results of excision of the fascia are sometimes disappointing. Greig
has obtained good results by resecting the head of the metacarpal
bone. When the little finger is completely flexed towards the palm it
may be amputated, as it is always in the way.

[Illustration: FIG. 174.--Splint used after Operation for Dupuytren's
Contraction.]

#Supernumerary Fingers (Polydactylism).#--These may coexist with
supernumerary toes, and the condition is often met with in several
members of the same family. Sometimes the extra finger is represented
by a mere skin appendage, the nature of which may only be indicated by
the presence of a rudimentary nail; sometimes it contains bone
representing one or more phalanges, or it may be fully formed (Fig.
175). In the majority of cases the superfluous finger should be
removed.

[Illustration: FIG. 175.--Supernumerary Thumb.

(Photograph lent by Sir George T. Beatson.)]

#Congenital Deficiencies in the Number of Fingers.#--One or more
fingers may be absent, such deficiency being often associated with
imperfect development of the radius or ulna; or they may be
represented by short rounded stumps, which are ascribed to the
strangulation of the digits by amniotic bands _in utero_--the
so-called intra-uterine amputation.

#Webbing of Fingers (Syndactylism).#--Congenital webbing or fusion of
the fingers may be associated with polydactylism or with congenital
hypertrophy, and, like other digital deformities, may affect several
members of the same family. The degree of fusion ranges from a web of
skin joining the fingers to a fusion of the bones, the latter being
well seen in skiagrams. If an operation is decided upon, it should not
be performed until the age of five or six years. In the simplest cases
it is only necessary to divide the web and to unite the cut edges of
skin along each finger by sutures, a skin graft being inserted into
the angle between the fingers. An operation in which the skin is
dissected up in the form of flaps may be required, but it should not
be lightly entered upon, as in young children it has been known to be
followed by gangrene of one or more of the digits.

#Congenital Hypertrophy of the Fingers.#--This is a form of local
giantism affecting one or more digits, and involving all the tissues.
The finger is usually of abnormal size at birth, and continues to
grow more rapidly than the others, and it may also come to deviate
from its normal axis. Such a finger should be trimmed down or removed,
to permit of the use of the other digits.

#Trigger Finger# (Fig. 176).--This is an acquired condition in which
movement of a finger or thumb, either in flexion or extension, is
arrested, and is only completed with the assistance of the other hand.
The obstacle to movement is usually overcome with a jerk or snap
suggesting a resemblance to the trigger of a gun or the blade of a
clasp-knife. The commonest cause is a disproportion between the size
of the tendon and its sheath, such as may result from a localised
thickening of the tendon. Recovery usually takes place under massage
and passive movements. Failing this, the thickened portion of the
tendon is pared down to its normal size; if it is the sheath of the
tendon that is narrow, it is laid freely open.

[Illustration: FIG. 176.--Trigger Finger.

(Photograph lent by Sir George T. Beatson.)]

#Drop# or #mallet finger# is described on p. 121.

CHAPTER XI

THE SCALP

Surgical Anatomy--Injuries: _Contusion_; _Hæmatoma_;
    _Cephal-hæmatoma_; _Wounds_; _Avulsion_--Diseases: _Infective
    conditions_; Cystic and solid tumours; Air-containing swellings;
    Vascular tumours.

#Surgical Anatomy.#--The _skin_ of the scalp is intimately united to
the _epicranial aponeurosis_ by a network of firm fibrous tissue
containing some granular fat, and representing the subcutaneous
connective tissue. These three layers constitute the scalp proper, and
they are so closely connected as to form a single structure which can
be moved to a certain extent by the action of the epicranius muscle.
The epicranius (occipito-frontalis) muscle with its aponeurosis
extends from the superciliary ridge in front to the superior nuchal
(curved) line of the occipital bone behind, and laterally to the level
of the zygoma where it blends with the temporal fascia. Between the
scalp proper and the _pericranium_ is a quantity of loose areolar
tissue, in the meshes of which extravasated blood or inflammatory
products can rapidly spread over a wide area. Blood extravasated under
the pericranium is limited by the attachments of this membrane at the
sutures.

The _blood supply_ of the frontal region is derived from the internal
carotid arteries through their supra-orbital branches; the remainder
of the scalp is supplied from the external carotids through their
temporal, posterior auricular and occipital branches. The vessels,
which run in the subcutaneous tissue, superficial to the epicranial
aponeurosis, anastomose freely with one another and across the middle
line. The main branches run towards the vertex, and incisions should,
as far as possible, be directed parallel with them.

The _venous return_ is through the frontal, temporal, and occipital
veins. These have free communications, through the _emissary veins_,
with the intra-cranial sinuses, and by these routes infective
conditions of the scalp may readily be transmitted to the interior of
the skull. The most important of the emissary veins are: the
_mastoid_, _condyloid_, and _occipital_, passing to the transverse
(lateral) sinus; the _parietal_, which enters the superior sagittal
(longitudinal) sinus; and a branch from the nose which traverses the
foramen cæcum and enters the anterior end of the superior sagittal
sinus.

The supra-trochlear, supra-orbital and auriculo-temporal branches of
the trigeminal nerve, together with the greater and lesser occipital
nerves, supply the scalp with sensation, while the muscles are
supplied from the facial nerve.

The _lymph vessels_ pass to the parotid, occipital, mastoid, and
submaxillary groups of glands, the different areas of drainage being
ill-defined.

INJURIES OF THE SCALP

#Subcutaneous Injuries.#--_In simple contusion_ of the superficial
layers, owing to the density of the tissues, the blood effused is
small in quantity and remains confined to the area directly injured,
which is firm and tender to the touch, swollen and discoloured. The
disappearance of the swelling may be hastened by elastic pressure and
massage.

_Hæmatoma of the scalp_ results when lacerated vessels bleed into the
sub-aponeurotic space. Owing to the laxity of the connective tissue in
this area, the effused blood tends to diffuse itself widely, and,
according to the position assumed by the patient, gravitates to the
region of the eyebrow, the occiput, or the zygoma. When a large artery
is torn the swelling may pulsate. A hæmatoma of the scalp may readily
be mistaken for a depressed fracture of the skull, owing to the fact
that the margins of the effusion are often raised and of a firm
resistant character. A differential diagnosis can usually be made by
observing that the swelling is on a higher level than the rest of the
skull; that the raised margin can to a large extent be dispersed by
making firm, steady pressure over it with the finger; and that, on
doing so, the smooth and intact surface of the skull can be
recognised. When a fracture exists, the finger sinks into the
depression and the irregular edge of the bone can be felt. In doubtful
cases, if cerebral symptoms are present, an exploratory incision
should be made.

Even a large hæmatoma is usually completely absorbed, but the
dispersion of the clot may be hastened by massage and elastic
pressure. Any excoriation or wound of the skin must be disinfected.

Sometimes a blood-cyst, consisting of a connective-tissue capsule
filled with a yellowish-red fluid, remains, and may require to be
emptied with a hollow needle.

These effusions are to be distinguished from the _cephal-hæmatoma_, in
which the blood collects between the pericranium and the bone. This is
oftenest seen in newly born children as a result of pressure on the
head during delivery, and is characterised by its limitation to one
particular bone--usually the parietal--the further spread of the blood
being checked by the attachment of the pericranium at the sutures.
Occasionally a permanent thickening of the edges of the bone remains
after the absorption of the extravasated blood. This condition is to
be diagnosed from traumatic cephal-hydrocele (p. 390).

#Wounds of the Scalp.#--So long as a scalp wound, however extensive,
is kept free from infection, it involves comparatively little risk,
but the introduction of organisms to even the most trivial wound is
fraught with danger, on account of the ease and rapidity with which
the infection may spread along the emissary veins to the meninges and
intra-cranial sinuses.

The deeper the wound, the greater is the risk. If the epicranial
aponeurosis is divided, the "dangerous area" between it and the
pericranium is opened, and if infection occurs, it may lead to
widespread suppuration. Should the wound extend through the
pericranium, infection is more liable to spread to the bone and to the
cranial contents.

The usual varieties of wounds--incised, punctured, contused, and
lacerated--are met with in the scalp, and they vary in degree from a
simple superficial cut to complete avulsion. For medico-legal purposes
it is important to bear in mind that a scalp wound produced by the
stroke of a blunt weapon, such as a stick or baton, may closely
simulate a wound made with a cutting instrument.

On account of the density of the integument and its close connection
with the aponeurosis, scalp wounds do not gape unless the epicranial
aponeurosis is widely divided. This facilitates union in incised
wounds, but interferes with drainage in the long narrow tracts which
result from punctures, and which are so liable to be infected and to
implicate the sub-aponeurotic space, the pericranium, or even the
bone. It also favours the inclusion in the wound of a foreign body,
such as the broken point of a knife, or a piece of glass. The bleeding
from scalp wounds is often profuse and difficult to control, because
the vessels, fixed as they are in the dense subcutaneous tissue,
cannot retract and contract so as to bring about the natural arrest of
hæmorrhage, and it is difficult to apply forceps or ligatures to their
cut ends, suture ligatures are more efficient. On account of the free
arterial anastomosis in the deeper layers of the integument, large
flaps of scalp will survive when replaced, even if badly bruised and
torn, and it is never advisable to cut away any un-infected portion of
the scalp, however badly it may be lacerated or however narrow may be
the pedicle which unites it to the head.

_Gun-shot wounds_ of the scalp are usually associated with damage to
the skull and brain. A spent shot, however, may pierce the scalp, and
then, glancing off the bone, lodge in the soft parts.

_Complete Avulsion._--In women, the scalp is sometimes torn from the
cranium as a result of the hair being caught in revolving machinery.
The portion removed, as a rule, consists of integument and aponeurosis
with portions of muscle attached. In a few cases the pericranium also
has been torn away. So long as any attachment to the intact scalp
remains, the parts should be replaced, and, if asepsis is maintained,
a satisfactory result may be hoped for. When the scalp is entirely
separated, recourse must be had to skin-grafting.

_Treatment of recent Scalp Wounds._--To ensure asepsis, the hair
should be shaved from the area around the wound, and the part then
purified. Gross dirt ground into the edges of lacerated wounds is best
removed by paring with scissors. Undermined flaps must be further
opened up and drained--by counter-openings if necessary. When there is
reason to suspect their presence, foreign bodies should be sought for.
Bleeding is arrested by forci-pressure or by ligature; when, as is
often the case, these measures fail, the hæmorrhage may be controlled
by passing a needle threaded with catgut through the scalp so as to
include the bleeding vessel. The wound is stitched with horse-hair or
silk, and, except in very small and superficial wounds, it is best to
allow for drainage. With the use of iodine as a disinfectant, it is
often advantageous to dispense with dressings altogether.

#Complications of Scalp Wounds.#--The most common complications are
those due to infection, which not only aggravates the local condition,
but is apt to lead to spreading cellulitis, osteomyelitis, meningitis,
or inflammation of the intra-cranial sinuses. These dangerous sequelæ
are liable to follow infection of any scalp wound, but more especially
such as implicate the sub-aponeurotic area, or the pericranium. In the
integument, a small localised abscess, attended with pain and œdema of
surrounding parts, may form. Pus forming under the aponeurosis is
liable to spread widely, pointing above the eyebrow, in the occipital
region, or in the line of the zygoma. Suppuration under the
pericranium tends to be limited by the inter-sutural attachments of
the membrane. Necrosis of the outer table, or even of the whole
thickness of the skull, may follow, although it is by no means
uncommon for large denuded areas of bone to retain their vitality.

The onset of infection is indicated by restlessness, throbbing pain
and heat in the wound, a feeling of chilliness or the occurrence of a
rigor, and tension of the stitches from œdema of the surrounding
tissues. The œdema often extends to the eyelids and face; a puffiness
of the eyelids, indeed, is not infrequently the first evidence of the
occurrence of infection in the wound.

_Treatment._--When suppuration ensues, the stitches should be removed,
the wound opened up and purified with eusol, and packed. A dressing of
ichthyol and glycerine should be employed for a few days.

_Erysipelas of the scalp_ may originate even in wounds so trivial as
to be almost invisible, or from suppurative processes in the region of
the frontal sinuses or nasal fossæ. It tends to be limited by the
attachments of deep fasciæ, and seldom spreads to the cheek or neck.
Symptoms of cerebral complications, in the form of delirium or coma,
and of meningitis may supervene. Cellulitis beneath the aponeurosis
from mixed infection is a dangerous complication.

DISEASES OF THE SCALP

#Infective Conditions.#--It is not uncommon for _localised abscesses_
to occur in the subcutaneous cellular tissue in delicate children, and
such collections are not infrequently associated with pediculi,
impetigo, or chronic dermatitis. They develop slowly and painlessly,
and are only covered by a thin, bluish pellicle of skin. It is not
improbable that they result from a mixed infection by pyogenic and
tuberculous organisms. As a rule they heal quickly after incision and
drainage, but when they are allowed to burst, tedious superficial
ulcers may form. Localised abscesses may also form in connection with
disease of the cranial bones. _Suppuration_ following upon injuries
has already been referred to.

_Boils and carbuncles_ are not common on the hairy part of the scalp.
_Lupus_ rarely originates on the scalp, although it may spread thither
from the face. _Syphilitic_ lesions are common and present the same
characters as elsewhere. Gummata may develop in the soft parts, but
more commonly they take origin in the pericranium or bone. _Eczema
capitis_ is of surgical importance only in so far as it often forms
the starting-point of infection of lymph glands by pyogenic and other
organisms.

#Cystic and Solid Tumours.#--A great variety of swellings is met with
in the scalp.

_Sebaceous cysts_ or _wens_ are of frequent occurrence, and have been
described in Volume I.

A _dermoid cyst_ is most commonly situated over the position of the
anterior fontanelle, in the region of the occipital protuberance, or
at the lateral angle of the orbit. As it frequently lies in a gap in
the skull, it may be connected by a pedicle with the dura mater, and
is liable to be mistaken for a meningocele.

[Illustration: FIG. 177.--Multiple Wens.

(Photograph lent by Sir George T. Beatson.)]

_Serous cysts_ are occasionally found in the occipital region, and are
believed to be meningoceles that have become shut off from the
interior of the skull before birth.

_Adenomas_ originating in the sebaceous or sweat glands are sometimes
multiple, of a purplish colour, and the skin covering them is thin and
glistening. They show a tendency to ulcerate and fungate, giving rise
to a fœtid discharge, and may be mistaken for epithelioma; they are
also liable to become the seat of epithelioma. They are treated by
excision.

Large, flat _papillomas_ or warts may be single or multiple; they are
of slow growth, and as they may also become the starting-point of
epithelioma, they should be removed.

[Illustration: FIG. 178.--Adenoma of Scalp.]

The _plexiform neuroma_ forms a loose soft tumour situated in the
course of one or more branches of the trigeminal nerve, especially
the supra-orbital branch. In its most aggravated form the tumour hangs
over the face or neck in large pendulous masses, and is described as a
_pachydermatocele_ (V. Mott).

A _sarcoma_ usually has its origin in the bones of the skull, and only
implicates the scalp secondarily.

_Epithelioma_ of the scalp may originate in relation to a wart, an
ulcerated wen or sebaceous adenoma, or the cicatrix of a burn. It may
affect comparatively young persons, may spread over a wide area, or
pass deeply and involve the bone. Free and early removal is indicated.

_Rodent cancer_ may originate on the scalp, but usually spreads
thither from the face.

In operating for extensive tumours of the scalp the hæmorrhage is
sometimes formidable. It may be controlled by an elastic tourniquet
applied horizontally round the head, or if, on account of the position
of the tumour or from other causes, this is not practicable, by
ligation or temporary clamping of the external carotid on one or on
both sides.

#Air-containing Swellings#--_Pneumatocele Capitis._--Cases have been
recorded in which, as a result of pathological or traumatic
perforations of the mastoid, and less frequently of the frontal cells,
air has passed under the pericranium and given rise to a tense rounded
tumour, resonant on percussion, and capable of being emptied by firm
pressure. Such swellings exhibit neither pulsation nor fluctuation;
and as they are painless, and give rise to almost no inconvenience,
they do not call for treatment.

_Emphysema of the scalp_ may follow fractures implicating any of the
air sinuses of the skull, the air infiltrating the loose cellular
tissue between the pericranium and the aponeurosis, and on palpation
yielding a characteristic crepitation. It usually disappears in a few
days.

#Vascular Tumours.#--_Nævi_ on the scalp present the same features as
elsewhere. If placed over one of the fontanelles, a nævus may derive
pulsation from the brain, and so simulate a meningocele.

_Cirsoid aneurysm_ is usually met with in the course of the temporal
artery, and may involve the greater part of the scalp. Large,
distended, tortuous, bluish vessels pulsating synchronously with the
heart are seen and felt. They can be emptied by pressure, but fill up
again at once on removal of the pressure. The patient complains of
dizziness, headache, and a persistent rushing sound in the head.
Ulceration of the skin over the dilated vessels, leading to fatal
hæmorrhage, may take place.

They may be treated by excision, after division and ligation of the
larger vessels entering the swelling; or the dilated vessels may be
cut across at several points and both ends ligated. Krogius recommends
the introduction of a series of subcutaneous ligatures so as to
surround the whole periphery of the pulsating tumour, and interrupt
the blood flow. Ligation of the main afferent vessels, or of the
external or common carotid, has been followed by recurrence, owing to
the free anastomatic circulation in the scalp. In some cases
electrolysis has yielded good results.

_Traumatic aneurysm_ of the temporal artery was comparatively common
in the days when the practice of bleeding from this vessel was in
vogue, but it is seldom met with now.

_Arterio-venous aneurysm_ may also occur in the course of the temporal
artery, as a result of injury, and is best treated by complete
extirpation of the segments of the vessels implicated.

CHAPTER XII

THE CRANIUM AND ITS CONTENTS

Anatomy and physiology--Cerebral localisation--Lumbar puncture. HEAD
    INJURIES--Concussion--Cerebral irritation--Compression--Contusion
    and laceration of the brain, and traumatic intra-cranial
    hæmorrhage: _Middle meningeal hæmorrhage_; _Hæmorrhage from
    internal carotid and venous sinuses_--Intra-cranial hæmorrhage of
    the newly born. Cerebral œdema--Wounds of brain--After-effects of
    head injuries--Traumatic epilepsy and insanity--Infective
    complications.

#Anatomy and Physiology.#--The _Cranium_ is irregularly ovoid in
shape, and its floor is broken up by various projections to form three
separate fossæ--anterior, middle, and posterior--in which rest
respectively the frontal, the temporal, and the occipital lobes of the
brain; the cerebellum, pons, and medulla oblongata also occupy the
posterior fossa.

The _outer_ table is the most elastic layer of the calvarium, and it
varies greatly in thickness in different skulls and in different parts
of the same skull. It is nourished chiefly from the pericranium which
is firmly bound down along the lines of the sutures. The _inner_ or
vibreous table is thin and fragile, and its smooth internal surface is
grooved by the middle meningeal and other arteries of the dura mater,
and by the large venous sinuses. The intermediate layer--the
_diploë_--is highly vascular, branches of the meningeal vessels
anastomosing freely in its open porous substance with branches derived
from the pericranial vessels. Some of its veins open into the external
veins, and others into the intra-cranial sinuses, and they communicate
with the emissary veins as these pass through the bone, which explains
the spread of infective processes from the structures outside the
skull to those within. The possibility of withdrawing blood from the
interior of the skull by leeching, bleeding, or cupping depends on the
existence of the emissary veins.

_The Membranes of the Brain._--The _dura mater_ is a fibro-serous
membrane, the outer, fibrous layer constituting the endosteum of the
skull, the inner, serous layer forming one of the coverings of the
brain. Between the fibrous layer and the bone the meningeal vessels
ramify; and along certain lines the two layers split to form channels
in which run the cranial venous sinuses. Inside the dura, and
separated from it by a narrow space--the _sub-dural space_--lies the
_arachno-pial membrane_, consisting of an outer (_arachnoid_) layer
which envelops the brain but does not pass into the sulci, and a
highly vascular inner layer--the _pia mater_--which closely invests
the brain and lines its entire surface.

The space between these layers--the _sub-arachnoid space_--is
traversed by a network of fine fibrous strands, in the meshes of which
the cerebro-spinal fluid circulates. Each nerve-trunk as it leaves the
skull or spinal canal carries with it a prolongation of each of these
membranes and their intervening spaces. The membranes gradually become
lost in the fibrous sheaths of the nerves, and the sub-dural and
sub-arachnoid spaces become continuous with the lymph spaces of the
nerves.

The _cerebro-spinal fluid_ is secreted by the choroid plexuses and
fills the cerebral ventricles, the central canal of the cord, the
sub-dural and sub-arachnoid spaces, and the sheaths of the
intra-cerebral blood vessels. At the base of the brain, particularly
in the posterior fossa, the sub-arachnoid space is wider than
elsewhere, forming "cisterns" filled with cerebro-spinal fluid which
supports the cerebral structures. Through the foramen of Magendie in
the roof of the fourth ventricle the sub-arachnoid fluid of the
cranial cavity communicates with that of the vertebral canal.

Although it differs in its chemical constitution from true lymph, the
cerebro-spinal fluid seems to functionate as lymph, in addition to
acting as a lubricating agent, and playing a part in regulating the
vascular supply of the brain. In cases of cerebral hæmorrhage,
abscess, tumour, or depressed fracture, room is made up to a certain
point for the extraneous matter by displacement of cerebro-spinal
fluid.

_Vascular supply._--The free anastomosis between the vessels entering
into the formation of the circulus arteriosus (circle of Willis)
ensures an abundant supply of blood to the brain. The larger arteries
run in the sub-arachnoid space and give off branches which ramify in
the pia mater before entering the cerebral substance. Within the
brain, each artery being more or less terminal, there is no free
anastomosis between adjacent vessels, with the result that if any
individual artery is obstructed the vitality of the area supplied by
it is seriously impaired. The venous arrangements are also peculiar in
that the veins are thin-walled and valveless, and open into the rigid,
incompressible sinuses which run between the layers of the dura mater.
Most of the blood passes to the internal jugular vein, and any
increase in the pressure of this vessel is immediately transmitted
back to the cerebral veins. As the blood vessels project into a rigid
case filled with incompressible material, and as the total _volume_ of
blood in the brain is constant (Munro and Kelly), any alteration in
the supply of blood to the cerebral tissue must be due to an increased
_velocity_ of flow, and this in turn depends upon changes in the
aortic and vena cava pressure. Thus, if the aortic pressure rises,
more blood will enter the cerebral vessels and will move along more
rapidly; while if the pressure in the vena cava rises there is
obstruction to the passage of blood in the arteries and diminished
velocity of flow. The ebb and flow of cerebro-spinal fluid in and out
of the spinal canal may also help to control the pressure.

#Nerve Elements.#--The nervous system is composed of a multitude of
units, called _neurones_, each neurone consisting of a nucleated cell,
with branching protoplasmic processes or _dendrites_ and one
_axis-cylinder_ or _axon_. The nutrition of an axis cylinder depends
on its continuity with a living cell. If the cell dies, the axis
cylinder degenerates. If the axis cylinder is severed at any point, it
degenerates beyond that point, and the nucleus of the nerve-cell
disintegrates--chromatolysis.

The axis cylinder of one cell ends in a number of fine filaments which
arborise around another nerve-cell, thus bringing it into
physiological, if not anatomical, relationship with the first cell.
The termination is called a cell-station or _synapsis_. In this way
the various sections of the nervous system are kept in association
with one another and with the rest of the body.

_Motor Functions and Mechanism._--The nerve centres, which together
make up the motor area, and govern the voluntary muscular movements of
the body, are situated in the grey matter of the præcentral or
ascending frontal gyrus, and of the frontal aspect of the central
sulcus (fissure of Rolando). The upper limit of the motor area reaches
on to the mesial aspect of the paracentral lobule, and the lower limit
stops short of the lateral cerebral fissure (fissure of Sylvius) (Fig.
179).

[Illustration: FIG. 179.--Relations of the Motor and Sensory Areas to
the Convolutions and to Chiene's Lines.

(After Cunningham.)]

Each group of muscles has its own regulating centre, the size of the
area representing any group depending upon the character and
complexity of the movements performed by the muscles, rather than upon
the amount of muscular tissue that is governed by the centre--for
example, the centre for the mouth, tongue, and vocal cords is larger
than that for the muscles of the trunk.

The motor centres have been localised on the surface of the brain with
approximate accuracy. For example, above the superior genu of the
præcentral gyrus, the centres governing the hip, knee, and toes are
grouped; opposite the genu are the centres for the movements of the
trunk; between the superior and middle genua lie the centres for the
upper extremity; opposite the middle genu, those for the neck, and
below it, those for the face, jaws, and tongue, pharynx and larynx.

#The Motor Tracts.#--It is now generally accepted that there are two
paths by which motor impulses pass from the brain: one--the
_rubro-spinal tract_--which controls the more elemental movements of
the body, such as standing, walking, breathing, etc.; the other--the
_pyramidal tract_--developed later in the evolution of the nervous
system, and concerned with the finer and more skilled movements.

The pyramidal tract is the more important clinically. From the
pyramidal cells in the cortex of the Rolandic area, the axis cylinders
pass through the centrum ovale towards the base of the brain. They
converge at the internal capsule, and pass through the anterior
two-thirds of its posterior limb (Figs. 180 and 195). The fibres for
the eyes, face, and tongue lie farthest forward, and next in order
from before backward, those for the arm and the leg.

From the internal capsule, the motor fibres pass as the _pyramidal
tract_ through the crusta of each crus cerebri, the pons and the
medulla oblongata. Throughout this part of its course, numerous axons
leave the tract, and enter the mid-brain, pons, and medulla in which
lie the nuclei of the motor cranial nerves.

At the _decussation of the pyramids_ in the lower third of the
medulla, the main mass of the motor fibres crosses the middle line,
and enters the lateral column of the spinal cord as the _crossed
pyramidal tract_. The remaining fibres pass down as the _direct
pyramidal tract_, and decussate in the cord near their termination.

The fibres forming the second path pass through the red nucleus in the
cerebral peduncle (crus cerebri) and thence by way of the rubro-spinal
tract in the lateral column of the cord.

The existence of this double motor path explains how after a
hemiplegic stroke in which the pyramidal tract is destroyed while the
rubro-spinal tract escapes, the patient is able to perform such
primitive movements as are involved in walking or standing, while he
is unable to carry out finer movements that require higher education.

The pyramidal and rubro-spinal tracts, in addition to conveying motor
impulses, convey impulses that influence muscle tonus and the deep
reflexes. The pyramidal tract conveys impulses that inhibit muscle
tonus, while the rubro-spinal tract is the path by which excitatory
impulses travel. When the inhibitory influences are cut off, as in a
lesion of the internal capsule, the paralysed muscles become spastic,
and the deep reflexes are exaggerated. When the excitatory impulses
are also lost, as in a total transverse lesion of the cord, the
paralysed muscles are flaccid and the deep reflexes disappear. In
destructive lesions of the lower neurones, the muscles are always
flaccid.

The axons passing from the cerebral cortex terminate at different
levels in the cord by breaking up into dendrites which arborise around
the cells on the grey matter of the posterior horns--this system of
cells, axons, and dendritic processes forming an _upper neurone_. From
this synapsis the _lower neurone_ proceeds, its axons travelling to
the anterior horn and arborising around the motor cells. The axis
cylinders pass out in the anterior nerve roots to the spinal nerves
and are continued in them to their distribution in voluntary muscles.

If the continuity of any group of these lower neurones is interrupted,
not only do the nerve fibres degenerate, but the nutrition of the
muscles supplied by them is interfered with and they rapidly
degenerate and waste, and after an interval show the reaction of
degeneration. In addition, the reflex arc is disturbed, and reflexes
are lost. As these changes do not occur in lesions of the upper
neurones, an appreciation of the differences enables us to distinguish
between lesions implicating the upper and the lower neurones.

#Sensory Functions and Mechanism.#--Three kinds of sensory impulses
pass from the periphery to the brain; (1) deep, or muscular
sensibility, (2) protopathic sensibility, and (3) epicritic
sensibility.

_Deep sensibility_ includes the recognition of (_a_) deep pressure,
say by the blunt end of a pencil; (_b_) the position of a joint on
passive movement (joint sense); (_c_) active muscular contraction
(kinesthetic sense). The fibres that convey these impulses to the
spinal cord pass in the afferent nerves from the muscles, tendons, and
bones, and so long as these nerves are intact these sensations are
retained, even if the surface of the skin is quite anæsthetic.

_Protopathic sensibility_ is of a lower order than epicritic. It
consists in the recognition of painful cutaneous stimuli and of
extreme degrees of heat and cold. The fibres concerned are
non-medullated and regenerate comparatively quickly after injury, so
that protopathic sensibility is regained before epicritic.

_Epicritic sensibility_ is the most highly specialised and permits of
the recognition of light touch, _e.g._, with a wisp of cotton wool, of
fine differences of temperature, and of discriminating as separate the
points of a pair of compasses 2 cm. apart. These sensations are
carried by medullated nerve fibres, and are slow to return after
injury to the nerves.

The sensory nerve fibres conveying these different impulses pass to
the ganglionic cells of the posterior nerve roots. From each of these
cells a process passes into the cord and bifurcates into an ascending
and a descending branch. In the cord the fibres rearrange themselves
and pass to the brain by a double path. Those that convey sensations
of pain and of temperature pass by the spino-thalamic route by way of
the tract of Gowers and the fillet to the optic thalamus; those that
are concerned with the muscular sense, the joint sense, and tactile
discrimination pass up the posterior columns in the tracts of Goll and
Burdach to the nuclei gracilis and cuneatus in the medulla, whence
they pass to the optic thalamus.

From the cell station in the optic thalamus the fibres proceed to the
_cortical sensory centres_, that for tactile sensation being situated
in the post-central (ascending parietal) gyrus; that for muscular and
stereognostic sense lying probably in the adjacent portions of the
parietal lobe.

In a unilateral lesion of the cord, pain and the temperature sense may
be disturbed in one limb, and motor power and tactile sensibility in
the other, as the fibres that convey impressions of pain, and those
that subserve the discrimination of temperature, pass up and decussate
in the cord a few segments above their point of entrance.

[Illustration: FIG. 180.--Diagram of the Course of Motor and Sensory
Nerve Fibres.]

#Effects of Lesions of the Motor and Sensory Mechanisms.#--Lesions of
the _motor mechanism_ differ in their fundamental characters according
as they affect the upper or the lower neurones. The signs also vary
according as the affected area is _destroyed_ or merely _irritated_,
say by the pressure of a tumour. Irritative lesions in general produce
muscular spasms or convulsions, while destructive lesions cause
paralysis. The essential differences in the effects of destructive
lesions of upper and lower neurones may be indicated thus:--

    _Upper Neurone Lesion._           _Lower Neurone Lesion._

    Spastic paralysis of voluntary    Flaccid paralysis of voluntary
       muscles.                          muscles.
    No marked wasting of paralysed    Marked wasting of paralysed
       muscles.                          muscles.
    No reaction of degeneration.      Reaction of degeneration.
    Exaggeration of reflexes.         Loss of reflexes.

Irritative lesions of the sensory mechanism cause numbness and
tingling (paræsthesia); more extensive paralytic lesions produce
anæsthesia, astereognosis, loss of muscle sense, loss of pain, or
inability to distinguish temperature, according to the tracts that are
affected.

_Lesions of the Upper Motor Neurone_ may occur in any part of its
course. _Localised lesions of the motor cortex_ of an irritative kind,
for example, a patch of meningitis, a tumour, meningeal hæmorrhage, or
a spicule of bone, produce spasms in those groups of muscles on the
opposite side of the body that are supplied by the centres
implicated--Jacksonian epilepsy. The cortical discharge may overflow
into neighbouring centres and cause more widespread convulsive
movements, or, if strong and long-continued, may even lead to general
convulsions. Consciousness is usually lost before the whole of one
side becomes implicated in the spasms; always before they spread to
the opposite side. Contracture may occur in the muscles affected after
the spasms cease.

If an area of the cortex is destroyed by the lesion, paralysis is
produced of the corresponding muscles on the opposite side of the
body. At first the paralysed muscles are flaccid, but spasticity soon
develops. In some cortical lesions, for reasons not yet understood,
the paralysis remains of the flaccid type. The seat and extent of the
paralysis depend upon the area of the cortex destroyed. In rare cases
the whole motor area is destroyed--_cortical hemiplegia_; more
generally the lesion affects one or more groups of muscles, and
occasionally all the muscles of one limb are paralysed--_cortical
monoplegia_. Lesions are often both irritative and destructive, and
lead to paralysis of one or more groups of muscles associated with