Chapter 16

suggestive name of "wandering acetabulum" (Fig. 108). The displacement of the femur resulting from these secondary changes is one of the causes of real shortening of the limb.

#Clinical Features.#--It is customary to describe three stages in the progress of hip disease, but this is arbitrary and only adopted for convenience of description.

_Initial Stage._--At this stage the disease is confined to a focus in the bone which has not yet opened into the joint or to the synovial membrane. The onset is insidious, and if injury is alleged as an exciting cause, some weeks have usually elapsed between the receipt of the injury and the onset of symptoms. The child is brought for advice because he has begun to limp and to complain of pain. There is a history that he has become pale and has ceased to take food well, that his sleep has been disturbed, and that the pain and the limp, after coming and going for a time, have become more pronounced. On walking, the affected limb is dragged in such a way as to avoid movement at the hip, and to substitute for it movement at the lumbo-sacral junction. The child throws the weight of the trunk as little as possible on to the affected limb, and inclines to rest on the balls of the toes rather than on the sole. There is usually some wasting of the muscles of the thigh and flattening of the buttock. Diminution or loss of the gluteal fold indicates flexion at the hip which might otherwise escape notice. Pain is complained of in the hip, or is referred to the medial side of the knee, in the distribution of the obturator nerve. Sometimes the pain is confined to the knee, and if the examination is restricted to that joint the disease at the hip may be overlooked. At this stage the attitude of the limb is not constant; at one time it may be natural, and at another slightly flexed and abducted. Tenderness of the joint may be elicited by pressing either in front or behind the head of the bone, but is of little diagnostic importance. Pain elicited on driving the head against the acetabulum may occasionally assist in the recognition of hip disease, but the diagnostic value of this sign has been overrated and, in our opinion, this test should be omitted.

Most information is gained by testing the functions of the joint, and if this is done gently and without jerking, it does not cause pain. The child should lie on his back, either on his nurse's knee or on a table; and to reassure him the movements should be first practised on the sound limb. On slowly flexing the thigh of the affected limb, it will be found that the range of flexion at the hip is soon exhausted, and that any further movement in this direction takes place at the lumbo-sacral junction. The child is next made to lie on his face with the knees flexed in order that the movements of rotation may be tested. The thigh is rotated in both directions, and on comparing the two sides it will be found that rotation is restricted or abolished on the side affected, any apparent rotation taking place at the lumbo-sacral junction. These tests reveal the presence of _rigidity_ resulting from the involuntary contraction of muscles, which is the most reliable sign of hip disease during the initial stage, and they possess the advantage of being universally applicable, even in the case of young children.

_Second Stage._--This probably corresponds with commencing disease of the articular surfaces, and progressive involvement of all the structures of the joint. The child complains more, and usually exhibits the attitude of abduction, eversion, and flexion (Fig. 109).

At first the attitude is maintained entirely by the action of muscles; but when it is prolonged, the muscles, fasciae, and ligaments undergo shortening, so that it becomes fixed.

On looking at the patient, the abnormal attitude may not be at once evident, as he usually restores the parallelism of the limbs by lowering the pelvis on the affected side and adducting the sound limb. This obliquity or tilting of the pelvis causes _apparent lengthening_ of the diseased limb, and is best demonstrated by drawing one straight line between the anterior iliac spines, and another to meet it from the xiphoid cartilage through the umbilicus; if the pelvis is in its normal position, the two lines intersect at right angles; if it is tilted, the angles at the point of intersection are unequal. The flexion may be largely compensated for by increasing the forward curve of the lumbar spine (lordosis), and by flexing the leg at the knee. There may also be an attempt to compensate for the eversion of the limb by rotating the pelvis forwards on the affected side.

To demonstrate the lordosis, the patient should be laid on a flat table; in the resting position the lordosis is moderate, when the hip is flexed it disappears, when it is extended the lordosis is exaggerated, and the hand or closed fist may be inserted between the spine and the table (Fig. 112).

When the functions of the joint are tested, it will be found that there is rigidity, and that both active and passive movements take place at the lumbo-sacral junction instead of at the hip. While rigidity is usually absolute as regards rotation, it may sometimes be possible with care and gentleness to obtain some increase of flexion. For diagnostic purposes most stress should therefore be laid on the presence or absence of rotation.

If the sound limb is flexed at the hip and knee until the lumbar spine is in contact with the table, the real flexion of the diseased hip becomes manifest, and may be roughly measured by observing the angle between the thigh and the table (Fig. 113). This is known as "Thomas' flexion test," and is founded upon the inability to extend the diseased hip without producing lordosis.

_Swelling_ is seen on the anterior aspect of the joint; it may fill up the fold of the groin and push forward the femoral vessels. It is doughy and elastic, but may at any time liquefy and form a cold abscess. Swelling about the trochanter and neck of the bone may be estimated by measuring the antero-posterior diameter with callipers, and comparing with the sound side. Swelling on the pelvic aspect of the acetabulum can sometimes be discovered on rectal examination.

_Third Stage._--This probably corresponds with caries of the articular surfaces, since pain is now a prominent feature, and there are usually startings at night. The attitude is one of adduction, inversion, flexion, and apparent or real shortening of the limb (Fig. 114). The _flexion_ is usually so pronounced that it can no longer be concealed by lordosis, so that when the patient is recumbent, although the spine is arched forwards, the limb is still flexed both at the hip and at the knee; with the spine flat on the table, the flexion of the thigh may amount to as much as a right angle. The _adduction_ varies greatly in degree; when it is slight, as is most often the case, the toes of the affected limb rest on the dorsum of the sound foot. When moderate, it is compensated for by raising the pelvis on the affected side, with _apparent shortening_ of the limb, this being the result of an effort on the part of the patient to restore the normal parallelism of the limbs, the sound limb being abducted to the same extent as the affected limb is adducted. It is important to recognise the cause of this shortening, as it can be corrected by treatment. As a result of the obliquity of the pelvis, the patient, when erect, exhibits a lateral curvature of the spine with the dorso-lumbar convexity to the sound side.

When adduction is pronounced, the patient is unable to restore the normal parallelism of the limbs, and the knee on the affected side may cross the sound limb. There is a deep groove at the junction of the perineum and thigh, great prominence of the trochanter, and the pelvis may be tilted to such an extent that the iliac crest comes into contact with the lower ribs.

As a result of the pressure of the carious articular surfaces against one another, the acetabulum is enlarged and the upper end of the femur is drawn gradually upwards and backwards within the socket. Examination will then reveal the existence of a variable amount of _actual shortening_; it will also be found that the trochanter is displaced above Nelaton's line, while above and behind the trochanter there is a prominent hard swelling corresponding to the enlarged acetabulum.

There may, therefore, be a combination of real and apparent shortening together amounting to several inches (Fig. 115).

In cases of long standing, beginning in childhood, the shortening is still further added to by deficient growth in length of the femur, and it may be of all the bones of the limb; even the foot is smaller on the affected side.

The most reasonable explanation of the attitudes assumed in hip disease is that given by Koenig. If the patient walks without crutches, as he is usually able to do at an early stage of the disease, the attitude of abduction, eversion, and slight flexion enables him to save the limb to the utmost extent; on the other hand, if he uses a crutch, as he is obliged to do at a more advanced stage, he no longer uses the limb for support, and therefore draws it upwards and medially into the position of adduction, inversion, and greater flexion. Similarly, if he is confined to bed, he lies on the sound side, and the affected limb sinks by gravity so as to lie over the normal one in the position of adduction, inversion, and flexion. Koenig's explanation accords with the fact that in the exceptional cases which begin with adduction and inversion we have usually to deal with a severe type of the disease, associated with grave osseous lesions--precisely those cases in which the patient is compelled from the outset to lie up or to adopt the use of crutches. Further, the transition from the abducted to the adducted position usually follows upon such an aggravation of the symptoms that the patient is no longer able to walk without the assistance of a crutch.

During the third stage the other signs and symptoms become more pronounced; the patient looks ill and thin, he is usually unable to leave his bed, his sleep is disturbed by startings of the limb, and the rigidity of the joint and the wasting of the muscles are well marked. The temperature may rise slightly after examination of the limb, or after a railway journey.

#Abscess Formation in Hip Disease.#--The formation of abscess is not related to any stage of the disease; it may occur before there is deformity, and it may be deferred until the disease is apparently cured. Its importance lies in the fact that if a mixed infection with pyogenic organisms occurs, the gravity of the condition is greatly increased.

An abscess may appear _in the thigh_ in front or behind the joint. The _anterior abscess_ emerges on one or other side of the psoas muscle; from the resistance offered by the fascia lata, the pus may gravitate down the thigh before perforating the fascia. It has occasionally happened that when such an abscess has been opened and become infected with pyogenic organisms, the femoral vessels have been eroded, and serious or even fatal haemorrhage has resulted. The _posterior abscess_ appears in the buttock and may make its way to the surface through the gluteus maximus; more often it points at the lower border of this muscle in the region of the great trochanter, or it may gravitate down the thigh.

Abscesses which form _within the pelvis_ originate either in connection with the acetabulum or in relation to the psoas muscle where it passes in front of the joint. Those that are directly connected with disease of the acetabulum may remain localised to the lateral wall of the pelvis, or may spread backwards towards the hollow of the sacrum. They may open into the bladder or rectum, or may ascend into the iliac fossa and point above Poupart's ligament (Fig. 115), or descend towards the ischio-rectal fossa. The abscess which develops in relation to the psoas muscle may be shaped like an hour-glass, one sac occupying the iliac fossa, the other filling up Scarpa's triangle, the two sacs communicating with each other through a narrow neck beneath Poupart's ligament.

So long as the skin is intact, the abscess is unattended with symptoms, and may escape notice. If it bursts externally, pyogenic infection is almost inevitable, and the patient gradually passes into the condition of hectic fever or chronic toxaemia; he loses ground from day to day, may become the subject of waxy disease in the viscera, or may die of exhaustion, tuberculous meningitis, or general tuberculosis.

#Dislocation# is a rare complication of hip disease, and is most likely to occur during the stage of adduction with inversion. It has been known to take place during sleep, apparently from spasmodic contraction of muscles. In the dorsal dislocation, which is the most common form, adduction and inversion are exaggerated, the trochanter projects above and behind Nelaton's line, and the head of the bone may be felt on the dorsum ilii. It is a striking fact that after dislocation has occurred there is less complaint of pain or of startings than before, and passive movements may be carried out which were previously impossible.

#Diagnosis of Hip Disease.#--The diagnosis is to be made not only from other affections of the joint, but also from morbid conditions in the vicinity of the hip, as in any of these the patient may seek advice on account of pain and a limp in walking. The patient should be stripped, and if able to walk, his gait should be observed. He is then examined lying on his back, and attention is directed to the comparative length of the limbs, to the attitude of the limbs and pelvis, and to the movements at the hip-joint, especially those of rotation. When there is any doubt as to the diagnosis, the examination should be repeated at intervals of a few days. In children, there are three non-febrile conditions attended with a limp and with shortening of the limb, which may be mistaken for hip disease,--_congenital dislocation_, _coxa vara_, and _paralysis following poliomyelitis_--but in all of these the movements are not nearly so restricted as they are in disease of the joint.

In tuberculous disease of the _sacro-iliac joint_, while the pelvis may be tilted, and the limb apparently lengthened, the movements at the hip are retained. In tuberculous disease of the _great trochanter_, or of either of the _bursae_ over it, while there may be abduction, eversion, impairment of mobility, and swelling in the region of the trochanter followed by abscess formation, the movements are less restricted than in disease of the joint.

In _psoas abscess_ associated with spinal disease, or in _disease of the bursa underneath the psoas_, the limb is flexed and everted, there may be lordosis, and the patient may limp in walking, but the movements at the hip are restricted only in the directions of extension and inversion, while in hip disease they are restricted in all directions.

_New-growths_ in the vicinity of the hip--especially central sarcoma of the upper end of the femur--are difficult to differentiate from hip disease without the help of the X-rays.

Among other conditions which by interfering with the free mobility of the hip may simulate hip disease, are appendicitis, inflammation of the glands in the groin, staphylococcal disease of the upper end of the femur, and sciatica.

The diagnosis _from other diseases of the hip-joint_ is made by careful consideration of the history, symptoms, and X-ray appearances.

#Prognosis.#--The prognosis in hip disease is more serious than in tuberculosis of other joints, excepting only those of the spine, and it is most unfavourable when there are gross lesions of the bones and infected sinuses.

Whatever the stage of the disease, recovery is a slow process, and even in early and mild cases it seldom takes place in less than one or two years, and is liable to be attended with some impairment of function. During the process of cure, complications are liable to occur, and after apparent recovery relapses are not uncommon. When arrested during the initial stage, recovery may be complete; but when there has been destruction of the articular surfaces, there is apt to be ankylosis of the joint and shortening of the limb.

In cases which terminate fatally, death usually results from meningeal, pulmonary, or general tuberculosis, or from pyogenic complications and waxy degeneration.

#Treatment.#--A large proportion of cases recover under conservative treatment, and the functional results are so much better than those following operative interference that unless there are special indications to the contrary, conservative measures should always be adopted in the first instance.

_Conservative Treatment._--The first essential is to take the weight off the limb and secure its fixation in the attitude of almost complete extension and moderate abduction. When the symptoms are well marked, the child is kept in bed and the limb is extended with a weight and pulley.

_Extension by Weight and Pulley_ (Fig. 116).--The weight employed varies from one to four pounds in children, to ten or more pounds in adolescents and adults, and must be adjusted to meet the requirements of each case. If pain returns after having been relieved, it is due to stretching of the ligaments, and the weight should be diminished or removed for a time. If there is deformity, the line of traction should be in the axis of the displaced limb until the deformity is got rid of. The extension should be continued until pain, tenderness, and muscular contraction have disappeared, and the limb has been brought into the desired attitude.

In restless children, in addition to the extension, a long splint is applied on the sound side and a sand-bag on the affected one; or, better still, a double long splint and cross-bar, the long splint on the affected side being furnished with a hinge opposite the hip to permit of varying the degree of abduction (Fig. 117).

When the deformed attitude does not yield rapidly to extension, it should be corrected under an anaesthetic, and if the adductor tendons and fasciae are so contracted that this is difficult, they should be forcibly stretched or divided.

The immediate correction of deformed attitudes under anaesthesia has largely replaced the more gradual method by extension with weight and pulley; and in hospital practice it is usually followed by the application of a plaster case. The plaster bandages are applied over a pair of knitted drawers; the pelvis and both thighs, the diseased one in the abducted position, are included. The case may be strengthened by strips of aluminium, and should be renewed every six weeks or two months.

_Ambulant Treatment._--When the patient is able to use crutches, the affected limb is prevented from touching the ground by fixing a patten on the sole of the boot on the sound side. This may suffice, or, in addition, the hip-joint is kept rigid by a Thomas' (Fig. 118) or a Taylor's splint. The Thomas' splint must be fitted to the patient under the supervision of the surgeon, who must make himself familiar with the construction of the splint, and its alteration by means of wrenches.

In children who are unable to use crutches, a double Thomas' splint is employed; the child thereby is converted into a rigid object, capable of being carried from one room to another and into the open air. Personally we have obtained satisfaction from the double Thomas' splint employed for spinal disease, which extends from the occiput to the soles of the feet.

The fixation of the hip-joint and the taking of the weight off the limb by one or other of the above methods, should, as a general rule, be continued for at least a year.

Should an abscess develop, it is treated on the usual lines.

_Operative Interference._--Widely diverse opinions are held on the question as to whether or not recourse should be had to operative interference.

Some surgeons are opposed to operative interference, on the grounds that however advanced the disease may be it will yield to conservative measures if judiciously and perseveringly carried out. Other surgeons advocate operative treatment in all cases which do not speedily show improvement under conservative treatment. An intermediate attitude may be adopted which recommends operation in cases in which the disease progresses in spite of conservative treatment, and in which periodic examination with the X-rays shows that there are progressive lesions in the upper end of the femur or in the acetabulum.

It is claimed by those who advocate operation under these conditions that pain and suffering are at once got rid of, sleep is restored, appetite returns, and there is a marked improvement in the general health, and that this result is obtained in months instead of years, and that the cure is more likely to be permanent. It is certainly unwise to delay operation until sinuses have formed, as such a course is largely responsible for the bad results which formerly followed excision of the joint.

_Amputation_ for tuberculous disease of the hip has become one of the rarest of operations, but is still required in cases which have continued to progress after excision, and when there is disease of the pelvis or of the shaft of the femur, with sinuses, albuminuria, and hectic fever.

#The Correction of Deformity resulting from Antecedent Disease of the Hip.#--From neglect or from improper treatment, deformity may have been allowed to persist, while the disease has undergone cure. It is associated with ankylosis of the joint, or contracture of the soft parts or both. The contracture of the soft parts involves specially the tendons, fasciae, and ligaments on the anterior and medial aspects of the joint, and is usually present to such a degree that, even if the joint were rendered mobile, these shortened structures would prevent correction of the deformity. The usual deformity is a combination of shortening, flexion, and adduction.

#Bilateral Hip Disease.#--Both hip-joints may become affected with tuberculous disease, either simultaneously or successively, and abscesses may form on both sides. The patient is necessarily confined to bed, and if the disease is recovered from, his capacity for walking may be seriously impaired, especially if the joints become fixed in an undesirable attitude. The most striking deformity occurs when both limbs are adducted so that they cross each other--one variety of the "scissor-leg" or "crossed-leg" deformity--in which the patient, if able to walk at all, does so by forward movements from the knees. An attempt should be made by arthroplasty to secure a movable joint at least on one side.

OTHER DISEASES OF THE HIP-JOINT

#Pyogenic Diseases# are met with in childhood and youth as a result of infection with the common pyogenic organisms, gonococci, pneumococci, or typhoid bacilli. While the organisms usually gain access to the tissues of the joint through the blood stream, a direct infection is occasionally observed from suppuration in the femoral lymph glands or in the bursa under the ilio-psoas.

The _clinical features_ are sometimes remarkably latent and are much less striking than might be expected, especially when the hip affection occurs as a complication of an acute illness such as scarlet fever. It may even be entirely overlooked during the active stage, and only noticed when the head of the femur is found dislocated, or the joint ankylosed. In the acute arthritis of infants also, the clinical features may be comparatively mild, but as a rule they assume a type in which the suppurative element predominates. The limb usually becomes flexed and adducted, and a swelling forms in front of the joint at the upper part of Scarpa's triangle; the upper femoral epiphysis may be separated and furnish a sequestrum.

The flexion and adduction of the limb favour the occurrence of dislocation. A child who has recovered with dislocation on to the dorsum ilii is usually able to walk and run about, but with a limp or waddle which becomes more pronounced as he grows up. The condition closely resembles a congenital dislocation, but the history, and the presence of gross alterations in the upper end of the femur as seen with the X-rays, should usually suffice to differentiate them.

_Treatment._--In the acute stage the limb is extended by means of the weight and pulley, and kept at rest with the single or double long splint, or by sand-bags. If there is suppuration, the joint should be aspirated or opened by an anterior incision, and Murphy's plan of filling the joint with formalin-glycerine may be adopted. In children, it is remarkable how completely the joint may recover.

If there is dislocation, the head of the femur should be reduced by manipulation with or without preliminary extension; it has been successful in about one-half of the cases in which it has been attempted. Preliminary tenotomy of the shortened tendons is required in some cases. When reduction by manipulation is impossible, the joint structures should be exposed by operation and the head of the bone replaced in the acetabulum. When the upper end of the femur has disappeared, the neck should be implanted in the acetabulum, and the limb placed in the abducted position.

#Arthritis Deformans.#--This disease is comparatively common at the hip, either as a mon-articular affection or simultaneously with other joints.

_The changes in the joint_ are characteristic of the dry form of the disease, and affect chiefly the cartilage and bone. The atrophy and wearing away of the articular surfaces are accompanied by new formation of cartilage and bone around their margins. The head of the femur may acquire the shape of a helmet, a mushroom, or a limpet shell, and from absorption of the neck the head may come to be sessile at the base of the neck, and to occupy a level considerably below that of the great trochanter (Fig. 120). These changes sometimes extend to the upper part of the shaft, and result in curving of the shaft and neck, suggesting a resemblance to a point of interrogation (Fig. 121). The acetabulum may "wander" backwards and upwards, as in tuberculous disease. It is usually deepened, and its floor projects on the pelvic aspect; its margins may form a projecting collar which overhangs the neck of the femur, or grasps it, so that even in the macerated condition the head is imprisoned in the socket and the joint locked. There is eburnation of the articular surfaces in those areas most exposed to friction and pressure.

These changes are necessarily associated with restriction of movement, and in advanced cases with striking deformity, which consists in shortening of the limb, usually with eversion and displacement of the trochanter upwards and backwards in relation to Nelaton's line.

The _clinical features_ are usually so characteristic that there is little difficulty in diagnosis. Restriction of the movements of abduction and adduction, the presence of cracking and of grating of the articular surfaces, and the aggravation of the pain and stiffness after resting the limb, are characteristic of arthritis deformans. The prominence of sciatic pain may lead to the disease being regarded as sciatica.

The greatest difficulty is met with in cases in which the disease occurs as mon-articular affection in adolescents, for the resemblance to tuberculous disease of the hip and to coxa vara may be close. Skiagrams do not always enable one to differentiate between them.

_Treatment_ is conducted on the same lines as in other joints. The normal movements are maintained by suitable exercises, and an effort is made to diminish the pressure on the articular surfaces in walking by the use of sticks or crutches.

Shortening of the limb may be compensated by raising the sole of the boot. When the X-rays show that the disability is mainly due to new bone locking the head of the femur, such new bone may be removed by operation, _cheilotomy_ (Sampson Handley). Excision of the joint has in some cases yielded satisfactory results; it is indicated in young patients who are otherwise healthy, and who are unable to walk on account of pain and deformity.

#Osteo-chondritis Deformans Juvenilis.#--Under this term Perthes describes an affection of the hip in children which differs in many respects from the juvenile form of arthritis deformans. Islands of cartilage appear in the epiphysis of the head of the femur, and the epiphysis itself becomes flattened without involvement of the articular surface or of the acetabulum.

The disease is met with in children between five and ten; there is a limp in walking without pain or sensitiveness, so that the child continues to take part in games. Abduction is markedly restricted and the trochanter is elevated and prominent. There is no crepitation on movement or other signs of involvement of the articular surfaces. The X-rays show the deformity of the head and clear areas in the interior of the upper epiphysis corresponding to the islands of cartilage; these clear areas resemble those due to caseous foci in tuberculous coxitis.

The disease runs a chronic course, and in the course of a year or two the limp and the restriction of abduction disappear, so that no active treatment is called for.

#Neuro-Arthropathies.#--_Charcot's disease_ is usually met with in men over thirty who suffer from tabes dorsalis. One or both hip-joints may be affected. Sometimes the first manifestation is a hydrops and a fluctuating swelling in the upper part of Scarpa's triangle. In many of the recorded cases, however, attention has first been directed to the disease by the deformity and limp associated with disappearance of the head of the femur, or by the occurrence of pathological dislocation. The absence of pain and tenderness is characteristic. When dislocation has occurred, the limb is short, and the upper end of the femur is freely movable on the dorsum ilii. When both hips are dislocated, the attitude and gait are similar to those observed in bilateral congenital dislocation. The rotation arc of the great trochanter may be much reduced as a result of the disappearance of the head of the femur. There may be considerable formation of new bone, giving rise to large tumour-like masses in relation to the capsular ligament and the muscles surrounding the joint.

The _treatment_ consists in protecting and supporting the joint. When the affection is unilateral, advantage may be derived from a Thomas' or other form of splint, along with a patten and crutches; in bilateral cases, from the use of crutches alone.

_Loose bodies in the hip_ are mostly the result of hypertrophy of synovial fringes in arthritis deformans and in Charcot's disease, and do not figure in the clinical features of these affections; Caird has observed a case in which the cavity of the joint and the bursa beneath the psoas were filled with loose bodies, many of which had undergone ossification and gave a characteristic picture with the X-rays.

_Hysterical affections_ of the hip resemble those in other joints.

THE KNEE-JOINT

The knee is more often the seat of disease than any other joint in the body.

The synovial membrane extends beneath the quadriceps extensor as a cul-de-sac, which either communicates with the sub-crural bursa, or forms with it one continuous cavity. When the joint is distended with fluid, this upper pouch bulges above and on either side of the patella, and this bone is "floated" off the condyles of the femur. When there is only a small amount of fluid, it is most easily recognised while the patient stands with his feet together and the trunk bent forwards at the hip-joints, and the quadriceps completely relaxed; the fluid then bulges above and on each side of the patella, and its presence is readily detected, especially on comparison with the joint of the other side.

On account of the great extent of the synovial membrane, a large quantity of serous effusion may accumulate in the joint in a comparatively short time, as a result either of injury or disease. The villous processes and fringes may take on an exaggerated growth, and give rise to pedunculated and other forms of loose body.

The bursae in the popliteal space, especially that between the semi-membranosus and the medial head of the gastrocnemius, as well as the sub-crural bursa, frequently communicate with the synovial cavity of the knee and may share in its diseases.

As the epiphyses at the knee are mainly responsible for the growth in length of the lower extremity, and are late in uniting with their respective shafts--twenty-one to twenty-five years--serious shortening of the limb may result if their functions are interfered with, whether by disease or injury. The epiphysial cartilages lie beyond the limits of the synovial cavity, so that infective lesions at the ossifying junctions are less likely to spread to the joint than is the case at the hip or shoulder, where the upper epiphysis lies partly or wholly within the joint; disease in the lower end of the femur is more likely to implicate the knee-joint than disease in the upper end of the tibia.

One of the commonest causes of prolonged disability and feeling of insecurity in the knee, is to be found in the wasting and loss of tone in the quadriceps extensor muscle; the feeling of insecurity is most marked in coming down stairs. The instability of the joint is often added to by stretching of the ligaments and lateral mobility. As a result of both of these factors the joint is liable to repeated slight strains or jars which irritate the synovial membrane and tend to keep up the effusion and excite the overgrowth of its tissue elements.

TUBERCULOUS DISEASE

While tuberculous disease of the knee is specially common in childhood and youth, it may occur at any period of life, and is not uncommon in patients over fifty. The disease originates in the synovial membrane and in the bones respectively with about equal frequency.

When the synovial membrane is diseased, it tends to grow inwards over the articular surfaces (Fig. 122), shutting off the supra-patellar pouch and fixing the knee-cap to the femur, and diminishing the area of the articular surfaces. The ingrowth of synovial membrane may fill up the cavity of the joint, or may divide it up into compartments. Ulceration of the cartilage and caries of the articular surfaces are common accompaniments.

The femur and tibia are affected with about equal frequency, and the nature and seat of the bone lesions are subject to wide variations. Multiple small foci may be found beneath the articular cartilage of the tibia, or along the margins of the femoral condyles--especially the medial. Caseating foci are comparatively rare, but they sometimes attain a considerable size--especially in the head of the tibia, where they may take the form of a caseous abscess. Sclerosed foci, which form sequestra, are comparatively common (Fig. 123).

#Clinical Types.#--(1) _Hydrops_ usually arises from a purely synovial lesion, but the joint may suddenly become distended with fluid when an osseous focus ruptures into the synovial cavity.

It is met with chiefly in young adults. As the fluid accumulates it gradually stretches the capsule, and pushes the patella forwards, so that it floats. There is little pain or interference with function; the patient is usually able to walk, but is easily tired. The amount of fluid diminishes under rest, and increases after use of the limb. In a certain number of cases it may be possible to recognise localised thickening of the synovial membrane, or the presence of floating masses of fibrin or melon-seed bodies. This is best appreciated if the knee is alternately flexed and extended by the patient while the surgeon grasps and compresses it with both hands. If the joint is opened, fibrinous material, often in the form of melon-seed bodies, may be found lining the synovial membrane.

Tuberculous hydrops is to be diagnosed from the effusion that results from repeated sprain, from the hydrops of loose body, gonorrhoea, arthritis deformans, Charcot's disease, and Brodie's abscess in the adjacent bone, and from the haemarthrosis met with in bleeders.

(2) _Papillary or Nodular Tubercle of the Synovial Membrane._--This is a condition in which there is a fringy, papillary, or polypoidal growth from the synovial membrane. It is most often met with in adult males. The onset and progress are gradual, and the chief complaint is of stiffness and swelling which are worse after exertion. Sometimes there are symptoms of loose body, such as occasional locking of the joint, with pain and inability to extend the limb; but the locking is easily disengaged, and the movements are at once free again. The patient may give a history of several years' partial and intermittent disability, with lameness and occasional locking, although he may have been able to go about or even to continue his occupation.

There is a moderate degree of effusion into the joint, and when this has subsided under rest it may be possible to feel ill-defined cords, or tufts, or nodular masses, and to grasp between the fingers those in the supra-patellar pouch. There is little wasting of muscles, and it is exceptional to have signs of disease of the articular surfaces or of cold abscess.

On opening the joint, there may escape fluid and loose bodies similar to those described under hydrops, and if the finger is introduced into the cavity, the upper pouch is felt to be occupied by fringes or polypoidal processes derived from the synovial membrane.

The diagnosis is to be made from arthritis deformans, and in some cases from loose body of other than tuberculous origin.

(3) _Cold abscess_ or _empyema_ of the knee is a rare condition, in which the joint becomes filled with pus. It usually results from a primary tuberculosis of the synovial membrane occurring in children reduced in health and the subject of tuberculosis elsewhere.

(4) _Diffuse Thickening of the Synovial Membrane--White Swelling._--So long as this form of the disease remains confined to the synovial membrane, the chief feature is that of an indolent elastic swelling in the area of the joint. The swelling tapers off above and below, so that it acquires a fusiform shape, and from the wasting of the muscles it appears greater than it really is. The range of movement is moderately restricted.

At first the patient limps, keeps the knee slightly flexed, and complains of tiredness and stiffness after exertion. As the articular surfaces become affected, there is pain, which is readily excited by jarring of the limb, or by any attempt at movement; the joint is held rigid, and there may be startings at night. If untreated, flexion becomes more pronounced--it may be to a right angle--the leg and foot are everted, and, in children, the tibia may be displaced backwards (Fig. 124). The wasting of muscles continues, the part becomes hot to the touch, the swelling increases, and may show areas of softening or fluctuation from abscess formation.

White swelling is to be differentiated from peri-synovial gummata, from myeloma and sarcoma of the lower end of the femur, and from bleeder's knee. In the first of these the swelling is nodular and less uniform, and there may be tertiary ulcers or depressed scars in the neighbourhood of the patella. In tumours the swelling is more marked on one side of the joint, it is uneven or nodular, it does not correspond to the shape of the synovial membrane, and may extend beyond the limits of the joint, and it involves the bone to a greater extent than is usual in disease of the joint. Skiagrams show expansion of the bone in central tumours, or abundant new bone in ossifying sarcoma. The diagnosis of bleeder's knee is to be made from the history.

(5) _Primary Tuberculous Disease in the Bones of the Knee._--So long as the foci are confined to the interior of the bone, it is impossible to recognise their existence, unless they are of sufficient size to cause enlargement of the bone or to be discernible in a skiagram.

#The formation of peri-articular abscess# takes place in rather more than fifty per cent. of cases. When left to themselves, such abscesses tend to spread up the thigh, or down the back of the leg between the superficial and deep layers of calf muscles, and numerous sinuses may result from their rupture through the skin.

#Attitudes of the Limb in Knee-Joint Disease.#--The attitude most often assumed is that of _flexion_, with or without _eversion of the leg and foot_. The flexion is explained by its being the resting attitude of the joint, and that which affords most ease and comfort to the patient. Once the joint is flexed, the involuntary contraction of the flexor muscles maintains the attitude, and if the patient is able to use the limb in walking, the weight of the body is a powerful factor in increasing it. The eversion of the leg is probably associated with contraction of the biceps muscle. _Backward displacement of the tibia_ is met with chiefly in neglected cases of chronic disease of the knee when the child has walked on the limb after it has become flexed.

In certain cases, _genu valgum_ or abduction of the leg is present along with a slight degree of flexion. The valgus attitude is associated with slight lateral displacement of the patella, with prominence and apparent enlargement of the medial condyle, with depression of the pelvis on the diseased side and apparent lengthening of the limb.

#Treatment of Tuberculous Disease of the Knee.#--Conservative measures are always indicated in the first instance, and are persevered with so long as there is a prospect of obtaining a movable joint.

_Conservative Treatment._--If the joint is sensitive and tends to be flexed, the patient is confined to bed, the limb is secured to a posterior splint, and extension with weight and pulley persevered with until these symptoms have disappeared; during this time, from three to six weeks, methods of inducing hyperaemia and other anti-tuberculous procedures are employed. If it is proposed to inject iodoform or other drug, the needle is inserted into the interval between the bones on the medial side of the ligamentum patellae or into the upper pouch when this is distended with fluid.

If there is no pain or tendency to flexion, or when these have been overcome, the limb is put up in a Thomas' splint (Fig. 125) and the patient allowed to go about. The splint is worn for a period varying from six to twelve months; before being discarded it may be left off at night; it is ultimately replaced by a bandage.

The indications for _operative treatment_ are: (1) marked symptoms of destruction of the articular cartilages; (2) a deformed attitude incapable of being rectified without operation; (3) a condition of the general health which requires that the disease should be got rid of as speedily as possible; (4) progress or persistence of the disease in spite of conservative treatment. When there is no prospect of recovery with a movable joint it is a waste of time and a possible source of danger to persevere with conservative measures. Operation permits of the disease being eradicated and the restoration of a useful limb within a reasonable time, averaging from three to six months.

In adults, the operation consists in excising the joint; in children the aim is to remove the diseased tissues without damaging the epiphysial cartilages.

Amputation is performed when the disease has relapsed after excision and there is persistent suppuration, and when life is threatened by the occurrence of tuberculosis in the lungs or elsewhere.

#Treatment of Deformities resulting from Antecedent Diseases of the Knee.#--Flexion is the commonest of these; when due to contracture of the soft parts, these are either stretched by degrees, the limb being encased in plaster after each sitting, or they are divided by open dissection in the popliteal space. If there is fibrous or osseous ankylosis, the choice lies between arthroplasty, the removal of a wedge of bone which includes the joint, or, in patients who are still growing, of a wedge from the femur above the level of the epiphysial cartilage. Backward displacement of the tibia, genu recurvatum, and genu valgum also require operative treatment.

OTHER DISEASES OF THE KNEE-JOINT

#Pyogenic diseases# result from infection through the blood stream, from one of the adjacent bones, or from a penetrating wound of the joint. The commoner types include the _synovitis_ associated with disease in the adjacent bone, _acute arthritis of infants_, joint suppuration in _pyaemia_, _pyogenic arthritis_ following upon penetrating wounds, and the affections which result from _gonorrhoeal_ or _pneumococcal_ infection.

_Treatment._--The limb is immobilised on a posterior splint so padded as to allow slight flexion at the knee, and extension applied with sufficient weight to relieve the pain; it is also of benefit to induce hyperaemia by one or other of the methods devised by Bier. To tap the joint, the needle is introduced obliquely into the supra-patellar pouch, and if it is necessary to open the joint, the incision is made on one or on both sides of the patella, and Murphy's plan of inserting formalin-glycerine may be employed. If the infection progresses and threatens the life of the patient, it may be necessary to lay the joint freely open from side to side, sawing across the patella, and, the limb being flexed, the whole wound is left open and packed with gauze. As the infection subsides, the limb is gradually straightened. If these methods fail, amputation through the thigh may be the only means of saving life.

#Arthritis deformans# affects the knee more frequently than any of the other large joints. The changes related to the synovial membrane here attain their maximum development, and may assume the form of hydrops with or without fibrinous bodies, or of overgrowth of the synovial fringes and the formation of pedunculated loose bodies. It is suggested that these synovial changes follow upon repeated sprains or upon a previous pyogenic infection of the joint. The effusion and stretching of the ligaments that follow upon a sprain are incompletely recovered from; the synovial membrane becomes puckered, the quadriceps atrophies and no longer puts the ligamentum mucosum on the stretch; and the infra-patellar pad of fat, not undergoing the normal compression during extension, is readily nipped between the femur and tibia. Each nipping implies a fresh sprain, with return of the effusion, and so a vicious circle is set up which terminates in what has been called a _villous arthritis_, with fringes and loose bodies; in time, the articular cartilage at the line of the synovial reflection undergoes fibrillation and conversion into connective tissue, and the process spreading to the articular surfaces, the picture of a rheumatoid arthritis is complete. Fibrillation of the cartilage imparts a feeling of roughness when the joint is grasped during flexion and extension, and lipping of the margins of the trochlear surface of the femur may be felt when the joint is flexed; it is also readily seen in skiagrams. When a portion of the "lipping" is broken off, it may give rise to a loose body. In advanced cases with destruction of the cartilages, there may be movement from side to side, with grating of the articular surfaces.

In the early stages, treatment consists in limiting the movements of extension by means of a splint provided with a hinge that locks at thirty degrees from full extension and vigorous massage of the quadriceps. In the dry, creaking forms of arthritis, the symptoms are relieved by introducing liquid vaseline into the joint. When the symptoms are due to the presence of fringes and loose bodies, these may be removed by operation. When the disease is of a severe type, and is confined to one knee, the question of excising the joint may be considered.

_Bleeder's knee_, _Charcot's disease_, _hysterical knee_, and _loose bodies_ in the joint have already been described.

THE ANKLE-JOINT

There is a common synovial cavity for the ankle and the inferior tibio-fibular joints. The epiphysial cartilage of the tibia lies above the level of this synovial cavity, but that of the fibula is included within its limits (Fig. 93). The talus is related to three articulations--the ankle above, the talo-navicular joint in front, and the calcaneo-taloid joint below. The tendon sheaths, especially those of the peronei and of the tibialis posterior, are liable to be infected by the spread of infective disease from the joint.

#Tuberculous Disease.#--Tuberculous disease at the ankle is met with at all ages. In the majority of cases the disease affects both bone and synovial membrane. Gross lesions in the bones are comparatively rare, and are chiefly met with in the head or neck of the talus.

_Primary synovial disease_ usually exhibits the features of white swelling, projecting beneath the extensor tendons on the dorsum, and, posteriorly, filling up the hollows on either side of the tendo Achillis and below the malleoli (Fig. 126). The foot may retain its normal attitude, or the toes may be pointed and adducted. The calf muscles are wasted, there is little complaint of pain, and the movements of the joint may be so little interfered with that the patient can walk without a limp. When the disease involves the articular surfaces, there is pain and sensitiveness, the movements are restricted or abolished, and the patient is unable to put the foot on the ground.

_A primary focus in the bone_ causes localised pain and tenderness, and a limp in walking, but the first sign may be the formation of abscess or the rapid development of articular symptoms. In such cases skiagrams afford valuable information.

Abscess formation is an early and prominent feature, whether the disease is of osseous or synovial origin, and sinuses are liable to form around the joint. Outlying abscesses and sinuses are usually the result of infection of the tendon sheaths in the neighbourhood.

_Diagnosis._--When teno-synovitis occurs independently of disease of the ankle, the swelling is confined to one aspect of the joint. In sarcoma of the lower end of the tibia, the swelling lacks the uniform distribution of that met with in joint disease. In Brodie's abscess of the lower end of the tibia there may be swelling of the ankle, but there is an area of special tenderness on percussion over the bone.

_Treatment._--The foot is immobilised at a right angle to the leg by splints or plaster of Paris; if articular symptoms are absent or have subsided, a Thomas' knee splint should be applied to enable the patient to move about without bearing his weight on the affected foot (Fig. 125). To inject iodoform, the point of the needle is inserted below either malleolus, and is then pushed upwards alongside of the talus. If localised disease in one of the bones is recognised before the joint is infected, it should be eradicated by operation.

When the disease is diffuse and resists conservative treatment, excision should be performed, the articular surfaces of the constituent bones being removed, and if necessary the whole of the talus.

Amputation is only called for in adults with rapidly progressing disease and diffuse suppuration, and in cases which have relapsed after excision.

The other diseases of the ankle include _pyogenic_, _gonorrhoeal_, _rheumatic_, _gouty_, and _hysterical_ affections, _arthritis deformans_, and _Charcot's disease_. The last-named is generally associated with a rapid and painless disintegration of the bones of the ankle and tarsus, resulting in great deformity and loss of the arch of the foot--sometimes associated with perforating ulcer of the sole.

Tuberculous disease in the #tarsus#, #metatarsus#, and #phalanges# has been considered in the chapter on Diseases of Bone.