CHAPTER IX

DISEASES OF INDIVIDUAL JOINTS

THE SHOULDER-JOINT

The shoulder is seldom the seat of disease, and most affections of the joint are met with in adults. In young subjects, infective processes result chiefly from extension of disease from the upper epiphysial junction of the humerus, which is partly included within the limits of the synovial cavity. The synovial membrane, in addition to lining the capsular ligament, is prolonged down the inter-tubercular (bicipital) groove around the long tendon of the biceps, and pus may escape from the joint by this diverticulum and gravitate down the arm; we have also observed loose bodies of synovial origin in this diverticulum. There is frequently a communication between the joint and the sub-deltoid bursa. There is no attitude characteristic of disease of the shoulder-joint, but the girdle is usually elevated, the upper arm held close to the side and rotated medially, while the elbow is carried a little backwards. In the later stages, the head of the humerus may be drawn upwards and medially towards the coracoid process. Fixation of the shoulder-joint is largely compensated for by movement of the scapula on the thorax, so that when testing for rigidity the scapula should be fixed with one hand while passive movements of the arm are carried out with the other. The deltoid is usually atrophied, allowing the acromion, coracoid, and great tuberosity of the humerus to stand out prominently beneath the skin. Swelling is rarely a prominent feature, except when there is a collection of synovial fluid or of pus in the bursa beneath the deltoid.

#Tuberculous Disease# is usually met with in young adults, and is more common in the right shoulder. The prominent features are pain, rigidity, and wasting of the deltoid and scapular muscles. The pain is sometimes severe, shooting down the arm and interfering with sleep, and it may be associated with tenderness on pressure over the upper end of the humerus. In cases with carious destruction of the articular surfaces there are starting pains, and the arm is shortened. If a cold abscess forms in the bursa underneath the deltoid, the pus may burrow and appear at the anterior or posterior boundary of the axilla or in the axillary space. Pus formed in the joint tends to gravitate along the inter-tubercular groove. The axillary glands may be infected.

The primary lesion is either a caseating focus in one of the bones--most often in the upper end of the humerus--or it is of the nature of caries sicca. The greater part of the head may disappear, and the upper end of the shaft be drawn against the socket. In exceptional cases, portions of the glenoid or humerus are found separated as sequestra, or the disease involves parts outside the joint, such as the acromion or coracoid process. Hydrops with melon-seed bodies is rare. In young subjects, destruction of the tissues at the ossifying junction may result in considerable shortening of the arm.

The _diagnosis_ is to be made from (1) arthritis deformans, in which the movements are less restricted, and are attended with grating and cracking; (2) paralysis involving the deltoid and scapular muscles--by the absence of pain, and the flail-like character of the movements; (3) disease in the sub-deltoid bursa--by the absence of rigidity and other evidence of implication of the articular surfaces; and (4) sarcoma of the upper end of the humerus--by the history of the case, the use of the X-rays or an exploratory incision. Injuries in the region of the upper epiphysis resulting in loss of movement, may, in the absence of a reliable history, be mistaken for tuberculous disease.

While the _prognosis_ is favourable on the whole, recovery is usually attended with fibrous ankylosis and incapacity to raise the arm above the level of the shoulder. The disease often progresses slowly, and may last for years.

_Treatment._--The limb should be immobilised in the position of abduction with the forearm and hand directed forwards; the most efficient apparatus is a plaster spica embracing the thorax and the upper limb down as far as the wrist. If the articular surfaces are affected and the disease is likely to lead to ankylosis, the arm should be abducted to a right angle. The severe pain of caries sicca may be relieved by blistering or by the application of the cautery. To inject iodoform, the needle is introduced either immediately outside the coracoid process, or just below the junction of the acromion process and spine of the scapula. When the disease does not yield to conservative measures, or the X-rays show a gross lesion in the bone, excision of the joint should be performed; a close fibrous ankylosis usually results, and the arm is quite a useful one provided the abducted position has been maintained throughout.

#Pyogenic Diseases.#--The shoulder-joint may be infected by extension of suppurative osteomyelitis from the upper end of the humerus, or from suppuration in the axilla, or through the blood stream by ordinary pus organisms, pneumococci, typhoid bacilli, or gonococci. Extension should be applied to the arm abducted at a right angle. When it is necessary to open the joint, the incision should be placed anteriorly in the line of the inter-tubercular groove; if a counter-opening is required it is made on the posterior aspect by cutting on the point of a dressing forceps introduced through the anterior incision.

#Arthritis Deformans.#--The shoulder is seldom affected alone, except when the arthritis is a sequel to injury, such as a fracture of the neck of the humerus. The common type of lesion is a dry arthritis with fibrillation and eburnation of the articular surfaces. The long tendon of the biceps is usually destroyed, the head of the bone is drawn upwards, and, after wearing through the capsule, rubs on the under surface of the acromion, which also becomes eburnated. The clinical features are pain, stiffness, and cracking on movement, and as these symptoms may also be caused by loose bodies in the joint, an X-ray picture should be taken to differentiate between them.

#Neuro-arthropathies# of the shoulder are met with chiefly in syringomyelia. In some cases there is a large fluctuating and painless swelling; in others marked and rapid wasting of the deltoid and scapular muscles with flail-like movements of the joint associated with disappearance of the upper end of the humerus (Fig. 104).

#Loose bodies# are rare in the shoulder; we have met with a case in which the joint-cavity was distended with loose bodies of synovial origin, and as most of these had undergone ossification, the X-ray appearances were highly characteristic. They were removed through an anterior incision.

#Ankylosis# is not so disabling at the shoulder as at other joints, as the mobility of the scapula on the chest wall largely compensates for the fixation of the joint.

THE ELBOW-JOINT

In disease of the elbow, the usual attitude is that of flexion with pronation of the hand. Swelling of the joint, whether from effusion of fluid or from thickening of the synovial membrane, is observed chiefly on the posterior aspect, above and on either side of the olecranon, because the synovial sac is here nearest the surface. The free communication between the elbow and the superior radio-ulnar joint should be borne in mind.

#Tuberculous disease# is the most common and important affection (Fig. 106). It usually occurs in patients under twenty, but may be met with at any age; in children the age-incidence is earlier than in the other large joints, a considerable proportion being met with in the first two years of life (Stiles). When the disease is confined to the synovial membrane, its onset is insidious, there is little or no pain, and no interference with any movement except complete extension. The chief evidence of disease is a white swelling on either side of and above the olecranon, obscuring the bony landmarks. The further progress is attended with wasting of the triceps, symptoms of involvement of the articular surfaces, and with abscess formation.

The occurrence of articular caries without swelling of the synovial membrane is exceptional, and is associated with a good deal of pain and considerable restriction of movement. Rigidity from muscular contraction occurs late, and is rarely complete. Tuberculous foci in the bones are met with chiefly in the lower end of the diaphysis of the humerus; in children, the epiphyses are so small that the ossifying junction is intra-articular. Foci are also met with in the upper end of the ulna. The grosser osseous lesions cause enlargement of the bone, and are readily demonstrated by skiagraphy. Abscess formation most commonly occurs beneath the triceps, and the abscess points at one or other edge of that muscle. A subcutaneous abscess may form over the upper end of the ulna or over the radio-humeral joint. Tuberculous hydrops with melon-seed bodies is rare.

_Treatment._--Conservative measures are persevered with so long as there is a prospect of securing a movable joint. The limb is placed in a light form of splint reaching from the axilla to the wrist, flexed to rather less than a right angle and with the hand semi-pronated and dorsiflexed. To inject iodoform or other anti-tuberculous agent, the needle of the syringe is easily introduced between the lateral condyle and the head of the radius. A localised focus of disease in one or other of the bones may be eradicated without opening into the synovial cavity.

If the articular surfaces are so involved that recovery is likely to be attended with ankylosis, the disease should be removed by operation, and cure with a useful and movable joint may then be reasonably anticipated within two or three months. When the patient's occupation is such that a strong stiff joint is preferable to a weaker movable one, bony ankylosis at rather less than a right angle should be aimed at.

#Arthritis deformans# occurs as a hydrops with hypertrophy of the synovial fringes and loose bodies, or as a dry arthritis with eburnation and lipping of the articular margins.

#Neuro-arthropathies# are met with chiefly in syringomyelia, and are attended with striking alterations in the shape of the bones and with abnormal mobility.

#Pyogenic diseases# result from staphylococcal osteomyelitis--chiefly of the humerus or ulna--and from gonorrhoea.

The remaining diseases at the elbow include syphilitic disease in young children, bleeder's joint, hysterical affections, and loose bodies, and do not call for special description.

#Ankylosis# of the elbow-joint, if interfering with the livelihood of the patient, may be got rid of by resecting the articular ends of the bones, or by inserting between them a flap of fascia and subcutaneous fat derived from the posterior aspect of the upper arm--_arthroplasty_.

THE WRIST-JOINT

The close proximity of the flexor sheaths to the carpal articulations permits of infective processes spreading readily from one to the other. The arrangement of the synovial membranes also favours the extension of disease throughout the numerous articulations in the region of the wrist.

#Tuberculous disease# is met with chiefly in young adults, but may occur at any age. It usually originates in the synovial membrane, but foci are frequently present in the carpal bones, and less commonly in the lower ends of the radius and ulna, or in the bases of the metacarpals. The clinical features are almost invariably those of white swelling, which is most marked on the dorsum where it obscures the bony prominences and the outlines of the extensor tendons. Wasting of the thenar and hypothenar eminences, and filling up of the hollows above and below the anterior annular ligament, render the appearance on the palmar aspect characteristic.

The attitude is one of slight flexion with drooping of the hand and fingers. The fingers become stiff as a result of adhesions in the tendon sheaths, and the power of opposing the thumb and fingers may be lost. Pain is usually absent until the articular surfaces become carious. Softening of the ligaments may permit of lateral mobility, and sometimes partial dislocation occurs. Abscess may be followed by sinuses and infection of the tendon sheaths, especially those in the palm.

The localisation of disease in individual bones or joints can be determined by the use of the X-rays.

_Treatment._--Conservative measures may be persevered with over a longer period than in most other joints. The forearm, wrist, and metacarpus are immobilised in the attitude of dorsal flexion, while the fingers and thumb are left free to allow of passive movements. It may be necessary to give an anaesthetic to obtain the necessary degree of dorsiflexion. To inject iodoform, the needle is inserted immediately below the radial or the ulnar styloid process. Sometimes the carpal bones are so soft that the needle can be made to penetrate them in different directions. Operative treatment is indicated in cases which resist conservative measures, or when the general health calls for speedy removal of the disease.

_Other diseases of the wrist_ are comparatively rare. They include pyogenic affections, such as those resulting from infective conditions in the palm of the hand, different types of gonorrhoeal, rheumatic, and gouty affections, and arthritis deformans. An interesting feature, sometimes met with in arthritis deformans, consists in eburnation of the articular surfaces of the carpal bones, although the range of movement is almost nil.

THE HIP-JOINT

Owing to the depth of this joint from the surface, it is not possible to detect the presence of effusion or of synovial thickening as readily as in other joints, hence in the recognition of hip disease we have to rely largely upon indirect evidence, such as a limp in walking, an alteration in the attitude of the limb, or restriction of its movements.

The whole of the anterior and fully one-half of the posterior aspect of the neck of the femur is covered by synovial membrane, so that lesions not only of the epiphysis and epiphysial junction, but also of the neck of the bone, are capable of spreading directly to the synovial membrane and to the cavity of the joint. Conversely, disease in the synovial membrane may spread to the bone in relation to it. Infective material may escape from the joint into the surrounding tissues through any weak point in the capsule, particularly through the bursa which intervenes between the capsule and the ilio-psoas, and which in one out of every ten subjects communicates with the joint.

TUBERCULOUS DISEASE

Tuberculous disease of the hip, morbus coxae, or "hip-joint disease," is especially common in the poorer classes. It is a frequent cause of prolonged invalidism, and of permanent deformity, and is attended with a considerable mortality. It is essentially a disease of early life, rarely commencing after puberty, and almost never after maturity.

#Pathological Anatomy.#--Bone lesions bulk more largely in hip disease than they do in disease of other joints--five cases originating in bone to one in synovial membrane being the usual estimate. The upper end of the femur and the acetabulum are affected with about equal frequency.

In addition to primary tuberculous lesions, secondary changes result from the inflamed and softened bones pressing against one another subsequent to the destruction of their articular cartilages. The head of the femur undergoes absorption from above downwards, becoming flattened and truncated, or disappearing altogether. In the acetabulum the absorption takes place in an upward and backward direction, whereby the socket becomes enlarged and elongated towards the dorsum