Movements at the wrist

Like the elbow, the wrist comprises two distinct components:

The movements at each component must be examined independently.

The radio-carpal joint. The normal range of flexion (palmar flexion) is 80 ° and of extension (dorsiflexion) 90 °. The range of adduction, or ulnar deviation, is about 35 °, and of abduction, or radial deviation, about 25 °. It is impracticable to measure the movements of the intercarpal joints individually, and it is simplest to regard them as integral parts of the radio-carpal joint.

A rapid and reasonably accurate method of comparing the range of flexion– extension movement on the two sides is as follows: To judge the range of extension: The patient places the palms and fingers of the two hands in contact in the vertical plane and lifts the elbows as far as he can while keeping the ‘heels’ of the hands together (Fig. 16.1). The angle between hand and forearm is easily compared on the two sides. To judge the range of flexion the manoeuvre is reversed. The patient places the backs of the hands together, with the fingers directed vertically downwards, and lowers the elbows as far as he can (Fig. 16.1). The angle between hand and forearm is compared on the two sides.

Fig. 16.1 A A simple method of comparing the range of extension and flexion at the two wrists. B Note the obvious impairment at the left wrist.

The inferior radio-ulnar joint. The normal range is 90 ° of supination and 90 ° of pronation. To determine the range accurately the patient’s elbows must be flexed to a right angle in order to eliminate rotation at the shoulder (see Fig. 15.1).

It must be emphasised that impaired rotation does not necessarily denote an abnormality of the wrist: it may equally well be caused by a disorder of the elbow or of the forearm.

Movements of the hand

Movements of the hand occur mainly at three groups of joints:

Carpo-metacarpal joint of thumb. This joint allows movement in five directions: flexion, or movement of the thumb metacarpal medially in the plane of the palm; extension, or movement of the thumb metacarpal laterally in the plane of the palm; adduction, or movement of the metacarpal towards the palm in a plane at right angles to it; abduction, or movement of the metacarpal away from the palm in a plane at right angles to it; and opposition, or rotation of the metacarpal to bring the thumb nail into a plane parallel with the palm (Fig. 16.2).

Fig. 16.2 To show the difference between flexion of the thumb across the palm A and true opposition B. In opposition the thumb metacarpal is rotated so that the thumb nail lies in a plane parallel with the palm.

Metacarpo-phalangeal joints of thumb and fingers. These joints allow flexion–extension movement through 90 ° (the range is variable and often through as little as 30 ° in the thumb), and a small range of abduction from, and adduction to, the midline of the middle finger.

Interphalangeal joints of thumb and fingers. These are true hinge joints, allowing only flexion and extension. In the fingers, the range of flexion is 90 ° at the proximal interphalangeal joints, and 45 ° at the distal interphalangeal joints. In the thumb, the range of movement at the interphalangeal joint is usually about 80 °.

Power

Test the power of each movement in turn. In the hand this examination demands considerable patience, for each muscle group must be tested individually. Thus in the thumb it is necessary to test the abductors, the adductor, the extensors (longus and brevis), the flexors (longus and brevis), and the opponens. In the fingers test the flexors (profundus and superficialis), the extensor digitorum and extensor indicis, the interossei and the lumbricals. Grip: Test the power of grip, which demands the combined action of the flexors and extensors of the wrist and the flexors of the fingers and thumb.

Nerve function

The state of the median, ulnar, and radial nerves is determined by tests of sensory function, motor function, and sweating. The ulnar nerve normally supplies sensation to the ulnar side of the hand together with the little finger and half the ring finger (Fig. 16.3).

Fig. 16.3 A and B Sensory distribution of the ulnar, radial and median nerves in the hand.

The remainder is largely innervated from the median nerve with some overlap on the dorsum of the hand from the radial nerve (Fig. 16.3). Only a small skin area at the base of the thumb is purely supplied by the radial nerve. Intact function of the median nerve is indicated by ability to oppose the thumb to the little finger (see Fig. 16.2). Intact ulnar nerve function is shown by ability to spread the fingers apart and to bring them together again to grip a card between the middle and ring fingers (Fig. 16.4). An index of radial nerve function is the ability to extend the thumb and to extend the fingers at the metacarpo-phalangeal joints.

Fig. 16.4 B Test of ulnar nerve motor function in interossei. B Test of radial nerve motor function in wrist and finger extensors.

Circulation

The state of the circulation is assessed from the condition of the arterial pulses, the warmth and colour of the digits, the capillary return at the nail beds, and cutaneous sensibility. It should be remembered that sensibility to touch in the fingers is a most useful index of the adequacy of the circulation. Nerves require a blood supply to enable them to conduct impulses, and if the circulation is interrupted sensibility is quickly lost.

Extrinsic sources of forearm and hand symptoms

It is sometimes difficult to determine whether symptoms and signs in the forearm or hand are caused by a local disorder or whether they are referred from a more proximal lesion. This difficulty arises mainly in neurological conditions. For instance, the symptoms of compression of the median nerve in the carpal tunnel may be mimicked closely by a prolapsed cervical disc, and the symptoms of constriction of the ulnar nerve at the elbow may likewise be confused with those from a low cervical disc lesion or a cervical rib. When symptoms in the hand are not satisfactorily explained by the local condition a search must be made for a possible cause in the neck, upper arm, or elbow.

Imaging

Radiographic examination. Routine radiographs should include antero- posterior and lateral projections of the forearm, wrist, and hand. For detailed study of the carpal bones additional oblique projections are required.

If it is suspected that the symptoms may be referred from the neck or proximal part of the limb, radiographs of the appropriate part should be obtained.

ACUTE OSTEOMYELITIS (General description of acute osteomyelitis, p. 85)

Acute osteomyelitis is rather uncommon in the forearm bones. As in other sites, the infection may be blood-borne (haematogenous) or it may be introduced from without, usually in consequence of a compound fracture. The haematogenous type occurs mainly in children. It affects the radius more often than the ulna, and the lower metaphysis rather than the upper (see Fig. 7.3B).

The clinical features and treatment are like those of acute osteomyelitis elsewhere.

CHRONIC OSTEOMYELITIS (General description of chronic osteomyelitis, p. 90)

As in other bones, chronic osteomyelitis of the radius or ulna follows an acute infection.

Treatment. In most cases treatment should follow the usual lines, reliance being placed on rest and antibacterial drugs for non-suppurative flares of infection, and on thorough drainage operations and sequestrectomy for persistent purulent discharge.

BONE TUMOURS IN THE FOREARM AND HAND

Benign tumours (General description of benign tumours of bone, p. 106)

Any type of benign tumour may occur in the bones of the forearm and hand. Only chondroma and giant-cell tumour require further mention here because of their more common occurrence at these anatomical sites.

Chondroma

Enchondroma, which grows within the bone and expands it, is prone to occur in the metacarpals and phalanges of the hand presenting with deformity or pathological fracture. The tumour may be solitary, but in the condition of multiple enchondromatosis, or Ollier’s disease, the tumours may affect many bones in the hand causing ugly swelling and deformity of the fingers (Fig. 16.5). Malignant transformation is hardly known in a solitary chondroma of a bone of the hand, but it is a possibility in cases of multiple enchondromatosis, leading to chondrosarcoma.

Fig. 16.5 Multiple enchondromata in the metacarpals and phalanges.

Treatment. If small, the tumour should be treated expectantly and fractures normally heal with simple splintage. Operation is required only if the tumour is found to be enlarging. Large tumours should be excised and sent for routine histological examination, the bone substance being restored by cancellous bone grafts.

Enchondromas of long bones are less common in the forearm, though these bones may be affected by multiple osteochondroma in the hereditary condition of diaphyseal aclasis (p. 63). These tumours may interfere with the normal growth of the affected bone resulting in shortening and deformity.

Enchondromas occur chiefly in multiple form, in the condition known as dyschondroplasia, Ollier’s disease, or multiple chondromatosis. Their special significance in the forearm lies in the fact that the tumours may interfere with the normal growth of the affected bone. If growth is retarded in one bone but proceeds normally in its partner marked curvature of the bones is to be expected, and it may cause ugly deformity, as seen commonly in dyschondroplasia.

Treatment. Severe deformity from uneven growth of the radius and ulna should be corrected by osteotomy, combined when necessary with excision of the distal ulna, or sometimes the head of the radius.

Giant-cell tumour (osteoclastoma)

The lower end of the radius is one of the common sites in the upper limb for the development of a giant-cell tumour, which though classed as benign may show invasive tendencies. The lower end of the ulna is also susceptible. The tumour extends into the former epiphysial region close up to the articular surface (Fig. 16.6).

Fig. 16.6 A and B Radiographs of wrist showing a giant cell tumour in the distal radius. The lucent lesion has ill-defined proximal margins with a narrow zone of transition and lies in a typical subarticular position in the epiphysis.

Treatment. If the tumour is in the lower end of the radius radical excision and replacement by a suitable bone graft is to be recommended. A graft obtained from the upper part of the fibula is suitable because its shape matches that of the original bone. Ideally, the graft should be taken with the supplying artery and veins, which are anastomosed to suitable vessels in the recipient area by a microsurgical technique. If the lower end of the ulna is the part affected the bone should be excised up to a point well proximal to the tumour. The resulting disability is negligible.

VOLKMANN’S ISCHAEMIC CONTRACTURE¹

This is a flexion deformity of the wrist and fingers from fixed contracture of the flexor muscles in the forearm.

Cause. It is caused by ischaemia of the flexor muscles, brought about by injury to, or obstruction of, the brachial artery near the elbow; or by tense oedema of the soft tissues of the forearm constrained within an unyielding fascial compartment.

Pathology. The effects of sudden occlusion of the brachial artery vary. In a few worst cases gangrene of the fingers will follow. Usually, however, the collateral circulation is sufficient to keep the hand alive, but not to nourish adequately the flexor muscles of the forearm or the main peripheral nerve trunks. The ischaemia that follows tense oedema in the anterior fascial compartment of the forearm, a consequence of severe injury in the region, has similar effects. Necrosis of muscle fibres of the forearm flexor group – especially the flexor digitorum profundus and flexor pollicis longus – with subsequent fibrosis and shortening, is the essential feature of Volkmann’s contracture. It is often associated with temporary or permanent ischaemic paralysis of the peripheral nerves, especially the median nerve.

Any major fracture in the elbow region or upper forearm may lead to arterial occlusion. That most commonly responsible is a supracondylar fracture of the humerus with displacement, the brachial artery being severed or contused by the sharp lower end of the main shaft fragment (Fig. 16.7). Contusion alone is sufficient to interrupt the flow of blood, because the artery goes into spasm and its lumen may be occluded by thrombosis.

Fig. 16.7 To show how a supracondylar fracture of the humerus may damage the brachial artery, with risk of gangrene or ischaemic contracture. Over-tight plaster or dressings may have the same result.

Progressive oedema within the closed anterior fascial compartment of the forearm – for instance after fracture of the forearm bones – is commonly responsible for obstruction of the arterial flow (compartment syndrome).

In some cases the cause of the vascular obstruction is an over-tight plaster or bandage.

Clinical features. The condition is commonest in children. After sustaining a supracondylar fracture of the humerus or some other injury in the elbow region or forearm, the child complains of severe pain in the forearm.

On examination in the incipient stage, the fingers are white or blue, and cold. The radial pulse is absent. Active finger movements are weak and painful. Passive extension of the fingers is especially painful and restricted. There may or may not be evidence of interruption of nerve conductivity – namely, anaesthesia of the fingers and paralysis of the small muscles of the hand.

In the established condition, which develops gradually within a few weeks of the injury, there is a striking flexion contracture of the wrist and fingers, from shortening of the fibrotic forearm flexor muscles (Fig. 16.8). Sensory and motor paralysis of the hand may persist as complicating factors, but they do not form an essential feature of Volkmann’s contracture as such.

Fig. 16.8 Typical appearance of the hand in established Volkmann’s ischaemic contracture.

Diagnosis. In the incipient stage absence of the radial pulse, with marked unwillingness to extend the fingers because of pain, should always arouse suspicion of Volkmann’s contracture. If there are also anaesthesia and paralysis of the hand the diagnosis is practically certain. In the established condition the history and clinical features make the diagnosis clear.

Volkmann’s ischaemic contracture bears no real resemblance to Dupuytren’s contracture (p. 321), for it affects the wrist as well as all the joints of the fingers, and there is no palpable thickening in the palm. Moreover the contracture is demonstrably brought about by shortening of the flexor muscles, because if the wrist is flexed passively to relax the flexor tendons the range of extension at the finger joints is increased. Conversely, if the tendons are relaxed by flexing the fingers fully the range of wrist extension is increased (Fig. 16.9).

Fig. 16.9 In Volkmann’s contracture the wrist can be partly extended if the fingers are flexed A, and the fingers can be partly extended if the wrist is flexed B : but the shortened fibrotic flexor muscles prevent extension of wrist and fingers together.

Treatment. In the incipient stage the problem is that of dealing with a sudden occlusion of the brachial artery or obstruction to the blood flow within a tightly congested fascial compartment. The case must be handled as an emergency, because the effects of occlusion become irreversible after about six hours. The following action must be taken:

First step. All splints, plaster, and bandages that might be obstructing the circulation are removed. In the case of a fracture, gross displacement of the fragments is corrected as far as possible by gentle manipulation and a well-padded plaster splint is applied. Likewise if the elbow is dislocated it must be reduced without delay. Heat cradles or hot bottles are applied over the other three limbs and trunk to promote general vasodilation.

If these measures fail to bring about a return of adequate circulation within half an hour, the next step is taken:

Second step. At operation the anterior fascia of the forearm is exposed and split longitudinally throughout its length to open the fascial compartment, allowing the muscles to bulge through the gap. The brachial artery is then explored. If there is occlusion from kinking or spasm of the artery an attempt is made to relieve it by freeing the vessel and applying papaverine. If this fails, the artery may be distended by the injection of saline between clamps. In the last resort, the artery may have to be opened and damaged intima removed; or the damaged length of artery may be excised and continuity restored by a vein graft. These procedures are best accomplished using magnification techniques, by a surgeon with wide experience of vascular surgery.

In the established stage restoration to normal is impossible: reconstructive surgery at best can only improve what function remains. The choice of treatment depends upon the circumstances of each case. In a mild case acceptable function may be restored by intensive exercises guided by a physiotherapist: such cases are however exceptional. In more severe cases the muscle shortening may be counteracted by shortening of the forearm bones, or by detachment and distal displacement of the flexor muscle origin (muscle slide operation).

In selected cases with severe muscle infarction, however, the best results are probably obtained by excision of the dead muscles and subsequent transfer of a healthy muscle (for example, a wrist flexor or a wrist extensor) to the tendons of flexor digitorum profundus and of flexor pollicis longus to restore active flexion of the digits. These muscle transfers may be combined, in appropriate cases, with arthrodesis of the wrist. When the median nerve is irreparably damaged by ischaemia nerve grafting is sometimes successful in restoring limited nerve function.

MADELUNG’S DEFORMITY¹ (Radio-ulnar dyschondrosteosis)

Madelung’s deformity (radio-ulnar dyschondrosteosis) is a congenital subluxation or dislocation of the lower end of the ulna, from malformation of the bones. Although it is seemingly a localised disorder there may be minor generalised abnormalities of bone structure, often with short stature.

A similar wrist deformity is more often caused by disease or injury, such as a fracture of the lower end of the radius with proximal displacement of the lower fragment.

The deformity varies in degree from a slight prominence of the lower end of the ulna at the back of the wrist, to complete dislocation of the inferior radio-ulnar joint with marked radial deviation of the hand (Fig. 16.10). The more severe types of deformity may be associated with congenital absence or hypoplasia of the radius.

Fig. 16.10 Relative shortening of radius with subluxation of inferior radio-ulnar joint, radial deviation of the hand and prominent head of ulna (Madelung’s deformity).

Treatment. If the disability justifies operation the lower end of the ulna should be excised. In a severe case, with marked radial deviation of the hand, it may be necessary also to fuse the radius (or ulna, if the radius is absent) to the carpus in order to gain satisfactory correction.

PYOGENIC ARTHRITIS OF THE WRIST AND HAND (General description of pyogenic arthritis, p. 96)

Pyogenic arthritis of the wrist is uncommon. Infection may be haematogenous, or it may be introduced through a penetrating wound. Spread from a focus of osteomyelitis is rare, partly because osteomyelitis itself is uncommon in the forearm bones, and partly because the lower metaphysis of the radius is entirely outside the capsule of the joint. (The lower metaphysis of the ulna is partly intracapsular (see Fig. 7.2).)

In the hand, any of the small joints may be infected by pyogenic organisms. The distal interphalangeal joints of the digits are prone to infection spreading from a suppurative lesion in the adjacent pulp space, or from a penetrating wound. These infections often cause permanent damage to the joint, with impairment of movement or even rigid ankylosis. Radiographs in the late stage of infection may show diffuse rarefaction, loss of cartilage space and some bone destruction.

The clinical features and treatment of pyogenic arthritis are similar to those at other sites.

RHEUMATOID ARTHRITIS OF THE WRIST AND HAND (General description of rheumatoid arthritis, p. 134)

Rheumatoid arthritis commonly affects the wrists and hands and is a major cause of serious loss of function and of ugly deformity. Usually many or all of the joints of the hand are affected, though occasionally the disease may begin in a single joint. Affected joints are swollen from synovial thickening, and movement is restricted. In the later stages articular cartilage and the underlying bone are eroded, and the fingers tend to deviate medially (‘ulnar drift’), with dorsal prominence of the metacarpal heads and characteristic visible deformity (Fig. 16.11A). At the wrist joint the disease commonly results in dorsal subluxation and dislocation of the ulnar head accompanied by subluxation of the carpus on the radius and radial deviation of the hand. Radiographs do not show any abnormality at first. Later, there is diffuse rarefaction of the bones. Later still, in progressive disease, destruction of cartilage leads to narrowing of the joint space (Fig. 16.11B), and the subchondral bone may be eroded.

Fig. 16.11 A Typical appearance of hand in long-established rheumatoid arthritis of wrist, metacarpo-phalangeal and interphalangeal joints. B Radiograph of the hand showing advanced erosive arthropathy due to rheumatoid arthritis. There is extensive destruction and subluxation of the radio-carpal, carpal, metacarpo-phalangeal, and interphalangeal joints with typical ulnar deviation of the fingers.

Important though these joint changes are in rheumatoid disease of the hand, equally serious disability may be caused by involvement of the soft tissues. These soft-tissue changes may take several forms, the most important of which are:

Chronic tenosynovitis. Masses of greatly thickened vascular synovial tissue envelop the flexor or the extensor tendons over the wrist or in the hand. Proliferation of the tenosynovium combined with nodular formation in the flexor tendon may produce symptoms of trigger finger.

Rupture of tendons. Both the extensor and the flexor tendons are liable to spontaneous rupture, from softening or fraying where they lie within inflamed synovial sheaths. The extensor pollicis longus, extensor digitorum, and extensor digiti minimi are the tendons that most commonly rupture.

Contracture of intrinsic muscles