16 The forearm, wrist, and hand

So much in everyday life depends upon the efficient working of the hand, and so great is the practical and economic consequence of its disablement, that the care of the diseased or injured hand has become one of the most vital branches of orthopaedic surgery. It is also one of the most fascinating.

Hand surgery is an art and a science in itself. Indeed it has already become a distinct speciality, demanding a knowledge and experience not only of orthopaedic surgery but also of plastic surgery, microvascular surgery, and neurology.

In the treatment of hand disorders the primary emphasis should always be on restoration of function. Keen judgement is often called for in deciding between the claims of rest and of movement. It should be remembered that the hand tolerates immobilisation badly. Whereas the wrist may be immobilised for many weeks or even months with impunity, to immobilise injured or diseased fingers for a long time is to court disaster in the form of permanent joint stiffness. Although rest may be essential in the early days after a hand injury or in the acute stage of an infection, active finger exercises must be insisted upon as soon as that stage has passed. It is wise to accept it as a general rule that fingers should never be immobilised for longer than two, or at most three, weeks.

SPECIAL POINTS IN THE INVESTIGATION OF FOREARM, WRIST, AND HAND COMPLAINTS

1. LOCAL EXAMINATION OF THE FOREARM, WRIST, AND HAND
Inspection
Bone contours	Metacarpo-phalangeal joints—
Soft-tissue contours	Flexion–extension; adduction–
Colour and texture of skin	abduction
Scars and sinuses	Interphalangeal joints—Flexion–extension
Palpation	Power
Skin temperature	Power of each muscle group in control of: 1 wrist movement; 2 thumb and finger movement; and 3 gripping
Bone contours
Soft-tissue contours
Local tenderness
Movements (active and passive)	Stability
At the wrist:	Tests for abnormal mobility
Radio-carpal joint—Flexion–extension; adduction–abduction	Nerve function
Inferior radio-ulnar joint—Supination and pronation	Tests of sensory function, motor function, and sweating in distribution of median, ulnar, and radial nerves
At the hand:	Circulation
Carpo-metacarpal joint of thumb—Flexion–extension; adduction–abduction; opposition	Arterial pulses, warmth and colour, capillary return, cutaneous sensibility
2. EXAMINATION OF POSSIBLE EXTRINSIC SOURCES OF FOREARM AND HAND SYMPTOMS
This is important if a satisfactory explanation for the symptoms is not found on local examination. The investigation should include: 1 the neck and thoracic inlet, with special reference to the brachial plexus 2 the upper arm 3 the elbow
3. GENERAL EXAMINATION
General survey of other parts of the body. The local symptoms may be only one manifestation of a more widespread disease

Movements at the wrist

Like the elbow, the wrist comprises two distinct components:

1 the radio-carpal joint (including the intercarpal joints), allowing flexion, extension, adduction, and abduction

2 the inferior radio-ulnar joint, allowing supination and pronation.

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:

1 the carpo-metacarpal joint of the thumb

2 the metacarpo-phalangeal joints

3 the interphalangeal 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.

DISORDERS OF THE FOREARM

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.

Malignant tumours (General description of malignant tumours of bone, p. 112)

The radius and ulna are seldom affected by malignant bone tumours, whether primary or metastatic. When osteosarcoma does occur in the forearm the lower end of the radius is the usual site. Malignant change to chondrosarcoma is more common when there are multiple enchondromas present in the small bones of the hand.

VOLKMANN’S ISCHAEMIC CONTRACTURE ¹

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).