The wrist joint is commonly injured in those sporting activities where falls are numerous on to hard surfaces as in rugby, football, ice-skating and so on. However, repetitive injuries to surrounding tendonous structures may be sustained by high levels of repetitive activity in tennis or badminton: usually the precipitating stresses are chronic and are exacerbated by the relative avascu-larity of the tendon structure which has a low metabolic rate.
The radio-carpal or wrist joint is a condyloid or bi-axial joint. The parts forming it are the distal end of the radius and lower surface of the articular disc which stretches from the ulnar margin of the radius to the notch at the base of the styloid process of the ulna above, and the lunate, scaphoid and triquetral bones below. The former constitute a transverse elliptical concave surface, the ‘receiving cavity’ and the latter form a smooth convex surface received into that cavity.
The line of the joint corresponds to a line convex upwards joining the styloid process of the radius and ulna .
The joint is surrounded by an articular capsule strengthened by anterior and posterior ligaments together with medial and lateral ligaments. The ‘articular disc’ is triangular in shape and binds the lower ends of the radius and ulna together. It is attached, by its apex, to a depression between the ulnar styloid and the inferior surface of the head of the ulna and, by its base, to the proximal edge between the ulnar notch of the radius and its carpal surface . When the hand is adducted, it articulates with the triquetral bone and when the hand is neutral, with the lunate. As hand movements on the forearm are not solely confined to the radio-carpal joint it is necessary to consider the mid-carpal joint in the context of wrist injuries. This consists of the joints between the proximal and distal row of carpal bones and between the carpal bones themselves in the proximal row.
The joints of the proximal row of carpal bones
The joints between the scaphoid, lunate and triquetral bones are of the plane variety and are connected by dorsal, palmar and interosseous ligaments. The dorsal and palmar ligaments are weaker than the dorsal (Chaubal, 1959). The interosseous ligaments are two narrow bundles, one connecting the lunate and scaphoid bones, the other the lunate and triquetral bones.
The joints of the two rows of carpal bones with each other The joint between the .scaphoid, lunate and triquetral bones on the one hand and the second row of carpal bones on the other is named the mid-carpal joint and is made up of two portions: on the medial side is the head of the capitate bone and the hamate bone which articulate with the concavity formed by the scaphoid, lunate and triquetral bones and constitute a modified condyloid joint; on the lateral side the trapezium and trapezoid articulate with the scaphoid and constitute a plane joint. The ligaments are the dorsal, palmar, medial and lateral. The lateral and medial ligaments are short: the one is placed on the radial and the other on the ulnar side of the carpus. The former, the stronger and more distinct, connects the scaphoid and trapezium, the latter the triquetral and hamate.
About 60 to 65 per cent takes place at the mid-carpal joint. The entire proximal surface of the scaphoid is in contact with the radius, the styloid process of which touches the trapezium. The lunate moves under the triangular cartilage.
About 50 per cent of ulnar deviation takes place at the mid-carpal joint. The line of transmission of forces passes through the capitate and the proximal half of the scaphoid and the radial styloid.
The tendons around the wrist
At the level of the lower radius and ulna a transverse section shows the tendons in distinct groupings, flexor tendons anteriorly, extensors dorsally and thumb tendons on the outer side of the radius . Two
Movements of hand and forearm
These movements involve both radio-carpal and mid-carpal joints. They are flexion, extension, radial deviation and ulnar deviation.
About 65 to 75 per cent of flexion occurs at the radiocarpal (wrist) articulation, the rest at the mid-carpal joint. The lunate is almost horizontal, so that most of its proximal articular surface is dorsal instead of being in contact with the articular surface of the radius.
Most movement takes place at the mid-carpal joint. In extension and hyperextension, the lunate turns its distal articular surface dorsally; the capitate turns and becomes vertical with its base orientated dorsally and its neck abuts against the posterior lip of the radius. The proximal end of the scaphoid follows the lunate and the distal part of the scaphoid follows the capitate only partially. A large part of the proximal articular surface of the lunate remains unsupported anteriorly by any bony socket. synovial sheaths envelop the flexors, one for the superficial and deep flexors of the fingers, the other for the flexor pollicis longus. On the back of the wrist, beneath the fibrous extensor retinaculum, lie the six tunnels for the passage of the extensor tendons. One tunnel on the lateral side is for the abductor pollicis longus and extensor brevis; next, behind the styloid process are the tendons of the extensor brevis and the longus of the wrist, on the medial side of the dorsal tubercle of the radius the extensor longus of the thumb, then the extensor digitorum and extensor indices. Between the radius and the ulna is the extensor digiti minimis and lastly, between the head styloid process of the ulna is the extensor carpi ulnaris.
INJURIES TO THE SOFT TISSUES
Sprains of the wrist
It is true that falls on the hand may sometimes cause a synovitis of the synovial membrane (lining the joint) and an effusion into the joint ensues concomitant to sprains of the volar wrist ligament. These injuries are far rarer than bone injuries but nevertheless one does see them without bone damage. The injury may be treated by a simple elastic bandage for ten to fourteen days.
In such sports as tennis, squash, badminton and rowing which require repetitious movement of the wrist tendons and owing to their relative avascularity, the wrist tendons become the site of swelling (tendinitis) or the investing synovium and fibrous sheaths become irritated (peritendinitis). The commonest site is certainly in the thumb extensor pollicis brevis and abductor pollicis longus on the radial side of the wrist. There is aching pain with slight swelling over the lower quarter of the radius and thumb movements are accompanied by ‘wash-leather creaking’. Temporary rest from sport is necessary. It is usually wise to apply a dorsal plaster of Paris slab to include the thumb, wrist and forearm or a local injection of anaesthetic and hyaluronidase prior to this helps relieve symptoms. Similar attacks in the flexor carpi radialis and extensor carpi ulnaris are occasionally seen with acute local tenderness or swelling over the area just prior to the insertions into bone: they are treated in a similar fashion to the thumb tendons.
Pain over the radial side of the wrist associated with thickening of the fibrous sheath (De Quervain’s disease, 1895) is a well-known entity. Careful palpation may reveal a small hard fibrous nodule about the size of half a pea. Pain is produced by adducting the thumb across the palm of the hand. Provided the condition is not chronic, hydrocortisone injections may give relief; however, if it is chrome, then division with removal of a segment cures the condition. Care has to be taken not to injure the filaments of the radial nerve which pass over this area as a divided nerve may leave a painful neuroma, which in itself is vulnerable to repeated trauma.
Acute peritendinitis crepitans
This is an inflammatory condition of acute onset which appears to involve a large area of tendon sheaths; it is commonly seen in athletes in the extensor longus tendon and its muscle. The swelling extends usually from the wrist across the lower forearm, and on thumb movements creaking is felt underneath the examining fingers. A similar condition is mainly seen in the extensor tendons crossing the dorsum of the wrist beneath the extensor retinaculum. The condition is best treated by splintage, resting the part for at least two weeks.
Injuries to the triangular cartilage of the wrist
This rare injury usually occurs on falls on the outstretched hand with an added rotational element. It involves detachment of the apex of the triangular cartilage from the ligamentous attachment to the fossa on the lower ulnar head . On rotation of the forearm, it gives rise to a disturbing ‘click’ which may be painful. If acute and diagnosed early, it is best treated by repair of the ligamentous attachment. If chronic, it is usually treated by excision of the whole cartilaginous structure.
FRACTURES AND DISLOCATIONS AROUND THE WRIST The scaphoid fractures
The scaphoid may be fractured at any of three levels -the distal pole, the waist or the proximal pole. The most common level is the ‘waist’ fracture, the others being comparatively rare. The blood supply variations of the scaphoid may account for the occasional ‘death’ of the proximal segment. One of the most common fractures seen in sports is the ‘waist’ fracture of the scaphoid , caused by falls on the outstretched hand or ‘hand-off injury in rugby. There is swelling of the wrist in the region of the ‘anatomical snuff-box’, with tenderness in the same area; there may initially be a negative x-ray but this should not put one off doing a further x-ray examination between the tenth and fourteenth day, when the fracture line may become evident.
The fracture should be immobilised by plaster which includes the thumb up to the distal joint and the forearm up to below the flexor elbow crease. The position of immobilisation should be in the ball-holding position of the hand with the wrist in dorsiflexion . This fixation should be maintained for six to twelve weeks. If, at the end of this period, healing is not evident on x-ray then the freedom of the hand should be allowed; however, if pain is encountered on activity then internal fixation by screws should be done (Maudsley and Chen, 1972). London (1961) has shown that the majority of fractures given this freedom will unite but the percentage of non-union in the experience of this author has been up to 25 per cent and screw fixation has been so successful that he has adopted this procedure.
Established non-union of the scaphoid
The inevitable result of non-union of the scaphoid is the establishment of degenerative arthritis of the mid-carpal and radio-carpal joints. Although this may be painless it always results in limitation of wrist movement, and in the athlete where wrist trauma is apt to occur injury causes further pain. In these instances the scaphoid should be curetted, packed with bone and internally fixed by screwing, with, perhaps, excision of the radial styloid.
Established painful arthritis
Painful arthritis is probably best treated by excision of the proximal carpus or wrist arthrodesis.
Rupture of the inter-osseous ligaments between scaphoid and lunate This results often and is not recognised; a gap occurs between the scaphoid and the lunate which can be painful. It is diagnosed by x-ray and the gap noted. The injury is best treated by operative re-position and internal fixation.
Dislocation of the lunate
The lunate is a wedge-shaped bone with its broad base forward. A fall on the outstretched wrist may displace it forward by rupture of its dorsal attachment to the capitate . The anterior proximity of the median nerve within the confines of the carpal tunnel often causes numbness or tingling in the thumb and radial three ringers. The diagnosis is confirmed by x-ray examination and in new cases re-position may be afforded by traction and a direct push from in front of the wrist. Old unreduced cases are best treated by operative removal of the lunate as are cases where the lunate dies from loss of blood supply even though successfully reduced.
Injury to the lower radius
Fractures of the lower radius are classified as forearm fractures but it is best to include them in wrist injuries. The usual cause in sports is a fall on the outstretched hand. In the young athlete before growth is complete the injury results in a backward displacement of the lower radial epiphysis . If displaced greater than one third of the way across the radius it is best treated by manipulation and fixation on a dorsal plaster slab.
In the adult, sporting injury may result in a vertical splitting of the lower radius with widening of the breadth of the articular surface of the radius in both planes . Although this often results in broadening of the radial articular surface the late results are good, often with, perhaps, some loss of dorsiflexion movement.
Falls on the wrist with the hand in palmar flexion may result in a fracture of the lower radius with varying degrees of obliquity of the fracture line .
This is known as a Smith fracture. If the fracture extends into the articular surface and displaces, the eponymous name of Barton is applied to it! The usual treatment is by manipulation and immobilisation of the forearm in full supination with plaster including the elbow and wrist.
FIRST AID TREATMENT
It is important in all spheres of sports that facilities be made available for adequate initial care to be afforded to all participants, and to spectators. This means that splints, slings and bandages should be available for mild or severe injuries around the wrist and personnel able to apply them adequately. Comfort by pain relief and elevation to reduce swelling often means that later treatment can be made much more easy.
Chaubal, K. V. (1959). Dislocations of lunate. Dissertation for Mch(Orth) thesis, Liverpool University.
De Quervain, F. (1895). Uber eine form von chronischer tendovaginitis. Korrespondenz-Blatt fur Sweitzer Arzte, 25, 389.
London, P. S. (1961). The broken scaphoid – the case against pessimism .Journal of Bone and Joint Surgery, 43-B, 237-244.
Maudsley R. H. and Chen, S. C. (1972). Screw fixation in the management of the fractured carpal scaphoid. Journal of Bone and Joint Surgery, 54-B, 432-441.