Traumatic wrist injuries occurring through sport

Traumatic injuries can be ligamentous or bony says Dr Arvind Mohan in the first of two articles focusing on the wrist

A review of the literature reveals that 3–9 per cent of all athletic injuries involve the hand and wrist.

Hand and wrist injuries can be divided into two major classifications: traumatic and overuse. Traumatic injuries can be further divided into ligamentous and bony.

Most of the injuries encountered in primary care are soft tissue injuries, mostly from overuse in sports such as golf, gymnastics and racket sports.

Scaphoid fractures
The most common and problematic fracture in the wrist of an athlete is the carpal scaphoid. The scaphoid is 80 per cent covered with cartilage and has complex biomechanics. More force is required to produce a scaphoid fracture than to produce a distal radial fracture.

Because of its peculiar blood supply, proximal pole fractures have a worse prognosis for healing than more distal injuries. Blood supply is from distal vessels that enter through the dorsal ridge of the bone distally and these supply 80 per cent of the blood.

The diagnosis of acute scaphoid fracture is sometimes difficult because initial plain radiographs often do not show the fracture. Any contact-sport athlete who has radial wrist pain should be considered to have a scaphoid fracture until proven otherwise. 
 
Examination may reveal tenderness in the ‘anatomic snuffbox’, a decreased range of motion, swelling and pain on dorsiflexion.

These patients need to be referred to hospital because they sometimes need further imaging in the form of MRI and CT scans.

Hamate fractures
Fractures of the body of the hamate may occur from trauma and usually occur in combination with fractures of the base of the fourth and fifth metacarpals. There is a high incidence of non-union.

Hook of the hamate fractures must be suspected in athletes participating in racket sports, golf or baseball who are seen with ulnar wrist pain, because this fracture occurs frequently in these sports.

On examination there is tenderness over the hook of the hamate, which lies on a line between the pisiform and second metacarpal head.

These patients require referral because they need special views such as carpal tunnel and supinated oblique views to reveal the fracture, and sometimes need a CT scan or bone scan to confirm the diagnosis.

Acute fractures of the lunate are rare, but repetitive trauma can produce avascular necrosis of the lunate known as Kienböck’s disease. This can be seen on X-ray. The treatment is usually conservative but occasionally a radial shortening osteotomy, arthroscopic debridement or vascularisation procedures of the lunate may be necessary.

The pisiform bone may be injured from a direct blow and it can undergo chondral changes from overuse, leading to pisotriquetral arthrosis. This is common in athletes who participate in racket sports.

Ligamentous injuries
The stability of the wrist depends on the geometry of the individual carpal bones and the ligamentous interconnections that control movement of one bone on another. The most common instabilities involve injury to the intrinsic ligaments of the wrist, mainly those that connect the scaphoid and lunate, and lunate and triquetrum bones.

A less common type of instability (midcarpal instability) results from injury or attenuation of the ligaments connecting the proximal and distal carpal rows. Patients with these injuries need an MRI to confirm the diagnosis. Many procedures involving the wrist ligaments can be treated by wrist arthroscopy.

Scapholunate injuries are the most common type of wrist ligament injury and result from excessive wrist extension and ulnar deviation with intercarpal supination, as can occur with a fall on a pronated hand. This injury occurs in contact sports. A good history of the mechanism of injury is important in making a diagnosis.

Applying a dorsal load to the distal pole of the scaphoid as the wrist is moved from an ulnar to radial deviation produces pain and a ‘popping’ noise, known as Watson’s sign.
It is difficult to do this test in acute settings because of pain but it is helpful in chronic injuries.

Lunotriquetral injuries
Lunotriquetral injuries are the result of a sudden axialload with wrist extension and radial deviation with intercarpal pronation as opposed to supination, as in scapholunate tears.

The lunotriquetral shear test involves applying a dorsally directed force over the triquetrum and a palmar-directed force on the lunate, which produces a click and reproduces the patient’s pain.

This occurs because of a lesion caused by attenuation of the ulnar V ligament connecting the capitate in the distal carpal row to the triquetrum of the proximal row. Patients with this instability have ulnar wrist pain and there is a painful ‘clunk’ sound with ulnar deviation. Normally, the proximal carpal row moves from a flexed position in radial deviation to an extended position in ulnar deviation smoothly.

In midcarpal instability, the proximal row stays flexed until late in ulnar deviation and then ‘snaps’ audibly into dorsiflexion, known as the ‘catch-up clunk’. It can be bilateral so it is important to examine the opposite wrist.

Athletes with midcarpal instability will respond to activity modifications, splinting and NSAIDs, and will be able to return to sport. 

Dislocation
Perilunate dislocation or volar lunate dislocation of the wrist results from excessive radiocarpal hyperextension and ulnar deviation plus intercarpal supination.

This injury should be suspected after trauma in collision sports when significant swelling and decrease in range of movement are observed.

Carpal tunnel syndrome with compression of the median nerve is often a complication of the injury.

Triangular fibrocartilage
The triangular fibrocartilage complex (TFCC) is the primary stabiliser of the distal radioulnar joint. It is a fibro-cartilaginous plate, which extends in a fan-shaped fashion from the apical attachment from the ulnar styloid process to the rim of the radial sigmoid notch.

It has attachments to the wrist capsule and lunotriquetral, ulnolunate, ulnar collateral ligaments and sheath of the extensor carpi ulnaris tendon. Peripheral attachments of the TFCC are vascular and heal well, whereas the central part is avascular and tears do not heal. These injuries can be treated with wrist arthroscopy.

 

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