Common Carpal (Wrist bone) Fractures

Scaphoid Fracture

Aetiology: Most common fracture, occurs after fall onto outstretched hand.

Examination: Have tenderness in the anatomical snuffbox. Also have pain on axial compression of the thumb towards the radius, or direct pressure on the scaphoid tuberosity with radial deviation of the wrist.

Investigation: Plain x-ray with scaphoid views should show the # but a normal x-ray doesn’t exclude a #. Bone scan (>72 hrs to be +ve) or MRI (+ve within hrs) may be done acutely, otherwise immobilize for 12 days then re-x-ray. Fine cut CT (scaphoid plane) best investigation.

Poor prognostic factors: # proximal pole; vertical/oblique # (potentially unstable); displacement (>1mm) & late diagnosis (>4 wks).

Treatment (3 options):

(1) Immobilize for 8 weeks in plaster extending from the forearm to but not including the thumb IP joint, the wrist should be in neutral position. Uncomplicated #s have a 95% union rate. RTS may take up to 3 months.

(2) Use a short arm thumb spica cast at rest, and a playing cast during sport (this has a higher non-union rate and more will require ORIF).

(3) Acute ORIF with a compression screw (best for unstable & proximal pole #s) allows for RTS in 4-6 weeks depending on the procedure.

Complications: Risk of delayed union or non-union- if still tender after 8 weeks immobilize for a further 4 weeks (after this further immobilization is unlikely to help). Displacement of >1 mm may require ORIF.

Non-union or AVN occurs in the majority of proximal ⅓ #’s and 30% of middle ⅓ #’s and may need bone grafting. This may be attempted over 6 months later.

Scaphoid non-union advanced collapse (SNAC) is a potential long term sequelae.

Post-plaster Rehab: The athlete will need mobilization of the wrist after plaster removal. They may return to sport with a protective device.

Hook of Hamate #

Aetiology: Accounts for 2-5% of carpal #’s. May occur swinging a golf club (especially if club hits the ground), tennis racquet or playing volleyball. May also get compression of the superficial and deep branches of the ulna nerve. There is often a delay in diagnosis of up to 5 months.

Examination: Patient complains of ↓ grip strength and ulnar wrist pain. There is tenderness over the hook, which lies on a line between the pisiform and 2nd MC head.

Investigation: X-rays need to have a carpal tunnel view with the wrist in dorsiflexion or ulnar oblique views. CT should show the #.

Treatment: Acute presentations should be placed in a short arm cast with immobilization of the 4th and 5th fingers. In 46% of cases will achieve bony union.  Delayed presentation usually requires surgical excision, with return to sport in around 6-8 weeks. There can be a loss of ~15% of grip strength following excision.

Pisiform Fractures

The pisiform bone may be injured from a direct blow and it can undergo chondral changes from overuse, leading to pisotriquetral arthrosis. This is frequently seen in athletes who participate in racquet sports. Diagnosis may be made by injection of local anaesthetic at the pisotriquetral articulation. In cases of pisotriquetral fractures, excision of the pisiform may be indicated, with return to sports in 6-8 weeks.

Triquetrum Fractures:

These result from hyperextension injuries with distal ulna impingement on the triquetrum typically causing an avulsion # from the distal cortex. This small avulsion typically becomes painless after immobilization in a short arm cast for 3 weeks.

Capitate Fractures:

These can result from a direct blow to the dorsum of the wrist or from forced dorsi or palmar flexion. There is swelling and tenderness at the base of the 3rd and 4th ray. Like the scaphoid blood supply is retrograde and proximal pole #s are at risk of AVN. Non-displaced #s are immobilized but displacement >2mm warrants ORIF.