Lunate dislocation

an uncommon traumatic wrist injury that require prompt management and surgical repair.

The lunate is displaced and rotated volarly and no longer has normal radiolunate articulation. The rest of the carpal bones are in a normal anatomic position in relation to the radius.

Epidemiology: Young adults, less then 10% of wrist injuries

Aetiology: High energy trauma - Loading of a dorsiflexed wrist

PC: Wrist pain following fall, swelling

Ix: X-ray

Tx: Urgent reduction and surgical repair of disrupted ligaments is required to prevent long-term joint dysfunction. Despite treatment, there remains a high risk of future degenerative arthritis and wrist instability.

Perilunate dislocation

These injuries involve dislocation of the capitate relative to the lunate which remains in normal alignment with the distal radius.

Involves rupture of - radioscaphocapitate, scapholunate and lunotriquetral ligaments

Epidemiology: Young adults, less then 10% of wrist injuries

Aetiology: High energy trauma = hyperextnded ulnar deviated hand. Around 60% of perilunate dislocations are associated with a scaphoid fracture which is then termed a trans-scaphoid perilunate dislocation

Occasionally median nerve injury, arterial compromise or compartment syndrome may be evident due to the dislocation.

Ix: x-ray