Open reduction and fixation of acute lunate or perilunate dislocation, with or without fracture

Acute and subacute perilunate dislocation or fracture-dislocation (<6 weeks).

• Patients who present more than 6 weeks after the injury may be better served by a salvage procedure, such as a proximal row carpectomy or partial wrist fusion.

Although urgent reduction of a perilunate dislocation can often be accomplished by closed means, operative fixation and consideration of open ligamentous repair are generally indicated.

Perilunate injury can be purely ligamentous (lesser arc injury) or associated with fracture of the scaphoid, capitate, or triquetrum (greater arc injury).

• A unique subset, termed scaphocapitate syndrome , is characterized by a transscaphoid transcapitate fracture with the head of the capitate rotated 90 or 180 degrees out of position.

Mayfield and colleagues described the progressive spectrum of pathology, moving from radial to ulnar across the carpus, associated with perilunate/lunate injury ( Table 28.1 ).

In lunate dislocation, the lunate is displaced volarly and the remaining carpal bones maintain alignment in relation to the distal radius.

In perilunate dislocation, the lunate remains within its fossa on the distal radius, and the remaining carpus dislocates dorsally ( Fig. 28.1 ).

Clinical examination may reveal extreme pain, wrist edema, tenderness, and ecchymosis with diminished active and passive wrist motion.

It may be accompanied by acute carpal tunnel syndrome (∼25% of patients), resulting in severe and progressive pain and paresthesia in the median nerve distribution.

If severity of pain progresses despite radiographically confirmed closed reduction, urgent carpal tunnel release and open reduction and fixation should be performed.

If closed reduction results in a decrease in pain severity and improvement in numbness, open reduction and fixation can be performed semielectively as soon as possible.

The standard radiographic assessment of the wrist should be conducted, including a careful evaluation of Gilula’s arcs ( Fig. 28.2 ) to identify carpal dislocation.

The radial shaft, lunate, capitate, and metacarpal shafts should be colinear on lateral x-ray.

Despite the severity of the injury, perilunate or lunate dislocation can be missed; therefore it is important to carefully examine all radiographic views.

Plain radiographs can also reveal associated fractures of the radial styloid, scaphoid, capitate, or triquetrum—demonstrating a greater arc pattern of injury ( Fig. 28.3 ).

In severe injuries, the dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments are often injured ( Fig. 28.4 ).

In a volar dislocation, the lunate is forced through the space of Poirier, a weak region in the volar capsule that is devoid of extrinsic ligaments. The arc of the radioscaphocapitate (RSC) and the ulnocapitate (UC) ligaments form the distal anatomic border of the space of Poirier ( Fig. 28.5 ).

In a dorsal perilunate dislocation, the lunate remains in normal position on the distal radius and the remaining carpus dislocates dorsally.

Perilunate dislocation requires interosseous—scapholunate (SL) and lunotriquetral (LT)—ligament injury. The dorsal SL ligament and volar LT ligament are repaired if possible.

In a Mayfield IV lunate dislocation, the blood supply to the lunate is maintained by the short radiolunate ligament volarly ( Fig. 28.6 ).

Reduction is performed through a series of specific steps:

• Encourage muscle relaxation via a limb block or sedation/anesthesia.

• Place around 10 lbs of longitudinal traction in finger traps for 10 to 15 minutes.

• Initiate with dorsally directed pressure on the volar aspect of the lunate and remove the traction weight once in this position.

• With the weight off, maximally extend the wrist; then, with manual longitudinal traction, flex the wrist. This should bring the capitate into flexion and onto the lunate, reducing the injury.