Perilunate Dislocation

Background

This represents a significant bony and ligamentous injury to the wrist and usually is caused by high energy trauma such as a fall from height, or a motor vehicle accident.

In this injury, the wrist bone ligamentous anatomy is deranged, such that the lunate bone ends up dislocated out of the wrist joint. Fractures of the distal radius (wrist) and several other carpal bones can occur at the same time.

Causes

High energy mechanism, such as fall from significant height, motor vehicle accident, motorcycle crash, industrial accident.

Symptoms

Pain and swelling are common. Numbness in the median nerve distribution is a sign of associated acute carpal tunnel syndrome which represents a surgical emergency.

Diagnosis

Physical examination and plain radiographs. Occasionally, a CT scan helps guide treatment, especially if associated fractures are present.

Treatment

The initial management includes basic trauma care to look for associated head/neck/spine/chest and abdominal injuries since the mechanism is high impact and other injuries are common. Once these have been ruled out, the wrist can be treated.

The urgency of this injury is dictated by the dislocation of the lunate bone and the need to bring it back into its appropriate position as soon as possible. This reduction of the lunate can be attempted in the emergency department under sedation and wrist traction.

The definitive management of the injury usually involves surgery. Besides releasing the carpal tunnel if there is acute pressure on the median nerve with numbness/tingling and pain, the wrist is usually explored, the lunate is reduced, the ligament between the scaphoid and the lunate is repaired, and any associated fractures are addressed.

In this following example, Dr. Dowlatshahi used the conventional method of reduction, ligament repair with a bone anchor, and placement of several pins which are eventually removed after approximately 6 weeks.

In this following case, a more sophisticated repair was completed using a dorsal spanning plate, as well as wires to repair a distal radius fracture, and a temporary headless compression screw to secure the repair of the scapholunate ligament. This is the dominant hand of a professional artist with a desire to return to work immediately postop.

The advantage of this technique is that casting is not necessary and all the hardware is buried, reducing the risk of infection, and allowing the patient to begin moving fingers immediately, showering and performing self care without a cumbersome cast. This shows the patient at one week postop:

One year postoperatively, his fracture is healed and the ligament repair remains intact.