Perilunate Dislocations
Authors: Newton William , Daley Dane , Daly Charles 
Published: November 2023

Background:
The all-dorsal scapholunate reconstruction technique is indicated for the treatment of scapholunate injuries in cases in which the carpus is reducible and there is no arthrosis present. The goal of this procedure is to reconstruct the torn dorsal portion of the scapholunate ligament in order to stabilize the scaphoid and lunate.

Description:
A standard dorsal approach to the wrist, extending from the third metacarpal distally to the distal radioulnar joint, is utilized. The extensor pollicis longus is transposed and retracted radially, and the second and fourth extensor compartments are retracted ulnarly. A Berger ligament-sparing capsulotomy is utilized to visualize the carpus. Volarly, an extended open carpal tunnel release is also utilized to relieve any median nerve compression and to aid in reduction. The contents of the carpal tunnel can be retracted radially, allowing for visualization of the carpal bones. Joystick pins are placed in order to reduce the scaphoid and lunate. Reduction is held provisionally by clamping the pins until 4 pins can be placed across the carpal bones. For scapholunate reconstruction, 3 holes are made: in the lunate, proximal scaphoid, and distal scaphoid. Suture tape is then utilized to hold the scaphoid and lunate in their proper position. The dorsal wrist capsule and extensor retinaculum are repaired during closure. The pins are cut near the skin and are removed in 8 to 12 weeks.

Alternatives:
Several other methods of scapholunate reconstruction have been described, including capsulodesis, tenodesis, and bone-tissue-bone repairs. Additionally, in patients who are poor candidates for scapholunate reconstruction, wrist-salvage procedures can be utilized as the primary treatment.

Rationale:
Scapholunate reconstruction has the advantage of preserving the native physiologic motion of the wrist, in contrast to the many different wrist-salvage procedures that include arthrodesis or arthroplasty. Avoiding arthrodesis is specifically advantageous in patients who have not yet developed arthrosis of the wrist bones.

Expected Outcomes:
Outcomes of scapholunate reconstruction vary widely; however, there is a nearly universal decrease in range of motion and strength of the wrist. Wrist range of motion is typically 55% to 75% of the contralateral side, and grip strength is typically approximately 65% of the contralateral side. In a prior study, 50% to 60% of patients whose work involved physical labor were able to return to their same level of full-time work. Disabilities of the Arm, Shoulder and Hand scores average between 24 and 30. Specific patients at risk for inferior outcomes are those with delayed surgical treatment, poor carpal alignment following reduction, or open injuries.

Important Tips:

Patients are counseled preoperatively regarding the likelihood of permanent wrist stiffness and the possibility of scapholunate diastasis even in the setting of technically successful repair.Traction and dorsally directed pressure on the lunate through an extended carpal tunnel incision can aid in reduction of the lunate.The joystick pin position in the dorsal scaphoid is angulated from distal to proximal and that in the lunate is angulated from proximal to distal in order to help correct flexion of the scaphoid and extension of the lunate by clamping together the Kirschner wires. Modifying the distance of the clamp from the carpus can allow precision in the degree of scapholunate angle fixation.Intercarpal Kirschner wire fixation of the scapholunate, lunotriquetral, and midcarpal joints (scaphocapitate and triquetrohamate) is best performed with 0.062-in (1.6-mm) Kirschner wires. The insertion angle is best visualized when the Kirschner wire is introduced from inside the incision through the skin, “inside out,” in order to best envision the trajectory on the dorsal carpus and define the starting point on the bone. The Kirschner wire is then advanced through the carpus from outside-in at a slightly more volarly translated (but not angulated) position. The Kirschner wires are then cut beneath the skin at a depth that will allow them to be retrieved but will not cause them to become exposed once swelling decreases.The wrist is generally immobilized until the pins are removed at 3 months postoperatively.

Acronyms and Abbreviations:

ROM = range of motionK-wire = Kirschner wireDASH = Disabilities of the Arm, Shoulder and HandDISI = dorsal intercarpal ligament instability