Review Question - QID 218901

Radioscaphocapitate (RSC) ligamentous disruption can result in multidirectional carpal instability and ulnar translocation of the carpus relative to the distal radius.

Radiocarpal dislocations are rare, high-energy injuries that necessitate operative fixation. Dorsal dislocations are more common than volar dislocations. The dislocation disrupts the radiocarpal ligaments, radial styloid, ulnar styloid, and/or other intercarpal injuries. The main ligamentous restraint to ulnar translation of the carpus is the volar radioscaphocapitate (RSC) ligament, which may be traumatically injured in radiocarpal dislocations or iatrogenically during proximal row carpectomy procedures. In either case, failure to address the disrupted RSC results in global instability of the wrist with ulnar translocation of the carpus relative to the distal radius. The resultant chronic instability pattern results in significant chronic wrist pain, disabling functionality, and early post-traumatic arthritis.

Ilyas and Mudgal provided a comprehensive review of radiocarpal fracture dislocations regarding the epidemiology, associated injuries, and management guidelines. They highlight the treatment principles to include concentric reduction of the radiocarpal joint, treatment of intercarpal injuries, and sound repair of the osseous-ligamentous injuries. In particular, they emphasize the repair of the origins of the short radiolunate and radioscaphocapitate ligaments to avoid late volar subluxation or ulnar translocation, respectively.

Green and colleagues provided an overview of the proximal row carpectomy with operative technique, pearls and pitfalls, and expected outcomes based on their prior retrospective review. They emphasize the importance of only indicating patients with good cartilage of the proximal pole of the capitate and in the lunate fossa of the radius. Further, they highlight the importance of careful dissection of the scaphoid to avoid the deleterious effects of injury to the RSC ligament. They conclude that with proper patient selection, the proximal row carpectomy can be successfully performed even in patients who require heavy manual activity.

Figure A shows a left-sided, dorsal radiocarpal dislocation with avulsion of the tip of the radial styloid (origin of the RSC). The radial styloid avulsion fracture was too small to facilitate operative fixation and was excised. The RSC ligament was subsequently repaired to its origin using a suture anchor (view obstructed by the dorsal spanning bridge plate, Illustration A). The radiolunate ligaments were similarly repaired in this manner with a separate suture anchor; the dorsal bridge plate was eventually removed 4 months later (Illustration A).

Incorrect Answers:

Answer 1: Figure B shows volar subluxation of the carpus relative to the distal radius classically seen after an unaddressed injury to the critical corner. The critical corner of the distal radius (volar-ulnar corner of the articular segment) is where the short radiolunate ligament attaches. This ligament is the primary restraint to the volar translation of the carpus relative to the distal radius. Therefore, failure to address this fracture pattern appropriately can result in volar translation of the carpus with devastating complications.
Answer 2: Figure C shows a scapholunate interosseous ligament (SLIL) injury. These are often missed on initial presentation and can result in a dorsal intercalated segment instability (DISI) deformity. Bilateral clenched fist views for comparison to the uninjured side can help aid in the diagnosis.
Answer 4: Figure E shows a patient with perilunate dissociation, which can similarly result after high-energy trauma while the wrist is in intercarpal supination. The resultant sequence of ligamentous failure is described in the Mayfield classification. Perilunate dissociation is similarly treated with acute operative intervention guided by the ligamentous/fracture pattern.
Answer 5: Figure F shows a Madelung deformity of the wrist. This is caused by a disruption of the ulnar volar physis of the distal radius, which can occur after a pediatric distal radius fracture or via dysplastic arrest. The resultant excessive radial inclination, volar tilt, and ulnar carpal impact can lead to chronic wrist pain, decreased range of motion, or other functional impairments.