Coincident rupture of the scapholunate and lunotriquetral ligaments without perilunate dislocation: pathomechanics and management.

Wrist injuries causing coincident disruptions of the scapholunate and lunotriquetral ligaments commonly result in perilunate dislocations. This article (1) describes our management of eight patients with wrist pain after coincident scapholunate and lunotriquetral ligament disruptions in the absence of perilunate dislocation; and (2) reports the results of biomechanical testing of some of the extrinsic and intrinsic wrist ligament and interprets these data to explain the injury seen clinically. The diagnosis of ligament failure was made on the basis of history, physical examination, arthrography and surgical exploration. Surgical treatment of seven patients consisted of concomitant scapho-trapezio-trapezoid fusion and lunotriquetral fusion. Three of seven patients were free of pain, two had pain only at the extremes of motion, and two required additional surgery. Biomechanical analysis of the scapholunate and lunotriquetral ligaments and two extrinsic wrist ligaments, the radiolunotriquetral and the radioscaphocapitate, confirmed the clinical suspicion that the intrinsic ligaments could be completely disrupted while the extrinsics are only partially injured. Such a scenario could account for the residual stability that prevents the development of perilunate dislocations. Coincident disruption of the scapholunate and lunotriquetral ligaments in the absence of perilunate dislocation is an unusual injury. Treatment with lunotriquetral fusion and scapho-trapezio-trapezoid fusion restored functional use in five of seven wrists while maintaining wrist motion.