Radio-luno-triquetral bone-ligament transfer as an additional stabilizer in scapholunate-instability

Abstract

IntroductionReconstruction of the scapho-lunate (SL) ligament is still challenging. Many different techniques, such as capsulodesis, tendon graft and bone-ligament-bone graft have been described to stabilize reducible SL dissociation. If primary ligament repair alone is not possible, an additional stabilizer is needed to achieve scapho-lunate stability. A new local bone-ligament transfer using half of the radio-luno-triquetral ligament is performed. The direction of traction of the transposed ligament is very similar to the original ligament. Ideal tension can be attained by fixation of the bone block at the dorsal ridge of the scaphoid. The biomechanical stability of this bone-ligament transfer shall be examined biomechanically.Material and methodsComputed tomography imaging was performed using eight cadaveric forearms with a defined position of the wrist. Axial load was accomplished with tension springs attached to the extensor and flexor tendons. Three series ([a] native, [b] divided SL ligament and [c]) after reconstruction with bone-ligament transfer] were reconstructed three-dimensionally to determine the angles between radius, scaphoid and lunate. The radial distal part including a bone fragment of the radio-luno-triquetral ligament was transferred from its insertion at the distal edge of the radius to be attached to the dorsal ridge of the scaphoid.ResultsSL gap was widened after its transection. Average SL distance was 6.6 ± 1.6 mm. After ligament reconstruction, the gap could be narrowed significantly to 4.2 mm (± 0.7 mm). The movement of the scaphoid and lunate showed significant changes, especially in wrist flexion, fist closure and radial deviation. These deviations could be corrected by the bone ligament transfer.ConclusionReconstruction of a transected SL ligament with a bone-ligament transfer from the radio-luno-triquetral ligament reduces SL dissociation under axial load. The described surgical technique causes low donor-side morbidity and can be considered in addition to improve stability if SL ligament suture alone does not appear sufficient.Level of evidenceLevel II, therapeutic investigating experimental study.