gms | German Medical Science

Objectives/Interrogation: Chronic lunotriquetral (LT) instability is rare and, hence, a variety of different treatment options exist. Up to date best results for chronic LT instability have been shown with soft tissue reconstruction techniques, which are technically demanding or are non-anatomic. Less demanding options include the arthrodesis with a reported high complication rate.

A technique combining the advantages of both existing techniques would be preferable. Using the dorsal bone-ligament-bone (BLB) reconstruction, we tested a less demanding technique that provides stability but also is thought to save the kinematics of the carpal bones.

We present the current literature and the biomechanical test results of our technique with a dorsally implanted bone-ligament-bone (BLB) graft.

Methods: A literature review using pubmed was performed. The anatomy, epidemiology, biomechanics and published treatment options of LT instability are summarized.

For biomechanical testing, 10 cadaveric forearms were evaluated with computertomography (CT) in different loaded positions. LT ligaments were sequentially sectioned. BLB reconstruction were performed harvesting the graft from the capitohamatal joint. Initially, the LT was also transfixed using a compression screw (CCS) simulating arthrodesis. At last the CCS screw was removed and the reconstruction alone was tested. CT's were performed at the beginning and after each single step. A 3-dimensional software calculated the motion between the carpal bones in comparison to the normal wrist after each of the steps.

Results and Conclusions: Sectioning of the dorsal part of LT had little effect on kinematics, however sectioning of the palmar part in addition, resulted in an increased mobility in the LT joint.

Arthrodesis showed to increase significantly the motion in the adjacent joints up to fourfold difference.

Restoration of the physiological kinematics could partially be achieved after removing the CCS screw testing the reconstruction alone. Compared to totally cut LT ligament the reconstruction showed less motion without significance, but was not as stable as the uncut ligament.

We present and compare the used BLB graft reconstruction to other techniques. Biomechanical testing with BLB grafts is satisfactory. Compared to arthrodesis, more physiologic carpal kinematics resulting in less straining of the adjacent joints was measured.