Scapholunate kinematics after flexible anchor repair

The scapholunate joint is one of the keystones of the wrist kinematics, and its study is difficult due to the carpal bones size and the richness of surrounding ligaments. We propose a new method of quantitative assessment of scapholunate kinematics through bone motion tracking in order to investigate scapholunate ligament lesion as well as repair techniques. On 6 intact wrists, steel beads were inserted into the bones of interest to track their motions. Experimental set up allowed wrist flexion extension and radio-ulnar deviation motions. Low-dose bi-planar radiographs were performed each 10 degrees of movement for different configurations: 1) intact wrist, 2) scapholunate ligament division, 3) repair by soft anchors at the posterior then 4) anterior part. Beads' 3D coordinates were computed at each position from biplanar X-Rays, allowing accurate registration of each wrist bone. The Monte Carlo sensitivity study showed accuracy between 0.2 degrees and 1.6 degrees for the scaphoid and the lunate in motions studied. The maximum flexion-extension range of motion of the scaphoid significantly decreased after anterior repair from 73 degrees in injured wrist to 62.7 degrees. The proposed protocol appears robust, and the tracking allowed to quantify the anchor's influence on the wrist kinematics. (C) 2019 IPEM. Published by Elsevier Ltd. All rights reserved.