Performance evaluation of surgical techniques for treatment of scapholunate instability in a type II wrist

Abstract

The scapholunate interosseous ligament (SLIL) is the primary stabiliser of the wrist and the most common injured ligament of the joint. The surgical reconstruction uses a portion of a tendon graft or artificial graft to reconnect the bones via trans osseous tunnels across the scaphoid and lunate bones; however, there are unresolved issues with regard to which technique restores better the interaction without affecting the normal kinematics. This thesis aimed to investigate the performance of scapholunate (SL) ligament reconstruction techniques employing a 3D finite element model of a type II wrist that reproduces carpal kinematics. The model was created from computer tomography (CT) data from a human wrist and considered bones, articular cartilages and ligaments. Each carpal bone has 6 degrees of freedom, its motion is only restricted by its interaction to other bones and a complex set of ligaments. The models were validated with data from cadaveric studies. In addition, a comparison of the carpal mechanics of type I and type II wrists was undertaken to elucidate the difference between the two types. The performance of the techniques was diverse in all the positions. In comparison to the intact ligament case, Corella reconstruction provided superior outcome restoring the dorsal gap, volar gap, and SL angle to within 3.5%, 7.1%, and 8.4% at clenched fist ulnar deviation posture, respectively. MBT performed better at flexion and extension positions, closing the SL gap at dorsal and volar, and reducing the SL angle to within 1.2% without significantly altering the carpal motion. SLAM did well at radial deviation where recovered the SL dorsal gap and reduced to within 6.2% the SL dorsal gap during ulnar deviation. Considering the full range of motion analysed, SLAM was better able to restore SL gap SL angle and carpal instability following scapholunate injury. SLAM performed well during radial and ulnar deviation because the generated connexion axis favoured the relative rotation between the scaphoid and lunate which is characteristic in a type II wrist column kinematics. In general, Corella restricted the in-plane rotations of the bones in several positions, whereas the MBT also restricted the rotation of the bones in the radial deviation posture which could lead to a loss of range of motion of the hand after surgery.

Date of Award	31 Dec 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Keith Davey (Supervisor)