Influence de la réconstruction du ligament radio-dorsal sur la stabilité de l’articulation trapeziometacarpien

Abstract

Introduction Biomechanical and anatomical research has shown that the dorsal radial ligament (DRL) is thicker and stiffer then the anterior oblique ligament (AOL). The DRL as the key stabilizing structure of the trapeziometacarpal (TMC) joint has been documented extensively. The aim of the current study is to quantify the influence of a surgical DRL reconstruction on TMC stability in non-traumatic instability patients. Methods Eight patients with symptomatic TMC instability but no radiographic signs of osteoarthritis were recruited and dynamic CT scans of the thumb were made during active abduction-adduction, flexion-extension and two functional grip task using a radiolucent jig. After image acquisition and segmentation, metacarpal translation was expressed relative to the trapezial articular surface. In addition, intersection points and inclination angles of instantaneous helical axes with an anatomically defined plane were determined to facilitate motion comparison between subjects. Scans were acquired before and 6–12 months after reconstruction of the DRL. Results During active motion, there is motion at both the trapeziometacarpal (TMC) and trapezioscaphoid (STT) joints. However, joint motion patterns, defined as changes in helical axis inclination angles during opposition, differ between patients. In most patients, dorsal luxation of the first metacarpal (MC1) could be clearly seen and quantified during the full range of motion, as well as during function grip tasks. Furthermore, dorsal luxation results in higher point loading of TMC cartilage as could be demonstrated by mapping the changes in articular contact area for each active motion. After DRL reconstruction, patients report improvement in pain and subjective stability in the joint. Analyses of the dynamic CT scans demonstrate reduced translation and luxation of MC1 in all patients as well as reduced cartilage point loading. Conclusion After DRL reconstruction, luxation of MC1 was reduced in all patients. We quantified movement in both TMC & STT joint, suggesting that pathologies at the TMC joint could lead to compensatory movements at the more proximal joints or vice versa. Simple DRL reconstruction is an attractive alternative for the more invasive anterior oblique ligament reconstruction described by Eaton, serving the same purpose, stabilizing the CMC joint. Future research should investigate if TMC instability and its altered kinematics lead to secondary joint problems (e.g. osteoarthritis) if left unattended.