Trapeziectomy and ligament reconstruction tendon interposition: an in vivo, patient-controlled, biomechanical study relating to pinch grip.

Introduction: Trapeziectomy and ligament reconstruction tendon interposition (LRTI) is a commonly used procedure in the management of first carpometacarpal osteoarthritis. Debate persists regarding the degree of biomechanical improvement following trapeziectomy and subsequently LRTI. This preliminary, single-centre, in vivo, biomechanical study addresses the biomechanical effect of LRTI following trapeziectomy at the time of surgery, with each participant acting as their own control.

Methods: Trapeziectomy and LRTI were performed under wide-awake local anaesthetic with no tourniquet (WALANT) with a flexor carpi radialis (FCR) donor graft. Key pinch grip was assessed in each participant.

Results: The surgical method that resulted in biomechanically the most significant decrease in grip strength compared with preoperative grip strength was trapeziectomy alone with a mean difference of 4.27kg, which was also statistically significant (Tukey's test p<0.001). Mean post-WALANT key pinch grip strength was 6.4kg (sd 2.61); post LRTI the mean key pinch grip strength was 6.33kg (sd 2.63). Following the surgical procedure (trapeziectomy and LRTI) the mean key pinch grip strength was -0.1kg (95% confidence interval -0.93 to 0.81) (Tukey's test p=1), demonstrating no statistically significant difference between the two values. This indicates that LRTI restores pinch grip strength.

Conclusions: Our preliminary research presents a novel method to evaluate for biomechanical advantages following trapeziectomy and LRTI. This supports the biomechanical advantages of FCR LRTI following trapeziectomy, at the time of surgery. There is scope for this research process to be applied more widely in future.