Thumb On The Palm Functional Reconstruction - Tendon Transfer Embedded Point Biomechanical Study

Objective: The optimal location for insertion of the transferred tendon in opposition transfer is controversial. The purpose of this study was to examine 4 commonly used insertion sites into the thumb and determine which maximizes thumb opposition.Methods: The flexor digitorum superficialis of the ring finger was used as a donor tendon and was attached in random order to the abductor pollicis brevis(APB)tendon, the APB and extensor pollicis longus, the flexor pollicis brevis(FPB) and dorsal radial extensor hood, and the ulnar extensor hood at the base of the proximal phalanx. As normal opposition was simulated, the minimum distance between the thumb and little finger, pisiform bone were measured at the incremental loading weight; the pinch force were measured at the maximal loading weight.Results: The FPB and radial dorsal extensor hood site resulted in the statistically highest pinch force. The FPB and radial dorsal extensor hood and the APB sites had statistically smaller minimum distances between the thumb and little finger than the ulnar extensor hood site. Conclusions: The APB insertion sites gave good thumb motion and the FPB and radial dorsal hood also resulted in good oppisition as well as superior pinch strength.