Extensor pollicis longus rerouting for thumb-in-palm deformity in cerebral palsy: a biomechanical analysis

Extensor pollicis longus rerouting is a common procedure to improve thumb abduction in thumb-in-palm deformity seen with spastic cerebral palsy. In 1985, Manske redirected the extensor pollicis longus tendon in this procedure through the first extensor compartment. They also proposed an alternative subcutaneous route around the extensor pollicis brevis and abductor pollicis longus tendons proximal to the extensor compartment. In this study, we performed a three-dimensional analysis of thumb motion on 11 cadaver arms with the subcutaneous route and the first extensor compartment route. We found that with the two different routing methods, the mean difference in thumb radial abduction and retropulsion (0° or 6°, respectively) was very small. Such differences are unlikely to have clinical relevance. We were unable to find significant differences in the motion range of the thumb after these rerouting techniques or sites of insertion. Our biomechanical data support the simpler subcutaneous route.