The "Z" strap: harnessing modification for patients with upper extremity amputations.

High level, upper extremity amputees have been observed to have problems affecting overall prosthetic function. These include: tendency of the Northwestern Ring to ride upward and difficulty with terminal device function above 90 degrees of elbow flexion. A simple modification of the control strap was tried to resolve these problems of function. The control strap was attached across the back to a buckle on the unamputated side at the shoulder to provide a more efficient anchor. This created more body contact across the back and formed a type of "Z" strap allowing full freedom of movement in any direction. Less forward shoulder flexion was necessary due to decreased cable travel and because the strap was not sliding up and over the shoulder. A single case study is described and the successful outcome for the amputee.