Effect of Biceps Tendon Rupture O and Forearm Su

INTRODUCTION It is well known that the biceps functions mainly as an elbow flexor and forearm supinator. In vivo elbow flexion and forearm supination strength testing after rupture of the long head of the biceps tendon has shown decreases of 0-16% and 0-21%, respectively [1,2]. Although many studies have attempted to identify the role of the long head of the biceps brachii muscle in elbow flexion and supination, the mechanical role of this biarticular muscle in these movements remains unclear. One reason it is difficult to pinpoint the roles of individual muscles is because there is no method to measure individual muscle forces in vivo. To overcome this problem, researchers [3-7] have developed computer models of the upper extremity to estimate individual muscle forces and joint-reaction forces at the shoulder, elbow, and wrist. The purpose of this study was to determine the individual muscle contributions to maximal isometric elbow flexion and forearm supination torque with and without a biceps tendon. Specifically, simulations representing an intact shoulder and simulations representing an isolated short head rupture, an isolated long head rupture and a combined (short+long head) biceps rupture were compared and contrasted.