Biomechanical Contribution of the Long and Short Heads of the Distal Biceps to Elbow Flexion and Supination Strength: Analysis of the Intact and Surgically Repaired Tendons

Recent anatomic studies have shown that the Distal Biceps Tendon (DBT) is comprised of two distinct tendons, a short head (SH) and a long head (LH). The individual contribution of the heads, and their importance to elbow function, has not been well defined. This study had two major objectives. Firstly, to measure the intact contribution of each of the heads to elbow function and secondly, to compare anatomic and non-anatomic repair of the ruptured tendons. Isometric supination torque and flexion force were recorded with the forearm mounted in an elbow simulator. The SH was found to be the greater flexor in all orientations. The SH was also a greater rotator when the forearm was in pronation and at neutral. The LH was the greater rotator when the arm is in supination. Anatomic repair restored near intact DBT supination strength while non-anatomic repair resulted in diminished strength.