Anatomy of the Biceps Tendon: Implications for Restoring Physiological Length-Tension Relation During Biceps Tenodesis With Interference Screw Fixation

Purpose: The purpose of this study was to characterize the normal length and diameter of the long head of the biceps tendon (BT) to provide guidelines for interference screw tenodesis. Methods: Twenty-one cadaveric shoulders were dissected. The BT length was measured from its origin to the humeral head articular margin (AM), lower subscapularis, upper pectoralis major, musculotendinous junction of the biceps (MTJ), and lower pectoralis major (LPM). Tendon diameter was measured at levels corresponding to tenodesis: (1) at the AM, (2) suprapectorally, and (3) subpectorally. Results: The mean tendon length was 24.9 mm from the origin to the AM, 56.1 mm to the lower subscapularis, 73.8 mm to the upper pectoralis major, 98.5 mm to the MTJ, and 118.4 mm to the LPM. The mean tendon diameter was 6.6 mm for tenodesis at the AM, 5.1 mm for suprapectoral tenodesis, and 5.3 mm for subpectoral tenodesis. During biceps tenodesis with interference screw fixation, restoring the normal length-tension relation of the BT depends on the site of tenodesis and the depth of the bone socket. At the AM, a 25-mm bone socket on average will maintain the length-tension relation. For tenodesis more distally, the length of tendon resection varies with bone socket length. Because the MTJ is above the LPM, subpectoral tenodesis should be performed proximal to the LPM. Conclusions: This study provides guidelines for restoring the normal length-tension relation during biceps tenodesis with interference screw fixation. The simplest way to restore this relation is with tenodesis adjacent to the humeral head AM and a bone socket of 25 mm in depth. For tenodesis at more distal locations, both the length of the BT and the depth of the bone socket must be considered.