Biceps Tenodesis/Tenotomy Disrupts Biomechanical Glenohumeral Stability in the Setting of Superior Labrum Anteroposterior Tear and Repair.

PURPOSE: To compare the biomechanical stability of the glenohumeral joint both before and after a SLAP tear to: (1) posterior SLAP repair, (2) posterior plus anterior SLAP repair, (3) biceps tenodesis with SLAP repair, and (4) biceps tenodesis without SLAP repair.

METHODS

Eight cadaveric shoulders were tested using a custom testing system. Twenty-two-Newton glenohumeral compressive force and 5-N biceps load was applied. All testing was performed in 30° and 60° of glenohumeral abduction. Humeral rotational range of motion was measured with 2.2 Nm torque. Glenohumeral anteroposterior (AP) and superoinferior (SI) translation was measured in 45° and 90° external rotation with 10 and 15 N loads. Six conditions were tested: intact; SLAP tear (10:00 to 2:00 o'clock); posterior SLAP repair (2 anchors at 10:30 and 11:30); posterior plus anterior SLAP repair (an additional anchor at 1:30); simulated biceps tenodesis with SLAP repair; and simulated biceps tenodesis without SLAP repair. Repeated measures analysis of variance with Tukey post hoc test was used for statistical analysis.

RESULTS

There were no significant differences with SLAP tear or repair in AP/SI translation or range of motion compared with intact. Both simulated tenodesis conditions increased max external rotation compared with intact (P < .006). Simulated tenodesis with SLAP repair significantly increased AP (6/8 positions) and SI translation (2/8 positions) compared with intact. Simulated tenodesis without SLAP repair significantly increased AP (all positions) and SI translation (3/8 positions) compared with intact.

CONCLUSIONS

The long head of the biceps has a pertinent biomechanical role in glenohumeral stability regardless of the condition of the superior labrum. The addition of an anterior anchor for SLAP repair did not restrict external rotation in this cadaveric model.

CLINICAL RELEVANCE: The potential contribution of the biceps to biomechanical stability should be a consideration when treating biceps pathology.