Determination of Anterior Labral Repair Stress During Passive Arm Motion in a Cadaveric Model

Purpose: The actual forces encountered at the labrum after anterior labral repair have yet to be quantified. The purpose of this study was to determine the amount of force experienced at the glenoid-labrum interface with passive range of motion after an isolated Bankart repair and Bankart repair with capsular shift. Methods: In 12 fresh-frozen cadaveric shoulders, anterior-inferior labral tears were created and then instrumented with a modified load cell. The labral lesions were repaired with either an anatomic "labral only" technique or a labral repair along with a capsular shift by use of a transglenoid technique. Shoulders were then taken through a series of movements (forward flexion, abduction, external rotation, and abduction and then external rotation) simulating passive range-of-motion rehabilitation while force measurements were taken. Maximum force (in Newtons) on the simulated repairs was recorded. Results: The forces experienced at the labrum showed a statistically significant difference between the group that underwent anatomic "labral only" repair and the group that underwent labral repair with capsular shift. The greatest mean force experienced (17.7 N) was in shoulders undergoing the labral repair with capsular shift with the arm in abduction and external rotation. Conclusions: In a transglenoid suture repair technique, the forces experienced at the repair site were significantly less than those determined by previous authors to be necessary to result in failure of the Bankart repair. The results of this study show that the forces experienced at the glenoid-labrum interface are higher when a capsular shift is included with a labral repair as opposed to labral repair alone. This difference was statistically significant. Clinical Relevance: These data suggest that early postoperative rehabilitation may safely allow greater passive range of motion than is presently accepted.