Quantifying the Extent of a Type II SLAP Lesion Required to Cause Peel-Back of the Glenoid Labrum-A Cadaveric Study

Purpose: To quantify the extent of labral disruption required to cause it to peel back when the peel-back test is performed. Methods: Ten cadaveric shoulders were prepared by removal of the deltoid and rotator cuff muscles. The glenohumeral joint was concentrically reduced and brought into 90° abduction and maximal external rotation. The peel-back of the labrum was graded 0, 1, or 2. The labrum was sequentially detached from the glenoid in the following order: biceps anchor only, 1 o'clock, 2 o'clock, 11 o'clock, and 3 o'clock positions. After each labral cut, the peel-back test was performed. Labral repair was performed with a single suture anchor placed at the 12:30 o'clock position; labral peel-back was reassessed. Results: A progressive increase was noted in peel-back grade with sequential cutting of the labrum posteriorly. However, disruption of the anchor alone did not lead to a positive peel-back sign. Disruption to the 2 o'clock position resulted in a positive peel-back sign overall in 9 of 10 shoulders (5 were grade 1, and 4 were grade 2). No increase was seen in peel-back grade with anterior extension of the labral detachment. Labral repair with a single anchor placed at the 12:30 o'clock position eliminated labral peel-back in 100% of shoulders. Conclusions: Detachment of the biceps anchor alone does not cause peel-back. The labrum must be disrupted to at least the 2 o'clock position before overt (grade 2) peel-back is observed. A single suture anchor placed at 12:30 o'clock eliminated peel-back of the labrum. Clinical Relevance: Validation of the peel-back test as an important diagnostic tool during shoulder arthroscopy.