Injury to the Suprascapular Nerve During SLAP repair

Abstract

Objectives:The suprascapular nerve is potentially at risk during superior labrum repair. We compared risk of injury to the suprascapular nerve during suture anchor placement through an anterosuperior versus a rotator interval portal. Our hypothesis was that the rotator interval portal provides a safer and more reproducible method for repair of Type-II SLAP tears.Methods:Each pair of ten bilateral fresh human cadaveric shoulders was randomized to suture anchor placement through an anterosuperior portal on one shoulder and a rotator interval portal on the contralateral shoulder. Suture anchors were placed into the glenoid rim (one o’clock, eleven o’clock, and ten o’clock positions for right shoulder; eleven o’clock, one o’clock, and two o’clock for left shoulder). Standard 3 × 14 mm suture anchors were placed, and the suprascapular nerve was carefully dissected. When glenoid perforation occurred, the distance from the suture anchor tip to the suprascapular nerve was measured. The anchors were removed, and the distance from the glenoid rim to the suprascapular nerve and drill hole depth at each suture anchor entry site was recorded.Results:All far posterior suture anchors (ten o’clock anchor for right shoulders, two o’clock anchor for left shoulders) perforated the glenoid rim using the anterosuperior or rotator interval portal. For the far posterior anchor, distance from anchor tip to suprascapular nerve averaged 8.02 mm (range, 3.4 to 14 mm) using the anterosuperior portal and 2.1 mm (range, 0 to 5.5 mm) using the rotator interval portal, a statistically significant difference of 5.92 mm (95% confidence interval [CI]: −7.81 to −4.04; p ≤ 0.001).Conclusion:Using an anterosuperior or rotator interval portal results in consistent penetration of one o’clock and two o’clock posterior suture anchors and may place the suprascapular nerve at risk of iatrogenic injury. Based on the high likelihood of glenoid perforation and closer proximity of the suture anchor tip to the suprascapular nerve, the risk of injury is significantly greater with a rotator interval portal for superior labrum anterior and posterior repair.Clinical Relevance:It is important to recognize the high rate of glenoid perforation and risk of injury to the suprascapular nerve when placing anchors in the posterior glenoid from either portal.