Injury to the suprascapular nerve during superior labrum anterior and posterior repair: is a rotator interval portal safer than an anterosuperior portal?

Abstract

The purpose of this study was to compare the risk of injury to the suprascapular nerve during suture anchor placement in the glenoid when using an anterosuperior portal versus a rotator interval portal. Ten bilateral fresh human cadaveric shoulders were randomized to anchor placement through the anterosuperior portal on one shoulder and the rotator interval portal on the contralateral shoulder. Standard 3 × 14 mm suture anchors were placed in the glenoid rim (1 o'clock, 11 o'clock, and 10 o'clock positions for the right shoulder). The suprascapular nerve was dissected. When glenoid perforation occurred, the distance from the anchor tip to the suprascapular nerve, the distance from the glenoid rim to the suprascapular nerve, and the drill-hole depth at each entry site were recorded. All far-posterior anchors perforated the glenoid rim when using the anterosuperior or rotator interval portal. The distance from the far-posterior anchor tip to the suprascapular nerve averaged 8 mm (range, 3.4 to 14 mm) for the anterosuperior portal and 2.1 mm (range, 0 to 5.5 mm) for the rotator interval portal (P ≤ .001). Using an anterosuperior or rotator interval portal results in consistent penetration of 1 o'clock and 2 o'clock posterior anchors and might place the suprascapular nerve at risk of iatrogenic injury. Based on closer proximity of the anchor tip to the suprascapular nerve, the risk of injury is significantly greater with a rotator interval portal. Using a rotator interval portal for suture anchor placement in the posterior aspect of the glenoid rim can lead to a higher likelihood of suprascapular nerve injury.