Purpose: This prospective study evaluated suprascapular nerve injury risk during arthroscopic superior labral repair in patients of average height or shorter.
Methods: From 2009 to 2011, 12 patients <179 cm tall undergoing arthroscopic superior labral repair were prospectively enrolled. Portal location, tear and anchor characteristics, and surgeon impression of medial glenoid wall perforation were collected. Suprascapular nerve conduction studies were obtained postoperatively. A musculoskeletal radiologist evaluated medial glenoid wall perforation and the distance from the anchor to the suprascapular neurovascular bundle on postoperative magnetic resonance images (MRI). DASH scores were recorded preoperatively and 6 months postoperatively.
Results: Medial wall perforation occurred in five (42 %) patients, with 3 patients having a single perforation and two patients having two perforations. Eight of 38 (21 %) anchors drilled into the superior half of the glenoid, and 6 of 20 (30 %) anchors inserted into the postero-superior quadrant of the glenoid, perforated the medial wall. Perforations occurred both through the portal of Wilmington and the antero-superior portal. The distance to the suprascapular neurovascular bundle from the perforating anchors ranged from 0 to 4 mm. Nerve conduction studies revealed subclinical signs of an incomplete nerve injury in one patient. DASH scores improved on average 29.3 points postoperatively (SD = 27.0, p = 0.007).
Conclusion: Medial wall perforation is common in smaller patients during arthroscopic superior labral repairs; the suprascapular nerve can be injured if perforation occurs. The clinical significance of these findings is unclear. In spite of a high drill-out rate, the nerve is rarely injured; however, an anchor designed for implantation into bone that is instead lodged in the soft tissues has the potential to harm these tissues and surrounding structures.
Level of evidence: Prospective cohort study, treatment study, Level III.