Drilling through lateral transmuscular portal lowers the risk of suprascapular nerve injury during arthroscopic SLAP repair

Purpose: The aim of our study was to evaluate the risk of medial glenoid perforation and possible injury to suprascapular nerve during arthroscopic SLAP repair using lateral transmuscular portal. Methods: Ten cadaveric shoulder girdles were isolated and drilled at superior glenoid rim from both anterior–superior portal (1 o’clock) and lateral transmuscular portal (12 o’clock) for SLAP repairs. Drill hole depth was determined by the manufacturer’s drill stop (20 mm), and any subsequent drill perforations through the medial bony surface of the glenoid were directly confirmed by dissection. The bone tunnel depth and subsequent distance to the suprascapular nerve, scapular height and width, were compared for investigated locations. Results: Four perforations out of ten (40 %) occurred through anterior–superior portal with one associated nerve injury. One perforation out of ten (10 %) occurred through lateral transmuscular portal without any nerve injury. The mean depth was calculated as 17.6 mm (SD 3) for anterior–superior portal and 26.5 mm (SD 3.6) for lateral transmuscular portal (P < 0.001). Conclusions: It is anatomically possible that suprascapular nerve could sustain iatrogenic injury during labral anchor placement during SLAP repair. However, lateral transmuscular portal at 12 o’clock drill entry location has lower risk of suprascapular nerve injury compared with anterior–superior portal at 1 o’clock drill entry location.