The course of the suprascapular nerve in the supraspinatus fossa and its vulnerability in muscle advancement.

Twenty-four cadaveric shoulders were evaluated to assess damage to the suprascapular nerve in relation to Debeyre's advancement of the supraspinatus muscle for rotator cuff repair. In all cases the neurovascular pedicle was tethered at the suprascapular notch and at the periosteum of the supraspinatus fossa. The medial motor branches were directed to the trigonum spinae or the superior angle of the scapula (group 1). The dorsal branches crossed the muscle at the bottom of the supraspinatus fossa (group 2) or directly entered the muscle (group 3). The lateral group remained in the supraspinatus fossa (group 4) or entered the infraspinatus fossa (group 5). The mean distance between the scapular notch and the point of entry of the medial branches into the muscle was 2.9 cm. Branches of group 1 and the main nerve are at risk of injury when detaching muscle from bone. This risk is minimized by subperiosteal detachment. Branches of group 1 are tensioned when advancing the muscle 1 cm laterally.