MORPHOLOGY OF THE AXILLARY NERVE IN AN ANTEROINFERIOR SHOULDER ARTHROSCOPY PORTAL

An anteroinferior portal can be safely used in arthroscopic shoulder s urgery but requires an in-depth knowledge of axillary nerve anatomy. T he purpose of this report is to present the qualitative and spatial an atomy of the axillary nerve and to describe patterns of arborization t hat may affect ct safe anteroinferior arthroscopic portal placement. M easurements were taken in 42 embalmed cadaveric shoulders (20 male, 22 female). The distance from the acromioclavicular (AC) joint to the ax illary nerve averaged 7.90 cm (range, 7.2 to 9.1 cm) in males and 6.37 cm (range, 5.2 to 8.1 fm) in females. We describe the axillary nerve index (distance of nerve from the AC joint/length of deltoid from AC j oint) which can be used to predict the location of the axillary nerve along the anterior clavicular line (ACL). The axillary nerve index ave raged 0.48 (range, 0.42 to 0.57) La males and 0.41 (range, 0.31 to 0.5 7) in females, Four types of morphology were noted in the axillary ner ve: (1) main trunk with superior and inferior branches, (2) main trunk with superior branches, (3) main trunk with inferior branches, and (4 ) main trunk only. Our work supports the traditional operable safe zon e for the axillary nerve.