Position of the anterior branch of the axillary nerve in relation to the humeral bone length.

Many studies have attempted to define a safety zone for the axillary nerve in lateral approaches to the deltoid, but with varying results. The main objective of our study was to analyze the variations in the position of this nerve, especially in relation to the length of the humerus. Overall, 16 cadaveric shoulders were dissected. The distances between both the anterolateral edge of the acromin (anterior distance) and the lateral edge of the acromion (posterior distance) to the axillary nerve were measured; the length of the humerus was also measured. Correlation analysis was performed between each distance and the length of the humerus. The average anterior and posterior distance were 7.2 cm ± 0.84 cm and 7.9 cm ± 0.92 cm, respectively; the average length of the humerus was 30.7 cm ± 3.2 cm. A significantly high positive correlation was found between the length of the humerus and both anterior distance (P = .94), and posterior distance (P = .92). In shoulder surgery, prior measurement of the length of the humerus could predict the distance between the acromion and the axillary nerve, and determine its position.