Proximity of the axillary nerve during bicortical drilling for biceps tenodesis

Purpose Pathology of the biceps tendon can contribute to significant shoulder pain and dysfunction for which biceps tenodesis may be indicated. A variety of techniques tenodesing the biceps tendon have been described. Recently, tenodesis using a uni- or bicortical button has been advocated. This cadaveric study investigates the proximity of the axillary nerve to the position of bicortical drill passages during biceps tenodesis. Methods Twelve cadaveric shoulder specimens were used. The axillary nerve was marked during a preparatory dissection using wire. Drills were passed through the humerus at the proximal and distal ends of the bicipital groove, and at the superior insertion point of pectoralis major (PM). These were left in situ. The distances between these drills and the axillary nerves were measured using computed tomography imaging. Results The drill bits placed at the superior insertion of PM were in closest proximity to the axillary nerve (3D distance mean 10.7 mm, 95 % confidence interval 7.2–14.2 mm). A drill placed at the distal end of the bicipital groove was a mean distance of 18.2 mm from the nerve. Conclusions This study highlights the need for caution when drilling the posterior humeral cortex during biceps tenodesis, particularly during drilling at the superior insertion of PM as this is the location that poses the highest risk to the axillary nerve. To our knowledge, this is the first cadaveric study to radiologically assess the proximity of the axillary nerve to the positions of biceps tenodesis. Surgeons should therefore be cautious when performing bicortical drilling for biceps tenodesis, and a supero-lateral drill trajectory would pose a smaller risk to the axillary nerve.