Axillary Nerve Proximity to the Humeral Guide Pin During Stemless Total Shoulder Arthroplasty

The proximity of the axillary nerve to the humeral head guide pin has not been described in current literature. Therefore, we aimed to elucidate the anatomical relationship through a cadaveric study. Ten fresh frozen cadaveric specimen were included in this study. Standard deltopectoral approach was utilized for appropriate exposure. The subscapularis and the long head of the biceps tendon were tenotomized to access the glenohumeral joint. Humeral head cut was then visually performed with humeral sizing and positioning. A Steinmann Pin was placed and advanced into the lateral cortex. Following dissection and visualization, the distance from the axillary nerve to the point of lateral humeral cortex was measured. On average, the axillary nerve was found 7.2 ± 3.1 mm from the tip of the Steinmann Pin at the level of the lateral humeral cortex and distal to the site of cortical penetration. Surgeons should be aware of the relationship between the axillary nerve and the humeral guide pin and care should be taken to protect the axillary nerve during piercing of the lateral humeral cortex during pin placement. This relationship continues to be of importance, even with evolving stemless implant systems in total shoulder arthroplasty.