Suprapectoral biceps tenodesis with bicortical drilling procedures: anatomic analysis of chondral and axillary nerve risk with transhumeral pin guide.

Background: Many biceps tenodesis (BT) procedures are described for treating proximal biceps pathology. Axillary nerve injury has been reported during BT using bicortical drilling techniques with variable results depending on the location. In addition, there is a risk of potential articular damage during suprapectoral BT. We sought to determine the distance between the axillary nerve and the posterior passage of a bicortical pin, as well as the risk of articular damage, and to analyze whether a lateral inclination of the pin could avoid the chondral risk during suprapectoral BT with bicortical drilling.

Methods: Ten cadaveric shoulders were divided into 2 groups. In the first group, we determined the axillary nerve distance from the posterior exit point of 3 pins in a suprapectoral position 15 mm distal to the humeral cartilage: perpendicular, 10° caudal, and 20° caudal inclination. We measured 2 distances from the pin: to the axillary nerve and to the cartilage border. In the second group, we set one pin at the same perpendicular position and set the second pin 15° laterally tilted to determine its extra-articular passage.

Results: No pin injured the nerve, whereas all pins showed a transchondral direction. The 20° caudal inclination was the nearest to the nerve (18.8 mm [95% confidence interval, 5.5-32 mm]), but the perpendicular position was the safer position (38.8 mm [95% confidence interval, 28-49.6 mm]). Tilting the pin direction 15° laterally prevented cartilage damage (P = .008).

Conclusions: Suprapectoral BT with bicortical drilling performed 15 mm distal to the humeral cartilage is a safe procedure regarding the axillary nerve. A potential humeral chondral injury could be prevented with 15° of lateral inclination of the pin guide.