Analysis of the bicipital groove as a landmark for humeral head replacement.

Many anthropometric studies of the normal glenohumeral relationship have been performed in an effort to identify reference points for the correct placement of the humeral head prosthesis in shoulder arthroplasty. The bicipital groove offers a useful landmark for placement of the lateral fin of the prosthesis. However, when fracture surgery is performed, only the distal portion of the bicipital groove may be available for reference. We evaluated the course of the bicipital groove as it moves distally along the humerus. Computer-assisted tomography axial images of 21 cadaveric humeri were obtained in order to follow the course of the bicipital groove from proximal to distal on the humerus. With use of the bisector of the transepicondylar axis as a reference point, the relative change in position of the bicipital groove from proximal to distal was measured. The mean change in rotation of the lateral lip from the proximal to the distal groove was 15.9 degrees, with an SD of 6.8 degrees (range, 4 degrees -32 degrees ). The 95% confidence interval range for the change was 12.8 degrees to 19 degrees. Thus, a significant amount of internal rotation occurs along the course of the bicipital groove. This has significant clinical implications when the bicipital groove is used as a landmark for humeral head replacement in fractures of the proximal humerus.