Surgical landmarks to determine humeral head retrotorsion for hemiarthroplasty in fractures.

Malrotation has been suggested as a cause of failure of hemiarthroplasty of the proximal humerus. Placing a shoulder prosthesis in relationship to the bicipital groove might reproduce individual anatomy more reliably than using a standardized retrotorsion. The purpose of this study was to determine criteria for accurate adjustment of retrotorsion even when the proximal bicipital groove is destroyed, as is the case in fractures. The distance of the humeral head equatorial plane to the center of the bicipital groove was measured by high-resolution computed tomography at 4 levels (proximal and distal with 2 intermediate levels). The distal distance was considered to correspond to available references in fracture cases. The mean proximal distance was 8.0 mm (10th percentile, 6.2 mm; 90th percentile, 9.8 mm), and the mean distal distance was 8.5 mm (10th percentile, 7.1 mm; 90th percentile, 9.9 mm). As to the clinical relevance, there was no statistically significant difference between distances. For practical purposes in fracture indications, it is adequate to adjust the retrotorsion of the prosthetic component to the distal bicipital groove.