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 usi ng a standardized retrotorsion. The purpose of this study was to determine criteria for accurate adjustment of retrotorsion even when the proximal bic ipital groove is destroyed, as is the case in fractures, The distance of th e humeral head equatorial plane to the center of the bicipital groove was m easured by high-resolution computed tomography at 4 levels (proximal and di stal with 2 intermediate levels). The distal distance was considered to cor respond to available references in fracture cases. The mean proximal distan ce was 8.0 mm (10th percentile, 6.2 mm; 90th percentile, 9.8 mm), and the m ean 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 significan t difference between distances. For practical purposes in fracture indicati ons, it is adequate to adjust the retrotorsion of the prosthetic component to the distal bicipital groove.