We applied a new methodology in 7 patients with a fracture of the upper humeral head that required hemiarthroplasty, to implant a humeral prosthesis with an individualized posterior version. Our goal was to determine preoperatively the distance from the posterior edge of the bicipital groove where the lateral fin of the humeral prosthesis should sit, in order to reproduce the individual retroversion during surgery. Using three computed tomography scan sections of the upper humerus and image processing software, we estimated the above-mentioned distance in the sound humerus and implanted the prosthesis in each patient accordingly. The differences in retroversion between the left and right humeral heads permit a better approximation to normal applying this methodology than inserting the prosthesis in a standard retroversion.