A mathematical model can be used to evaluate the biomechanical status of the hip after sur­gical intervention. By using such a model, it is possible to evaluate changes in the magnitude of the hip-joint reaction force and its inclination, as well as the forces of the hip abductors at various positions of the greater trochanter with respect to the center of the femoral head. The purpose of this study was to establish whether the mathematical model for determination of the resultant hip force in a one-legged stance can appropriately describe the clinical status of the hip joint following surgery. The final analysis was performed for 71 patients with an average age of 73 years, who had been treated at the Clinical Department of Traumatology, Ljubljana, Slovenia, for medial femoral neck fracture over the past ten years. Out of these, 49 patients had been treated by implantation of a bipolar partial endoprosthesis, and 22 with a total endoprosthesis. The average follow-up period was four years. At the time of the last examination, the clinical status of the hip was evaluated and a radiograph of the hip and both joints was analyzed. A special computer-aided system for digitalization of radiographs was used to calculate the shift in the position of the greater trochanter of the operated hip joint with respect to the situation prior to injury. The clinical status of the hip joint was evalua­ted using the Harris hip score. The obtained results indicate an association between the biomechanical hip status and Harris clinical hip evaluation in patients with an implanted bipolar partial endoprosthesis. The Harris hip score increases with a lateral shift of the grea­ter trochanter, and decreases with its medialization (r=0.25). No correlation was found between the Harris hip score and a shift of the greater trochanter in a vertical direction. The method for determining the geometrical hip parameters was improved by accurately determining the magnification of the x-ray for each patient. No correlation was found between the magnifi­cation of the x-ray and the patient’s body weight (r = 0.09).