A total of 1,051 Zweymuller-type femoral components of cementless hip endoprostheses from the Instrumentaria manufacturer were implanted in 979 patients in the Orthopedic Clinic of the Zagreb Clinical Hospital Center during the four-year period from August 2014 to July 2018. The survival analysis of these endoprostheses performed in 2023 showed that the femoral stem was surgically revised in 8.4% of patients available for follow-up. This study aims to analyze the radiological changes of the revised femoral stems until the beginning of 2024. X-rays of the hips taken before and immediately after surgery as well as later during follow-up were used in the analysis. Of the 74 revised femoral stems, radiological documentation required for the analysis was available for 56 patients (75.7 %). The femoral stem was not primarily placed in the ideal position in four patients (7.1 %). During follow-up, loss of proximal cortical bone density (stress shielding) was observed in 49 patients (87.5 %). Cortical hypertrophy on the distal part of the femoral stem was observed in 21 patients (37.5 %). Radiolucent lines on the contact surface between the cortical bone and the femoral stem were present in 50 patients (89.3 %). Lucencies wider than 2 millimeters were found in 27 (48.2 %) patients. Subsidence of the stem into the femoral canal was found in 44 patients (78.6 %). The average subsidence was 6.7 millimeters (range 1-21 millimeters). Subsidence of more than 5 millimeters was recorded in 25 patients (44.6 %). Stem migration regarding the longitudinal axis of the femur was observed in 24 patients (42.9 %). A total of 12 revised patients had no radiological signs of femoral component loosening. Radiological signs of instability of the femoral stem of Instrumentaria manufacturer were present in 78.6 % of patients. The most common radiological signs of femoral stem instability are the subsidence of the stem and the appearance of a progressive radiolucent line.