The immediate postoperative X-rays showed that the rotation center of the hip was 5,2 mm [0–10] far from the ideal rotation center (26% of cases: 0 mm) and the PE cup was implanted with a lateral inclination of 42,5° [30–55]. In postoperative X-ray follow up, one case of acetabular aseptic loosening was found which didn’t need hip revision. In all other cases no modification of implants position neither of hip rotation center was noted. In 79% of cases, we had total graft incorporation; in 17% of cases, an non evolutive radiolucent area between graft and bone and in 4% of cases (loosening) a graft migration.
The differences between the hemi- and inverted arthroplasty groups concerned the Constant score, which was significantly better in the inverted prostheses (65.5) than in the hemiarthroplasties (46.1), for all subscores. Active elevation was 138° for the inverted prostheses and 97° for the Aequalis prostheses (p <
0.01). Mean external rotation in position 1 was 22° for the Aequalis prostheses and 11° for the inverted prostheses (p <
0.01) with no difference in elevation rotation. These results remained equivalent and significant over time, even beyond five years. Radiographically, there was one case with an anomalous humeral component (impaction) in the inverted group. For the inverted prostheses, there were three migrations that have not been revised to date and three partial screw loosenings. The main problem was the development of notches in the scapular column observed in 50% of the cases including 20% which reached the lower screw. For the Aequalis prostheses, the main problem was deterioration of the acromial vault observed in 50% of the cases leading to altered function.