What does the SOFCOT-RENACOT 2024 hip prosthesis register tell us?

Introduction: The French Society of Orthopedic and Traumatology Surgery (SOFCOT) multicenter register of hip prostheses (HP) has been collecting data from nearly 100 centers in France since 2006. After 18 years of collection, this analysis was carried out to deduce the main conclusions.

Hypothesis: Despite its low representativeness (3%), this register provides instructive information on the evolution of hip arthroplasty techniques and implants in France.

Material And Methods: As of the 31st of December 2023, 58,314 primary HP were recorded, mainly for primary osteoarthritis (44,535 hips, 76.4%), followed by femoral neck fractures (4,880, 8.4%). The mean age was 71 years (SD, 11.6) with 57% (33,305) women. In total, 73% of the implants were uncemented and 170 brand names were listed. Over the same period, 5,853 first reoperations were recorded. Social security number matching identified 777 revisions of an already registered primary HP. The revision index for 100 components observed per year (RCOY) allows the performance of implants to be compared (alert threshold if >1.3).

Results: The causes of these 777 early first revisions at a short mean follow-up (MF) of 1.4 years were: dislocation (191/777, 24.6%), peri-prosthetic fracture (175, 22.5%), aseptic loosening (103, 13.3%) and acute infection (101, 13%). The RCOY for all primary HP was 0.25 at 5.4 years of MF. This index: (i) Depended on the type of implant: 0.23 for HP with dual-mobility cups (DMC) at 4.7 years of MF; 0.25 for HP with short femoral stems at 4.4 years; and 0 for resurfacing after only 2.5 years (due to the creation of a specific mandatory register, since 2015, which put an end to the voluntary inclusion of resurfacing in this general register). (ii) Depended on the method of fixation: 0.21 for completely cemented HP at 7.8 years of MF and 0.29 at 4.9 years for completely uncemented HP. (iii) Based on the friction torque: 0.12 for conventional metal-metal HP at 9.7 years of MF and 0.29 at 5.1 years for alumina-alumina HP. (iv) Finally, 3 arthroplasties with 3 uncemented stems had an RCOY > 1.3.

Discussion: Although the RCOY of HP with conventional cemented femoral stems is only 0.16 at 6.6 years of MF, while that of HP with conventional uncemented stems is 0.29 at 4.9 years, the trend towards uncemented femoral fixation has continued to intensify. Resurfacing gives good results following careful selection of implants but with a short MF of 2.5 years. Conventional metal-metal bearings continue to give excellent results at almost 10 years of MF. The 10-year survival of HP with short femoral stems is favorable compared to that of HP with conventional stems. There is no significant difference between the survival of HP with conventional versus highly cross-linked polyethylene liner.

Conclusion: Despite its low representativeness, this register provides information on the techniques and implants used in France. The addition of clinical monitoring and PROM within the new SOFCOT-RENACOT registry as well as re-certification obligations should help promote its development.

Level Of Evidence: III; prospective comparative study.