Jean Shanaa, Jacob Stoebner, Theodor Di Pauli von Treuheim, Ran Schwarzkopf, Anna Cohen-Rosenblum, Vinay K Aggarwal
The incidence of IPD in MDM implants is low, with pooled rates remaining below 1%. Revision rates were modest and consistent with published data on complex hip arthroplasty. No significant differences between manufacturers were detected, though findings are limited by the small number of non-Stryker implants reported. These findings suggest that MDM designs appear safe with overall low numbers of IPD-related complications, however, larger registry-based studies are needed to better define potential design-related differences in IPD risk.
INTRODUCTION: Intraprosthetic dislocation (IPD) is a rare but potentially catastrophic complication of dual-mobility (DM) implants, defined by dissociation of the inner femoral head from the polyethylene liner. Modular dual-mobility (MDM) designs were introduced to improve intraoperative flexibility and expand indications for DM technology. However, increasing reports of IPD have raised concerns that implant design and manufacturing differences may influence risk. The true incidence of IPD across MDM manufacturers remains unclear.
METHODS: A systematic search of PubMed, Embase, and Web of Science was performed. Studies reporting IPD incidence and stratified outcomes by implant manufacturer were included. A random-effects proportion meta-analysis was conducted to estimate pooled IPD incidence and revision rates overall and by manufacturer.
RESULTS: Of 523 identified articles, 32 met inclusion criteria, representing 3996 implants (2711 primary; 1285 revision). Mean follow-up was 3.48 years and mean age was 67.48 years. The overall IPD incidence was 0.38% (15/3996), with a pooled estimate of 0.1% (95% CI, 0-0.5%). Stratified analyses showed IPD rates of 0% for Stryker (95% CI, 0-0.7%), 0% for Zimmer (95% CI, 0-100%), and 0% for Groupe Lépine (95% CI, 0-100%). Reoperation rates were 1.4% (95% CI, 0.9-2.1%) in primary and 8.3% (95% CI, 6.0-11.3%) in revision THA.
CONCLUSIONS: The incidence of IPD in MDM implants is low, with pooled rates remaining below 1%. Revision rates were modest and consistent with published data on complex hip arthroplasty. No significant differences between manufacturers were detected, though findings are limited by the small number of non-Stryker implants reported. These findings suggest that MDM designs appear safe with overall low numbers of IPD-related complications, however, larger registry-based studies are needed to better define potential design-related differences in IPD risk.