Ten-Year Clinical and Radiological Outcomes of 100 Total Hip Arthroplasty Cases with a Modern Cementless Dual Mobility Cup.

Introduction: The original cementless Sunfit® dual mobility cup (SERF, Décines, France) exhibited limited osseointegration due to its hydroxyapatite and alumina coating. We hypothesized that replacement of the alumina with plasma-sprayed titanium + hydroxyapatite and improvement of the external geometry (Sunfit TH®) would not increase the risk of aseptic loosening. The primary goal of this study was to determine the survivorship and clinical and radiological outcomes among patients with the Sunfit TH® implant.

Material And Methods: This was a single-center, prospective study of the first 100 consecutive total hip arthroplasty (THA) cases performed using the combination of a press-fit Sunfit TH® dual mobility cup and a cementless straight stem. All of the cases were primary THA and the posterolateral approach was used. The patients underwent regular clinical and radiological monitoring. Radiological measurements were carried out using OsiriX® software (Pixmeo, Geneva, Switzerland).

Results: As of the final follow-up, 19 patients had died and 4 could not be contacted. Of the remaining patients, there were zero cases of aseptic loosening, dislocation or intraprosthetic dislocation (IPD). The survivorship was 100% at 10.03 years of follow-up. No significant implant migration was measured on radiographs.

Conclusion: The excellent long-term outcomes with the Sunfit TH® cup are likely due to the use of plasma-sprayed titanium + hydroxyapatite in the coating and the addition of supplementary ridges and grooves to the outside of the cup. The absence of aseptic loosening, dislocation and IPD further confirms the high stability and good survivorship that can be achieved with these implants. We believe dual mobility cups should be used in patients above 60 years of age and in those below 60 years of age with a high risk of postoperative instability.