Minimum 10-year outcomes of a curved anatomic femoral stem designed for the Japanese femora including dysplastic hips in total hip arthroplasty.

Purpose: This study aimed to evaluate the minimum 10-year outcomes of total hip arthroplasty (THA) using the CentPillar-TMZF, a curved anatomic stem developed based on anatomical data from Japanese patients including those with hip dysplasia.

Methods: Among 331 consecutive THA procedures, the CentPillar-TMZF was implanted in 80 primary THAs (24 %) following standardized selection criteria based on preoperative CT data. X-rays taken at the 10-year follow-up were assessed to evaluate stem fixation and the degree of stress shielding. Kaplan-Meier survivorship was calculated, with revision for any reason as the endpoint.

Results: Seventy-three of the 80 hips (91 %) were followed for 10 years or until revision surgery. In all hips followed more than 10 years, stem fixation was classified as bone-ingrown stable with first- or second-degree stress shielding. The survivorship rate, with revision as the endpoint, was 98 % (95 % CI 90 %-99 %) at 10 years. Before the 10-year follow-up, one patient required revision due to a periprosthetic fracture, and another required revision for dislocation.

Conclusion: In THA using CentPillar-TMZF, no aseptic loosening was observed until postoperative 10 years in patients whose femoral medullary canal shape was preoperatively determined to be compatible based on CT evaluation.