Relationship between stem-bone contact patterns and clinical outcomes of taper-wedged stem designed to fit the bone morphology of the Japanese.

INTRODUCTION

Taper-wedged stems have a stable fit and favorable clinical results. However, detailed studies on stem-bone contact patterns and clinical outcomes specific to Japanese patients are limited. This study aimed to describe stem-bone contact patterns and assess clinical outcomes in Japanese patients undergoing primary total hip arthroplasty (THA) with taper-wedged stems designed to fit the bone morphology of the Japanese population.

METHODS

We retrospectively reviewed 125 Japanese patients who underwent THA via a direct anterior approach using taper-wedged stems designed to fit the bone morphology of the Japanese population. Relationships between stem-bone contact patterns and clinical and radiographic outcomes were examined. Preoperative radiographs were evaluated to assess femoral morphology. Postoperative radiographs were evaluated to determine stem-bone contact patterns and the canal filling ratio. We divided the patients into proximal and distal fitting groups according to the stem-bone contact pattern. Osseointegration was assessed on the last follow-up radiograph using the Engh and O-SS scores.

RESULTS

The mean follow-up period was 5.1 years. Proximal femoral stem-bone contact was achieved in 90.4% of the cases. Both groups had good clinical and radiographic outcomes. Except for differences in preoperative bone morphology, there were no differences in demographics or clinical outcomes between the groups. The distal fitting type was more common in cases with champagne flute morphology. No aseptic loosening or revision was observed, and good osseointegration was obtained in either group.

CONCLUSION

THA with taper-wedged stems designed to fit the bone morphology of Japanese patients achieved favorable stem-bone contact patterns and acceptable short- to mid-term clinical and radiographic outcomes. Population-specific implant designs tailored to Japanese bone morphology may improve surgical outcomes and implant longevity.