Outcomes of Second-Generation Tapered Wedge Femoral Stem

Newer generation cementless femoral stems have been designed to emulate more precisely the anatomy of the native femur. However, few studies have evaluated these designs. The purpose of this study was therefore to evaluate outcomes of primary total hip arthroplasty (THA) in patients who received a second-generation, tapered wedge stem by analyzing (1) all-cause and aseptic implant survivorships; (2) clinical and patient-reported outcomes; (3) radiographic outcomes; and (4) incidence of complications.

We evaluated 202 primary THA patients (37% men, 63% women) who had a mean age of 63 years (range, 18 to 88) and a mean body mass index (BMI) of 29 (range, 18 to 40). All patients underwent THA using a press-fit, tapered wedge stem with a morphometric design containing a size-specific medial curvature, which optimizes initial press-fit stability. Kaplan-Meier analysis was performed to determine implant survivorship, and Harris Hip Scores (HHS) and the Short form-36 (SF-36) were used to evaluate clinical and patient-reported outcomes. Early postoperatively and annually thereafter, pelvic radiographs were reviewed for evidence of osteolysis or loosening. Complications were identified through a comprehensive chart review and were classified as either surgical or medical.

At final follow-up, the all-cause and aseptic survivorships for the femoral stem were 99.5% and 100%, respectively. At final follow-up, the mean HHS was 87 (range, 35 to 100). The SF-36 mental and physical component scores were 47 (range, 19 to 65) and 47 (range, 23 to 65), respectively, at final follow-up. No progressive radiolucencies or loosening were observed. Surgical complications included nerve palsy, posterior trochanteric avulsion, arthrofibrosis, and periprosthetic fracture. The only medical complication was acute renal failure.

This second-generation stem demonstrated excellent short-term survivorship and functional outcomes. The improved patient fit of this stem may yield continued favorable results with longer-term follow-up.