Ten-year results of a bone-preserving low-modulus composite total hip replacement stemWhite SP, Lee MB, Galpin J, Learmonth ID.
A cementless composite femoral stem was developed with the aim of reducing bone loss secondary to stress shielding. Thirty-one stems were implanted in 27 patients, combined with a cementless acetabular component with polyethylene bearing surface in 30 cases and a bipolar head in 1 case. Patients were followed-up annually with clinical and radiographic evaluation. Fourteen hips underwent dual X-ray absorptiometry (DEXA) scans to monitor postoperative bone mineral density around the stem. The mean follow-up was 10.1 years. The mean Harris hip score improved from 57 to 92. To date, no stem has required revision. All stems are radiographically stable. Acetabular component revision has been required in 8 cases; 3 for liner dissociation and 5 for polyethylene wear. Radiographs and DEXA scans have shown some improvement in bone mineral density (BMD) between the 2 and 5-year follow-up. A cohort of patients displayed improvement in radiographic appearance and BMD in Gruen zone 7.
This stem shows evidence of proximal bone preservation and has excellent results at medium to long-term follow-up. The limiting factor in our cohort of patients has been the polyethylene bearing surface.