Cementless femoral component designs supplemented with hydroxyapatite (HA) coating have been hypothesised to enhance osseointegration, thereby improving stability and clinical outcomes. We herein offer interim results at 5 years from a prospective, multi-centre study of a femoral stem (SL-PLUS™ Hip Stem Prosthesis), forged from titanium alloy (Ti6Al7Nb) and consisting of a titanium plasma sprayed coating (0.3mm) with an additional 0.05mm layer of HA. Investigators at 2 centres enrolled patients between 18–75 years of age who underwent primary total hip arthroplasty (THA) with this HA-coated stem. The study's primary outcome was the clinical efficacy of the stem, as measured by the Harris Hip Score (HHS), Western Ontario & McMaster Universities Osteoarthritis (WOMAC) Score calculated out of Hip Disability and Osteoarthritis Outcome Score (HOOS), and the EuroQol EQ-5D-3L index score and visual analogue scale (VAS). Its secondary outcomes included a radiographic assessment of implant position and fixation, and overall safety, as measured by intraoperative/early postoperative complications and survivorship calculated using Kaplan-Meier estimates.INTRODUCTION
METHODS
We reviewed 80 patients (87 hips) who were older than 80 years of age at the time of cementless total hip arthroplasty. An Alloclassic SL stem had been implanted in all patients. A variety of cementless acetabular components was used. After a mean follow-up of 69.3 months (39.2 to 94.1) 48 hips in 43 patients were analysed clinically and radiologically. One patient had sustained a traumatic periprosthetic fracture of the femur with subsequent exchange of the stem 73 months after operation. Thirty-two patients (34 hips) had died and five patients (five hips) were unavailable for follow-up because of health reasons (four patients) or lack of co-operation (one patient). If the endpoint is defined as removal of the prosthesis because of aseptic loosening, the survival rate was 100% for the cup and stem after 78 months. The mean Harris hip score was 81.9 points. Radiolucent lines and osteolysis were seldom found.