Wear of XLPE liner against zirconium heads in cementless total hip arthroplasty for patients under 40 years of age.

INTRODUCTION: Total hip arthroplasty (THA) in the young is challenging. The purpose of this study was to retrospectively determine the clinical, radiographic, and polyethylene wear rate of relatively young patients.

METHODS: We evaluated the outcome of consecutive patients receiving primary THA who were under 40 years of age with a minimum 10-year follow-up. Indications for THA in these patients were osteoarthritis due to developmental dysplasia of the hip joint (9 hips), osteonecrosis of the femoral head (7 hips), juvenile idiopathic arthritis (2 hips), and osteoarthritis due to Perthes disease (1 hip). All THA were performed with a cross-linked ultra-high-molecular-weight polyethylene (XLPE) liner against zirconium heads with cementless implants.

RESULTS: The average Japanese Orthopaedic Association hip score significantly improved from 42 to 93 points at the latest follow-up. The mean steady wear was 0.015 mm/year (maximum 0.033 mm/year), and the mean creep wear was 0.111 mm (maximum 0.4 mm). Osteolysis was observed around 1 acetabular component and 2 stems. 1 femoral component had subsidence over 5 mm. All of the femoral components achieved fixation with an optimal interface with spot welds at the latest follow-up. Stress shielding was observed in all hips.

CONCLUSIONS: THA using an XLPE liner against zirconium heads appeared to have improved THA longevity. However, the imaging findings in some cases were suggestive of wear debris. A rigorous continual follow-up is required for relatively young patients undergoing THA.