Polarstem Versus Corail; a Comparison of Micromotion and Periprosthetic Bone Remodelling of Two Femoral Stems

A randomised controlled trial comparing a recently introduced femoral stem with an established stem for total hip arthroplasty (THA). 60 patients will be randomised into one of the two groups 1. Polarstem uncemented femoral stem (Smith \& Nephew) 2. Corail uncemented femoral stem (De Puy) All patients will receive a 32mm cobalt-chromium (CoCr) femoral head and an R3 acetabular cup with a 10 Mrad highly cross-linked polyethylene (XLPE) liner (Smith \& Nephew). Radiostereometric analysis (RSA) will be used to measure stem migration. Dual-energy x-ray absorptiometry (DXA) measurements will be used to measure bone mineral density. Clinical outcome will be assessed at different time point to evaluate satisfaction and function. Data from the Norwegian Arthroplasty Register will be used to investigate the risk of revision.

Inclusion Criteria: * primary arthritis * secondary arthritis * aseptic necrosis of the femoral head * acute hip fracture * sequelae after hip fracture * can use standard implants Exclusion Criteria: * active malignant disease * rheumatoid arthritis or other generalised auto-immune arthritic disease * BMI\>35 * insulin dependent diabetes mellitus * chronic or recurrent infection * liver disease * Pagets disease * dementia or lack of compliance for other reasons * uncompensated cardiac- or pulmonary disease (ASA class 3 or 4)