Abstract
Introduction: The annual wear rate in polyethylene articulations should be 0.1 mm or less to avoid future osteolysis. Highly Crosslinked polyethylene demonstrates 80–90% wear reduction in hip simulator testing, but the clinical documentation of this new polyethylene is still inadequate. We evaluated the highly crosslink PE in two prospective randomised clinical studies. Patients and Methods: Thirty two patients (12 male, 20 female, 64 hips) with a median age of 48 years (range, 29–70 years) with bilateral primary or secondary arthrosis of the hip received hybrid THA. With liners made of highly cross-link on one side and conventional PE on the other one. Twenty-seven patients in this study have passed 2 years follow up. Further Sixty patients (61 hips) with a median age of 55 years (range, 35–70 years) were randomized to receive either highly crosslink or conventional cemented all PE of the same design. Forty-nine patients have been followed for 3 years. In both studies all patients received Spectron stems with 28mm cobalt-chromium head. Radiostereometric examinations with the patient supine or standing were done at regular intervals. Wear was measured in the supine position from the postoperative week, whereas standing examinations were initiated three months after the operation. Results: The penetration rate was almost identical in the study and control groups in 6 months after the operation. Thereafter the penetration rate levelled out in the 2 groups with highly crosslink PE. At two years the highly crosslink PE liner showed 62% lower proximal penetration and 31% lower total (three-dimensional) penetration when the patients were examined in supine position. The highly crosslink all PE cemented cups showed significantly lower proximal penetration in both position. Discussion: The better wear performance of highly crosslink PE could increase the implant longevity. Longer follow up is needed to evaluate if this new material is associated with less occurrence of osteolysis.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
