Cross-linked Compared with Historical Polyethylene in THA: An 8-year Clinical Study

• DOI: 10.1007/s11999-008-0628-2
• Publication Date: 2008-11-21T21:35:12Z
• Authors: Carel H. Geerdink; Bernd Grimm; Wendy Vencken; Ide C. Heyligers; Alphons J. Tonino
• Keywords: Male; Arthroplasty, Replacement, Hip; Acetabulum; Osteolysis; Middle Aged; Prosthesis Design; Prosthesis Failure; 3. Good health; 03 medical and health sciences; Cross-Linking Reagents; Treatment Outcome; 0302 clinical medicine; Polyethylene; Health Status Indicators; Humans; Female; Hip Joint; Hip Prosthesis; Prospective Studies; Range of Motion, Articular; Aged

Wear particle-induced osteolysis is a major cause of aseptic loosening in THA. Increasing wear resistance of polyethylene (PE) occurs by increasing the cross-link density and early reports document low wear rates with such implants. To confirm longer-term reductions in wear we compared cross-linked polyethylene (irradiation in nitrogen, annealing) with historical polyethylene (irradiation in air) in a prospective, randomized clinical study involving 48 patients who underwent THAs with a minimum followup of 7 years (mean, 8 years; range, 7-9 years). The insert material was the only variable. The Harris hip score, radiographic signs of osteolysis, and polyethylene wear were recorded annually. Twenty-three historical and 17 moderately cross-linked polyethylene inserts were analyzed (five patients died, three were lost to followup). At 8 years, the wear rate was lower for cross-linked polyethylene (0.088 +/- 0.03 mm/year) than for the historical polyethylene (0.142 +/- 0.07 mm/year). This reduction (38%) did not diminish with time (33% at 5 years). Acetabular cyst formation was less frequent (39% versus 12%), affected fewer DeLee and Charnley zones (17% versus 4%), and was less severe for the cross-linked polyethylene. The only revision was for an aseptically loose cup in the historical polyethylene group. Moderately cross-linked polyethylene maintained its wear advantage with time and produced less osteolysis, showing no signs of aging at mid-term followup.Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.