Different wear in two highly cross-linked polyethylene liners in THA: wear analysis with EBRA

INTRODUCTION: The purpose of this study was (1) to compare early wear rates in bedding-in periods of two highly cross-linked polyethylene liners frequently used in THA and (2) to evaluate risk factors indicating a possible higher wear rate. MATERIALS AND METHODS: 1120 patients who received a Crossfire or a Marathon highly cross-linked (HXLPE) ultra-high-molecular-weight polyethylene liner in primary THA at our Department between 2004 and 2018 were retrospectively reviewed. Patients with (1) only alumina heads on HXLPE acetabular bearings, (2) a minimum of four radiographs per patient for EBRA analysis, (3) no osteolysis around the acetabular cup and (4) no dislocations that occurred during the study period were included. RESULTS: A total of 328 patients (female: 183; male: 145; Marathon: 179; Crossfire: 149) fulfilled the inclusion criteria. Mean follow-up was 24 (range 7–51) months. With 0.22 (SD 0.27) mm mean total wear for the Marathon was three times greater than for the Crossfire, namely 0.07 (SD 0.14) mm. Mean cup migration during the investigated follow-up period was 0.7 (SD 0.8) mm for the Pinnacle and 0.5 mm (SD 0.7) for the Trident PSL cups. CONCLUSION: Initial early wear of highly cross-linked polyethylene in combination with alumina heads differs strongly between products. Long-term survivorship of these liners should be observed to determine whether early wear has an impact on aseptic loosening. LEVEL OF EVIDENCE: Level III (retrospective comparative study with prospective cohort).