HIGHLY CROSS-LINKED VERSUS CONTEMPORARY POLYETHYLENE. RANDOMIZED EVALUATION OF THE PENETRATION RATE AT 4.8 YEAR FOLLOW-UP USING THE MARTELL SYSTEM.

Abstract

Introduction: The purpose of this prospective randomized study was to compare the minimum 4-year follow-up penetration of polyethylene inserts of identical desing in two configurations in a consecutive series of hybrid total hip arthroplasty.

Method: Between August 2000 and december 2001, 102 patients (102 hips) with a mean age of 69.2 years were randomized to receive either highly cross-linked (Durasul, 49 hips) or contemporary (Sulene, 53 hips) polyethylene inserts. Other parameters, including the 28 mm cobalt-chrome femoral head, the cementless cup (Fitmore, Zimmer) and cemented stem (Emeraude, Zimmer), were identical in both groups. The primary criterion for evaluation was head penetration measurement, using the Martell System.

Results: At a minimum 4-year follow-up evaluation, 34 hips in the durasul group and 30 hips in the Sulene group had complete radiologic data available for analysis (median follow-up of 4.8 and 4.9 years in the Durasul and Sulene group, respectively). The median femoral head penetration rate was 0.029 mm/year in the Durasul group versus 0.123 mm/year in the Sulene group (Mann and Whitney test, p=0.0027). The median volumetric penetration rate was 7.99 mm3/year in the Durasul group versus 41.93 mm3/year in the Sulene group. The yearly volumetric penetration rate was 80% lower in the Durasul group (Mann and Whitney test, p=0.0034).

Discussion and Conclusion: This study demonstrate a signifiant reduction of the yearly linear and volumetric femoral head penetration in highly cross-linked poly-ethylene. Longer-term results ae needed to warrant that these early data generate less occurence of osteolysis.