Sequentially annealed highly cross-linked polyethylene reduced in vivo wear particle generation in total knee arthroplasty.

INTRODUCTION: Sequentially annealed highly cross-linked polyethylene (HXLPE) was recently introduced to reduce the wear in total knee arthroplasty (TKA). However, an in vivo advantage of sequentially annealed HXLPE on wear particle generation is still controversial. The purpose of this study is to compare the characteristics of in vivo wear particles between sequentially annealed HXLPE and conventional polyethylene after TKA.

MATERIALS AND METHODS: Synovial fluid was obtained from the eight knees with sequentially annealed HXLPE and from eight knees with conventional polyethylene 12 months after the operation. Polyethylene particles were isolated and examined using a scanning electron microscope and image analyzer.

RESULTS: Total number of wear particles in each knee was 2.1 ± 1.0 × 107 with sequentially annealed HXLPE (mean ± standard deviation) and 4.9 ± 3.6 × 107 with conventional polyethylene ( p = 0.036). Particle size (equivalent circle diameter) was 1.01 ± 0.26 μm with sequentially annealed HXLPE and 1.02 ± 0.20 μm with conventional polyethylene ( p = 0.674). Aspect ratio was 1.33 ± 0.04 with sequentially annealed HXLPE and 1.39 ± 0.10 with conventional polyethylene ( p = 0.462).

CONCLUSIONS: The sequentially annealed HXLPE reduced the in vivo polyethylene wear particles by 58% compared with conventional polyethylene without the significant change of particle size and shape.