McKellop et al. tested whether crosslinking UHMWPE acetabular cups — using either peroxide chemistry or gamma radiation — could dramatically reduce wear in hip simulator testing. The study also examined whether remelting irradiated cups after crosslinking could prevent the long-term oxidation that degrades conventional polyethylene. Testing ran for up to 5 million cycles, with mechanical properties and oxidation resistance evaluated across a range of radiation doses (3.3 to 100 Mrad).
The UHMWPE bearing surfaces used in total hip arthroplasty for most of the 20th century produced billions of submicron wear particles annually. This particle burden drove periprosthetic osteolysis and aseptic loosening — the dominant mode of THA failure. No bearing material had been rigorously validated to address this at the time of this paper.
This study quantified the dose-response relationship between gamma crosslinking and wear reduction, and identified remelting as the critical step that prevents the long-term oxidative degradation plaguing prior-generation polyethylene sterilized by gamma irradiation in air.
When evaluating a young or active patient for THA, this paper is the scientific basis for choosing highly crosslinked polyethylene over conventional UHMWPE. The wear reduction is not marginal: a 93% decrease in wear rate translates directly into fewer osteolytic particles and longer implant survival.
The crosslinking benefit is hip-specific. The crossing-path motion of the hip articulation is what makes crosslinking effective. In the knee, where motion is more unidirectional, crosslinking provides far less advantage. A distinction with direct implications for implant selection across joints.
This paper directly enabled the development of first-generation highly crosslinked polyethylenes (Longevity, Crossfire, Marathon) released in the late 1990s, which have since demonstrated markedly reduced osteolysis rates at 10+ year follow-up in clinical studies.
McKellop et al. tested whether crosslinking UHMWPE acetabular cups — using either peroxide chemistry or gamma radiation — could dramatically reduce wear in hip simulator testing. The study also examined whether remelting irradiated cups after crosslinking could prevent the long-term oxidation that degrades conventional polyethylene. Testing ran for up to 5 million cycles, with mechanical properties and oxidation resistance evaluated across a range of radiation doses (3.3 to 100 Mrad).
The UHMWPE bearing surfaces used in total hip arthroplasty for most of the 20th century produced billions of submicron wear particles annually. This particle burden drove periprosthetic osteolysis and aseptic loosening — the dominant mode of THA failure. No bearing material had been rigorously validated to address this at the time of this paper.
This study quantified the dose-response relationship between gamma crosslinking and wear reduction, and identified remelting as the critical step that prevents the long-term oxidative degradation plaguing prior-generation polyethylene sterilized by gamma irradiation in air.
When evaluating a young or active patient for THA, this paper is the scientific basis for choosing highly crosslinked polyethylene over conventional UHMWPE. The wear reduction is not marginal: a 93% decrease in wear rate translates directly into fewer osteolytic particles and longer implant survival.
The crosslinking benefit is hip-specific. The crossing-path motion of the hip articulation is what makes crosslinking effective. In the knee, where motion is more unidirectional, crosslinking provides far less advantage. A distinction with direct implications for implant selection across joints.
This paper directly enabled the development of first-generation highly crosslinked polyethylenes (Longevity, Crossfire, Marathon) released in the late 1990s, which have since demonstrated markedly reduced osteolysis rates at 10+ year follow-up in clinical studies.