AIMS: The aims of this randomized controlled trial (RCT) was to compare the long-term insert wear and migration of the tibial and femoral components between highly crosslinked polyethylene (HXLPE) inserts and conventional polyethylene (PE) inserts in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA).
METHODS: A double-blinded RCT was conducted including 96 TKAs. The wear of the insert, and migration of both the tibial and femoral components, was measured with model-based radiostereometric analysis up to ten years postoperatively. Patient-reported outcome measures (PROMs) were collected preoperatively and at follow-up.
RESULTS: There was no progression of (medial) wear (from 0.15 mm at five years to 0.13 mm at ten years) for the HXLPE group after five years, whereas the wear rate increased for the PE group (from 0.22 mm at five years to 0.46 mm at ten years). There was no clinically relevant difference in terms of migration of the tibial and femoral component or PROMs between the HXLPE and PE groups at ten years. Migration of the tibial component (maximal total point motion; MTPM) after the ten-year follow-up for the HXLPE group was 0.99 mm (95% CI 0.83 to 1.18), and for the PE group, was 1.05 mm (95% CI 0.87 to 1.24). Migration of the femoral component (MTPM) after the ten-year follow-up for the HXLPE group was 1.16 mm (95% CI 0.99 to 1.35), and for the PE group, MTPM was 1.04 mm (95% CI 0.87 to 1.22).
CONCLUSION: There was no discernible increased wear for the HXLPE group after five years, whereas the wear for the PE group continued. After the initial migration, the uncemented TKA components remain stable at the ten-year follow-up. The use of HXLPE inserts are safe, when used in uncemented TKA, when considering wear and component migration.
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