Five- year migration of uncemented femoral components in total knee arthroplasty with either highly cross- linked or conventional polyethylene inserts: a blinded randomized controlled trial using radiostereometric analysis

Aims The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross- linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate- retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient- reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients. Methods A double- blinded randomized controlled trial was conducted including 96 TKAs. The migration of the femoral component was measured with radiostereometry (RSA) at three and six months and one, two, and five years postoperatively. PROMs were collected preoperatively and at all periods of follow- up. Results There was no clinically relevant difference in terms of migration of the femoral component or PROMs between the HXLPE and PE groups. The mean difference in migration (maximum total point motion), five years postopeatively, was 0.04 mm (95% CI-0.06 to 0.16) in favour of the PE group. Conclusion There was no clinically relevant difference in migration of the femoral component, for up to five years between the two groups. These findings will help to establish a benchmark for future studies on migration of femoral components in TKA.