Aseptic loosening in non-augmentable versus augmentable tibial baseplate total knee arthroplasty designs: a single-centre comparative 10-year outcomes study.

Background: Aseptic tibial loosening is a leading cause of revision in total knee arthroplasty (TKA). Previous work has highlighted concerns over the 5-year survivorship of a specific non-augmentable NexGen Legacy Posterior Stabilised (LPS) tibial baseplate. This study compares the long-term outcomes of augmentable versus non-augmentable tibial implants with a minimum 10-year follow-up.

Methods: A retrospective analysis identified patients undergoing primary cemented TKA between 2009 and 2014. Patients were categorised by tibial baseplate type (augmentable vs. non-augmentable). The primary outcome was aseptic loosening, assessed using Kaplan-Meier survival analysis. Secondary outcomes included overall revision rates and reasons for revision with a subgroup analysis by age and BMI.

Results: Among 1830 TKAs, revision rates were significantly higher in the non-augmentable group (6.4 % vs. 4.1 %; p = 0.036). Aseptic loosening was five times more common with non-augmentable implants (2.5 % vs. 0.7 %; p = 0.005). Kaplan-Meier analysis showed significantly reduced survivorship in the non-augmentable group due to aseptic loosening (p = 0.0012, HR = 0.262), with a marked decline after 100 months. Patients under 65 with higher BMI had greater risk, with aseptic loosening occurring in 9.1 % of those with BMI > 40 kg/m.

Conclusion: Non-augmentable NexGen LPS tibial implants are associated with higher rates of aseptic tibial loosening at long-term follow-up when used in combination with a posterior stabilised NexGen femoral implant. Younger, high-BMI individuals are at particular risk. These findings support the need for further investigation into the mechanisms of implant failure, as well as a more granular approach to data reporting within large-scale registries to avoid camouflage by more successful implants of the same brand.