Aseptic loosening is associated with medial tilting and anterior translational migration of the tibial implant in mechanically aligned total knee arthroplasty.

Abstract

Aseptic loosening is a significant cause of implant revision in total knee arthroplasty, and radiostereometric analysis has been used to predict loosening by measuring implant migration over time relative to its position at the time of the index surgery. Studies have suggested that analyzing specific migration patterns may improve prediction of loosening, compared to using measures of the Maximum Total Point Motion alone. Therefore, the objective of this study was to determine whether patients monitored using radiostereometric analysis who experienced either aseptic loosening or revision exhibited distinctive tibial implant migration patterns. Extending a previous study using radiostereometric analysis, we calculated the 6-degree-of-freedom tibial implant migration patterns for seven patients with cemented mechanically aligned total knee arthroplasty implants who either developed aseptic loosening or were candidates for revision. We used simple linear regression to identify trends over time. We observed two trends that achieved statistical significance: negative rotation in the coronal plane (medial tilting) of the tibial implant (b = 0.26⁰/month, p < 0.001) and anterior translation (b = 0.67 mm/month, p = 0.005). Our study showed two statistically detectable migration trends associated with tibial component aseptic loosening. Although we were unable to assess in this study whether focusing on migration patterns in these directions provides greater predictive value than using Maximum Total Point Motion, the results suggest that certain migration mechanisms are more prevalent than others, which could motivate further research into the causes of such migration patterns.