Aims The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthro-plasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinemat-ics, measured using... Show moreAims The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthro-plasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinemat-ics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA).Methods A total of 40 patients with end- stage osteoarthritis were included in this randomized controlled trial. All patients performed a step -up and lunge task in front of a monoplane fluoroscope one year postoperatively. Femorotibial contact point (CP) locations were deter- mined at every flexion angle and compared between the groups. RSA images were taken at baseline, six weeks, three, six, 12, and 24 months postoperatively. Clinical and functional outcomes were compared postoperatively for two years.Results The BCR- TKA demonstrated a kinematic pattern comparable to the natural knee's screw-home mechanism in the step -up task. In the lunge task, the medial CP of the BCR- TKA was more anterior in the early flexion phase, while laterally the CP was more posterior during the entire movement cycle. The BCR- TKA group showed higher tibial migration. No differ- ences were found for the clinical and functional outcomes.Conclusion The BCR- TKA shows a different kinematic pattern in early flexion/late extension compared to the CR- TKA. The difference between both implants is mostly visible in the flexion phase in which the anterior cruciate ligament is effective; however, both designs fail to fully rep- licate the motion of a natural knee. The higher migration of the BCR- TKA was concerning and highlights the importance of longer follow- up. Show less
