Influence of gap balance on the sagittal movement of a specific mobile bearing floating platform design in total knee arthroplasty

We analyzed 119 knees implanted with mobile bearing floating platform prostheses using the navigation-assisted gap balancing technique to analyze the relationship between intraoperative sagittal movement of floating platforms and soft tissue balancing. The 95 (79.8%) knees were classified into the positive rollback group (mean insert posterior rollback 5.86 ± 1.24. mm), and the remaining 24 (20.2%) into the negative rollback group. Lateral flexion gap (LFG) differed significantly between knees with positive and negative rollback (20.5 ± 1.7. mm vs 22.1 ± 1.7. mm, P= .021). Only LFG significantly influenced the occurrence of bearing sagittal movement. Sagittal translation of the insert occurred in about 80% of knees implanted with mobile bearing floating platforms in TKA, and was affected by flexion gaps, especially on the lateral side.