Feasibility and reliability of shear wave elastography-guided collateral ligament balancing during total knee arthroplasty : an ex vivo study on porcine knees.

Aims: To assess the feasibility and reliability of shear wave elastography (SWE) as an intraoperative tool for real-time monitoring and adjustment of collateral ligament tension during total knee arthroplasty (TKA). Methods: A total of 33 porcine knee specimens were divided into stretching (n = 13) and minimally invasive needle puncture (MNP) groups (n = 20). The stretching experiment evaluated correlations between distraction forces (20 to 60 N) and shear wave speed (SWS) in medial (MCL) and lateral collateral ligaments (LCL). The MNP experiment assessed SWS and medial gap changes during 45 punctures at 90° flexion or full extension under 45 N force. Pearson correlation, generalized linear mixed models (GLMMs), and two-way analysis of variance analyzed relationships and effects. Intra- and interobserver reliability were calculated using intraclass correlation coefficients (ICCs). Results: In the stretching experiment, SWS increased linearly with distraction force (r = 0.67 to 0.80, p < 0.001), unaffected by ligament thickness or structure. In the MNP experiment, SWS decreased with puncture count (r = 0.73, p < 0.001), detecting tension changes earlier than medial gap measurements (5 vs 20 punctures in flexion; 10 vs 20 in extension). GLMMs confirmed significant effects of force and puncture count on SWS (p < 0.001). Reliability was excellent (ICC > 0.88). Conclusion: SWE is a reliable, noninvasive tool for monitoring ligament tension changes during TKA, offering greater sensitivity than gap measurements. It shows great potential for optimizing knee ligament tension, improving soft-tissue balancing, and enhancing TKA outcomes.