Soft Tissue Balance/Joint Stability: Mid-Flexion Stability

The acquisition of an appropriate soft tissue balance leads to good postoperative outcomes and high patient satisfaction in total knee arthroplasty (TKA). Moreover, an inappropriate soft tissue balance may cause polyethylene wear, postoperative pain, and implant migration. However, the boundary between appropriate and inappropriate soft tissue balance is vague, as it is difficult to determine the proper target balance in TKA. Furthermore, standardized variations exist among surgeons [1], some of whom often rely on subjectivity by using hand sensations; others utilize objective measurements such as tension meters, navigation systems, and pressure sensors. Therefore, accurate evaluation is difficult unless the reproducibility of the amount of stress and flexion angle of the knee joint at the time of measurement is ensured. In addition, research on mid-flexion stability has been the focus of many researchers because it is required for daily life movements.