Evaluating Ligament Laxity Profiles Across Full Range of Motion in Total Knee Arthroplasty: Insights Into the Tibia‐First Technique

Alignment techniques in total knee arthroplasty (TKA) continue to evolve with advancements in implantation technologies. The recent possibility of reliably characterizing the soft-tissue envelope has enabled the development of TKA alignment techniques such as functional alignment, which aims to restore constitutional alignment while achieving proper soft-tissue balance. Although these techniques offer guidelines for bone cut parameters in terms of alignment boundaries, the definition of laxities remains unclear. In this regard, this study focuses on tibia-first TKA cases, evaluating laxity signatures when defining femoral cut parameters. This retrospective review analyzed 1762 TKA cases performed by 20 surgeons using a computer assisted orthopaedic surgery (CAOS) system. The cases were stratified based on the bearing type into three classes: posterior-stabilized (PS), cruciate-retaining (CR), and cruciate-retaining constrained (CRC). Statistical analysis, including two-way analysis of variance and post hoc Tukey multiple comparisons of the group means, demonstrated substantial surgeon-to-surgeon variability in intraoperative laxity profiles, irrespective of bearing type, compartment side, and tibial cut preference. This study highlights surgeon-specific differences in laxity profiles derived during intraoperative femoral planning, emphasizing the need for patient-specific guidelines to optimize TKA outcomes.