While Total Knee Arthroplasty (TKA) is generally considered a clinically successful procedure for end-stage knee osteoarthritis, orthopedic surgeons are increasingly adopting personalized TKA strategies to improve patient-reported satisfaction. To date, most personalized knee replacement philosophies have focused primarily on coronal plane bony alignment. However, despite the innovation of precise bone resections and implant positioning, TKA patient-reported dissatisfaction remains around 10% and is often linked to soft tissue instability. The recent classification Laxity-Functional Knee Phenotype (L-FKP), provides a framework to quantitatively assess the soft tissue state, representing various combinations of collateral ligaments’ balance in flexion and extension.

The objective of this study is to leverage this phenotype classification to comparatively evaluate the impact of two distinct TKA planning philosophies, measured kinematic alignment (mKA) and inverse kinematic alignment (iKA), during simulated robotic-assisted TKA (tibia-first workflow). With a cohort of 85 arthritic knees, a custom Planning Analysis Tool (PAT) was used to simulate a mKA plan that maintains bony alignments and an iKA plan that aims for soft tissue balance for each patient based on their intraoperatively acquired native alignment. These results represent the predicted state of the knee after tibia bone resection but before any corrective secondary measures are taken.

This study demonstrates that mKA, an anatomical restoration philosophy, does not ensure soft tissue balance preservation, while iKA, a soft tissue targeted approach, achieves predictable soft tissue balance after the tibia resection. The mKA simulation unpredictably altered the soft tissue balance, with a systematic bias towards altering the flexion laxity (p=0.013). Conversely, the iKA simulation converged 87% of knees to a target soft tissue phenotype. These findings reveal a fundamental trade-off between philosophies, underscoring the clinical need for predictive tools to inform intraoperative decision making.

This thesis provides quantitative evidence that both planning philosophies adjust soft tissue laxities and that no single “systematic” philosophy is the most optimized approach for all patients. By identifying these biases or systematic shifts, this work provides insight into the downstream trade-offs between anatomical restoration and soft tissue balance.