Patient specific alignment and balancing with computer assisted surgery in total knee arthroplasty

Background: Achieving optimal outcomes in total knee arthroplasty (TKA) remains challenging due to the complex interplay between patient anatomy, implant design, and surgical technique. While neutral mechanical alignment was traditionally considered the gold standard for implant survivorship, recent evidence suggests that restoring constitutional alignment may improve functional scores and "forgotten knee" outcomes without compromising long-term stability.

Objective: This article describes a computer-assisted surgical strategy aimed at achieving patient-specific alignment and ligament balancing, utilizing a gap-balancing technique to restore native kinematics.

Key Points: The methodology employs navigation software to model knee laxity and plan bone cuts that accommodate the patient's pre-osteoarthritic axis. By adjusting the obliquity of tibial and distal femoral cuts within a ±3° range and modifying femoral rotation between 8° external and 2° internal, surgeons can achieve symmetric flexion and extension gaps without extensive soft tissue release. In a series of 199 primary TKAs using this technique, 79.9% of patients achieved neutral alignment (±3°), while 18% retained a constitutional deformity of 4–5°. Only 2% of cases were outliers exceeding 5°. Soft tissue releases were required in only 5% of the cohort, and no patellar dislocations were observed at three months postoperatively.

Conclusion: Navigation-assisted TKA allows for precise, individualized alignment targets that replicate native joint physiology. This approach facilitates excellent ligament balance and reduces the necessity for invasive peripheral releases, potentially improving postoperative functional recovery by respecting the patient's unique constitutional anatomy.