Laxity phenotyping in total knee arthroplasty: A current concept article.

Area of Science:

• Orthopedic surgery
• Biomechanics
• Arthroplasty

Background:

• Phenotypic variation in the knee is influenced by bone anatomy and ligamentous laxity.
• Understanding this interplay is crucial for assessing patient-specific laxity.
• Current total knee arthroplasty (TKA) balancing may not account for diverse laxity phenotypes.

Purpose of the Study:

• To develop a clinically applicable classification system for knee laxity phenotypes.
• To create a corresponding treatment algorithm for balancing during TKA.
• To personalize TKA procedures based on individual patient anatomy and laxity.

Main Methods:

• Evaluated patient-specific laxity phenotypes in relation to bony phenotypes.
• Developed a 3x3 classification system based on coronal gap characteristics in extension and flexion.
• Created a treatment algorithm to guide corrective strategies for gap imbalance.

Main Results:

• Identified nine distinct knee laxity phenotypes.
• Lateral laxity was the most common flexion phenotype (>60%).
• Only two phenotypes met standard gap balance criteria; seven required correction.

Conclusions:

• A treatment algorithm addresses imbalance via bone cuts, soft-tissue releases, insert selection, or implant constraint.
• Standardized balancing goals may compromise bone or soft-tissue reconstruction.
• Tailoring TKA balancing to patient-specific laxity phenotypes is essential.