Does knee stability in the coronal plane in extension affect function and outcome after total knee arthroplasty?

Area of Science:

• Orthopedic surgery
• Biomechanics
• Medical imaging

Background:

• Total knee arthroplasty (TKA) aims to restore knee function and patient satisfaction.
• Understanding the relationship between in-vivo mechanics and clinical outcomes is crucial for improving TKA design and surgical techniques.

Purpose of the Study:

• To investigate the correlation between static varus-valgus laxities in extension, dynamic femoral condylar lift-off during walking, and patient-reported outcomes following posterior-stabilized TKA.

Main Methods:

• Ninety-four posterior-stabilized TKA knees were assessed for varus-valgus laxity using stress radiography.
• Patient-reported outcomes were evaluated using the New Knee Society Score (KSS).
• Femoral condylar lift-off during walking was measured in 15 patients using 3D-to-2D image-to-model registration.

Main Results:

• No statistically significant correlations were found between varus-valgus laxities and KSS components (p > 0.05).
• The average femoral condylar lift-off was 1.4 mm medially and 1.3 mm laterally.
• Femoral condylar lift-off did not correlate with varus-valgus laxities or KSS scores (p > 0.05).

Conclusions:

• In well-aligned TKAs, static coronal laxities do not appear to influence dynamic femoral condylar lift-off during walking.
• Minor variations in coronal laxities after TKA do not significantly impact patient-reported outcomes.