Dynamic knee behaviour: does the knee deformity change as it is flexed-an assessment and classification with computer...

Area of Science:

• Orthopedic surgery
• Biomechanics
• Knee kinematics

Background:

• Osteoarthritis significantly impacts knee joint mechanics.
• Pre-operative assessment of knee alignment is critical for successful total knee arthroplasty (TKA).
• Understanding dynamic coronal plane changes in arthritic knees is essential.

Purpose of the Study:

• To assess the dynamic kinematics of arthritic knees in the coronal plane before TKA.
• To identify and categorize distinct patterns of deformity during knee flexion.
• To investigate the hypothesis that arthritic knees follow specific kinematic patterns.

Main Methods:

• Analysis of coronal plane alignment (femoro-tibial mechanical angle - FTMA) in 512 arthritic knees.
• Data collected using non-image-based navigation systems.
• Measurements taken in extension and at 30°, 60°, 90°, and maximum flexion.

Main Results:

• Arthritic knees displayed 4 major kinematic patterns (and 8 subgroups) in the coronal plane from extension to 90° flexion.
• Varus deformities were more prevalent (73.8%) than valgus (21.1%).
• A significant proportion of knees (14.1%) exhibited a reversal of deformity during flexion (Types 3 and 4C).

Conclusions:

• Distinct, categorized kinematic patterns exist in arthritic knees during flexion.
• These dynamic changes may influence surgical decisions regarding collateral ligament releases.
• Failure to account for dynamic changes could lead to flexion instability, particularly in Types 3 and 4C knees.