Variability in knee pivoting behavior and condylar translation: Insights from a dynamic CT study

Area of Science:

• Orthopedics
• Biomechanics
• Medical Imaging

Background:

• Replicating physiological knee kinematics is a key objective in total knee arthroplasty (TKA).
• Natural variability in knee pivoting behavior, especially in osteoarthritic (OA) knees, is not well understood.
• Dynamic computed tomography (CT) offers a method to study knee motion.

Purpose of the Study:

• To characterize pivot patterns and femoral condyle translation in healthy and osteoarthritic (OA) knees.
• To compare the differences in knee kinematics between healthy individuals and patients with OA.
• To inform personalized TKA alignment strategies based on preoperative pivot characteristics.

Main Methods:

• Dynamic CT scans of 98 healthy knees and 11 OA knees were analyzed during non-weight-bearing flexion-extension.
• Femoral condyle motion and center of rotation (CoR) were assessed by fitting cylinders and projecting centers onto a tibial plane.
• The CoR was classified into medial, central, lateral, or no pivot categories.

Main Results:

• Healthy knees predominantly displayed a medial pivot (58.2%), followed by no pivot (31.6%).
• OA knees showed a higher prevalence of no pivot (45.5%) and lateral pivot (27.3%) patterns.
• Medial femoral condyle translation was significantly greater in OA knees (6.2 mm) compared to healthy knees (3.7 mm).

Conclusions:

• Healthy knees typically exhibit a medial pivot during non-weight-bearing extension.
• Osteoarthritic knees demonstrate a shift towards alternative pivot patterns and increased medial femoral condyle translation.
• Preoperative pivot patterns in OA knees may deviate from physiological motion, necessitating cautious interpretation for personalized TKA.