Varus thrust is a multiplanar dynamic phenomenon: Evidence from three-dimensional gait analysis in a population-based...

Area of Science:

• Biomechanics
• Orthopedics
• Gait Analysis

Background:

• Knee osteoarthritis (OA) affects millions globally.
• Varus thrust is a common gait deviation observed in individuals with knee OA.
• Understanding the underlying knee kinematics is crucial for developing effective interventions.

Purpose of the Study:

• To investigate the detailed three-dimensional (3D) knee kinematics associated with varus thrust.
• To compare these kinematics in healthy individuals versus those with knee OA.
• To identify specific kinematic patterns linked to varus thrust using gait analysis data.

Main Methods:

• Utilized 3D gait analysis data from the Matsudai Knee OA Epidemiological Survey.
• Included 383 participants with complete data, analyzing the right limb.
• Classified participants into varus thrust groups (-, ±, +) and compared six-degree-of-freedom kinematics during stance using ANOVA and ANCOVA.

Main Results:

• The varus thrust (+) group exhibited greater shank adduction and internal rotation relative to the thigh (Grood frame).
• In the world frame, this corresponded to increased shank lateral inclination and thigh medial/external rotation.
• These kinematic differences remained significant after adjusting for age, sex, BMI, and other relevant factors.

Conclusions:

• This study provides the first epidemiological characterization of knee kinematics in varus thrust using 3D gait analysis.
• A consistent, segment-specific kinematic pattern associated with varus thrust was identified.
• Further longitudinal and interventional studies are needed to determine the clinical relevance for OA progression and rehabilitation.