A method for concise reporting of joint reaction forces orientation during gait

Area of Science:

• Biomechanics
• Orthopedics
• Medical Imaging

Background:

• Joint reaction forces (JRF) are vital for understanding load-related joint pathologies like osteoarthritis (OA).
• Current methods often present JRF components at discrete time points, lacking temporal orientation insights.
• A novel method is needed for intuitive and concise representation of JRF orientation over time.

Purpose of the Study:

• To develop and demonstrate a novel method for representing joint reaction force (JRF) orientation.
• To analyze differences in JRF orientation between individuals with knee osteoarthritis (OA) and healthy controls.
• To provide better visualization and insight into joint contact force behavior in pathologies.

Main Methods:

• A scaled musculoskeletal lower limb model was utilized, incorporating walking gait data from 10 knee OA patients and 10 healthy controls.
• Muscle forces and subsequent JRF were computed using the musculoskeletal model.
• A 95% confidence ellipse of JRF vector intersections with a transverse plane was calculated to derive orientation metrics (Area, Ratio, Angle, Center position).

Main Results:

• The osteoarthritis (OA) group exhibited a more anterior-posterior (AP)-oriented JRF at the knee (p=0.03).
• OA patients showed less overall variation (p<0.001) and fewer medial-lateral (ML) fluctuations (p=0.01) in JRF orientation compared to controls.
• Significant differences in JRF orientation were also observed at the hip and ankle joints.

Conclusions:

• The developed method offers a concise and intuitive representation of JRF orientation.
• This approach enhances visualization and understanding of joint contact force dynamics in clinical conditions like OA.
• The findings highlight distinct JRF orientation characteristics in knee OA, potentially aiding in pathology assessment and treatment strategies.