This study elucidates a longitudinal relationship between varus knee thrust noticed during walking and knee pain. The use of biomechanical interventions to mitigate thrust in the prevention of new and worsening of pain can be justified by using the longitudinal relationship between knee thrust and WOMAC pain.

To investigate two year association of varus knee thrust perceived during walking with odds of worsening WOMAC knee pain in elderly with or at risk of OA.

The researchers assessed the video recordings of self-paced walking trials of MOST (Multicenter Osteoarthritis Study) participants for the presence of varus thrust at the baseline. WOMAC questionnaire was used to record Knee pain at baseline and two years. Estimation of the odds of worsening defined as either an increase in WOMAC score or clinically-significant worsening knee pain, adjusting for age, sex, race, BMI, clinic site, gait speed, and static knee alignment was carried out through logistic regression. Arranged by baseline radiographic OA status and among the subset of knees without baseline WOMAC pain the analyses were repeated. 

3204 knees of 1623 participants were used to calculate results. Varus thrust was observed in 31.5% knees. The knees with varus thrust at 95% CI: 1.19, 1.73 had 1.44 times the odds of any and at 95% CI: 1.11, 1.69 had 1.37 times the odds of clinically-significant worsening WOMAC pain compared to knees without thrust. Knees with thrust without baseline WOMAC pain portrayed 2.01 (95% CI: 1.47, 2.74) times the odds of incident total pain. 

Results showed that varus thrust is a risk factor for worsening and incident of knee pain. In older adults, targeting varus thrust through non-invasive therapies could prevent worsening or development of knee pain or in those at risk for knee OA.