Asymmetric plantar loading during gait is prospectively associated with early changes in knee and hip pain in community-dwelling older adults.

BACKGROUND

Asymmetric mechanical loading during gait alters lower-limb force distribution and may influence joint stress, yet its contribution to early changes in hip and knee pain before clinically apparent osteoarthritis remains poorly understood. This prospective cohort study examined whether plantar loading asymmetry during walking is associated with subsequent changes in joint pain in community-dwelling older adults.

METHODS

Community-dwelling adults aged ≥65 years underwent baseline 10-m walking trials using in-shoe loadsol® sensors to quantify plantar force kinetics. Bilateral hip and knee pain was assessed using the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index at baseline and at the 1-year follow-up. Between-limb asymmetry indices were calculated for plantar impulse and loading rate. Correlation analyses and multivariable regression models were used to evaluate associations between loading asymmetry and 1-year changes in joint pain.

FINDINGS: Of 98 participants assessed at baseline, 67 completed the 1-year follow-up. Greater midfoot impulse asymmetry was significantly associated with worsening left knee pain (p = 0.001). Worsening left hip pain was associated with both overall loading rate asymmetry (p = 0.012) and midfoot impulse asymmetry (p = 0.047). These associations remained significant after adjustment for relevant covariates.

INTERPRETATION: Asymmetric plantar loading during walking was prospectively associated with early worsening and emergence of hip and knee pain in older adults. These findings suggest that gait-related kinetic asymmetry, particularly involving midfoot impulse and loading rate, may reflect biomechanical mechanisms preceding overt joint pathology. Quantitative gait assessment using wearable sensors may help bridge laboratory biomechanics and early clinical symptom development.