Immediate effects of foot orthoses on gait biomechanics in individuals with persistent patellofemoral pain

Background: The efficacy of foot orthoses in reducing patellofemoral pain (PFP) is well documented; however, the mechanisms by which foot orthoses modulate pain and function are poorly understood. Research question: This within-subject study investigated the immediate effects of foot orthoses on lower limb kinematics and angular impulses during level walking and stair ambulation in individuals with persistent PFP. Methods: Forty-two participants with persistent PFP (≥3 months duration) underwent quantitative gait analysis during level walking, stair ascent and stair descent while using: (i) standard running sandals (control); and (ii) standard running sandals fitted with prefabricated foot orthoses. Hip, knee, and ankle joint kinematics and angular impulses were calculated and statistically analyzed using paired t-tests (p < 0.05). Results: Relative to the control condition, foot orthoses use was associated with small but significant decreases in maximum ankle inversion angles during walking (mean difference [95% confidence interval]: −1.00° [−1.48 to −0.53]), stair ascent (−1.06° [−1.66 to −0.45]) and stair decent (−0.94° [−1.40 to −0.49]). Foot orthoses were also associated with decreased ankle eversion impulse during walking (−9.8Nms/kg [−12.7 to −6.8]), and decreased ankle dorsiflexion and eversion impulse during stair ascent (−67.6Nms/kg [−100.7 to −34.6] and −17.5Nms/kg [−23.6 to −11.4], respectively) and descent (−50.4Nms/kg [−77.2 to −23.6] and −11.6Nms/kg [−15.6 to −7.5], respectively). Ankle internal rotation impulse decreased when participants ascended stairs with foot orthoses (−3.3Nms/kg [−5.4 to −1.3]). Limited changes were observed at the knee and hip. Significance: In individuals with persistent PFP, small immediate changes in kinematics and angular impulses – primarily at the ankle – were observed when foot orthoses were worn during walking or stair ambulation. The clinical implications of these small changes, as well as the longer-term effects of foot orthoses on lower limb biomechanics, are yet to be determined