Effects of foot core training combined with hip and knee strengthening on patients with patellofemoral pain: a randomized controlled trial

BACKGROUND: Patellofemoral pain (PFP) is a common musculoskeletal condition associated with strength deficits and altered lower-limb kinematics. Impaired "foot-core" function and foot-ankle mechanics may contribute to altered patellofemoral joint loading, but the added value of combining foot-core training with conventional hip-knee strengthening remains unclear. OBJECTIVE: To examine the effects of adding foot-core training to a hip-knee strengthening program on pain, function, strength, and three-dimensional step-down kinematics in individuals with PFP. METHODS: In this assessor-blinded randomized controlled trial, 40 participants with PFP were randomly allocated to an experimental group (EG; foot-core plus hip-knee strengthening; age 23.89 ± 1.58 years) or a control group (CG; hip-knee strengthening; age 22.94 ± 2.11 years) for 6 weeks. The primary outcome was the worst pain during daily activities measured with a visual analog scale (VAS). Secondary outcomes were function (Anterior Knee Pain Scale, AKPS), concentric isokinetic relative peak torque at 60°/s during hip extension/abduction and knee extension/flexion of the affected limb, and three-dimensional hip, knee, and ankle joint angles at initial contact (contralateral toe contact) during a single-leg step-down task. Outcomes were assessed at baseline and immediately post-intervention. RESULTS: EG demonstrated a greater reduction in post-intervention VAS than the CG (P = 0.022; ηp² = 0.135). AKPS was also higher in the EG than in the CG at post-intervention (P = 0.001; ηp² = 0.257). For step-down kinematics, the EG showed more favorable frontal-plane alignment than the CG, including lower hip adduction and knee valgus (both P < 0.001; ηp² = 0.676 and 0.525), and greater ankle dorsiflexion (P < 0.001; ηp² = 0.805). In isokinetic strength outcomes, the EG exceeded the CG in quadriceps and hip abductor relative peak torque (both P < 0.001; ηp² = 0.669 and 0.594), whereas hamstrings and hip extensors showed no between-group differences (P ≥ 0.398). CONCLUSION: Adding foot-core training to a hip-knee strengthening program resulted in small additional improvements in pain and function and produced larger between-group effects in selected kinematic variables and strength outcomes. The clinical significance of these biomechanical changes requires further investigation. TRIAL REGISTRATION: chictr.org.cn. NO: ChiCTR2400087664. Date 01/08/2024.