The Immediate Biomechanical Effects of a Flat, Flexible School Shoe in Adolescents with Patellofemoral Pain

Abstract

ABSTRACT Introduction Treatment options for adolescent patellofemoral pain (PFP) are limited. School footwear might be a suitable intervention to modulate patellofemoral joint (PFJ) loads in adolescents with PFP. This study examined the immediate effects of a flat, flexible school shoe compared to a traditional school shoe on knee joint kinematics and kinetics, and PFJ reaction force during walking and running in adolescents with PFP. Methods 28 adolescents (12 female, 16 male, mean ± standard deviation age 14.3 ± 1.7 years) with PFP walked and ran on an instrumented treadmill in two randomly ordered conditions: (i) flat, flexible school shoe and (ii) traditional school shoe. Three-dimensional marker trajectory and ground reaction force data were sampled at 250 and 1000 Hz, respectively. Continuous ankle and knee joint angles and moments, PFJ reaction force and ankle power were compared between conditions using one-dimensional statistical parametric mapping paired t-tests (alpha <0.05). Results Walking in the flat, flexible school shoe resulted in a significant reduction in knee flexion (15-35% of gait cycle, p < 0.001), knee extension moment (15-40% of gait cycle, p < 0.001) and PFJ reaction force (15-40% of gait cycle, p < 0.001) compared to the traditional school shoe. During running, knee flexion (10-33% of gait cycle, p < 0.001), knee extension moment (15-25% of gait cycle, p < 0.001) and PFJ reaction force (15-25% of gait cycle, p < 0.001) were lower when wearing the flat, flexible school shoe compared to the traditional school shoe. Conclusions PFJ reaction force is reduced when adolescents walk and run in a flat, flexible school shoe compared to a traditional school shoe. Flat, flexible school shoes may be an effective intervention to modulate biomechanical factors related to PFP.