Effects of Shoe-Stiffening Inserts on Lower Extremity Kinematics in Individuals With First Metatarsophalangeal Joint Osteoarthritis

Objective To examine the effects of shoe-stiffening inserts on lower extremity kinematics in individuals with first metatarsophalangeal (MTP) joint osteoarthritis (OA). Methods Forty-eight individuals with radiographically confirmed first MTP joint OA (24 male and 24 female; mean +/- SD age 57.8 +/- 10.5 years) were randomized to receive either shoe-stiffening inserts or sham inserts and underwent gait analysis during level walking using a 10-camera infrared Vicon motion analysis system. Sagittal plane kinematics of the first MTP, ankle, knee, and hip joints were compared between the shoe only (control) and insert conditions in both groups (within-groups) and between both insert conditions (between-groups). Results Compared to the shoe only condition, the sham insert reduced knee flexion and total excursion, and the shoe-stiffening insert reduced first MTP joint maximum dorsiflexion and ankle joint maximum plantarflexion, and increased maximum knee flexion and total excursion. Between-group comparisons indicated that the shoe-stiffening inserts significantly decreased first MTP joint maximum dorsiflexion, ankle joint maximum plantarflexion, and total excursion and increased knee joint maximum flexion and total excursion compared to the sham inserts. Conclusion Carbon fiber shoe-stiffening inserts significantly alter sagittal plane lower extremity joint kinematics during walking, particularly first MTP joint maximum dorsiflexion. These findings provide insights into the mechanisms that may be responsible for their clinical effectiveness in the treatment of first MTP joint OA and potentially explain changes in symptoms in other lower extremity joints.