Effect of insole material on lower limb kinematics and plantar pressures during treadmill walking

Background: Currently there is a paucity of research providing recommendations on the type of orthotic or material used in its construction for different patient requirements.Objectives: To gain a greater understanding of the characteristics of orthotic materials and how they affect gait so to enhance the clinical decision-making process.Study Design: Repeated measures.Methods: Plantar pressures and kinematics were evaluated for 10 participants while walking on a treadmill under various conditions which included, shoes only and shoes with four different flat insoles and custom devices created in each of two densities of two materials.Results: For the flat insoles, medium density ethyl vinyl acetate was found to produce greater peak pressures than at least one of the other material conditions and low and medium density polyurethane were most effective at increasing average contact area and at reducing pressure time integral. For the custom devices, while no significant differences were evident, when compared to the shoe only condition, medium density polyurethane increased average contact area by a greater percentage than the other materials.Conclusions: Results for medium density polyurethane suggest a possible difference in loading characteristics, indicating a potential material suitability for patients with a compromised ability to deal with pressure.Clinical relevanceFindings from the present study provide information for a clinician to draw an evidence-based orthotic prescription based on material properties.