A comparison of the biomechanical and clinical effects of a biaxial ankle-foot orthosis and lateral wedge insole in individuals with medial knee osteoarthritis

Purpose This study aimed to compare a biaxial ankle-foot orthosis (AFO) with a lateral wedge insole in terms of the biomechanical and clinical outcomes in individuals with knee osteoarthritis. Materials and methods A cross-over randomized design was used where 31 individuals (25 females and six males, mean age of 52.19 +/- 4.12 years) with knee osteoarthritis wore each intervention for two weeks with two weeks washout period. Three-dimensional kinematic and kinetic data and clinical outcomes were collected to evaluate the effects of each intervention on knee adduction moment (KAM), pain, stiffness, and function. Results Both orthoses significantly improved pain by 17 and 22%, function by 11 and 14%, the first peak KAM by 15.7 and 19.2%, the second peak KAM by 10.4 and 16.7%, and KAM impulse by 14.8 and 22.2%, respectively. However, the biaxial AFO significantly reduced the KAM and improved function compared to the lateral wedge insole (p < 0.01). Conclusions The results of this study have shown that both orthoses have a potential role in the conservative management of medial knee osteoarthritis. The biaxial AFO proved statistically better at improving function and KAM; though these differences do not seem to be clinically significant.IMPLICATION FOR REHABILITATION Orthotic interventions have been reported to be effective in the management of medial knee osteoarthritis. Lateral wedge insole and biaxial ankle-foot orthosis (AFO) are effective in the improvement of pain, function, and knee adduction moment (KAM) in people with medial knee osteoarthritis. The biaxial AFO, compared with lateral wedge insole, contributes to statistically more improvement of function and KAM. However, these differences do not seem to be clinically significant.