['This study aimed to evaluate the immediate effects of medial arch supports on indices of medial knee joint load (the peak external knee adduction moment (KAM) and knee adduction angular (KAA) impulse) and knee pain during walking in people with medial knee osteoarthritis (OA).', 'Twenty-one people with medial compartment OA underwent gait analysis in standardised athletic shoes wearing (1) no medial arch supports and (2) prefabricated medial arch supports, in random order. Outcomes were the first and second peaks in the external KAM, the KAA impulse and severity of knee pain during testing. Outcomes were compared across conditions using paired t tests (gait data) and Wilcoxon Signed Ranks test (pain data).', 'There were no significant changes in either first or second peak KAM, or in the KAA impulse, with the addition of medial arch supports (all P > 0.05). Considerable individual variation in response to the arch supports was observed across participants. There was no immediate change in knee pain during walking when medial arch supports were worn (P = 0.56).'] Does medial arch support do not significantly alter the knee adduction moment in people with knee osteoarthritis?