Footwear for self-managing knee osteoarthritis symptoms: protocol for the Footstep randomised controlled trial

BACKGROUND: Knee osteoarthritis (OA) is a leading cause of musculoskeletal pain and disability globally, and abnormal knee loading is central to disease pathogenesis. Clinical guidelines recommend clinicians provide advice regarding appropriate footwear for people with knee OA, yet there is little research comparing the effects of different footwear on knee OA symptoms. Research suggests that wearing flat flexible shoes is associated with lower knee joint loads compared to stable supportive shoe styles. This two-arm pragmatic, comparative effectiveness randomised controlled trial will compare the effects of daily use of flat flexible shoes and stable supportive shoes on knee OA clinical outcomes, over 6 months. METHODS: 164 people with symptomatic medial tibiofemoral OA of moderate to severe radiographic severity (Kellgren and Lawrence Grade 3 & 4) will be recruited from the community. Following baseline assessment, participants will be randomly allocated to receive either i) flat flexible shoes or; ii) stable supportive shoes. Participants will choose two different pairs of shoes from a selection that fulfil the criteria in their allocated shoe class. Limited disclosure will blind participants to group allocation. Participants will be instructed to wear their allocated shoes daily for 6 months (minimum of 6 h/day), after which participants will be reassessed. The primary outcomes are knee pain severity on walking (measured by numerical rating scale) and self-reported physical function (measured by the Western Ontario and McMaster Universities Osteoarthritis Index), assessed at baseline and 6 months. Secondary outcomes include additional measures of knee pain, function, sport and recreation participation and quality-of-life (measured using subscales of the Knee Osteoarthritis Outcome Score), as well as pain at other sites (measured by numerical rating scale), self-reported global ratings of change in pain and physical function (measured by 7-point rating scale), and