Effectiveness of a long-term use of a minimalist footwear versus habitual shoe on pain, function and mechanical loads in knee osteoarthritis: a randomized controlled trial

BACKGROUND Recent studies have shown an important reduction of joint overload during locomotion in elderly women with knee osteoarthritis (OA) after short-term use of minimalist shoes. Our aim is to investigate the chronic effect of inexpensive and minimalist footwear on the clinical and functional aspects of OA and gait biomechanics of elderly women with knee OA. METHODS/DESIGN Fifty-six elderly women with knee OA grade 2 or 3 (Kellgren and Lawrence) are randomized into blocks and allocated to either the intervention group, which will use flexible, non-heeled shoes- Moleca®-for six months for at least six hours daily, or the control group, which could not use these shoes. Neither group is undergoing physical therapy treatment throughout the intervention period. Moleca® is a women's double canvas, flexible, flat walking shoe without heels, with a 5-mm anti-slip rubber sole and a 3-mm internal wedge of ethylene vinyl acetate. Both groups will be followed for six months and will be assessed at baseline condition, after three months, and after six months (end of intervention). All the assessments will be performed by a physiotherapist that is blind to the group allocation. The primary outcome is the pain Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score. The secondary outcomes are global WOMAC score; joint stiffness and disability WOMAC scores; knee pain with a visual analogue scale; walking distance in the six-minute walk test; Lequesne score; amount and frequency (number of days) of paracetamol (500 mg) intake over six months; knee adduction moment during gait; global medical assessment score; and global patient auto-assessment score. At baseline, all patients receive a diary to record the hours of daily use of the footwear intervention; every two weeks, the same physiotherapist makes phone calls to all patients in order to verify adherence to treatment. The statistical analysis will be based on intention-to-treat analysis, as well as general linear models of analysis of variance for repeated measure to detect treatment-time interactions (α = 5%). DISCUSSION This is the first randomized, clinical trial protocol to assess the chronic effect of minimalist footwear on the clinical and functional aspects and gait biomechanics of elderly women with knee osteoarthritis. We expect that the use of Moleca® shoes for six months will provide pain relief, reduction of the knee adduction moment when walking, and improve joint function in elderly women with knee OA, and that the treatment, thus, can be considered another inexpensive and easy-to-use option for conservative OA treatment. TRIAL REGISTRATION NCT01342458.