Background/Purpose: Positive outcomes of minimalist shoes on reduction of overload in patients with knee osteoarthritis (OA) have been highlighted. We have recently shown beneficial effects of acute use of a low-cost minimalist flat, flexible and non-heeled footwear in aged women with knee OA. Based on the chronic aspect of the disease, we now aim to investigate the long-term effects of this same footwear on gait biomechanics, clinical, and functional features of elderly women affected by knee OA.

Methods: Twenty-eight elderly women with grade 2 or 3 Kellgren and Lawrence knee OA were randomized and allocated to either intervention group (IG, n=16) which wore this minimalist shoe (Moleca) for 6 months for at least 6 hours daily, or to control group (CG, n=12) which did not wear these nor similar shoes. Physical therapy treatment was not allowed throughout the study. A diary was used to record the amount of daily use of the footwear intervention and paracetamol intake; every 2 weeks, adherence to treatment was verified through phone calls. All patients were assessed at baseline, 3^th and 6^thmonth by a physician and a physiotherapist, both blinded to group allocation. Primary outcome was pain WOMAC score and secondary ones were global WOMAC; joint stiffness and disability WOMAC scores; amount of paracetamol rescue medication intake over 6 months; knee adduction moment (KAM) during gait; knee edema and joint effusion. Multiple imputation methods and intention-to-treat analysis were performed. Treatment-time interactions were detected by general linear models of analysis of variance for repeated measure. Statistical significance is based at α = 5%.

Results: Interaction effect was observed for WOMAC pain (p=.007), function (p=.035) and WOMAC total score (p=.012). The percentage changes are in table 1. IG experienced a reduction by 18% (p=.043) in first peak KAM, 39% (p=.025) in KAM during midstance phase, and 29% (p=.041) in KAM impulse compared with CG at the end of intervention. Paracetamol intake was lower IG vs. CG at 4^th (p=.004), 5^th (p=.006) and 6^thmonths (p=.012). Clinical aspects as knee edema and effusion did not present any difference in both IG and GC at the end of intervention.

Conclusion: Long-term use of this flat, flexible and non-heeled shoe proved to be beneficial in elderly women with knee OA and thus can be prescribed as a low-cost non-invasive treatment capable to decrease pain and knee overload, and to improve overall function.

Table 1 – Percentage of change in the 3^rd and in the 6^thmonth by both groups in the WOMAC scores.