Biomechanical footwear may improve knee OA symptoms

Individually calibrated biomechanical footwear therapy may be effective in reducing knee pain and physical function in individuals with symptomatic knee osteoarthritis (OA), according to the results of the BIOTOK* trial.

The prevalence of knee OA is rising due to the ageing population and the increasing obesity rates. Biomechanical remedies have been developed to reduce pain and disease progression and improve function, owing to the adverse effects and limited efficacy of the most commonly used drugs. [Osteoarthritis Cartilage 2014;22:363-388; Pain Pract 2012;12:550-560; Lancet 2017;390:e21-e33] “[However,] evidence of their effectiveness has been inconclusive,” said the researchers.

“[Our findings show that] use of biomechanical footwear compared with control footwear resulted in an improvement in pain [in this patient group] at 24 weeks of follow up,” they said.

This was reflected in the greater reduction in mean standardized WOMAC** pain subscore from baseline following biomechanical vs control footwear use (from 4.3 to 1.3 vs from 4.0 to 2.6; between-group difference, −1.3, 95 percent confidence interval [CI], −1.8 to −0.9; p<0.001). [JAMA 2020;323:1802-1812]

Between-group differences were also seen in other WOMAC parameters such as physical function subscore (−1.1), stiffness subscore (−1.4), and global score (−1.2) in favour of the biomechanical footwear.

According to the researchers, the greater benefit with biomechanical footwear could have been due to the longer self-reported wear time.

Serious adverse events (SAEs) were more prevalent with the control vs the biomechanical footwear (n=9 vs 3) but none were treatment related. The SAEs were mostly musculoskeletal and circulatory in nature. Two participants experienced falls with the biomechanical footwear.

The study included 220 participants with symptomatic, radiologically confirmed knee OA (mean age 65.2 years, 47.3 percent women, 91 percent with medial knee OA). Participants were randomized 1:1 to wear*** either biomechanical footwear involving shoes with two individually adjustable external convex pods on the outsoles or control footwear with visible but nonadjustable outsole pods that did not create a convex walking surface.

Given the single-centre setting, generalizability of the findings may be limited, noted the researchers. The exclusion of individuals at high risk of falls and the underrepresentation of those with severe knee pain may have also limited the results.

Apart from a prospective nonrandomized trial showing results correlating with the current findings, [BMC Musculoskelet Disord 2010;11:179] no other randomized trial has comprehensively investigated the efficacy of a biomechanical footwear system in this setting, they said. Moreover, despite the statistically significant results in the current study, the clinical importance of biomechanical footwear remains uncertain.

Further exploration is thus warranted to ascertain the long-term efficacy and safety of biomechanical footwear in knee OA and to boost the current results before formulating solid conclusions about the clinical significance of the device, noted the researchers.