May 14, 2020
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Biomechanical footwear system reduces pain in knee osteoarthritis

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Peter Jüni

Patients with knee osteoarthritis experienced improved pain at 24 weeks after wearing specially designed footwear affixed with individually calibrated convex pods on the outsoles, according to data published in JAMA.

“Biomechanics plays an important role in the development of osteoarthritis of the knee,” Peter Jüni, MD, of the University of Toronto and St. Michael’s Hospital, told Healio Rheumatology. “We did a 24-week randomized clinical trial of a novel individualized biomechanical footwear system. The shoes have two convex pods on the outsoles that can be individually calibrated and may alter the biomechanics of the lower limb. The shoes should be used daily for progressively increasing amounts of time.”

To analyze the impact of these specially designed shoes, compared with regular footwear, on OA knee pain, Jüni and colleagues conducted the Biomechanical Therapy for Osteoarthritis of the Knee (BIOTOK) randomized clinical trial. Researchers from the Boston University School of Medicine, the University of Toronto and the University of Bern recruited 220 participants with symptomatic, radiologically confirmed knee OA between April 20, 2015, and Jan. 10, 2017.

Researchers randomly assigned 111 of those participants to receive the biomechanical footwear with individually adjustable pods, while 109 were assigned control shoes, which had visible outsole pods but were not adjustable and did not provide a convex walking surface. The primary outcome was knee pain at 24 weeks of follow-up, using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain sub-score. Secondary outcomes included WOMAC physical function and stiffness sub-scores and the WOMAC global score, as well as serious adverse events. Two hundred-thirteen participants completed follow-up.

Patients with knee osteoarthritis experienced improved pain at 24 weeks after wearing specially designed footwear affixed with individually calibrated convex pods on the outsoles
Patients with knee OAexperienced improved pain at 24 weeks after wearing specially designed footwear affixed with individually calibrated convex pods on the outsoles, according to data.

According to the researchers, the mean standardized WOMAC pain sub-score at 24 weeks improved from 4.3 to 1.3 among those in the biomechanical footwear group, and from 4 to 2.6 in the control group (between-group difference in scores = –1.3; 95% CI, –1.8 to –0.9). These results were consistent for WOMAC physical function (–1.1; 95% CI, –1.5 to –0.7), WOMAC stiffness (–1.4; 95% CI, –1.9 to –0.9) and WOMAC global scores (–1.2; 95% CI, –1.6 to –0.8). The researchers recorded three serious adverse events in the biomechanical footwear group, compared with nine in the control group, with none related to treatment.

“This is the first randomized clinical trial suggesting that a change of biomechanics of the lower limb will benefit people with knee osteoarthritis,” Jüni said. “We believe that this system has an edge over other biomechanical devices, such as wedges, because of individual calibration and because of the neuromuscular retraining associated with walking on the convex pods.”

“Additional randomized clinical trials are required to confirm our results independently, including long-term trials beyond 24 weeks to assess efficacy and safety,” he added. “If confirmed in independent trials, our findings mean that we have a biomechanical treatment to offer to patients with knee osteoarthritis that actually works and – unlike many of the drugs out there – is safe.” – by Jason Laday

Disclosures: Jüni reports grants from AstraZeneca, Biotronik, Biosensors, the Canadian Institutes of Health Research, the Medicines Company and St. Jude Medical; honoraria from Amgen and Fresenius paid through to institution for participation on advisory boards; and unpaid membership of steering committees for trials funded by AstraZeneca, Biotronik, Biosensors, St. Jude Medical and the Medicines Company.