according to a randomized trial that included more than 160 patients.
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“Contrary to our hypothesis, flat flexible shoes were not superior to stable supportive shoes,” reported Kade L. Paterson, PhD, of the University of Melbourne, and colleagues. Their study was published Jan. 12 in Annals of Internal Medicine.
Research gap
Abnormal knee joint loading has been implicated in the pathogenesis of knee OA. Guidelines recommend that patients wear appropriate footwear, but research has not established which shoes are best.
The 2019 American College of Rheumatology clinical guidelines note that “optimal footwear is likely to be of considerable importance for those with knee and/or hip OA,” but “the available studies do not define the best type of footwear to improve specific outcomes for knee or hip OA.”
Some doctors call for thick, shock-absorbing soles and arch supports, based on expert opinion. On the other hand, studies have found that knee loading is lower with flat flexible shoes, and preliminary evidence has suggested that flat flexible shoes may improve OA symptoms, the investigators said.
To study this question, they enrolled in their trial 164 patients aged 50 years and older who had radiographic medial knee OA. Participants had knee pain on most days of the previous month, tibiofemoral osteophytes, and moderate to severe tibiofemoral OA.
The researchers randomly assigned 82 participants to flat flexible shoes and 82 participants to stable supportive shoes, worn for at least 6 hours a day for 6 months.
In the trial, flat flexible shoes included Merrell Bare Access (men’s and women’s), Vivobarefoot Primus Lite (men’s and women’s), Vivobarefoot Mata Canvas (men’s), Converse Dainty Low (women’s), and Lacoste Marice (men’s).
Stable supportive shoes included ASICS Kayano (men’s and women’s), Merrell Jungle Moc (men’s), Nike Air Max 90 Ultra (women’s), Rockport Edge Hill (men’s), and New Balance 624 (women’s).
After participants were randomly assigned to a group, they chose two different pairs of shoes from their assigned footwear group.
“Participants were not told that the purpose of the study was to compare flat flexible with stable supportive shoes,” the researchers noted. “Instead, they were informed only that the trial was comparing the effects of ‘different shoes’ on knee OA symptoms.”
The primary outcomes were changes in walking pain on a 0-10 scale and physical function as assessed by the Western Ontario and McMaster Universities Osteoarthritis Index subscale at 6 months. The researchers also assessed other measures of pain and function, physical activity, and quality of life.
In all, 161 participants reported 6-month primary outcomes. The between-group difference in change in pain favored stable supportive shoes (mean difference, 1.1 units). In the flat flexible shoe group, overall average knee pain while walking decreased from 6.3 at baseline to 5.2 at 6 months. In the stable supportive shoe group, knee pain while walking decreased from 6.1 to 4.
In addition, improvements in knee-related quality of life and ipsilateral hip pain favored stable supportive shoes.
Participants who wore stable supportive shoes also were less likely to report adverse events, compared with those who wore flat flexible shoes (15% vs. 32%). Knee pain, ankle or foot pain, and shin or calf pain were among the adverse events reported.