Flexible soles slow down knee osteoarthritis
By Margaret Jaworski
Relief for knees swollen and stiff from osteoarthritis looks like a shoe-in. The results of a soon-to-be published study confirm that wearing footwear with flexible soles can alleviate the pain of knee osteoarthritis and potentially slow down disease progression by significantly reducing stress on knee joints. Joint overload is a key factor in the development of osteoarthritis of the knee and other joints.
Traditionally, footwear has been engineered to provide maximum support and comfort for the foot, with little attention paid to the biomechanical effects on the rest of the leg, said Dr. Najia Shakoor, a rheumatologist at Rush University Medical Center in Chicago and author of the upcoming study and other research evaluating footwear’s effect on knee osteoarthritis. The shoes we wear have a substantial impact on the load on the knee joints, particularly when we walk, Dr. Shakoor said.
Symptoms of Knee Osteoarthritis
In one study, published online in Arthritis Care & Research (March 2010), Dr. Shakoor and her colleagues analyzed the relative impact of different shoe styles on knee joint stress in 31 patients with osteoarthritis. The researchers found that clogs and other stability shoes, the type of footwear conventionally believed to provide appropriate cushioning and support, increased loading on the knee joints by up to 15 percent. Flat, flexible footwear significantly reduced the load on the knee joints compared with supportive, stable shoes with less flexible soles, Dr. Shakoor said.
In follow-up research, Dr. Shakoor looked at how wearing flat, flexible shoes designed specifically for her study affected knee osteoarthritis over varying time periods. “We designed the shoe to allow natural foot mobility, to mimic the action of walking barefoot,” she said. In the randomized control study, 16 patients were arbitrarily assigned the mobility shoe or a nonflexible control shoe that looked just like the flex-soled shoe.
The study participants, all in their 50s, had medial compartment osteoarthritis, which affects the inner knee and accounts for 70% of all arthritis involving that joint. It’s just the way we are all designed as human beings,” Dr. Shakoor said. “Most people put three times more load on that medial compartment when they walk, so that’s where people tend to get arthritis.”
The participants wore the shoe for six hours a day, six days a week. Assessments, made at six, 12, and 24 weeks, showed an increasing reduction in knee load. After wearing the shoes for six months, participants experienced up to 20% less joint stress.
“This study showed that specialized footwear was beneficial in reducing knee loads substantially over six months,” Dr. Shakoor told Pain Resource. “It is also the first study to show that chronic use of a mechanical, knee-load-reducing intervention could lead to favorable alterations in the way participants walk ”even once the intervention is removed.”