PRAGUE — In patients with osteoarthritis—and even in healthy subjects—standard walking shoes result in significantly more knee adduction compared with barefoot walking or walking with a specially designed “unloading” shoe, Dr. Najia Shakoor reported in a poster at the 2006 World Congress on Osteoarthritis.
“High [dynamic] loading has been associated with both the presence and progression of OA,” said Dr. Shakoor in an interview, noting that increased loading results in increased adduction. In light of these findings, “in normal individuals, closer examination of the design and biomechanical effects of modern footwear on lower-extremity joint loading is warranted, both in healthy individuals who may be at risk for OA as well as [in] those with established OA.”
In a previous study, Dr. Shakoor and colleagues from Rush Medical College, Chicago, showed that in subjects with knee OA, walking barefoot significantly decreases peak external knee adduction compared with walking in standard walking shoes (Arthritis Rheum. 2006;54:2923–7). The group subsequently designed a shoe to mimic the unloading characteristics of barefoot walking and tested it in a cohort of 26 healthy subjects.
The 18 females and 8 males, with a mean age of 42 years, received gait evaluations while wearing their self-selected normal walking shoes. All of the subjects also had a gait analysis while walking barefoot, and 19 were analyzed while they wore the specially designed unloading shoes.
“The shoes are very flat and thin-soled, with a soft upper that wraps around the foot like a glove,” Dr. Shakoor said. “There are slit lines in the sole to conform to the major natural flexion points of the foot.”
Although a provisional patent has been filed and the group hopes that the shoes will eventually be marketed as a therapeutic intervention, they do not currently have any company affiliations.
Overall, a significant 13% reduction in subjects' external knee adduction was noted during their walking while barefoot and with the unloading shoes, compared with walking in their normal walking shoes. The researchers also have data showing similar unloading effects of the shoes in patients with OA, Dr. Shakoor said at the conference, which was sponsored by the Osteoarthritis Research Society International.