Commonly used, over-the-counter orthotics may actually contribute to knee osteoarthritis, according to a recent study in Medicine & Science in Sports & Exercise.
In the study, 22 physically active young adults ran and walked in running shoes with and without arch support cushions. The participants ran on an instrumented treadmill designed to measure ground reaction force data. Three-dimensional motion capture cameras tracked motion of the knee joints.
The researchers found that, with the orthotic in place, forces on the knee joint increased by a statistically significant 6% during walking and 4% during running. “The addition of material under the medial aspect of the foot by way of a flexible arch support promotes a medial force bias during walking and running, significantly increasing knee varus torque,” the researchers wrote in their report.
The researchers recommended discretion when prescribing an over-the-counter orthotic insole.