A small change in foot angle while walking cut knee osteoarthritis pain in a year-long clinical trial, and researchers said it may also slow damage inside the joint.
The study, from researchers at the University of Utah, New York University and Stanford University, tested a personalised form of gait retraining in people with mild to moderate osteoarthritis on the inner side of the knee.
Participants were trained to make a slight change to the angle of their foot while walking. Researchers said the change was tailored to each person, because some reduced knee loading by turning their toes inward, while others did better by pointing them outward.
“We’ve known that for people with osteoarthritis, higher loads in their knee accelerate progression, and that changing the foot angle can reduce knee load,” said Scott Uhlrich, an assistant professor of mechanical engineering at the University of Utah. “So the idea of a biomechanical intervention is not new, but there have not been randomized, placebo-controlled studies to show that they’re effective.”
The trial enrolled 68 participants. During the first two visits, each person had a baseline MRI and walked on a pressure-sensitive treadmill while motion-capture cameras measured their gait.
Researchers then worked out if that person would benefit more from turning their toes inward or outward, and if a 5 degree or 10 degree adjustment was best. People whose knee loading did not improve with any of the tested changes were excluded from the trial.
Half the participants were assigned to the real gait retraining group. The other half received a sham treatment designed to control for the placebo effect. In that group, participants were assigned foot angles that matched their natural walking pattern.
Both groups returned for six weekly training sessions. They walked on a treadmill wearing a device on the shin that gave vibration feedback to help them keep their assigned foot angle. After that, they were encouraged to practise the walking pattern for at least 20 minutes a day.
Follow-up visits found participants stayed, on average, within 1 degree of their prescribed foot angle.
After one year, participants reported their knee pain levels and had a second MRI.
“The reported decrease in pain over the placebo group was somewhere between what you’d expect from an over-the-counter medication, like ibuprofen, and a narcotic, like oxycontin,” Uhlrich said. “With the MRIs, we also saw slower degradation of a marker of cartilage health in the intervention group, which was quite exciting.”
Uhlrich said earlier trials had applied the same walking change to everyone, which could miss the mark for some people.
“Previous trials prescribed the same intervention to all individuals, resulting in some individuals not reducing, or even increasing, their joint loading,” he said. “We used a personalized approach to selecting each individual’s new walking pattern, which improved how much individuals could offload their knee and likely contributed to the positive effect on pain and cartilage that we saw.”
One participant said the treatment appealed because it did not involve medicine, surgery, braces or wearing a device all day.
“I don’t have to take a drug or wear a device…it’s just a part of my body now that will be with me for the rest of my days, so that I’m thrilled with.”
The researchers said people should not try to copy the approach on their own, because the wrong change could increase stress on the knee instead of reducing it. They also said the current process still relies on expensive, time-consuming motion-capture testing.
“We and others have developed technology that could be used to both personalize and deliver this intervention in a clinical setting using mobile sensors, like smartphone video and a ‘smart shoe’,” Uhlrich said.
The study, “Personalised gait retraining for medial compartment knee osteoarthritis: a randomised controlled trial,” was published in The Lancet Rheumatology.
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