A simple change in walking style may help people with knee osteoarthritis reduce pain and protect their joints. Researchers found that personalized gait retraining rivaled medication in effectiveness, opening the door to a new kind of treatment.
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A new study led by a Utah engineering professor shows that gait retraining can reduce pain and slow cartilage damage.
Almost one in four adults over the age of 40 live with painful osteoarthritis, a condition that has become one of the leading causes of disability. The disease gradually wears away the cartilage that cushions joints, and there is currently no way to restore this damage. For now, treatment typically focuses on pain management with medication, followed eventually by joint replacement.
Scientists from the University of Utah, New York University, and Stanford University are now pointing to a promising alternative: gait retraining.
In a year-long randomized controlled trial, participants who adjusted the angle of their foot while walking reported pain relief comparable to medication. Importantly, these individuals also showed slower cartilage deterioration in their knees compared with those who received a placebo treatment.
At the beginning of the study, participants received a baseline MRI and walked on a force-sensitive treadmill while motion-capture cameras recorded their walking mechanics.
Credit: Utah Movement Bioengineering Lab
First placebo-controlled proof
Published in The Lancet Rheumatology and co-led by Scott Uhlrich of Utah’s John and Marcia Price College of Engineering, these findings come from the first placebo-controlled study to demonstrate the effectiveness of a biomechanical intervention for osteoarthritis.
“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 Uhlrich, an assistant professor of mechanical engineering. “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.”
Tailoring treatment to each patient
Backed by the National Institutes of Health and other federal agencies, the researchers focused on patients with mild-to-moderate osteoarthritis in the medial compartment of the knee (the inner side of the leg), which carries more weight than the lateral, outer compartment. This type of osteoarthritis is the most widespread, but the best foot angle to lessen stress on the medial knee varies for each individual, depending on their natural gait and how it shifts when they adopt a new walking style.
“Previous trials prescribed the same intervention to all individuals, resulting in some individuals not reducing, or even increasing, their joint loading,” Uhlrich 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.”
Using motion capture cameras, the researchers tracked the degree to which participants walked with their toes pointed inward or outward. Researchers could then calculate the loading in participants’ knees and prescribe the change in foot angle that reduced each individual’s loading. During weekly gait training visits, participants received vibrations on their lower leg after each step, teaching them to walk precisely with their prescribed foot angle.
During their first two sessions, participants underwent a baseline MRI and practiced walking on a pressure-sensitive treadmill while motion-capture cameras tracked their movements. These assessments revealed whether turning the foot inward or outward reduced knee loading more effectively, and whether a 5° or 10° adjustment was most suitable.
This individualized evaluation also excluded participants for whom no foot angle adjustment could reduce knee stress. Including such individuals in earlier studies may explain why those trials produced inconclusive results on pain reduction.
Placebo versus intervention
After the initial intake sessions, the 68 participants were divided into two groups. Half were placed in a sham treatment group designed to measure the placebo effect. These individuals were instructed to walk with foot angles that were identical to their natural gait. In contrast, participants in the intervention group were assigned a foot angle adjustment that most effectively reduced stress on their knees.
Both groups then took part in six weekly lab-based training sessions. During these sessions, participants received biofeedback in the form of gentle vibrations from a device attached to the shin, which guided them in maintaining the prescribed foot angle while walking on a treadmill. Following the training phase, participants were asked to continue practicing their new gait for at least 20 minutes each day until it became habitual. Regular follow-up visits confirmed that participants were sticking closely to their assigned gait, typically within a one-degree margin.
After a year, all participants self-reported their experience of knee pain and had a second MRI to quantitatively assess the damage to their knee cartilage.
Lead researcher Scott Uhlrich measures a participant’s gait. At the beginning of the study, participants received a baseline MRI and walked on a force-sensitive treadmill while motion-capture cameras recorded their walking mechanics.
Credit: Utah Movement Bioengineering Lab
“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.”
Beyond the quantitative measures of effectiveness, participants in the study expressed enthusiasm for both the approach and the results. One participant said: “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.”
A long-term option Participants’ ability to adhere to the intervention over long periods of time is one of its potential advantages.
“Especially for people in their 30’s, 40’s, or 50’s, osteoarthritis could mean decades of pain management before they’re recommended for a joint replacement,” Uhrlich said. “This intervention could help fill that large treatment gap.”
Before this intervention can be clinically deployed, the gait retraining process will need to be streamlined. The motion-capture technique used to make the original foot angle prescription is expensive and time-consuming; the researchers envision this intervention to eventually be prescribed in a physical therapy clinic and retraining can happen while people go for a walk around their neighborhood.
“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. Future studies of this approach are needed before the intervention can be made widely available to the public.
Those interested in participating in future studies can contact Uhlrich’s Movement Bioengineering Lab by filling out
this web form.
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