Scientists report that a simple adjustment in the way people walk can relieve arthritic knee pain as effectively as prescription medications, while slowing the deterioration of cartilage.
Nearly a quarter of people over the age of 40 suffer from painful osteoarthritis, caused by the breakdown of the cartilage that protects the joints – and there is currently no way to reverse this damage. The only option is to manage the pain with medication and possibly joint replacement.
Now, researchers from the University of Utah, New York University and Stanford are demonstrating the potential of another option: retraining to walk.
By slightly adjusting the angle of their foot while walking, participants in a year-long randomized controlled trial experienced pain relief equivalent to medication.
Importantly, these participants also showed less degradation of knee cartilage over this period compared to a group that received a placebo treatment.
Published on August 13 in The Lancet Rheumatology, these results come from the first placebo-controlled study demonstrating the effectiveness of a biomechanical intervention against osteoarthritis.
“We know that in people with osteoarthritis, higher loads on the knee accelerate progression and that changing the angle of the foot can reduce the load on the knee,” said Scott Uhlrich, assistant professor of mechanical engineering at Utah.
“But no randomized, placebo-controlled study has shown their effectiveness.”
A personalized approach to walking rehabilitation
With support from the National Institutes of Health, researchers specifically studied patients with mild to moderate osteoarthritis in the medial compartment of the knee, on the inside of the leg, which tends to bear more weight than the lateral, outer compartment.
This form of osteoarthritis is the most common, but the ideal foot angle to reduce the load on the medial side of the knee differs from person to person, depending on their natural gait and how it changes when they adopt the new walking pattern.
“Previous trials prescribed the same intervention to all individuals, resulting in some individuals not reducing or even increasing joint loading,” Uhlrich said. “We used a personalized approach to select each individual’s new walking pattern, which improved the individuals’ ability to unload their knee and likely contributed to the positive effect we saw on pain and cartilage.”
During their first two visits, participants received a baseline MRI and practiced walking on a pressure-sensitive treadmill while motion-capture cameras recorded the mechanics of their gait. This allowed researchers to determine whether turning the patient’s toe inward or outward would further reduce the load and whether a 5-degree or 10-degree adjustment would be ideal.
After their initial intake sessions, half of the 68 participants were assigned to a sham treatment group to control the placebo effect, prescribing foot angles that were actually identical to their natural gait.
After one year, all participants reported experiencing knee pain and underwent a second MRI to quantitatively assess damage to the knee cartilage.
“The reported decrease in pain compared to the placebo group was somewhere between what is expected from an over-the-counter medication, like ibuprofen, and a narcotic like oxycontin,” Uhlrich said. “Through the MRI scans, we also saw slower degradation of a marker of cartilage health in the intervention group, which was very exciting.”
Beyond quantitative measures of effectiveness, study participants expressed enthusiasm for both the approach and the results. One participant said, “I don’t have to take any medication or wear a device…it’s just a part of my body now that will be with me for the rest of my life, and so I’m excited about that.” »
The ability of participants to adhere to the intervention over long periods of time is one of its potential advantages.
“Particularly for people in their 30s, 40s or 50s, osteoarthritis could require decades of pain management before they are recommended joint replacement,” Uhrlich said. “This intervention could help fill this important treatment gap.” »
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How the study was conducted
Participants in both groups returned to the lab for six weekly training sessions, during which they received biofeedback (vibrations from a device worn on the shin) that helped them maintain the prescribed foot angle while walking on the lab’s treadmill. After the six-week training period, participants were encouraged to practice their new gait for at least 20 minutes a day, until it became natural. Periodic check-in visits showed that participants adhered to the prescribed foot angle to within one degree on average.
However, the team explained that before this intervention can be rolled out clinically, the process of walking retraining will need to be streamlined, so that it can eventually be prescribed in a physiotherapy clinic, and retraining can take place while people walk around their neighborhood.
Individuals interested in participating in future studies can contact Scott Uhlrich’s Movement Bioengineering Lab by completing this web form.
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