Teaching people with knee arthritis to walk with a subtle change in their foot angle can significantly reduce pain and may slow the progression of the disease.
The research, conducted at Stanford University, marked a major step forward in the search for non-surgical treatments for this common and debilitating condition.
Roughly 33 million American adults, mostly 45 and older, suffer from osteoarthritis, a painful condition that causes cartilage lining the joints to break down over time, causing bones to rub together, leading to severe pain when moving.
The study enrolled 68 adults with an average age of 64 and mild-to-moderate medial compartment knee osteoarthritis, a form of the disease in which the inner portion of the knee joint experiences excessive wear due to uneven load distribution during walking.
All participants reported at least moderate knee pain at the start of the study, with an average pain score of four on an 11-point scale.
Researchers used a personalized approach, first testing each participant to determine whether adjusting their foot progression angle, by toeing-in or toeing-out slightly, could reduce the mechanical load passing through the arthritis-ridden portion of their knee.
Nearly three-quarters of those tested lowered the strain on their knee and almost all of the participants who changed their walking style also had significantly lower pain scores after a year of doing it.
‘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,’ said Scott Uhlrich, an engineer at the University of Utah.
Roughly 33 million American adults, mostly 45 and older, suffer from osteoarthritis, a debilitating condition where cartilage breaks down, causing bones to rub together and severe pain with movement (stock)
Researchers randomly placed participants into two groups. One received the real walking treatment; the other received a fake version for comparison.
Over six weekly lab visits, both groups walked on a treadmill while wearing a buzzer that guided them to keep a specific foot angle.
The critical difference was the target angle.
The treatment group worked to adopt a personalized toe-in or toe-out angle that had been shown to reduce the load on their knees, while the placebo group was instructed to maintain their natural walking angle.
After one year, people in the personalized intervention group reported an average reduction in medial knee pain of 2.5 points on the 11-point scale, compared to a 1.3-point reduction in the placebo group.
This between-group difference of 1.2 points was both statistically significant and clinically meaningful.
More than 90 percent of the intervention group achieved at least a one-point pain reduction, a threshold considered clinically important, compared to 66 percent of the sham group.
The group that learned the personalized walking angle put significantly less stress on their arthritic knee had an average pain score reduction of 0.17 units on a key measurement scale.
This amounts to roughly a five percent reduction in the pressure placed on the joint.
The personalized walking group (blue) showed less cartilage breakdown than the placebo group (red) in the medial (inner) knee. The difference was significant. No difference was seen in the lateral (outer) compartment
The placebo walking group, meanwhile, saw their knee stress go up slightly by 0.08, meaning the real treatment group ended up with a 7.5 percent bigger reduction in joint pressure and they kept that benefit for the full year.
The study, published in The Lancet Rheumatology, is the first to suggest that changing how a person walks might actually slow down knee arthritis itself, not just mask the pain.
Researchers used sensitive MRI scans to see inside the knee cartilage. They looked for signs of wear and tear at the microscopic level.
In the placebo group, the cartilage continued to break down as expected, but in the group that learned the new walking angle, that breakdown happened much more slowly.
And the treatment was safe. Only two of 34 people — about six percent — in the real treatment group dropped out because their knee pain worsened. That is on par with or better than many exercise programs.
One person in the placebo group also quit due to worsening pain, but no one in either group had a serious medical problem from the study.
Most people with the condition turn to over-the-counter pain relievers like ibuprofen or naproxen to get through the day.
When those stop working, doctors often prescribe stronger anti-inflammatories or even opioids, though side effects and addiction risks are real concerns.
MRI scans of a treatment participant and a placebo participant, week 0 (left) and year 1 (right). Less red coloration at year 1 indicates improved cartilage quality, not less
Physical therapy and exercise help some patients strengthen the muscles around the joint. For others, steroid injections offer temporary relief, but the effects wear off after a few months.
When nothing else works, joint replacement surgery becomes the final option. This is a major operation that replaces the worn-out parts of the knee with metal and plastic parts.
The technology behind this treatment is moving out of the lab. When the study began, measuring knee stress required expensive motion-capture cameras.
Now, smartphone videos can do the same job, and sensor-equipped shoes can deliver walking feedback anywhere.
These advances could make personalized gait retraining a routine option at a physical therapist’s office.
The pain relief matches over-the-counter pain relievers but without the drug risks.
The study also showed that screening is key. Testing patients first to see if a foot-angle change works for them was a major reason for the positive results.
Patients should ask their healthcare provider whether this approach might be right for them.
While the original study required many lab visits, simpler home-based and clinic-based versions are on the horizon.
