“We need three months or more to look at the effect on pain,” says Hunt. “And we also need to see what is going on in other joints. Are we taking the burden off the knee and putting it somewhere else?”

Nor is it clear how much lean is enough, says Hunt. And too much lean, even if terrific for the joint, may not be best for balance.

Challenges Ahead

Movement retraining is so new that scientists are still pinning down terms and ways to measure the load on the knee. And as long as those measurements are uncertain, so are the therapy’s results, says B.J. Fregly, PhD, professor of Mechanical Aerospace Engineering at the University of Florida in Gainesville.

 “What is ‘bad load’ on the knee that will cause osteoarthritis to progress?” asks Fregly. “The current theory of what is ‘bad’ is an assumption. And one of the problems too is that we don’t know exactly what ‘bad’ motion is.”

Measuring “load” is difficult because you can’t actually get inside the joint to do that. It’s done by measuring something called the external adduction moment, the moment when you put your weight on your leg while walking. 

“It’s been shown clinically that people who had the lowest moments after [high tibial osteotomies] had the best clinical outcomes,” says Fregly. “And people who had the highest moment at baseline had the most [osteoarthritis] progression five years later. So there are reasons to believe that ‘moment’ is related to force on the knee.”

Using that “moment” measure, researchers at Stanford found that participants who turned their toes inward reduced their knee load more than those who walked with their toes out or with more sway in their trunks.

Although gait training has been highly individual so far, researchers hope to winnow to a more uniform approach that physical therapists can use without fancy measuring instruments or a lab.

“We’re hoping that by the end of our research we can identify movements that will be helpful to most people [with medial knee osteoarthritis],” says orthopedic surgeon Jason Dragoo, MD, assistant professor in the Department of Orthopedic Surgery at Stanford, who has been working with Shull and others on gait retraining research. 

What Patients Can Do Now

The goal of the Stanford team is to begin to spread their movement retraining program and haptic sensors that patients can use to others clinics by late 2013.

For now, patients can get movement retraining by working with a physical therapist, says Dr. Dragoo: “The physical therapist can help them to walk symmetrically and to spend equal time on both legs, making sure that the trunk is over the legs and not swaying side to side. When you limp, you lose efficiency and that can make knee pain worse.”

What’s most important is to practice the new movement, says Dr. Dragoo: “Once the physical therapist teaches you how to walk differently, you have to be committed to watching the way you walk. That’s why it’s difficult.”