Close to Barefoot Best for Arthritic Knees

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"Depending on what the sole of the shoe is made of, it may or may not absorb shock," said Shuemann, who pointed out that these results may be due in part to stability shoes having a more firm sole and less shock absorption as a result. Yet, she said, a more flexible sole may not be the long-term answer to knee pain. "The question is what is the alignment of the shoe. If your foot falls to the inside of the arch, you're going to be hurting your knee because you are not bearing weight on it."

Schuemann advised people who have been told to wear stability shoes to talk to their doctor about these results before slipping into flip-flops. Stability shoes are usually prescribed to help align the leg from foot to hip and also may be necessary for other reasons, such as arches that are too high or too low.

"If you have osteoarthritis and perfectly aligned feet, the more flexible shoes are probably helpful," she said. But only a minority of people can claim perfect alignment and as people get older and arches fall, that adds more stress to the feet, said Schuemann. The average age of people in the study was 56 -- prime fallen arch years.

The research, according to Shakoor, "gives a better understanding of the biomechanics of the lower extremity."

This is only the first step for the researchers, who plan to evaluate the long-term effects of specific shoes on joint loads in a controlled clinical trial.

"I think [this research] is actually quite novel from the standpoint of understanding that stresses and strains on feet and knees and hips aren't all to be regarded the same way," said rheumatologist Eric Matteson, of the Mayo Clinic. "What's interesting is that we have this emphasis on proper shoe wear, but we need to consider that what we wear has an impact on other joints."

Matteson said there are still some questions that need to be answered.

"We need to do a little bit more work on this. The study was very small and there are a lot of ways that gait analysis can be performed, although they did a pretty sophisticated gait analysis," he explained. "They don't have a lot of different kinds of patients with different kinds of knee problems and they don't have a great diversity of shoewear relating it to different kinds of problems, but it does make me reflect on some of the advice that I have been giving."