While using shock absorbing insoles for people suffering from arthritic knee pain seems to make perfect sense, there is little evidence that they actually work. That was, until a recent study indicated just that. According to researcher and physical therapist Judy Foxworth, using a $20 off-the-shelf shock absorbing insole in the shoes of 60 seniors suffering from arthritic knee pain significantly reduced knee pain after a 6-minute walk. Surprisingly, in evaluating the subjects' gait mechanics and ability of the insoles to reduce forces in the knee, no differences were found as compared with those without the shock absorbing insoles. However, since the seniors reported less pain after using the off-the-shelf shock absorbing insoles, it appears to be worth the $20 even if it's unclear how they reduced arthritic knee pain.
Source: American College of Sports Medicine; 55th Annual Meeting - May 28-31, 2008.