The effect of extension assist orthosis with pneumatic bladders on pain and function for patients with early knee osteoarthritis

Background: There are few non-invasive treatment options to slow the progression of osteoarthritis (OA). Recently, a novel knee unloader brace with knee extension assist has become commercially available. Therefore, the purpose of this study was to evaluate the preliminary effectiveness of using a novel unloader brace with extension assist to improve pain and functional outcomes for patients with knee OA. Methods: Thirty subjects (17 control group, 13 brace group) completed baseline and 6-week follow up testing with no brace. Patients were randomized into a Brace or No Brace group after baseline testing. Functional tests [timed up and go (TUG), stair climbing test (SCT) and six-minute walk (6MW)], self-reported measures [Knee Outcome Survey (KOS), pain, Patient Specific Functional Scale (PSFS)] and isometric knee extension strength were assessed. Repeated measure ANOVAs were used to identify differences in group and time. Pearson correlation coefficients were calculated for both average number of steps in the brace and exercises compliance compared to change in clinical scores for each group. Results: There was a significant interaction effect for "worst pain" (P=0.002), the brace group improved from a 7.3/10 to 4.7/10 at follow-up (P=0.006) while the control group had no change. There was an effect of time for the SCT (P=0.02), "best knee pain" (P=0.050), and knee extension range of motion (ROM) (P=0.041). There were no significant correlations between exercise compliance and change in outcomes, but when the groups were collapsed there was a significant correlation between compliance and change in knee extension ROM (r=0.526; P=0.025). Conclusions: The extension assist pneumatic unloader brace group demonstrated a significant and important reduction in the "worst knee pain". This may indicate that wearing the brace was able to reduce painful flares. Both groups improved over time for the SCT, "best knee pain", and knee extension ROM, which can be attributed to the stretching protocol. This unloader brace is a promising non-invasive treatment option for patients with knee OA when combined with a stretching program.