Michael J. Callaghan, PhD, MPhil, MCSP

Abstract

Study Design
Secondary analysis of a randomized controlled trial.

Background
The use of external supports has been questioned because they may lead to weakness in the surrounding muscles. To our knowledge, there is no investigation into the effect of knee supports or braces on quadriceps muscle strength and quadriceps inhibition in individuals with patellofemoral joint (PFJ) osteoarthritis (OA).

Objectives
To investigate the effects of a flexible knee support on quadriceps maximum voluntary contraction (MVC) and arthrogenous muscle inhibition (AMI) in patients with PFJ OA.

Methods
The study included 108 participants who had at least 3 months of patellofemoral pain and a Kellgren-Lawrence score of 2 or 3 for PFJ OA. The participants were randomized to a group that wore a flexible knee support (brace) or a group that did not wear a support (no brace) in a 6-week randomized controlled trial, followed by an open-label trial, in which all participants wore the brace for a total of 12 weeks. Quadriceps MVC, measured isometrically, and quadriceps AMI, measured by twitch interpolation, were assessed at the 6-week and 12-week time points.

Results
After 6 weeks, MVC did not differ between the brace and no-brace groups (9.09 Nm; 95% confidence interval [CI]: −4.89, 23.07; P = .20). Arthrogenous muscle inhibition significantly decreased in the brace group (−8.62%; 95% CI: −13.90%, −3.33%; P = .002). After 12 weeks, in all of the participants who wore a flexible knee support, MVC increased by 7.98 Nm (95% CI: 2.52, 13.45; P = .004) and AMI decreased (−8.42%; 95% CI: −11.48%, −5.36%; P<.001). Although statistically significant, these results have doubtful clinical significance.

Conclusion
A patellofemoral flexible knee support in participants with PFJ OA does not have an adverse effect on quadriceps MVC or AMI. Using a knee support should not be discouraged because of concerns about deleterious effects on quadriceps strength and inhibition.

Level of Evidence
Therapy, level 1b. J Orthop Sports Phys Ther 2016;46(1):19–25. Epub 10 Nov 2015. doi:10.2519/jospt.2016.5093