Michael J. Callaghan, PhD

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 PFJOA.

Objective
To investigate the effects of a flexible knee support on quadriceps maximum voluntary contraction (MVC) and arthrogenous muscle inhibition (AMI) in patients with patellofemoral joint osteoarthritis (PFJOA).

Methods
108 participants were included with at least 3 months of patellofemoral pain and a K-L score 2 or 3 for PFJOA. Each was randomized to wear a flexible knee support (‘brace’) or no support (‘no brace’) in a 6 weeks RCT, after which followed an open label trial with all participants wearing the brace for a total of 12 weeks. At the 6 and 12 weeks’ time points quadriceps MVC was measured isometrically and quadriceps AMI was measured by twitch interpolation.

Results
After 6 weeks, MVC did not differ between the ‘brace’ and ‘no brace’ group (9.09Nm; 95% CI -4.89Nm to 23.07Nm, p = 0.20). AMI significantly decreased in the brace group (-8.62%; 95% CI -13.90 to -3.33%, p = 0.002). After 12 weeks of all participants wearing a flexible knee support, MVC increased by 7.98Nm (95% CI 2.52Nm to 13.45Nm, p = 0.004). AMI decreased by -8.42% (95% CI -11.48% to -5.36%; p<0.001).). Although statistically significant, these results have doubtful clinical significance.

Conclusion
A patellofemoral flexible knee support in participants with PFJOA 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, Epub 10 Nov 2015. doi:10.2519/jospt.2016.5093