Functional knee brace use for 21 h leads to a longer duration to achieve peak vertical ground reaction forces and the removal of the brace after 17.5 h results in faster loading of the knee joint

PurposeTo investigate the landing strategies used after discontinuing and continuing the use of a functional knee brace (FKB) while performing a drop jump.MethodsFollowing published methodology and power analysis, 23 uninjured male athletes, mean age of 19.4 +/- 3.0 years, performed seven tests, during three test conditions (nonbraced, braced and removed brace or continued brace use), over 6 days of 12 testing sessions (S) for a total of 38.5 h. Each subject was provided with a custom-fitted FKB. This study focuses on the single leg drop jump kinetics during S12 when subjects were randomly selected to remove the FKB after 17.5 h or continued use of FKB. The time to peak vertical ground reaction forces (PVGRF) and PVGRF were recorded on landing in eight trials.ResultsAfter brace removal, a significantly shorter mean time to PVGRF was recorded (9.4 +/- 22.9 msec (3.9%), p = 0.005, 95% confidence interval (95% CI): -168.1, 36.1), while continued brace use required a nonsignificant (n.s.) longer mean duration to achieve PVGRF (19.4 +/- 53.6 msec (8.9%), n.s., 95% CI: -49.7, 73.4). No significant mean PVGRF difference was found in brace removal (25.3 +/- 65.8 N) and continued brace use (25.1 +/- 23.0 N).ConclusionRemoval of FKB after 17.5 h of use led to a significantly shorter time to achieve PVGRF, while continued brace use for 21 h required a longer duration to achieve PVGRF, suggesting faster and slower knee joint loading, respectively. Understanding the concerns associated with the use of FKB and the kinetics of the knee joint will assist clinicians in counselling athletes about the risks and benefits of using an FKB.Level of EvidenceLevel II. The risk of noncontact anterior cruciate ligament (ACL) injury increases with greater vertical ground reaction force and faster knee joint loading. After 21 h of functional knee brace use by healthy athletes, a longer duration to achieve peak vertical ground force was possible, while removing the functional knee brace after 17.5 h led to faster loading of the knee joint.'An eye-catching colour image' image