ObjectiveThe purpose of the present review was to examine current experimental research on the effectiveness of functional knee braces (FKBs) used by patients with anterior cruciate ligament injury during dynamic performance tests.Data sourcesTwelve studies published in peer-reviewed journals and listed in theExcerpta Medicasystem were reviewed.Study selectionAll studies compared braced and unbraced tests performed by the same subjects, using tests characterized by weight bearing/axial loading.Data extractionStudies were reviewed independently by three investigators.Data synthesisTests included one-leg hop, figure-of-eight run, stair climbing, walking, cutting, agility runs, straight running, and bicycle ergometry. Experimental situations were classified as follows: (a) maximal effort tests, which compared overall measures of performance such as the distance hopped and the time to run a specific distance; and (b) matched submaximal effort tests, which compared specific variables such as electromyography, range of motion, ground reaction forces, and energy costs. Bracing was found to be advantageous in three of the 16 maximal effort situations, disadvantageous in two, and of no measurable effect in 11. Six of the 10 matched effort situations reported differences in the criterion measurements when braced, while four reported no differences.ConclusionsIf FKB prescription is to be based solely on empirical evidence of efficacy from performance tests, then further investigation is required to provide this evidence. Future research needs to examine the subjective and psychological aspects of FKB usage along with the results of objective performance tests.