Abstract: A pair of cuffs are positioned on the thigh and calf respectively adjacent the knee joint. Each of these cuffs encloses and is backed by a fluid-filled chamber made of a flexible resilient material. The inner surface of this chamber is bonded to an elasticized fabric band which encircles the leg and positions each of the cuffs immediately adjacent the knee joint.An accordion-folded section of tubing extends from the upper to the lower fluid filled chamber along each side of the knee forming a unitary fluid-filled system. A pair of flexible but inextensible straps overlays each of the accordion-folded tubes and is securely fastened to the cuffs. Upon lateral impact, fluid migrates from the side of the knee which has been struck to the opposite side causing the cuffs to firmly grip the thigh and calf, and the accordion-folded tube on the opposite side to fill with fluid, creating compressive force between the knee joint and the tensioned straps and preventing dislocation of the knee joint.