Abstract: A knee brace for controlling ligament instability in all planes while allowing full natural action of the knee. The brace includes a shin plate and a thigh plate connected in hinged relationship. The shin plate has a pair of flanges extending from opposing corners of its top edge which are positionable over the side tibia tubricals. A tensioned popliteal strap attached at opposing ends to opposing flanges is positionable in a substantially horizontal plane around the back of the upper calf adjacent the knee to compress the flanges against the side tibia tubricals for increasing the rotational stability of the knee. The interior of the shin plate is parabolic-shaped to prevent chafing against the crest of the tibia and the elongated edges of the shin plate grasp opposing sides of the triangular-shaped tibia to further increase the rotational stability of the knee. An adjustable extension check strap, which prevents a complete unbending of the knee, passes through a ring positioned on the back of a calf band.