Abstract: A knee hyperextension orthotic device includes an elongated plate which is curved to form a flush fit against a patient's leg, with an upper portion fastened anterior of the thigh, a lower portion fastened anterior of the lower leg and a central portion fastened anterior of the knee. The central portion of the plate has a narrower width than the upper and lower portions, forming rearwardly extending wings on the upper and lower plate portions. A pair of length adjustable straps are connected between the upper and lower wings on each side of the plate, to permit adjustment of the angle of maximum knee extension. A central strap is connected to the central plate portion and extends posterior of the knee to maintain the knee in appropriate position within the orthotic device. A plurality of apertures in the plate permit the leg to "breathe" when the device is being worn.