The PreStride4, model 9008 is the same as model 9007, except it utilizes our new Stride4 (Patent Pending) stance control knee joints. The Stride4 is comprised of a four bar linkage mechanism that offers (3) modes of operation: Stance control, free motion and locked with stance phase flexion. An integral extension assist spring housed within the midsection assists with knee extension, while an adjustable extension stop allows the practitioner to adjust and fine tune the point at which the joint enters into its stable/locked state. A button on the Stride4 knee joint allows the practitioner to switch between stance control and locked modes of operation. When the lock option is selected and engaged by the clinician, the joint will allow approximately 3° of flexion to provide some shock absorption to the patient. An additional advantage of the PreStride4 is that it may be used as an effective gait training tool during rehabilitation.