The UTX® was designed and developed by Dr. Nils van Leerdam, of Ambroise Holland bv. It is a lightweight (less than two pounds) knee-ankle-foot-orthosis that stabilizes the knee during the stance phase of gait, but enables knee flexion during swing phase. At the end of swing phase, as the knee reaches full extension, a ratchet engages to stabilize the knee. A cable runs inside the distal side member from the ankle joint to the knee joint. At the end of stance phase, as the ankle dorsiflexes, this cable linkage causes the knee joint to unlock and destabilize the knee. The UTX® is also available as a non-stance control KAFO model, ""Stable"", that locks and unlocks by control of the user. Other models of the UTX® are also available including an ""FS"" (frontal stability) model to control genu valgum. All UTX® models can be equipped with a medial ankle joint to provide additional control in the coronal and transverse planes.