It is used when the index escapes backwards, inwards, or outwards.

The soft top and bottom suspension sleeves and popliteal interface combine with adjustable straps to hold the frame in place while the straps adjust to provide a "stop" to control knee backsliding (hyperextension).

(compared to the Swedish Knee Cage) reduces the amount of pressure required on the femur and tibia to control hyperextension and improves patient tolerance of the orthosis. Biaxial joints allow for full knee flexion (bending the knee) and allow each of the four posts to move independently, from extension to flexion, allowing the orthosis to follow the natural movement of the leg and prevent downward displacement. Low profile hinges with thin studs that are easily shaped to conform to the contours of the legs to create an orthosis that becomes almost unnoticeable under clothing. After initial donning, the user closes or opens only one side of the front straps for simple application and removal.