Variable friction utilizes a fluid control system (hydraulic or pneumatic) to control the amount resistance to knee bend. As knee bend increases, resistance increases and vice versa.
- Progressive resistance as knee bends.
- Can be found in both monocentric (single axis) and polycentric (multi axial) knees.
- More natural gait.
- Can be adjusted to allow for a range of cadences.
- Can be expensive.
- Heavier and more complex than other systems.
- Requires accurate adjustment by trained practitioner.
- May require periodic adjustment.