Osteoarthritis (OA) knee braces are designed to relieve the knee pain that is associated with uni-compartmental osteoarthritis. This condition is marked by pain and or deterioration of the cartilage on either the inside or the outside of the affected knee. An OA brace differs from other types of knee braces in that it is specifically designed to address this type of condition.

GOALS OF OA BRACING
Clinically:	To decrease the pain and allow people to maintain their lifestyle.
Pathologically:	To slow the deterioration of the cartilage that cushions the knee joint.
Biomechanically:	To reduce the load that the joint experiences during the weight bearing phase of gate to relieve the affected compartment. This is achieved by applying a corrective force.

The knee is designed to act as a modified hinge with elements of rotation. The joint is broadly divided into two compartments called the medial (inside) and the lateral (outside). In an average person the weight bearing load is somewhat evenly distributed across both compartments with the medial side receiving more load during the gait cycle. If the mechanical axis angle is abnormal to any degree, the load bearing is uneven and the side bearing the most load wears out faster. OA patients are generally diagnosed as either having medial or lateral compartment disease. Based on the affected compartment, the brace needs to apply a corrective force that reduces the load on the affected compartment.

All knee braces aim to impart a constant predictable force on the underlying skeleton. In OA bracing the goal is to exert a force on the leg in order to achieve several objectives:

• To apply a corrective force that reduces the load on the affected compartment
• To prevent grinding of the joint surfaces during movement of the knee
• To realign the joint surfaces in contact within the knee

If these objectives are achieved then the patient will experience pain relief, have a higher tolerable activity level, and the progression of their disease will be slowed.


BIOMECHANICAL BRACE FIXATION

An effective Three-Point Pressure System is an essential component of a brace that is intended to apply a constant, predictable, corrective force.

1 - At the Knee Joint Line
This force is directed from the side opposite the affected compartment toward the affected compartment and is intended to open up the narrowed joint space. In addition, the hinge built into a brace must mimic knee movement accurately and be placed at the exact level of the knee joint.

2 - Above the Knee Joint on the Femur
The force placed on the thigh opposes the aforementioned force and provides a point of fixation for the brace. It stabilizes the brace on the leg, and provides an extended lever arm for the force that is applied.

3 - Below the Knee Joint on the Tibia
The force placed on the lower leg or tibia also opposes the joint line force and functions similarly to the thigh force. It too stabilizes the brace on the leg, and provides an extended lever arm for the force that is applied.

It is easy to see how these three points of pressure function to open up the joint space and unload the affected compartment.


ROTATION AND THE KNEE

Tibial rotation is a considerable factor relative to the pain and deterioration of the arthritic knee. During gait as the knee straightens, the tibia externally rotates and as the knee flexes the tibia internally rotates. However slight this rotation may be, it is constant during gait and its effects are considerable. This "grinding" force is a source of pain for OA patients and further contributes to the degeneration of the joint structures.


ADDRESSING ROTATION

Some OA braces like the V-Force attempt to minimize the aforementioned rotation and grinding by controlling and reducing tibial rotation. By fixating the upper section of the brace on the thigh and controlling the lower leg with the tibial section, we thus reduce overall rotation and minimize joint pain and deterioration.