They are designed to take the load off the damaged side and transfer it to the undamaged side. They are of particular relevance in patients who:
- wish to delay osteotomy (surgical correction of bony deformity) or knee arthroplasty
- are unfit or too old for such surgery or who are reluctant to have surgery.
but are probably likely to be avoided in patients who:
- are obese, as it may be difficult to achieve optimal brace fixation
- are severely affected but too young for knee replacement, in whom osteotomy is likely to be the preferred choice of management
- have a severe valgus (knock knees) as the good leg may chafe against the joint of the brace on the inner side
It seems that unloader braces really do offer real help to patients suffering with osteoarthritis in one compartment and may delay the need for knee replacement surgery. Studies generally show that unloader braces diminish pain, increase walking tolerance and provide better function, although there is no difference in dynamic gait parameters (the pattern of the limp or walk), nor significant improvements in stair climbing or squatting. The Bledsoe unloader, however, has been reported to show an improvement in gait pattern as well.
Most of the unloaders use a three-point pressure system to decrease the deformity and to widen the affected joint space, thereby decreasing the friction between the lower surface of the femur and the upper surface of the tibia. In contrast, the GII unloader brace is unusual in delivering its corrective force through an adjustable dynamic force strap.
Types of unloaders include:
- Össur Unloader One
- GII (Generation II USA Inc)
- Bledsoe Thruster (Bledsoe)
- Monarch O.A. brace (Smith & Nephews)
- Oasys brace (Innovation Sports)
- Align O.A. knee orthosis (Omni Scientific Inc)
- The Reliever (Townsend Design)