An orthopedic device has upper and lower frames hingedly connected to each other by first and second primary hinges on opposed sides of the device and providing movement between flexion and extension. Each of the upper and lower frames includes opposed first and second medial-lateral portions connected by a central portion. A force strap is connected to the upper and lower frames and spiraling therebetween, and the force strap generally extends at a first location proximate to the first primary hinge and is generally urged in a first direction at the first location to the second primary hinge. The upper frame is rigid or semi-rigid, and includes means for permitting movement in proximal-distal directions and means for permitting movement in lateral-medial directions.
