Disclosed is a knee brace that incorporates hinges that allow the brace to pivot simultaneously about a flexion-extension axis and a longitudinal rotation axis as the brace flexes and/or extends. The hinges include a medial hinge and a lateral hinge. The medial hinge defines a medial pivot axis and the lateral hinge defines a lateral pivot axis. The medial pivot axis does not coincide with the lateral pivot axis, and neither axis coincides with the flexion-extension axis. Calf portions of each hinge are pivotable with respect to their respective uprights about an axis that is substantially parallel to the longitudinal rotation axis. The pivotability of the calf portions with respect to the calf frame eliminates stresses that would otherwise develop in the hinges as the brace flexes and/or extends.