A knee brace that is divided into anterior and posterior sides by a frontal plane, and having first and second sides divided by a median plane. The knee brace includes a ventilated, flexible proximal shell generally extending between the first and second sides on the anterior side of the brace, and a flexible distal shell connected to the proximal shell and generally extending across the first and second sides on the anterior side of the brace. The distal shell has an extension segment extending from one of the first and second sides to the posterior side of the brace. The proximal and distal shells include suitable openings and slots for attaching brackets and mechanical devices. The proximal and distal shells each include a body portion and a compliant edge. The compliant edges are formed from flexible resilient material that is configured to extend beyond the outer perimeter of the body portion of each the proximal and distal shells.