A hyperextension brace with a frame construction has adjustable upper and lower supports as well as adjustable side members. The frame comprises a sub-clavicula support and a pelvic and pubic support connected by side members. The height of the side members and the width of the sub-clavicula support and the pubic support are adjustable by using non-rotational telescopic and lockable connections. The sub-clavicula support may be connected by a turnbuckle screw arrangement to the side members. The frame may be made of composite material, suitably a polymer reinforced by glass fiber and/or carbon fiber. All adjustments may be made without requiring any tools.