An apparatus for determining 3D load displacement characteristics of an anatomical joint formed by a first body portion and a second body portion moveable with respect to the first body portion. The apparatus includes a first frame for receiving and securing the first body portion and a load displacement assembly. The load displacement assembly includes a first axis for alignment with a first anatomical plane of the joint, a second frame for receiving and securing the second body portion. The second frame is movable relative to the first frame. The load displacement assembly also includes a first counterweight configured to balance the weight of the second frame, a force for applying a load to the second frame, and a displacement sensor for measuring displacement of the second frame relative to the first frame upon application of the force.