A cartilage replacement or repair prosthesis comprises a layer of streamlined elastomer elements, preferably in the form of spheres, supported in a matrix material so that the radially opposed surfaces of the spheres are positioned on opposite surfaces of the layer and make contact with the opposed surfaces of the femur and tibia and the forces exerted between these bones extend through the streamlined elements. The matrix material has a substantially lower resistance to deformation than the spheres to control the position of the spheres relative to one another without significantly restraining their load-responsive deformation under forces exerted between the femur and tibia. The layer, with its elastomeric inserts, is sufficiently thin and flexible to allow it to be rolled for arthroscopic insertion into a knee joint.
