Elastic disc prosthesis

Claim 1

An intervertebral disc prosthesis for implanting between two vertebrae of a spine comprising, first and second plates having a middle portion, said first and second plates having oppositely oriented outer faces adapted to contact the vertebrae and having opposing inner surfaces, said first and second plates being oriented in generally parallel planes, said prosthesis having first and second elastically deformable partitions extending between and joining said first and second plates in such a manner as to exert differing reactive forces to said first and second plates when loads are applied to urge said first and second plates toward one another, said first and second partitions being oriented in planes which are generally not parallel to said parallel planes of said first and second plates, said second partition being solely resiliently compressible to apply a dampening reactive force to said first and second plates upon initial application of a first load to urge said first and second plates toward one another and said first partition being bendable to permit a tilting of said first and second plates relative to one another after initial compression of said second partition when a load greater than said first load is applied to urge said first and second plates toward one another, whereby said first and second partitions are oriented relative to said first and second plates such that said prosthesis exhibits different stiffness characteristics directly dependent on loads applied to said first and second plates when implanted between the vertebrae.