A spinal disc prosthesis comprises an upper flat rigid plate, a lower flat rigid plate, and a flat elastomeric core interposed between said plates and adhered to the plates. A plurality of spaced-apart protuberances extend outwardly from the exposed faces of the plates for engagement with vertebrae above and below the plates. A porous coating covers the exposed surfaces of the plates. The elastomeric core is made of a polyolefin rubber having mechanical properites similar to a natural spinal disc.
A spinal disc prosthesis to replace a damaged spinal disc in a spinal column of a human includes an upper rigid plate having an outer perimeter and a lower rigid plate having an outer perimeter. A body of elastomeric material located between and bonded to the upper and lower rigid plates includes a main portion and a peripheral portion extending around the main portion. The upper and lower plates each have a curved convex plate surface extending around the respective outer perimeters and facing the peripheral portion of the body of elastomeric material. The peripheral portion of the body of elastomeric material has a first part which is bonded to the curved convex plate surfaces of the upper and lower plates and extends toward the main portion. The first part of the peripheral portion increases in thickness as the first part extends from the curved convex plate surfaces toward the main portion. The first part of the peripheral portion of the body of elastomeric material has a convexly curved outer surface which forms a part of the outer surface of the body of elastomeric material.
An articulated vertebral body spacer is constituted by a pair of upper and lower joint pieces to be inserted between vertebras. The lower joint piece includes a convex portion formed on a central portion of its upper surface and having a convex sliding contact surface, and a stopper surface surrounding the convex portion. The upper joint piece includes a concave portion formed on a central portion of its lower surface and having a concave sliding contact surface which is sliding contact with the convex sliding contact surface, and an abutment surface which surrounds the concave portion and abuts against the stopper surface. A cavity for allowing the upper joint piece to pivot in accordance with forward/backward and bending motions of vertebral bodies to respective levels is formed between the abutment surface and the stopper surface.
A spinal facet prosthesis for a diseased or painful facet joint comprises a superior component and an inferior component. The superior component is roughly conical or pyramidal in form and is fastened to and over the distal tip of the inferior articular process of the diseased or painful facet joint. The inferior component is also roughly conical or pyramidal in form with one side elongated postero-medially and distally. The outer surface of the elongated side of the inferior component is of low friction, such as polished chromium coating or medical grade high-density polyethylene. The inferior component is fastened to and over the superior articular process of the diseased or painful facet joint. Each component is made of a biocompatible material. The inner surface of each component which is in contact with its respective articular process is coated with a porous coating to enhance the adhesion of each component to its respective articular process.
An intervertebral disk prosthesis designed to replace at least partially an intervertebral disk which is composed of a left half-disk, and a right half-disk, each of the half-disks covering a half-disk surface. The prosthesis is at least one prosthetic member each of which having a rigid upper plate, a rigid lower plate, and an elastic cushion placed between the upper plate and the lower plate. The elastic cushion has an upper face attached to the upper plate and a lower face attached to the lower plate. Each prosthetic member covers no more than the half-disk surface so as to replace either or both of the left half-disk and the right half-disk.
A composition of a porous body for use as biomaterial according to the present invention is produced by adding Al (aluminum) in the amount of 0.1 to 3.0 atomic % to a porous composition consisting of titanium, nickel, iron and molybdenum, and it promotes the growth of living tissue and cells into pores. By the addition of Al to Ni, Ti, Fe and Mo, the temperature of formation of the liquid phase is lowered, and thus the diffusion of the constitutional elements of the composition is promoted, and the uniform distribution of the constitutional elements increases. As a result, the proportion of micropores in the porous body becomes increased to the extent that the distribution of micropores having the size in the range of 10.sup.-2 .mu.m.about.10 .mu.m is more than 5% in the metal bridge.
