Abstract: A modular hydraulic spinal intervertebral prosthetic device offering individualized optimization of an implantable disc prosthesis by having selectable crown plates modules with differing lordosis angles and differing cross-sectional profiles, and selectable bellows cartridges having differing load-bearing capabilities. The device offers substantially full physiological degrees of motion, and by the incorporation of both a dashpot mechanism and a biasing element within reversibly displaceable and tiltable bellows provides hydraulic load bearing capability. The bellows assembly is advantageously pre-loaded to sub-atmospheric pressure. The dashpot assembly further increases resistance to lateral shear loading beyond the bellows convolutions acting alone. Rotational coupling of the upper crown plate and center bearings plate permits normal twisting movements, and spinal flexural freedom is provided by the bellows interposed between the center bearings plate and the lower end plate.

Abstract: A modular hydraulic spinal intervertebral prosthetic device offering individualized optimization of an implantable disc prosthesis by having selectable crown plates modules with differing lordosis angles and differing cross-sectional profiles, and selectable bellows cartridges having differing load-bearing capabilities. The device offers substantially full physiological degrees of motion, and by the incorporation of both a dashpot mechanism and a biasing element within reversibly displaceable and tiltable bellows provides hydraulic load bearing capability. The bellows assembly is advantageously pre-loaded to sub-atmospheric pressure. The dashpot further increases resistance to lateral sheer loading beyond the bellows convolutions acting alone. Rotational coupling of the upper crown plate and center bearings plate permits normal twisting movements, and spinal flexural freedom is provided by the bellows interposed between the center bearings plate and the lower end plate.

Abstract: An improved spinal intervertebral prosthetic device that offers all degrees of motion afforded by the anatomic spinal intervertebral disc, and by virtue of the incorporation of a dashpot assembly mechanism within reversibly displaceable bellows, provides hydraulic load bearing capability as well as limiting the maximum pressure that can be exerted on the bellows assembly by limiting the compression stroke of the device. The dashpot assembly also increases resistance to lateral shear loading in excess of the bellows convolutions acting alone. The spinal intervertebral prosthetic device absorbs varying axial loads via hydraulic pressure transfer to the bellows convolutions which can flex in a spring-like fashion. Rotational coupling of the upper crown plate and center bearings plate permits normal twisting movements, and spinal flexural freedom is provided by the bellows that are interposed between the center bearings plate and the lower crown plate.

Abstract: A modular hydraulic spinal intervertebral prosthetic device offering individualized optimization of an implantable disc prosthesis by having selectable crown plates modules with differing lordosis angles and differing cross-sectional profiles, and selectable bellows cartridges having differing load-bearing capabilities. The device offers substantially full physiological degrees of motion, and by the incorporation of both a dashpot mechanism and a biasing element within reversibly displaceable and tiltable bellows provides hydraulic load bearing capability. The bellows assembly is advantageously pre-loaded to sub-atmospheric pressure. The dashpot further increases resistance to lateral sheer loading beyond the bellows convolutions acting alone. Rotational coupling of the upper crown plate and center bearings plate permits normal twisting movements, and spinal flexural freedom is provided by the bellows interposed between the center bearings plate and the lower crown plate.

Abstract: A spinal prosthetic device (10) which is hydraulically expanded or retracted, either pre-implantation or in-situ, thereby being adjustable for the exact intravertebral axial spacing required for the patient. Thrust bearing members (22) are positioned between the vertebra engaging members (12) and a pair of bellows (26), allowing the collapsible/expandable bellows (26) to be rotated with respect to the vertebra engaging members (12). The device (10) can be readjusted, on an out-patient basis, months after initial implantation. The spinal prosthetic device (10) offers all degrees of motion afforded by the anatomical spinal disc and by virtue of incorporating no rubbing contact of any parts, exhibits and infinite working life. The spinal prosthetic device (10) reproduces the same hydraulic load bearing capability as the nucleus pulposis and flexural freedom of movement similar to the annulus fibrosis.