A spinal implant prosthetic insert for implantation into a void in the spinal column in place of a diseased or injured vertebra that has been removed. The insert maintains the height of the anterior spinal column, thus preventing deformity from occurring. The prosthesis insert is implanted into the spinal column after the anterior vertebral body has been removed. The insert is rigidly fixed in place with bone screws that will screw into the adjacent upper and lower vertebrae after the insert has been positioned in place, through the operation of a drive that is accessible after the insert has been implanted into place. The insert is contoured so that no substantial part of it protrudes outside of the margins of the anterior vertebral column, making it usable as an implant even in the lumbar region where protrusions from the spinal column cannot be tolerated. The device is easily actuated after the anterior region of the spinal column has been exposed, and provides a rigidity that is limited only by the integrity of the bone of the adjacent vertebrae in which to is fixed.