Abstract: A surgical bone fixation screw having a head, an end segment distally from the head and an intermediate shank having outwardly protruding screw threads. The improvement is a self guiding, threadless, elongated end segment having a smooth outer surface with no cutting edges, a length of at least 8 mm and preferably 15 mm and a bluntly rounded end with an outer contour that is smoothly blended to the shank. Most preferably, the bluntly rounded end is substantially a prolate hemispheroid.

Abstract: A surgical bone fixation screw having a head, an end segment distally from the head and an intermediate shank having outwardly protruding screw threads. The improvement is a self guiding, threadless, elongated end segment having a smooth outer surface with no cutting edges, a length of at least 8 mm and preferably 15 mm and a bluntly rounded end with an outer contour that is smoothly blended to the shank. Most preferably, the bluntly rounded end is substantially a prolate hemispheroid.

Abstract: Improvements for a pedicle screw that is pre-connected to a support rod by an articulation joint so that the pedicle screw can be installed with the support rod attached to it. A first driven interlock element is joined to the pedicle screw. A driver interlock element is formed at a first end of the support rod and is matingly engageable with the driven interlock element of the pedicle screw. The support rod is retained in the joint in a manner that allows it to be pivoted between a position that is substantially coaxial with the pedicle screw and an installed position transverse to the pedicle screw. The support rod, when aligned coaxially with the pedicle screw is able to slide axially within the articulation joint to permit engagement of the driver interlock element of the rod with the driven interlock element of the screw.

Abstract: A method and a distracter for replacing a removed, intervertebral disc with a prosthesis. An inter-body distracter is inserted within the intervertebral space between adjacent vertebrae, the vertebrae are distracted and are supported by the distracter. A fluid, curable polymer is injected into the intervertebral space and around the distracter and then the polymer is cured to a semi-rigid, pliable, elastically deformable state. The distracter is then disabled from supporting compressive forces applied by the vertebrae and remains in place. The preferred distracter is a scissors jack having intermediate bearings joined by links to support feet. One of the bearings has a threaded lateral bore and the second bearing has a lateral bore. A rod extends through the bores and has a threaded portion extending from a first end of the rod and threadedly engaging the threaded bearing.