Abstract: A spinal distraction apparatus has a distraction rod extending along an axis and having in turn a center part, a pair of end parts secured in, extending axially oppositely from, and rotatable about the axis relative to the center part, and a screwthread connection between each of the end parts and the center part. The screwthread connections are of opposite hand so that rotation of the center part in one direction moves the end parts axially toward each other and opposite rotation moves them axially apart. The end parts are axially nondisplaceable relative to the center part except on rotation of same about the axis. Respective anchors axially nondisplaceable on the end parts are adapted to be secured to respective vertebra. Formations between the anchors and the respective end parts prevent rotation of the end parts about the axis relative to the anchors.

Abstract: A spinal distraction splint has two like anchor screws extending along respective longitudinal screw axes and adapted to be anchored in the pelvis with the axes crossing. Each of the screws has a head formed with a transversely open recess centered on a respective transverse axis and with an annular array of teeth centered on and angularly equispaced about the respective transverse axis. A bolt extends through one of the recesses and is threaded in the other recess. Thus the bolt secures the heads together with the transverse axes coaxial and the teeth interengaged. Respective distraction rods each have one end braced on the respective screw and another end braced oppositely against a vertebra. Once the two anchor screws are properly inserted and then their heads are locked together the interfitting teeth on the heads absolutely locks them against angular rotation relative to each other about the axis of the fastener bolt and all other relative motion is eliminated by the clamping action of this bolt.