Methods for correction of spinal deformities

A method of treating a spinal column shape deformation, which comprises:

• fixing at least two fixation screw assemblies to respective vertebrae in which each fixation screw assembly comprises a fixation screw having a threaded shaft and a head, a channel which comprises a pair of approximately parallel arms and a base which extends between them, and an arm extension provided on each of the channel arms which is configured to be readily detached from the arm in which:
• the rod can be received in the channel between the arms,
• the base has a bore formed in it which is configured so that the shaft of the fixation screw but not the head thereof can extend through the bore, in which the channel can be swung through a range of angles relative to the fixation screw, at least in the plane which contains the two arms, the midpoint of the range of angles being angularly offset relative to the axis of the screw,
• in which the fixation step involves screwing the fixation screw into the pedicle, and orienting the channel so that it is inclined relative to the axis of its fixation screw and swung laterally relative to the spinal column,
• sliding the rod generally in the coronal plane so that it is positioned between the arm extensions on each of the fixation screw assemblies,
• swinging the channels relative to the heads of the fixation screws so that the channels become less inclined to the axes of the fixation screws, and so that the rod is located generally posteriorly of the spinal column,
• locking the channel against swinging relative to the screw,
• rotating the rod about its axis relative to at least one of the channels, and
• locking the rod against movement relative to the channel.