Modular interspinous fixation system with threaded component

A modular interspinous fixation system comprising:

• a first member;
• a second member;
• one of said first member or said second member having at least one female thread associated therewith;
• the other of said first member or said second member supporting a generally elongated rotatable screw that mates with said at least one female thread;
• a modular insert extending between the end plates and generally enclosing said generally elongated rotatable screw;
• and
• at least a portion of said modular insert being slidable into and through one of said first member or said second member in response to rotation of said generally elongated rotatable screw.

An interspinous fixation system comprising:

• a set of elongated end plates in parallel spaced opposing relation;
• the plates having opposing bone engaging projections;
• one of the end plates having spaced opposing threads disposed between spaced guide ways;
• the other end plate supporting an elongated rotatable screw extending between the opposing threads in the opposing end plate;
• a bone spacer module extending between the end plates and enclosing the screw;
• and
• the spacer module extending into the guide ways and slidable in the guide ways to maintain alignment of the end plates in response to rotation of the screw.