Modular tulip assembly
A modular tulip assembly has a rod receiving tulip and a saddle. The saddle is interlockingly held inside a distal portion of the tulip. The saddle has an external locking groove or recess. The tulip has a locking projection. The locking projection is positioned into the external locking groove or recess and holds the saddle in a pre-loaded unlocked state ready to be pushed onto a head of an implanted bone screw. Upon receiving the head of the bone screw, the saddle can be moved distally relative to the tulip to a locked state by moving the locking groove or recess distally past the locking projection to where the proximal end of the saddle is past abutting the locking projection.
1. A method of assembling a tulip comprises the step of:
providing a tulip with a locking projection; and
positioning a saddle with a concave locking surface inside the tulip onto the locking projection inside the tulip in a pre-loaded unlocked state to receive a head of a bone screw;
pushing the tulip with the pre-loaded unlocked saddle onto an implanted bone screw previously threaded into bone; and
moving the saddle to a locked state by moving a locking groove or recess from the locking projection and the proximal end of the saddle distally past abutting against the locking projection by engaging internal threads of the saddle with a threaded end of a tool, rotating the tool to axially move the saddle from the pre-loaded unlocked state distally to the locked state after attaching the saddle onto the head of the implanted screw.
2. The method of claim 1 further comprises the step of:
unlocking the locked tulip assembly by moving the saddle from the locked state to the pre-loaded unlocked state by engaging threads of the saddle with the threaded end of the tool and rotationally pulling the saddle proximally relative to the tulip.