Modular tulip assembly

Abstract

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.

What is claimed is: 
     
         1 . A modular tulip assembly comprises:
 a rod receiving tulip;   a saddle interlockingly held inside a distal portion of the tulip, the saddle having an external locking groove or recess; and   wherein 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 and 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 proximal end of the saddle past the locking projection, the locking projection fixing the saddle from moving proximally.   
     
     
         2 . The modular tulip assembly of  claim 1  wherein the tulip has a pair of opposing internally threaded walls defining a slotted opening for receiving a rod, an open bore with an open distal end for passing the polyaxial head of the bone screw, and the locking projection is axially spaced below the internal threads of the opposing wall and above the open distal end. 
     
     
         3 . The modular tulip assembly of  claim 2  wherein the saddle has an axis defined by a center opening, the saddle having a proximal end with a concavity for holding the rod and a distal portion with a plurality of arcuate fingers spaced by slots, the plurality of fingers curved to form a hemispherical shaped concavity for receiving and holding the head of the bone screw, the fingers extending to a distal end, the saddle having the external locking groove or recess positioned between the proximal end and above the arcuate fingers, the saddle being sized to pass through the open distal end of the tulip and move axially inside the tulip below the internal threads 
     
     
         4 . The modular tulip assembly of  claim 3  wherein the tulip has an enlarged internal chamber to accommodate the arcuate fingers and sized to allow the fingers to flex outwardly over and past a maximum diameter of the screw head on attachment. 
     
     
         5 . The modular tulip assembly of  claim 4  wherein the saddle center opening at the proximal end has internal threads to engage threads of an end of a tool configured to axially move the saddle relative to the tulip. 
     
     
         6 . The modular tulip assembly of  claim 5  wherein the saddle is pre-positioned in an unlocked bone screw receiving state when the locking groove or recess is moved past the locking onto the locking projection and after being attached onto an implanted bone screw polyaxial hemispherical head, the saddle is configured to be moved relative to the tulip by rotation of the tool to the locked state by moving the locking groove or recess distally off the locking projection and having the proximal end of the saddle distally past and abutting the locking projection causing the arcuate fingers at the distal end to flex and be compressed at the distal end of the tulip between the screw head and distal opening. 
     
     
         7 . The modular tulip assembly of  claim 6  wherein the locked saddle can be repositioned to the unlocked state by attaching the threaded end of the tool to the saddle and rotating the tool as it abuts a proximal end of the tulip causing the saddle locking groove or recess to disengage and move onto the locking projection allowing the arcuate fingers to release the screw head and the tulip assembly to be removed from the bone screw. 
     
     
         8 . A modular tulip assembly configured to receive and lock onto an implanted bone screw having a threaded shank and a hemispherical polyaxial head, the tulip subassembly comprising:
 a tulip having a pair of opposing internally threaded walls defining a slotted opening for receiving a rod, an open bore with an open distal end for passing the polyaxial head of the bone screw, and a locking projection being axially spaced below the internal threads of the opposing wall and above the open distal end;   a saddle having an axis defined by a center opening, the saddle having a proximal end with a concavity for holding the rod and a distal portion with a plurality of arcuate fingers spaced by slots, the plurality of fingers curved to form a hemispherical shaped concavity for receiving and holding the head of the bone screw, the fingers extending to a distal end, the saddle having an exterior locking groove or recess positioned between the proximal end and above the arcuate fingers, the saddle sized to pass through the open distal end and move axially inside the tulip below the internal threads; and   wherein the saddle is pre-positioned in an unlocked bone screw receiving state when the locking groove or recess is moved past the distal projection and onto the locking projection and thereafter can be attached onto an implanted bone screw polyaxial hemispherical head, the saddle being configured to be moved to a second locked state by moving the locking groove or recess distally off the locking projection and the proximal end of the saddle distally past abutting the locking projection causing the arcuate fingers at the distal end of the tulip to flex and be compressed at the open distal end of the tulip between the head of the bone screw and the distal end of the tulip.   
     
     
         9 . The modular tulip assembly of  claim 8  wherein the tulip has an enlarged internal chamber to accommodate the arcuate fingers and sized to allow the fingers to flex outwardly over and past a maximum diameter of the screw head on attachment. 
     
     
         10 . The modular tulip assembly of  claim 9  wherein the saddle center opening at the proximal end has internal threads to engage threads of an end of a tool configured to axially move the saddle relative to the tulip. 
     
     
         11 . The modular tulip assembly of  claim 10  wherein the saddle is pre-positioned in an unlocked bone screw receiving state when the locking groove or recess is past the onto the locking projection and after being attached onto an implanted bone screw polyaxial hemispherical head, the saddle is configured to be moved relative to the tulip by rotation of the tool to the locked state by moving the locking groove or recess distally off the locking projection and the proximal end of the saddle distally past and abutting the locking projection causing the arcuate fingers at the distal end to flex and be compressed at the distal end of the tulip between the head of the bone screw and the end of the tulip. 
     
     
         12 . The modular tulip assembly of  claim 11  wherein the locked saddle can be repositioned to the unlocked state by attaching the threaded end of the tool to the saddle and rotating the tool as it abuts a proximal end of the tulip causing the saddle locking groove or recess to reengage the locking projection moving onto the locking projection allowing the arcuate fingers to release the screw head and the tulip assembly to be removed from the bone screw. 
     
     
         13 . 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.   
     
     
         14 . The method of  claim 13  further comprises the step of:
 pushing the tulip with the pre-loaded unlocked saddle onto an implanted bone screw previously threaded into bone. 
 
     
     
         15 . The method of  claim 14  further comprises the step of:
 moving the saddle to a locked state by moving the locking groove or recess from the locking projection and the proximal end of the saddle distally past abutting against the locking projection. 
 
     
     
         16 . The method of  claim 15  of moving the saddle to a locked position further includes engaging internal threads of the saddle with a threaded end of a tool, rotating the tool to move the saddle from the pre-loaded unlocked state to the locked state after attaching the implanted screw. 
     
     
         17 . The method of  claim 16  further comprises the step of:
 unlocking the locked tulip assembly by moving the saddle by moving the saddle from the locked state to the pre-loaded unlocked state. 
 
     
     
         18 . The method of  claim 17  wherein the step of unlocking the tulip assembly includes engaging threads of the saddle with the threaded end of the tool and rotationally pulling the saddle proximally relative to the tulip. 
     
     
         19 . A modular tulip system with a bone screw comprises:
 a bone screw, the bone screw having a head and a threaded shank;   a rod receiving tulip;   a saddle interlockingly held inside a distal portion of the tulip, the saddle having an external locking groove or recess; and   wherein 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 onto the head of the bone screw, the saddle can be moved distally relative to the tulip to a locked state by moving the proximal end of the saddle past the locking projection, the locking projection fixing the saddle from moving proximally.   
     
     
         20 . The modular tulip system of  claim 19  wherein the tulip has a pair of opposing internally threaded walls defining a slotted opening for receiving a rod, an open bore with an open distal end for passing the polyaxial head of the bone screw, and the locking projection is axially spaced below the internal threads of the opposing wall and above the open distal end. 
     
     
         21 . The modular tulip system of  claim 20  wherein the saddle has an axis defined by a center opening, the saddle having a proximal end with a concavity for holding the rod and a distal portion with a plurality of arcuate fingers spaced by slots, the plurality of fingers curved to form a hemispherical shaped concavity for receiving and holding the head of the bone screw, the fingers extending to a distal end, the saddle having the external locking groove or recess positioned between the proximal end and above the arcuate fingers, the saddle being sized to pass through the open distal end of the tulip and move axially inside the tulip below the internal threads 
     
     
         22 . The modular tulip system of  claim 21  wherein the tulip has an enlarged internal chamber to accommodate the arcuate fingers and sized to allow the fingers to flex outwardly over and past a maximum diameter of the screw head on attachment. 
     
     
         23 . The modular tulip system of  claim 22  wherein the saddle center opening at the proximal end has internal threads to engage threads of an end of a tool configured to axially move the saddle relative to the tulip. 
     
     
         24 . The modular tulip system of  claim 23  wherein the saddle is pre-positioned in an unlocked bone screw receiving state when the locking groove or recess is moved past the locking onto the locking projection and after being attached onto the bone screw having a polyaxial hemispherical head, the saddle is configured to be moved relative to the tulip by rotation of the tool to the locked state by moving the locking groove or recess distally off the locking projection and having the proximal end of the saddle distally past and abutting the locking projection causing the arcuate fingers at the distal end to flex and be compressed at the distal end of the tulip between the screw head and distal opening. 
     
     
         25 . The modular tulip system of  claim 24  wherein the locked saddle can be repositioned to the unlocked state by attaching the threaded end of the tool to the saddle and rotating the tool as it abuts a proximal end of the tulip causing the saddle locking groove or recess to disengage and move onto the locking projection allowing the arcuate fingers to release the screw head and the tulip assembly to be removed from the bone screw. 
     
     
         26 . A modular tulip system configured to lock onto a bone screw, the modular tulip system comprising:
 a bone screw, the bone screw having a threaded shank and a hemispherical polyaxial head;   a tulip having a pair of opposing internally threaded walls defining a slotted opening for receiving a rod, an open bore with an open distal end for passing the polyaxial head of the bone screw, and a locking projection being axially spaced below the internal threads of the opposing wall and above the open distal end;   a saddle having an axis defined by a center opening, the saddle having a proximal end with a concavity for holding the rod and a distal portion with a plurality of arcuate fingers spaced by slots, the plurality of fingers curved to form a hemispherical shaped concavity for receiving and holding the head of the bone screw, the fingers extending to a distal end, the saddle having an exterior locking groove or recess positioned between the proximal end and above the arcuate fingers, the saddle sized to pass through the open distal end and move axially inside the tulip below the internal threads; and   wherein the saddle is pre-positioned in an unlocked bone screw receiving state when the locking groove or recess is moved past the distal projection and onto the locking projection, the saddle being configured to be moved to a second locked state by moving the locking groove or recess distally off the locking projection and the proximal end of the saddle distally past abutting the locking projection causing the arcuate fingers at the distal end of the tulip to flex and be compressed at the open distal end of the tulip between the head of the bone screw and the distal end of the tulip.   
     
     
         27 . The modular tulip system of  claim 26  wherein the tulip has an enlarged internal chamber to accommodate the arcuate fingers and sized to allow the fingers to flex outwardly over and past a maximum diameter of the screw head on attachment. 
     
     
         28 . The modular tulip system of  claim 27  wherein the saddle center opening at the proximal end has internal threads to engage threads of an end of a tool configured to axially move the saddle relative to the tulip. 
     
     
         29 . The modular tulip system of  claim 28  wherein the saddle is pre-positioned in an unlocked bone screw receiving state when the locking groove or recess is past the onto the locking projection and after being attached onto an implanted bone screw polyaxial hemispherical head, the saddle is configured to be moved relative to the tulip by rotation of the tool to the locked state by moving the locking groove or recess distally off the locking projection and the proximal end of the saddle distally past and abutting the locking projection causing the arcuate fingers at the distal end to flex and be compressed at the distal end of the tulip between the head of the bone screw and the end of the tulip. 
     
     
         30 . The modular tulip system of  claim 29  wherein the locked saddle can be repositioned to the unlocked state by attaching the threaded end of the tool to the saddle and rotating the tool as it abuts a proximal end of the tulip causing the saddle locking groove or recess to reengage the locking projection moving onto the locking projection allowing the arcuate fingers to release the screw head and the tulip assembly to be removed from the bone screw.