Modular uniplanar pedicle screw assembly for use with a polyaxial bone fastener

Abstract

A modular uniplanar pedicle screw assembly for use with a polyaxial bone fastener. The modular assembly comprises a uniplanar tulip assembly adapted to be coupled to a head of the polyaxial bone fastener, wherein the uniplanar tulip assembly includes a longitudinal slot. The modular assembly further includes an adapter having a lower portion and an upper portion. The lower portion is sized and shaped to be received in a recess of the bone fastener head. The upper portion extends from the lower portion and is adapted to slide along the longitudinal slot of the uniplanar tulip assembly to allow movement of the uniplanar tulip assembly in a first plane along a direction that is parallel to a longitudinal axis of the longitudinal slot, the longitudinal slot preventing movement of the uniplanar tulip assembly in a second plane lateral to the first plane relative to the bone fastener.

What is claimed is: 
     
         1 . A pedicle screw assembly on a bone fastener that has been inserted into a vertebra, the pedicle screw assembly comprising:
 a tulip assembly having a body, a pair of lateral arms, and a through-hole disposed under each of the pair of lateral arms;   a saddle element configured to be disposed in a bore of the body of the tulip assembly;   a translation rod, having a longitudinal axis, that is configured to be inserted into the tulip assembly through each through-hole of the tulip assembly;   wherein the tulip assembly is configured to engage the bone fastener such that the bone fastener is disposed within the bore and is configured to receive the translation rod, and   wherein when engaged with the bone fastener, the tulip assembly is configured to rotate about the translation rod in a direction that is perpendicular to the longitudinal axis of the translation rod.   
     
     
         2 . The pedicle screw assembly of  claim 1 , wherein the tulip assembly has one or more slots to receive a saddle retainer. 
     
     
         3 . The pedicle screw assembly of  claim 2 , wherein the saddle element has a lip that engages each of the saddle retainers. 
     
     
         4 . The pedicle screw assembly of  claim 1 , wherein the saddle element has teeth to engage an upper surface of the bone fastener to limit movement of the tulip assembly. 
     
     
         5 . The pedicle screw assembly of  claim 1 , wherein there is a gap between the saddle element and the bone fastener to facilitate rotational movement of the tulip assembly. 
     
     
         6 . The pedicle screw assembly of  claim 1 , wherein the translation rod is peened to prevent the translation rod from coming out of each through-hole. 
     
     
         7 . The pedicle screw assembly of  claim 1 , wherein the translation rod is configured to further pass through through-holes in the bone fastener. 
     
     
         8 . The pedicle screw assembly of  claim 1 , wherein the tulip assembly is configured to translate laterally with respect to the bone fastener. 
     
     
         9 . The pedicle screw assembly of  claim 1 , wherein the saddle element is configured to seat a fusion rod. 
     
     
         10 . The pedicle screw assembly of  claim 9 , wherein the pair of lateral arms are configured to receive a set screw to engage the fusion rod to lock the assembly. 
     
     
         11 . A pedicle screw assembly for implantation into a vertebra, the pedicle screw assembly comprising:
 a tulip assembly having a body and a pair of lateral arms, the body further including a bore and a through-hole disposed under each of the pair of lateral arms;   a saddle element configured to be disposed in the bore;   a translation rod, having a longitudinal axis, that is configured to be inserted into the tulip assembly through each through-hole of the body;   a bone fastener configured to engage the vertebra and to be received in the tulip assembly;   wherein the tulip assembly is configured to engage the bone fastener such that the bone fastener is disposed within the bore and is configured to receive the translation rod, and   wherein when assembled, the tulip assembly is configured to be engaged with the bone fastener and rotate about the translation rod in a direction that is perpendicular to the longitudinal axis of the translation rod.   
     
     
         12 . The pedicle screw assembly of  claim 11 , wherein the tulip assembly has one or more slots to receive a saddle retainer. 
     
     
         13 . The pedicle screw assembly of  claim 12 , wherein the saddle element has a lip that engages each of the saddle retainers. 
     
     
         14 . The pedicle screw assembly of  claim 11 , wherein the saddle element has teeth to engage an upper surface of the bone fastener to limit movement of the tulip assembly. 
     
     
         15 . The pedicle screw assembly of  claim 11 , wherein there is a gap between the saddle element and the bone fastener to facilitate rotational movement of the tulip assembly. 
     
     
         16 . The pedicle screw assembly of  claim 11 , wherein the translation rod is peened to prevent the translation rod from coming out of each through-hole. 
     
     
         17 . The pedicle screw assembly of  claim 11 , wherein the translation rod is configured to further pass through through-holes in the bone fastener. 
     
     
         18 . The pedicle screw assembly of  claim 11 , wherein the tulip assembly is configured to translate laterally with respect to the bone fastener. 
     
     
         19 . The pedicle screw assembly of  claim 11 , wherein the saddle element is configured to seat a fusion rod. 
     
     
         20 . The pedicle screw assembly of  claim 19 , wherein the pair of lateral arms are configured to receive a set screw to engage the fusion rod to lock the assembly.