Prostheses, tools and methods for replacement of natural facet joints with artifical facet joint surfaces

Abstract

Cephalad and caudal vertebral facet joint prostheses and methods of use are provided. The cephalad prostheses are adapted and configured to be attached to a lamina portion of a vertebra without blocking a pedicle portion of the cephalad vertebra.

What is claimed is:  
     
         1 . A prosthesis to replace a cephalad portion of a natural facet joint on a vertebra, the prosthesis comprising: 
 an artificial facet joint element adapted and configured to replace a cephalad portion of the natural facet joint; and    a fixation element extending from the artificial facet joint element, the fixation element being adapted and configured to be inserted through a lamina portion of a vertebra to affix the artificial facet joint element to the vertebra.    
     
     
         2 . The prosthesis of  claim 1  wherein the fixation element is further adapted and configured to be inserted through the lamina portion of the vertebra to affix the artificial facet joint element to the vertebra without blocking access to a pedicle portion of the vertebra.  
     
     
         3 . The prosthesis of  claim 1  wherein the lamina portion is a first lamina portion, the fixation element being further adapted and configured to be inserted through a second lamina portion of the vertebra to affix the artificial facet joint element to the vertebra.  
     
     
         4 . The prosthesis of  claim 3  wherein first and second lamina portions are on opposite sides of a midline of the vertebra, the fixation element being further adapted and configured to traverse the midline to affix the artificial facet joint element to the vertebra.  
     
     
         5 . The prosthesis of  claim 1  wherein the artificial facet joint element comprises a cephalad bearing surface adapted and configured to be in an anatomically correct position with respect to the vertebra when the prosthesis is affixed to the vertebra by the fixation element.  
     
     
         6 . The prosthesis of  claim 1  wherein the artificial facet joint element comprises a cephalad bearing surface adapted and configured to be in other than an anatomically correct position with respect to the vertebra when the prosthesis is affixed to the vertebra by the fixation element.  
     
     
         7 . The prosthesis of  claim 1  further comprising an attachment element adapted and configured to attach the artificial facet joint element to the fixation element.  
     
     
         8 . The prosthesis of  claim 1  wherein the fixation element comprises an artificial facet joint element attachment end and an insertion tool engagement end, the artificial facet joint attachment end being adapted and configured to lie on one side of the lamina portion and the artificial facet joint attachment end being adapted and configured to lie on another side of the lamina portion.  
     
     
         9 . The prosthesis of  claim 1  wherein the artificial facet joint element is adapted and configured to be disposed between a caudal facet joint bearing surface and a portion of the vertebra.  
     
     
         10 . The prosthesis of  claim 1  wherein the artificial facet joint element comprises a cephalad bearing surface having a substantially convex shape.  
     
     
         11 . The prosthesis of  claim 1  wherein the artificial facet joint element further comprises an installation fixture attachment mechanism.  
     
     
         12 . A prosthesis to replace a cephalad portion of a natural facet joint on a vertebra, the prosthesis comprising: 
 an artificial facet joint element adapted and configured to replace a cephalad portion of the natural facet joint; and    a fixation element adapted and configured to affix the artificial facet joint element to the vertebra without blocking access to a pedicle portion of the vertebra.    
     
     
         13 . The prosthesis of  claim 12  wherein the artificial facet joint element comprises a cephalad bearing surface adapted and configured to be in an anatomically correct position with respect to the vertebra when the prosthesis is affixed to the vertebra by the fixation element.  
     
     
         14 . The prosthesis of  claim 12  wherein the artificial facet joint element comprises a cephalad bearing surface adapted and configured to be in other than an anatomically correct position with respect to the vertebra when the prosthesis is affixed to the vertebra by the fixation element.  
     
     
         15 . The prosthesis of  claim 12  further comprising an attachment element adapted and configured to attach the artificial facet joint element to the fixation element.  
     
     
         16 . The prosthesis of  claim 12  wherein the fixation element comprises an artificial facet joint element attachment end and an insertion tool engagement end, the artificial facet joint attachment end being adapted and configured to lie on one side of a lamina portion of the vertebra and the artificial facet joint attachment end being adapted and configured to lie on another side of the lamina portion.  
     
     
         17 . The prosthesis of  claim 12  wherein the artificial facet joint element is adapted and configured to be disposed between a caudal facet joint bearing surface and a portion of the vertebra.  
     
     
         18 . The prosthesis of  claim 12  wherein the artificial facet joint element comprises a cephalad bearing surface having a substantially convex shape.  
     
     
         19 . The prosthesis of  claim 12  wherein the artificial facet joint element further comprises an installation fixture attachment mechanism.  
     
     
         20 . A prosthesis to replace a caudal portion of a natural facet joint on a vertebra, the prosthesis comprising: 
 an artificial facet joint element comprising a vertebra contacting surface and a caudal bearing surface, the caudal bearing surface being adapted and configured to replace a caudal portion of a natural facet joint and to be substantially entirely posterior of a contact portion of the vertebra when the vertebra contacting surface contacts the contact portion; and    a fixation element extending from the artificial facet joint element, the fixation element being adapted and configured to be inserted into the vertebra to affix the prosthesis to the vertebra.    
     
     
         21 . The prosthesis of  claim 20  wherein the caudal bearing surface is further adapted and configured to be in an anatomically correct position with respect to the vertebra when the prosthesis is affixed to the vertebra by the fixation element.  
     
     
         22 . The prosthesis of  claim 20  wherein the caudal bearing surface is further adapted and configured to be in an other than anatomically correct position with respect to the vertebra when the prosthesis is affixed to the vertebra by the fixation element.  
     
     
         23 . The prosthesis of  claim 20  further comprising an attachment element adapted and configured to attach the artificial facet joint element to the fixation element.  
     
     
         24 . The prosthesis of  claim 20  wherein the caudal bearing surface has a substantially concave shape.  
     
     
         25 . The prosthesis of  claim 20  wherein the artificial facet joint element further comprises an installation fixture attachment mechanism.  
     
     
         26 . A prosthesis to replace a caudal portion and a cephalad portion of a natural facet joint of cephalad and caudal vertebrae, the prosthesis comprising: 
 an artificial cephalad facet joint element adapted and configured to replace a cephalad portion of the natural facet joint, the artificial cephalad facet joint element comprising a cephalad bearing surface;    a cephalad fixation element, the cephalad fixation element being adapted and configured to be inserted through a lamina portion of the cephalad vertebra to affix the artificial cephalad facet joint element to the cephalad vertebra;    an artificial caudal facet joint element adapted and configured to replace a caudal portion of the natural facet joint, the artificial caudal facet joint element comprising a caudal bearing surface adapted and configured to mate with the cephalad bearing surface.    
     
     
         27 . The prosthesis of  claim 26  wherein the cephalad fixation element is further adapted and configured to be inserted through the lamina portion of the vertebra to affix the artificial facet joint element to the vertebra without blocking access to a pedicle portion of the vertebra.  
     
     
         28 . The prosthesis of  claim 26  wherein the lamina portion is a first lamina portion, the cephalad fixation element being further adapted and configured to be inserted through a second lamina portion of the vertebra to affix the artificial facet joint element to the vertebra.  
     
     
         29 . The prosthesis of  claim 28  wherein first and second lamina portions are on opposite sides of a midline of the vertebra, the cephalad fixation element being further adapted and configured to traverse the midline to affix the artificial facet joint element to the vertebra.  
     
     
         30 . The prosthesis of  claim 26  wherein the artificial cephalad facet joint element is adapted and configured to be disposed between the caudal facet joint bearing surface and a portion of the cephalad vertebra.  
     
     
         31 . The prosthesis of  claim 26  further comprising a caudal fixation element extending from the artificial caudal facet joint element, the caudal fixation element being adapted and configured to be inserted into the caudal vertebra to affix the artificial caudal facet joint element to the caudal vertebra.  
     
     
         32 . The prosthesis of  claim 26  wherein the cephalad bearing surface and the caudal bearing surface are adapted and configured to be in anatomically correct positions with respect to the cephalad and caudal vertebrae when the prosthesis is affixed to the cephalad and caudal vertebrae, respectively.  
     
     
         33 . The prosthesis of  claim 26  wherein the cephalad bearing surface and the caudal bearing surface are adapted and configured to be in other than anatomically correct positions with respect to the cephalad and caudal vertebrae when the prosthesis is affixed to the cephalad and caudal vertebrae, respectively.  
     
     
         34 . The prosthesis of  claim 26  wherein cephalad bearing surface and the caudal bearing surface each has a width along its respective transverse axis, the cephalad bearing surface width being shorter than the caudal bearing surface width.  
     
     
         35 . The prosthesis of  claim 26  wherein the cephalad bearing surface has a substantially convex shape and the caudal bearing surface has a substantially concave shape.  
     
     
         36 . The prosthesis of  claim 26  wherein the artificial caudal facet joint element further comprises a vertebra contacting surface, the entire caudal bearing surface being adapted and configured to be posterior of a contact portion of the caudal vertebra when the vertebra contacting surface contacts the contact portion.  
     
     
         37 . A prosthesis to replace a caudal portion and a cephalad portion of a natural facet joint of cephalad and caudal vertebrae, the prosthesis comprising: 
 an artificial cephalad facet joint element adapted and configured to replace a cephalad portion of the natural facet joint, the artificial cephalad facet joint element comprising a cephalad bearing surface;    a cephalad fixation element adapted and configured to affix the artificial cephalad facet joint element to the cephalad vertebra without blocking access to a pedicle portion of the cephalad vertebra; and    an artificial caudal facet joint element adapted and configured to replace a caudal portion of the natural facet joint, the artificial caudal facet joint element comprising a caudal bearing surface adapted and configured to mate with the cephalad bearing surface.    
     
     
         38 . The prosthesis of  claim 37  wherein the artificial cephalad facet joint surface is adapted and configured to be disposed between the caudal facet joint bearing surface and a portion of the cephalad vertebra.  
     
     
         39 . The prosthesis of  claim 37  further comprising a caudal fixation element extending from the artificial caudal facet joint element, the caudal fixation element being adapted and configured to be inserted into the caudal vertebra to affix the artificial caudal facet joint element to the caudal vertebra.  
     
     
         40 . The prosthesis of  claim 37  wherein the cephalad bearing surface and the caudal bearing surface are adapted and configured to be in anatomically correct positions with respect to the cephalad and caudal vertebrae when the prosthesis is affixed to the cephalad and caudal vertebrae, respectively.  
     
     
         41 . The prosthesis of  claim 37  wherein the cephalad bearing surface and the caudal bearing surface are adapted and configured to be in other than anatomically correct positions with respect to the cephalad and caudal vertebrae when the prosthesis is affixed to the cephalad and caudal vertebrae, respectively.  
     
     
         42 . The prosthesis of  claim 37  wherein the cephalad bearing surface and the caudal bearing surface each has a width along its respective transverse axis, the cephalad bearing surface width being shorter than the caudal bearing surface width.  
     
     
         43 . The prosthesis of  claim 37  wherein the cephalad bearing surface has a substantially convex shape and the caudal bearing surface has a substantially concave shape.  
     
     
         44 . The prosthesis of  claim 37  wherein the artificial caudal facet joint element further comprises a vertebra contacting surface, the entire caudal bearing surface being adapted and configured to be posterior of a contact portion of the caudal vertebra when the vertebra contacting surface contacts the contact portion.  
     
     
         45 . A method for implanting a facet joint prosthesis to replace a removed cephalad portion of a natural facet joint on a vertebra, the method comprising the steps of: 
 inserting a fixation element through a lamina portion of the vertebra; and    placing an artificial cephalad facet joint bearing surface in a position to form a cephalad portion of a facet joint.    
     
     
         46 . The method of  claim 45  further comprising attaching an artificial facet joint element to an end of the fixation element after the inserting step.  
     
     
         47 . The method of  claim 45  further comprising attaching an artificial facet joint element to an end of the fixation element prior to the inserting step.  
     
     
         48 . The method of  claim 45  wherein the inserting step comprises inserting the fixation element through the lamina portion of the vertebra without blocking access to a pedicle portion of the vertebra.  
     
     
         49 . The method of  claim 45  wherein the lamina portion is a first lamina portion, the inserting step comprising inserting the fixation element through a second lamina portion.  
     
     
         50 . The method of  claim 49  wherein the first lamina portion and the second lamina portion are on opposite sides of a midline of the vertebra, the inserting step comprising traversing the midline with the fixation element.  
     
     
         51 . The method of  claim 45  wherein the placing step comprises disposing the artificial facet joint bearing surface between a caudal facet joint bearing surface and a portion of the vertebra.  
     
     
         52 . The method of  claim 45  wherein the placing step comprises placing the artificial facet joint bearing surface in an anatomically correct position with respect to the vertebra.  
     
     
         53 . The method of  claim 45  wherein the placing step comprises placing the artificial facet joint bearing surface in an other than anatomically correct position with respect to the vertebra.  
     
     
         54 . The method of  claim 45  further comprising the step of aligning the artificial cephalad facet joint bearing surface with a corresponding caudal bearing surface.  
     
     
         55 . The method of  claim 45  further comprising the step of defining an insertion path through the lamina prior to the inserting step.  
     
     
         56 . The method of  claim 55  further comprising forming a passage through the lamina corresponding to the insertion path.  
     
     
         57 . The method of  claim 55  wherein the defining step comprises aligning a guide with the artificial facet joint element to direct the location and orientation of the insertion path.  
     
     
         58 . The method of  claim 57  further comprising forming a passage through the lamina corresponding to the insertion path.  
     
     
         59 . The method of  claim 45  wherein the inserting step comprises inserting the fixation element through the lamina portion of the vertebra to affix the fixation element to the vertebra without using cement.  
     
     
         60 . A method for implanting a cephalad facet joint prosthesis to replace a removed cephalad portion of a natural facet joint on a vertebra, the method comprising the steps of: 
 aligning the cephalad facet joint prosthesis with a caudal facet joint bearing surface; and    attaching the cephalad facet joint prosthesis to the vertebra without blocking a pedicle portion of the vertebra.    
     
     
         61 . The method of  claim 60  wherein the attaching step comprises inserting a fixation element through a lamina portion of the vertebra.  
     
     
         62 . The method of  claim 60  wherein the attaching step comprises disposing the cephalad facet joint prosthesis between the caudal facet joint bearing surface and a portion of the vertebra.  
     
     
         63 . The method of  claim 60  wherein the attaching step comprises placing the cephalad facet joint prosthesis in an anatomically correct position with respect to the vertebra.  
     
     
         64 . The method of  claim 60  wherein the attaching step comprises placing the cephalad facet joint prosthesis in an other than anatomically correct position with respect to the vertebra.  
     
     
         65 . The method of  claim 60  wherein the attaching step comprises inserting a fixation element into a portion of the vertebra.  
     
     
         66 . The method of  claim 65  further comprising the step of defining an insertion path in the vertebra prior to the inserting step.  
     
     
         67 . The method of  claim 66  further comprising forming a passage in the vertebra corresponding to the insertion path.  
     
     
         68 . The method of  claim 66  wherein the defining step comprises aligning a guide with the artificial facet joint element to direct the location and orientation of the insertion path.  
     
     
         69 . The method of  claim 68  further comprising forming a passage in the vertebra corresponding to the insertion path.  
     
     
         70 . A method for implanting a facet joint prosthesis to replace removed cephalad and caudal portions of a natural facet joint of cephalad and caudal vertebrae, the method comprising the steps of: 
 affixing an artificial caudal facet joint element to the caudal vertebra;    inserting a cephalad fixation element through a lamina portion of the cephalad vertebra; and    placing an artificial cephalad facet joint bearing surface in a position to form a cephalad portion of a facet joint.    
     
     
         71 . The method of  claim 70  further comprising attaching an artificial cephalad facet joint element to an end of the fixation element after the inserting step, the artificial cephalad facet joint element comprising the artificial cephalad facet joint bearing surface.  
     
     
         72 . The method of  claim 70  further comprising attaching an artificial cephalad facet joint element to an end of the fixation element prior to the inserting step, the artificial cephalad facet joint element comprising the artificial cephalad facet joint bearing surface.  
     
     
         73 . The method of  claim 70  wherein the affixing step comprises affixing the artificial caudal facet joint element at or near to a pedicle of the caudal vertebra.  
     
     
         74 . The method of  claim 70  wherein the affixing step comprises placing the artificial caudal facet joint element in an anatomically correct position with respect to the caudal vertebra.  
     
     
         75 . The method of  claim 70  wherein the affixing step comprises placing the artificial caudal facet joint element in an other than anatomically correct position with respect to the caudal vertebra.  
     
     
         76 . The method of  claim 70  wherein the inserting step comprises inserting the fixation element through the lamina portion of the cephalad vertebra without blocking access to a pedicle portion of the cephalad vertebra.  
     
     
         77 . The method of  claim 70  wherein the lamina portion is a first lamina portion, the inserting step comprising inserting the fixation element through a second lamina portion of the cephalad vertebra.  
     
     
         78 . The method of  claim 77  wherein the first lamina portion and the second lamina portion are on opposite sides of a midline of the cephalad vertebra, the inserting step comprising traversing the midline with the fixation element.  
     
     
         79 . The method of  claim 70  wherein the placing step comprises disposing the artificial cephalad facet joint bearing surface between the artificial caudal facet joint element and a portion of the cephalad vertebra.  
     
     
         80 . The method of  claim 70  wherein the placing step comprises placing the artificial cephalad facet joint bearing surface in an anatomically correct position with respect to the cephalad vertebra.  
     
     
         81 . The method of  claim 70  wherein the placing step comprises placing the artificial cephalad facet joint bearing surface in an other than anatomically correct position with respect to the cephalad vertebra.  
     
     
         82 . The method of  claim 70  further comprising aligning the artificial cephalad facet joint bearing surface with a corresponding caudal bearing surface of the artificial caudal facet joint element.  
     
     
         83 . The method of  claim 82  wherein the aligning step comprises mounting an artificial cephalad facet joint element and the artificial caudal facet joint element in an installation fixture, the artificial cephalad facet joint element comprising the artificial cephalad facet joint bearing surface.  
     
     
         84 . The method of  claim 70  further comprising the step of defining an insertion path through the lamina prior to the inserting step.  
     
     
         85 . The method of  claim 84  further comprising forming a passage corresponding to the insertion path.  
     
     
         86 . The method of  claim 84  wherein the defining step comprises aligning a guide with the artificial cephalad facet joint element to direct the location and orientation of the insertion path.  
     
     
         87 . The method of  claim 86  further comprising forming a passage corresponding to the insertion path.  
     
     
         88 . The method of  claim 86  wherein the aligning step comprises orienting the guide with an installation fixture to which the artificial cephalad facet joint element has been attached.  
     
     
         89 . A method for implanting a facet joint prosthesis to replace removed cephalad and caudal portions of a natural facet joint of cephalad and caudal vertebrae, the method comprising the steps of: 
 affixing an artificial caudal facet joint element to the caudal vertebra; and    affixing an artificial cephalad facet joint element to the cephalad vertebra in alignment with the artificial caudal facet joint element and without blocking access to a pedicle portion of the cephalad vertebra.    
     
     
         90 . The method of  claim 89  wherein the first affixing step comprises affixing the artificial caudal facet joint element to at or near to a pedicle of the caudal vertebra.  
     
     
         91 . The method of  claim 89  wherein the first affixing step comprises placing the artificial caudal facet joint element in an anatomically correct position with respect to the caudal vertebra.  
     
     
         92 . The method of  claim 89  wherein the first affixing step comprises placing the artificial caudal facet joint element in an other than anatomically correct position with respect to the caudal vertebra.  
     
     
         93 . The method of  claim 89  wherein the second affixing step comprises disposing the artificial cephalad facet joint element between the artificial caudal facet joint element and a portion of the cephalad vertebra.  
     
     
         94 . The method of  claim 89  wherein the second affixing step comprises placing the artificial cephalad facet joint element in an anatomically correct position with respect to the cephalad vertebra.  
     
     
         95 . The method of  claim 89  wherein the second affixing step comprises placing the artificial cephalad facet joint element in an other than anatomically correct position with respect to the cephalad vertebra.  
     
     
         96 . The method of  claim 89  further comprising aligning a cephalad bearing surface of the artificial cephalad facet joint element with a corresponding caudal bearing surface of the caudal facet joint element.  
     
     
         97 . The method of  claim 96  wherein the aligning step comprises mounting the cephalad facet joint element and the caudal facet joint element in an installation fixture.  
     
     
         98 . The method of  claim 89  further comprising the step of defining an insertion path in the cephalad vertebra prior to the second affixing step.  
     
     
         99 . The method of  claim 98  further comprising forming a passage in the cephalad vertebra corresponding to the insertion path.  
     
     
         100 . The method of  claim 98  wherein the defining step comprises aligning a guide with the artificial cephalad facet joint element to direct the location and orientation of the insertion path.  
     
     
         101 . The method of  claim 100  further comprising forming a passage in the cephalad vertebra corresponding to the insertion path.  
     
     
         102 . The method of  claim 100  wherein the aligning step comprises orienting the guide with an installation fixture to which the artificial cephalad facet joint element has been attached.