Dynamic Fixation Device and Method of Use

Abstract

A dynamic fixation device is provided that allows the vertebrae to which it is attached to move in flexion within the normal physiological limits of motion, while also providing structural support that limits the amount of translation motion beyond normal physiological limits. The present invention includes a flexible portion and two ends that are adapted for connection to pedicle screws. In at least one embodiment of the present invention, the normal axis of rotation of the vertebrae is substantially duplicated by the dynamic fixation device. The flexible portion of the dynamic fixation device can include a geometric shape and/or a hinge portion.

1 - 20 . (Canceled) 
     
     
         21 . A method comprising:
 manufacturing a dynamic fixation device comprising:
 a moveable rod including:
 a lower rod arm; 
 an anterior-posterior segment connected to the lower rod arm at an anterior end of the anterior-posterior segment; and 
 an upper rod arm connected to the anterior-posterior segment at a posterior end of the anterior-posterior segment; and 
 
   providing instructions for installing the dynamic fixation device in a patient comprising:
 providing instructions to connect the upper and lower rod arms to connectors; and 
 providing instructions to connect the connectors to bone anchors. 
   
     
     
         22 . The method of  claim 21 , wherein providing instructions for installing the dynamic fixation device comprises providing instructions that the anterior end of the anterior-posterior segment is to be located anterior of the upper rod arm and the posterior end of the anterior-posterior segment is to be located posterior of the upper rod arm when the dynamic fixation device is installed in the patient and the patient is in a neutral position. 
     
     
         23 . The method of  claim 21 , wherein providing instructions for installing the dynamic fixation device comprises providing instructions that the anterior-posterior segment is slanted downward from horizontal when the dynamic fixation device is installed in the patient and the patient is in a neutral position. 
     
     
         24 . The method of  claim 21 , wherein providing instructions to connect the upper and lower rod arms to connectors comprises providing instructions to connect the upper rod arm to a first connector of the connectors and to connect the lower rod arm to a second connector of the connectors. 
     
     
         25 . The method of  claim 24 , wherein providing instructions to connect the connectors to bone anchors comprises providing instructions to connect the first connector to a first bone anchor of the bone anchors and to connect the second connector to a second bone anchor of the bone anchors. 
     
     
         26 . The method of  claim 25 , wherein providing instructions for installing the dynamic fixation device comprises providing instructions that an angle between the lower rod arm and the second bone anchor is to be less than ninety degrees when the dynamic fixation device is installed in the patient and the patient is in a neutral position. 
     
     
         27 . The method of  claim 25 , wherein providing instructions for installing the dynamic fixation device comprises providing instructions that an angle between the lower rod arm and the second bone anchor is different than an angle between the upper rod arm and the first bone anchor when the dynamic fixation device is installed in the patient and the patient is in a neutral position. 
     
     
         28 . The method of  claim 24 ,
 wherein manufacturing the dynamic fixation device comprises manufacturing a first end of the lower rod arm connected to the anterior-posterior segment and a first end of the upper rod arm connected to the anterior-posterior segment;   wherein providing instructions to connect the upper rod arm to the first connector comprises providing instructions to connect a second end of the upper rod arm to the first connector, the second end of the upper rod arm being opposite the first end of the upper rod arm; and   wherein providing instructions to connect the lower rod arm to the second connector comprises providing instructions to connect a second end of the lower rod arm to the second connector, the second end of the lower rod arm being opposite the first end of the lower rod arm.   
     
     
         29 . The method of  claim 21 , wherein providing instructions for installing the dynamic fixation device in a patient comprises providing instructions to install first and second bone anchors of the bone anchors in vertebrae of the patient's spine. 
     
     
         30 . The method of  claim 21 , wherein manufacturing the dynamic fixation device comprises manufacturing the dynamic fixation device to expand to accommodate flexion of the patient's spine and to compress to accommodate extension of the patient's spine. 
     
     
         31 . The method of  claim 21 , wherein manufacturing the dynamic fixation device comprises manufacturing the anterior-posterior segment to comprise two segments, wherein the lower rod arm is connected to first ends of the two segments and the upper rod arm is connected to second ends of the two segments, wherein the first ends are opposite the second ends. 
     
     
         32 . The method of  claim 21 , wherein manufacturing the dynamic fixation device comprises manufacturing a first end of the lower rod arm connected to the anterior end of the anterior-posterior segment and a second end of the lower rod arm adapted to be connected to the second connector, the second end being opposite the first end. 
     
     
         33 . The method of  claim 32 , wherein the first end of the lower rod arm is connected to the anterior end of the anterior-posterior segment by being integrally formed of the same material. 
     
     
         34 . The method of  claim 32 , wherein the first end of the lower rod arm is connected to the anterior end of the anterior-posterior segment by a coupler. 
     
     
         35 . The method of  claim 21 , wherein manufacturing the dynamic fixation device comprises manufacturing a first end of the upper rod arm connected to the posterior end of the anterior-posterior segment and a second end of the upper rod arm adapted to be connected to the first connector, the second end being opposite the first end. 
     
     
         36 . The method of  claim 35 , wherein the first end of the upper rod arm is connected to the posterior end of the anterior-posterior segment by being integrally formed of the same material. 
     
     
         37 . The method of  claim 35 , wherein the first end of the upper rod arm is connected to the posterior end of the anterior-posterior segment by a coupler. 
     
     
         38 . The method of  claim 21 , wherein the moveable rod is manufactured of a material selected from the group consisting of ceramics, plastics, metals, and carbon fiber composites. 
     
     
         39 . The method of  claim 21 , wherein the moveable rod comprises a pin. 
     
     
         40 . The method of  claim 21 , wherein providing instructions for installing the dynamic fixation device comprises providing instructions to orient the moveable rod in a plane that is substantially parallel to a sagittal plane of the patient.