Centrally driven expandable implant and method

Abstract

Embodiments of the invention include expandable, implantable devices and methods. Devices expand linearly to provide secure fixation between or among anatomical structures. In some embodiments, an implant replaces one or more vertebral bodies of the spine.

1 - 14 . (canceled) 
     
     
         15 . A method of placing an expandable vertebral body replacement device comprising:
 making an incision adjacent to a vertebral body;   removing at least a portion of the vertebral body;   placing an expandable vertebral body replacement device on an insertion end of a contracted expansion instrument, wherein the contracted expansion instrument is configured to pass through a central portion of the expandable vertebral body replacement device without extending onto any surface of the expandable vertebral body replacement device that is lateral to an insertion direction;   inserting the vertebral body replacement device at least in part into a volume left open after removal of the portion of the vertebral body;   expanding the expansion instrument to secure the vertebral body replacement device; and   removing the expansion instrument through the incision.   
     
     
         16 . The method of  claim 15  further comprising placing bone growth promoting substance within the vertebral body replacement device prior to expansion of the vertebral body replacement device. 
     
     
         17 . The method of  claim 15  further comprising placing bone growth promoting substance within the vertebral body replacement device after expansion of the vertebral body replacement device. 
     
     
         18 . The method of  claim 15  further comprising implanting additional fixation devices to supplement the fixation of the vertebral body replacement. 
     
     
         19 . (canceled) 
     
     
         20 . A system comprising:
 a first tubular member with a connection end, an opposite skeletal interface end, and a central expansion instrument opening;   a second tubular member with a connection end configured to engage with the connection end of the first tubular member, the second tubular member having an opposite skeletal interface end, the connection end of the second tubular member having an end surface on a distal most portion of the connection end opposite the skeletal interface end of the second tubular member; and   an expansion instrument insertable through the central expansion instrument opening and expandable against the first tubular member and the end surface of the second tubular member to expand the medical implant.   
     
     
         21 . The system of  claim 20 , wherein the first tubular member includes a relief cut to facilitate portions of the first tubular member flexing away from the second tubular member to permit translation between the first and second tubular members. 
     
     
         22 . The system of  claim 21 , wherein the relief cut includes the central expansion instrument opening. 
     
     
         23 . The system of  claim 22 , wherein there are two relief cuts on opposite sides of the first tubular member through which the expansion instrument is inserted. 
     
     
         24 . The system of  claim 20 , wherein the first tubular member includes a set of adjacent protrusions. 
     
     
         25 . The system of  claim 24 , wherein the second tubular member includes a set of protrusions that are not all adjacent and that interdigitate with one or more of the adjacent protrusions. 
     
     
         26 . The system of  claim 20 , wherein the first and second tubular members are generally cylindrical. 
     
     
         27 . The system of  claim 20 , wherein an insertion end of the expansion instrument has collapsed configuration in which the insertion end has a generally round cross-section and an expanded configuration in which the insertion end has a generally non-round cross-section. 
     
     
         28 . A system comprising:
 an expandable implant having:
 a first tubular member extending along a first axis having a first end portion opposing a second end portion, the first tubular member having a first elongated slot extending along a length of the first tubular member between the first and second end portions and a second elongated slot on an opposing side of the first tubular member from the first elongated 
 a second tubular member movably connected to the first tubular member, the second tubular member having a third end portion opposing a fourth end portion, the third end portion defining a first recess and a second recess on an opposing side of the second tubular member from the first recess, wherein the first and second recessed are respectively aligned with the first and second elongated slots to define a first and second openings for receiving an expansion instrument. 
   
     
     
         29 . The system of  claim 28 , wherein the first and second openings provide access to a channel extending substantially transverse to the first axis through the first and second tubular members. 
     
     
         30 . The system of  claim 28 , further comprising the expansion instrument insertable through the first opening and expandable against the first and second tubular members to expand the implant along the first axis. 
     
     
         31 . The system of  claim 30 , wherein the expansion instrument is comprised of an upper and lower segment each having a semi-circular cross section. 
     
     
         32 . The system of  claim 30 , wherein the first recess and the first elongated slot each include a rounded engagement surface matching the profile of the upper and lower segments of the expansion instrument. 
     
     
         33 . The system of  claim 30 , wherein the expansion instrument is expandable to move the first tubular member away from the second tubular member to increase an overall height of the implant, and wherein the engagement of the first end portion with the third end portion maintains the overall height of the implant after expansion. 
     
     
         34 . The system of  claim 28 , wherein the first opening increases in length as the expandable instrument expands the implant generally along the first axis. 
     
     
         35 . The system of  claim 28 , wherein the first elongated slot extends in the direction of the first axis along a majority of the length of the first tubular member.