Apparatus for providing proper vertebral spacing

Abstract

An expandable osteosynthesis implant has branches ( 5 ) each connected at one end to a seat ( 7 ) which is pierced by an orifice ( 8 ), suitable for being slid from a posterior direction between the facing faces of two consecutive vertebrae in order to hold them a given distance apart and restore stability of the spinal column. According to the invention, said branches ( 5 ) and said seat ( 7 ) define a hollow cage ( 1 ) which, in a “rest” position, has an outside general shape that is a cylinder of circular section, and a portion at least of the inside volume ( 9 ) of the cage ( 1 ) towards the distal ends of said branches ( 5 ) is in the form of a circular truncated cone whose large base is towards said seat ( 7 ), which implant has at least three branches ( 5 ) and, inside said inside volume ( 9 ) at least one spacer ( 2 ) suitable for passing through said orifice ( 8 ) and the large base of the truncated cone.

1 . (canceled)  
   
   
       2 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae, comprising: 
 a body extending along a longitudinal axis having a first portion and two or more legs depending from said first portion, said first portion having a first end having a width of a first lateral distance, said legs laterally spaced apart from each other and defining a second end of said body spaced opposite from said first end, said second end having a width of a second lateral distance, said legs defining an engaging member receiving cavity; and    an engaging member secured to said body and received within said engaging member receiving cavity, wherein said engaging member is secured to said body only by engagement of said engaging member with said legs.    
   
   
       3 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said engaging member slidably contacts said body whereby when said engaging member is positioned at a first position the second lateral distance approximately equals the first lateral distance and when the engaging member is positioned at a second position said engaging member causes said legs to flex and the second lateral distance is different than the first lateral distance.  
   
   
       4 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein when said engaging member is positioned at the second position the second lateral distance is greater than the first lateral distance.  
   
   
       5 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 3 , wherein said engaging member positioned at the second position is adjacent said second end.  
   
   
       6 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said first portion is substantially cylindrical in shape.  
   
   
       7 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 6 , wherein said first portion is hollow.  
   
   
       8 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said legs are spaced apart from each other defining a passageway through said body.  
   
   
       9 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 8 , wherein said legs define a passageway extending along an axis transverse to the longitudinal axis.  
   
   
       10 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said first portion and said legs have curved outer surfaces, each of said outer surfaces having the same radius of curvature.  
   
   
       11 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said body has an outer surface having a radial projection.  
   
   
       12 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 11 , wherein said body outer surface comprises a plurality of radial projections in the form of grooves.  
   
   
       13 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 12 , wherein said grooves are defined on more than half of the length of said fusion device.  
   
   
       14 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said first portion includes an inner surface that defines a hollow cavity that is in communication with the engaging member receiving cavity.  
   
   
       15 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , further comprising an end cap, said first portion includes an inner surface defining a passageway having an open end, wherein said end cap attaches to said first end of said first portion and closes off the open end of the passageway.  
   
   
       16 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said body is made from a material capable of withstanding opposing forces between adjacent vertebrae and capable of flexing during expansion of the device.  
   
   
       17 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said first portion is substantially cylindrical in shape and includes an inner surface that defines a hollow cavity that is in communication with the engaging member receiving cavity, said first leg and said second leg defining a passageway extending along an axis transverse to the longitudinal axis for bone mass to grow therethrough.  
   
   
       18 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 17 , wherein said body has an outer surface that includes a radial projection.  
   
   
       19 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said engaging member is secured to said second end of said body by moving said engaging member from a position external of said body to engage with said second end of said body.  
   
   
       20 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein at least one of said legs includes an inner surface that defines a ramp, whereby movement of said engaging member along the longitudinal axis contacts said ramp causing said leg to flex in a lateral direction and varying the second lateral distance.  
   
   
       21 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 15 , wherein said end cap is made of a material which prevents bone matter from escaping from the device.  
   
   
       22 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said first portion defines one or more passageways for permitting bone mass to grow therethrough.  
   
   
       23 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , where said engaging member includes a threaded passageway for threadably receiving an adjustment rod for engaging said engaging member with said legs.  
   
   
       24 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 2 , wherein said engaging member is a disc.  
   
   
       25 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 11 , wherein said radial projection extends from at least one of said legs.  
   
   
       26 . A dynamic fusion device for facilitating arthrodesis in a disc space between adjacent vertebrae as claimed in  claim 12 , wherein said grooves are defined on said legs.