Methods and devices for bilaterally expanding intervertebral body fusion devices

Abstract

An embodiment includes devices and methods for using an expandable intervertebral body fusion device with two expansion wedges within a generally hollow main body. After implantation into the intervertebral disc space, the expansion wedges are simultaneously moved from the center of the device toward the ends, which flexes the arms of the cage and increases the size of the implant. This expansion stabilizes the device in the disc space and increases the disc height, thereby reducing foraminal compression of spinal nerves and creating a stable motion segment for eventual fusion. Other embodiments are described herein.

What is claimed: 
     
         1 . An intervertebral spacing implant comprising:
 a seat having an outer surface, a first lateral end and a second lateral end;   two or more first arms, each having a first arm interior surface and a first arm exterior surface, coupled to the first lateral end of the seat and extending in a first lateral direction away from the seat to a first arm distal end, the two or more first arms defining a first internal volume wherein the first internal volume has a first interior perimeter at a first interior location proximal to the seat and a second interior perimeter at a second interior location distal to the first interior location that is less than the first interior perimeter when the two or more first arms are unextended;   a first spacer configured to moveably fit within the first cage and move in the first lateral direction; and   two or more second arms, each having a second arm interior surface and a second arm exterior surface, coupled to the second lateral end of the seat and extending in a second lateral direction away from the seat to a second arm distal end, the two or more second arms defining a second internal volume.   
     
     
         2 . The intervertebral spacing implant of  claim 1  wherein the second internal volume has a third interior perimeter at a first second interior location proximal to the seat and a fourth interior perimeter at a second interior location distal to the first interior location that is less than the third interior perimeter when the two or more first arms are unextended. 
     
     
         3 . The intervertebral spacing implant of  claim 1  wherein the one or more of the two or more first arms form a first shoulder on the first arm interior surface at the first arm distal end. 
     
     
         4 . The intervertebral spacing implant of  claim 1  further comprising a second moveable spacer configured to fit within the second internal volume and move in the second lateral direction. 
     
     
         5 . The intervertebral spacing implant of  claim 4  wherein the one or more of the two or more second arms form a second shoulder at the second arm distal end. 
     
     
         6 . The intervertebral spacing implant of  claim 1  wherein the two or more first arms defining the first internal volume form a first cage. 
     
     
         7 . The intervertebral spacing implant of  claim 1  wherein the two or more second arms defining the second internal volume form a second cage. 
     
     
         8 . The intervertebral spacing implant of  claim 1  further comprising threads on the exterior arm surface of at least one of the two or more first arms and the two or more second arms. 
     
     
         9 . The intervertebral spacing implant of  claim 1  wherein the first and second cages comprise a direct lateral interbody fusion (DLIF) cage. 
     
     
         10 . A method of implanting an intervertebral spacing implant comprising:
 providing an interveterbral spacing implant comprising
 a seat having an outer surface, a first lateral end and a second lateral end; 
 two or more first arms, each having a first arm interior surface and a first arm exterior surface, coupled to the first lateral end of the seat and extending in a first lateral direction away from the seat to a first arm distal end, the two or more first arms defining a first internal volume wherein the first internal volume has a first interior perimeter at a first interior location proximal to the seat and a second interior perimeter at a second interior location distal to the first interior location that is less than the first interior perimeter when the two or more first arms are unextended; 
 a first spacer configured to moveably fit within the first cage and move in the first lateral direction; and 
 two or more second arms, each having a second arm interior surface and a second arm exterior surface, coupled to the second lateral end of the seat and extending in a second lateral direction away from the seat to a second arm distal end, the two or more second arms defining a second internal volume; 
   positioning the intervertebral spacing implant between a first vertebra and a second vertebra adjacent the first vertebra;   moving the first spacer in the first lateral direction away from the seat; and   increasing an exterior perimeter of the intervertebral spacing implant at a location along a length of the two or more first arms.   
     
     
         11 . The method of  claim 10  further comprising the step of flexing one or more of the two or more first arms radially outward. 
     
     
         12 . The method of  claim 10  further comprising the step of increasing the exterior perimeter of the intervertebral spacing implant distal to the seat by flexing one or more of the two or more first arms radially outward. 
     
     
         13 . The method of  claim 10  further comprising the steps of:
 providing a second spacer configured to moveably fit within a second cage and move in a second lateral direction, two or more second arms; 
 moving the second spacer in the lateral direction away from the seat; and 
 increasing an exterior perimeter of the intervertebral spacing implant at a location along a length of the two or more second arms. 
 
     
     
         14 . The method of  claim 13  further comprising the step of providing a first instrument and a second instrument, wherein the first instrument pulls on the first spacer and the second instrument pushes the second spacer. 
     
     
         15 . The method of  claim 13  wherein the radial lateral direction of at least one of the two or more first arms and at least one of the two or more second arms is simultaneous and asynchronous. 
     
     
         16 . The method of  claim 13  further comprising the steps of at least one of:
 securing the first spacer within a first shoulder positioned at a distal end of two or more first arms; and 
 securing the second spacer within a second shoulder positioned at a distal end of two or more second arms. 
 
     
     
         17 . The method of  claim 10  further comprising the steps of:
 providing threads on the exterior surface of one or more arms of the two or more first arms and the two or more second arms 
 using the threads on the exterior surface to secure the intervertebral spacing implant in a location between the first vertebra and the second vertebra. 
 
     
     
         18 . The method of  claim 10  further comprising the steps of:
 providing a plug; and 
 positioning the plug within at least one of a first spacer orifice and a second spacer orifice.