Patent Publication Number: US-2023139238-A1

Title: Expandable implant expansion driver

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/997,870, filed Aug. 19, 2020, which claims the benefit of the filing date of U.S. Provisional Application No. 62/888,976 which was filed on Aug. 19, 2019. The contents of each of the foregoing applications are incorporated by reference in their entirety as part of this application. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates generally to medical devices, and more particularly to an instrument for use with expandable implants. 
     Description of the Related Art 
     Back problems are one of the most common and debilitating occurrences. In the United States alone, over 500,000 spine lumbar and cervical fusion procedures are performed each year. One of the causes of back pain and disability results from the rupture or degeneration of one or more intervertebral discs in the spine. 
     Surgical procedures are commonly performed to correct problems with displaced, damaged, or degenerated intervertebral discs due to trauma, disease or aging. Generally, spinal fusion procedures involve removing some or all of the diseased or damaged disc, and inserting one or more intervertebral implants into the resulting disc space. Anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion, e.g. XLIF® (NuVasive, Inc., San Diego, Calif.), and transforaminal lumbar interbody fusion (TLIF) are techniques that spine surgeons use to access the portions of the spine to be repaired or replaced. 
     Replacement of injured or deteriorated spinal bone with artificial implants requires a balance of knowledge of the mechanisms of the stresses inherent in the spine, as well as the biological properties of the body in response to the devices. Further, the size, configuration, and placement of an artificial implant requires precision positioning and handling by a skilled surgeon. 
     SUMMARY OF THE INVENTION 
     This disclosure includes instruments for expandable implants and methods of using the same. 
     In some embodiments, the instrument includes: a first driver having a first gear disposed at a first end thereof; and a second driver having a second gear disposed at a first end of the second driver; and a differential operably connected to the first driver and the second driver, the differential engaging each of the first gear and the second gear and configured to transfer a torque to at least one of the first driver and the second driver. 
     In some embodiments, a differential for expansion drivers may include: at least one bevel gear, a first drive gear connected to a first output shaft, and a second drive gear connected to a second output shaft, the at least one bevel gear rotatably connected to a first drive source and configured to rotate around a first axis, wherein upon a rotation of the at least one bevel gear about the axis by the drive source, a torque will be transferred from the at least one bevel gear to one or more of the first drive gear and the second drive gear. 
     In some embodiments, a differential for expansion drivers may include: a first drive gear connected to a first output shaft configured to rotate around a first axis, a second drive gear connected to a second output shaft configured to rotate around the first axis, and a rotating carrier rotatably connected to a first drive source and configured to rotate around the first axis, wherein upon a rotation of rotating carrier about the axis, a torque will be transferred from the rotating carrier to one or more of the first drive gear and the second drive gear. 
     In some embodiments, the instrument includes: a first driver having a first gear disposed at a first end thereof; and a second driver having a second gear disposed at a first end of the second driver; and a handle operably connected to the first driver and the second driver, the handle having at least one bevel gear rotatably attached thereto, the at least one bevel gear engaging each of the first gear and the second gear; wherein upon a rotation of the handle a torque is applied to at least one of the first driver or the second driver. 
     In some embodiments, the instrument includes: a first driver having a first gear disposed at a first end thereof; a second driver, at least a portion of the second driver extending axially through the first driver, and a second gear disposed at a first end of the first driver, the second gear opposing the first gear; and a handle operably connected to the first driver and the second driver, the handle having a first bevel gear and a second bevel gear rotatably attached thereto, the first bevel gear and the second bevel gear each configured to communicate with the first gear and the second gear; wherein upon a rotation of the handle a torque is configured to be transferred to at least one of the first driver and the second driver. 
     In some embodiments, the expansion driver includes: a first driver having a first end and a second end, with a first gear disposed at the first end and the second end configured to mate with a first lead screw of an expandable implant; a second driver having a first end and a second end, a second gear disposed at the first end and configured to oppose the first gear of the first driver, at least a portion of the second end of the second driver extending axially through at least a portion of the first driver and configured to mate with a second lead screw of the expandable implant; and a handle operably connected to the first driver and the second driver, the handle having a first bevel gear and a second bevel gear rotatably attached thereto, the first bevel gear and the second bevel gear each configured to communicate with the first gear and the second gear; wherein upon a rotation of the handle the torque is configured to be transferred from the handle to the first bevel gear and the second bevel gear, with the first bevel gear and the second bevel gear configured to rotate at least one of the first driver and the second driver. 
     In some embodiments, the expansion driver includes: a first driver having a first end and a second end, with a first gear disposed at the first end and the second end configured to mate with a first lead screw of an expandable implant; a second driver having a first end and a second end, a second gear disposed at the first end and configured to oppose the first gear of the first driver, at least a portion of the second end of the second driver extending axially through at least a portion of the first driver and configured to mate with a second lead screw of the expandable implant; and a handle operably connected to the first driver and the second driver, the handle having a rotating carrier attached thereto, the rotating carrier configured to communicate with the first gear and the second gear; wherein upon a rotation of the handle the torque is configured to be transferred from the handle to the rotating carrier, with the rotating carrier configured to rotate at least one of the first driver and the second driver. 
     In some embodiments, a splitter attachment for an expansion driver includes an input configured to interface with an expansion driver, a first splitter output shaft configured to rotate a first actuator of an expandable implant, and a second splitter output shaft configured to rotate a second actuator of the expandable implant, wherein the splitter attachment is configured to transfer torque from the expansion driver to at least one of the first splitter output shaft and the second splitter output shaft. 
     An exemplary method of treating a spinal deformity is provided, the method including: preparing an intervertebral disc space of a patient; placing an expandable implant within the prepared intervertebral disk space of the patient; adjusting the expandable implant using an expansion driver having: a first driver, a second driver, and at least one bevel gear, wherein the at least one bevel gear is configured to rotate at least one of the first driver or the second driver to adjust the expandable implant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features may be further understood by those with skill in the art upon a review of the appended drawings, wherein: 
         FIG.  1    shows a perspective view of an expansion driver in accordance with a first embodiment; 
         FIG.  2    shows a cross-sectional view of the expansion driver in accordance with the first embodiment; 
         FIG.  3    shows perspective view of the expansion driver in accordance with the first embodiment, the housing removed revealing some of the internal components of the expansion driver; 
         FIG.  4    shows the differential including a first gear of the first driver, a second gear of the second driver, and at least one bevel gear of the handle; 
         FIG.  5    shows an exploded view of the expansion driver in accordance with the first embodiment; 
         FIG.  6    shows a tip of an expansion driver in accordance with a second embodiment, the tip configured to interface with an expandable implant; 
         FIG.  7    shows a front view of the expansion driver configured to interface with the expandable implant; 
         FIG.  8    shows a rear perspective view an expandable implant in accordance with a first embodiment; 
         FIG.  9    shows a rear view of the expandable implant; 
         FIG.  10    shows the tip of the expansion driver in accordance with the second embodiment, the tip removably secured to and adjusting the expandable implant; 
         FIG.  11    shows a side view of an expansion driver in accordance with a third embodiment; 
         FIG.  12    shows a schematic top view of a rotating carrier of the expansion driver in accordance with the third embodiment of  FIG.  11   ; 
         FIG.  13    shows top view of a splitter attachment for an expansion driver in accordance with a first embodiment; 
         FIG.  14    shows the splitter attachment integrated with an expansion driver; 
         FIG.  15    shows a cross-sectional view of the splitter attachment integrated with an expansion driver; 
         FIG.  16    shows an expandable implant and an expansion driver integrated with the splitter attachment and configured to adjust the expandable implant; 
         FIG.  17    shows the expandable implant being adjusted by the expansion driver integrated with the splitter attachment; and 
         FIG.  18    shows the expandable implant adjusted to an exemplary angle of lordosis, with the expansion driver having the splitter attachment removed from the expandable implant. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary sill in the art having the benefit of this disclosure. 
     Expandable implants may include: intervertebral cages, plates, distraction rods, and other adjustable medical device. Some expandable implants may include for example: an upper endplate, a lower endplate, and an actuator configured to change a dimension of the expandable implant. The change of dimension of the expandable implant may include, a change in height, a change in width, a change in length, and a change in an angle of lordosis. 
     In some embodiments, an expandable implant may be designed to be inserted into the intervertebral disc space between a patient&#39;s adjacent vertebral bodies using e.g. a lateral or posterior approach among others. Expandable implants are generally made of any suitable biocompatible material or combination of materials. For example, the implant components may include one or more of: metal, thermoplastics such as poly ether ether ketone (PEEK), and a combination of the metal and PEEK. The expandable implant may be configured to be inserted into the disc space in a first collapsed configuration, and upon being placed in a desired location within the disc space, the expandable implant may be adjusted in one or more of a height, width, length, and an angle of lordosis. For example: the anterior height of the implant may be greater than the posterior height of the implant, thereby restoring a more natural lordotic curvature of a particular segment of the lumbar spine. 
     Adjustment of expandable implants may be accomplished for example by engaging an actuator with an expansion driver to activate the actuator and cause a movement of the first endplate relative to the second endplate to change one or more of a height, a width, a length, and an angle of lordosis of the expandable implant. The actuator may include, for example, at least one actuator and at least one translating wedge configured to move along the length of the at least one actuator upon a rotation of the actuator, with the wedge configured to move one or more of the first endplate and the second endplate relative to each other, to thereby change one or more of a height and an angle of lordosis of the expandable implant. 
     In some embodiments, the actuator of the expandable implant may include two or more actuators. In some embodiments, a first actuator is axially accessible to an expansion driver through a hollow opening in a second actuator. In other embodiments, the first actuator is disposed in an anterior portion of the implant and the hollow second actuator is disposed in an anterior portion of the implant. In some embodiments the second actuator is annularly and rotatably disposed around the first actuator. And in some embodiments, as disclosed below, the first actuator and the second actuator may not be coaxial, rather for example parallel, and may be separated by a distance. All various placements known and used in the art are hereby contemplated and incorporated. 
     Adjustment of expandable spinal implants may require an expansion driver. The expansion driver described herein is capable of delivering one or more of simultaneous and equal amounts of torque to both a first actuator and a second actuator of an expandable implant that has two independent expansion mechanisms to allow for independent expansion of a first portion and a second portion of the implant. 
     According to an exemplary embodiment, the expansion driver has two or more coaxial driver shafts and a handle. The handle and the two or more coaxial driver shafts are operably coupled by a differential for an expansion driver. A differential for an expansion driver may include: at least one bevel gear, a first drive gear connected to a first output shaft, and a second drive gear connected to a second output shaft. The at least one bevel gear may be rotatably connected to a first drive source and configured to rotate around a first axis. The teeth of the at least one bevel gear may be simultaneously in communication with the teeth of the first drive gear and the second drive gear. Upon a rotation by the drive source of the at least one bevel gear, a torque may be transferred from the first drive source to the at least one bevel gear, and to one or more of the first drive gear and the second drive gear. If the first output shaft is experiencing a greater input resistance than the second output shaft, the torque of the at least one bevel gear will be transferred to the second drive gear of the second output shaft. If the second output shaft is experiencing a greater input resistance than the first output shaft, the torque of the at least one bevel gear will be transferred to the first drive gear of the first output shaft. If the input resistance is substantially equal on the first output shaft and the second output shaft, the torque of the at least one bevel gear will be transferred to both the first drive gear of the first output shaft and the second drive gear of the second output shaft. This can be explained in that the torque effectively chooses the gear of least resistance, and where all else is the same, drives both the first gear and the second gear. 
     As one with skill in the art may appreciate, a bevel gear may include a pinion and any type of known gear, and more gearing may be added to step up or step down the output torque of one or more of the first drive shaft and the second drive shaft. For example, one or more additional gears may be added between the first drive gear and the first output shaft to increase an amount of torque outputted at the first output shaft. Similarly, one or more additional gears may be added between the second drive gear and the second output shaft to increase an amount of torque outputted at the second output shaft. 
     Additionally, in some embodiments, the differential may include an epicyclic differential, a spur-gear differential, an active differential, a passive differential, and any differential known and used in the art. 
       FIGS.  1 - 5    show an expansion driver  100  including: a first driver  110  having a first gear  111  disposed at a first end thereof; a second driver  120 , at least a portion of the second driver  120  extending axially through the first driver  110 , and a second gear  121  disposed at a first end of the second driver  120 , the teeth of the second gear  121  facing in a direction opposing the teeth of the first gear  111 ; and a handle  130  operably connected to the first driver  110  and the second driver  120 , the handle  130  having a first bevel gear  132  and a second bevel gear  133  rotatably attached thereto, the first bevel gear  132  and the second bevel gear  133  each configured to communicate with the first gear  111  and the second gear  121 ; wherein upon a rotation of the handle  130  a torque is configured to be transferred to at least one of the first driver  110  and the second driver  120 . 
     In  FIG.  1    the expansion driver  100  is shown including a housing  150  configured to enclose at least a portion of the first driver  110  and at least a portion of the second driver  120 . In some embodiments, the housing  150  of the expansion driver  100  may be configured to removably secure an expandable implant to the distal end of the expansion driver  100  via, for example, tabs or other projections extending from the distal end of the housing and configured to engage an expandable implant  900  (see,  FIGS.  8 - 10   ). 
     The expansion driver  100  is configured to adjust an expandable implant  900  having a first actuator  930  disposed at a first end of the expandable implant  900  and a second actuator  940  disposed at a second end of the expandable implant  900 , with the first actuator  930  hollow and configured to receive at least a portion of the second driver  120  therethrough allowing the second driver  120  access to adjust the second actuator  940 . The first driver  110  is configured to communicate with the first actuator  930  and rotate the first actuator  930  upon a rotation of the first driver  110 . The second driver  120  is configured to communicate with the second actuator  940  and rotate the second actuator  940  upon a rotation of the second driver  120 . In both cases, rotation of either actuator is configured to cause movement of the first endplate  910  of the expandable implant  900  relative to second endplate  920  to change one or more of a height, a width, a length, and an angle of lordosis of the expandable implant  900 . 
     The expansion driver  100  is configured such that, upon activation of the drive source which includes the rotation of the handle  130 , a torque is transferred from the handle  130  to at least one of a first bevel gear  132  and a second bevel gear  133 , with the first bevel gear  132  and the second bevel gear  133  configured to rotate one or more of the first driver  110  and the second driver  120 , depending on an amount of resistance on the first actuator and the second actuator of the expandable implant  900 . 
     Expandable implants  900  placed between vertebral bodies of a patient experience numerous forces, particularly during adjustment. As one with skill in the art may appreciate, in an expandable implant  900  having an actuator including a first actuator  930  and a second actuator  940 , each actuator is going to experience a different amount of resistance upon adjustment which depends on the instantaneous load and state of the vertebral bodies relative to the expandable implant  900 . When driving the first actuator  930  and the second actuator  940  using a fixed expansion driver, for example, unequal resistance can result in uneven adjustment of the expandable implant  900 . In the instant embodiment however, the first bevel gear  132  and the second bevel gear  133  allow for selective driving by the expansion driver to ensure an equal amount of torque is delivered. 
     For example, when a first amount of resistance from the first actuator  930  on the first driver  110  is less than a second amount of resistance from the second actuator  940  on the second driver  120 , the first bevel gear  132  and the second bevel gear  133  are configured to rotate the first driver  110 . The first driver  110  will in tum rotate the first actuator  930  to thereby adjust the expandable implant  900 . The second driver  120  will not adjust the second actuator  940 , and thus the first actuator  930  will continue to be rotated adjusting the angle of lordosis of the expandable implant  900  until a substantially equal amount of resistance is observed by the first actuator  930  and the second actuator  940 . 
     When a first amount of resistance from the first actuator  930  on the first driver  110  is more than a second amount of resistance of the second actuator  940  on the second driver  120 , the first bevel gear  132  and the second bevel gear  133  are configured to rotate the second driver  120 . The second driver  120  will in turn rotate the second actuator  940  to thereby adjust the expandable implant  900 . The first driver  110  will not adjust the first actuator  930 , and thus the second actuator  940  will continue to be rotated, adjusting the angle of lordosis of the expandable implant  900  until a substantially equal amount of resistance is observed by the first actuator  930  and the second actuator  940 . 
     When a first amount of resistance from the first actuator  930  on the first driver  110  is substantially equal to a second amount of resistance of the second actuator  940  on the second driver  120 , the first bevel gear  132  and the second bevel gear  133  are configured to rotate both the first driver  110  and the second driver  120 . The first driver  110  will in turn rotate the first actuator  930 , the second driver  120  will in turn rotate the second actuator  940 , and both actuators will simultaneously adjust the expandable implant  900 . As one with skill in the art may appreciate, in the instant embodiment of an expandable implant  900  simultaneous adjustment of the first actuator  930  and the second actuator  940  will result in a change in height of the expandable implant  900 . 
     As shown in  FIG.  2   , the expansion driver  100  includes: the first driver  110  having a first gear  111  disposed at a first end thereof; a second driver  120 , at least a portion of the second driver  120  extending axially through a hollow cavity of the first driver  110 , and a second gear  121  disposed at a first end of the second driver  120 , the teeth of the second gear  121  opposing the teeth of the first gear  111 ; and a handle  130  operably connected to the first driver  110  and the second driver  120 , the handle  130  having a first bevel gear  132  and a second bevel gear  133  rotatably attached thereto, the teeth of the first bevel gear  132  and the teeth of the second bevel gear  133  configured to communicate with the first gear  132  of the first driver  110  and the second gear  133  of the second driver  120 ; wherein upon a rotation of the handle  130  a rotational torque is configured to be transferred to at least one of the first driver  110  and the second driver  120 . 
     The housing  150  of the expansion driver  100  is configured to enclose at least a portion of the first driver  110  and the second driver  120  within a cavity of the handle  130 . The expansion driver  100  also includes a threaded cap  131  configured to communicate with a threaded surface of the cavity of the handle  130  to secure the first end of the first driver  110 , the first end of the second driver  120 , the first gear  111 , the second gear  121 , the first bevel gear  132  and the second bevel gear  133  within an interior cavity  134  of the handle  130 . 
     The first bevel gear  132  and the second bevel gear  133  may be rotatably disposed within the interior cavity  134  of the handle  130 , and rotatably secured to a sidewall of the cavity  134  by for example a pin. At least a portion of the surface of the interior cavity  134  may be threaded. 
     In  FIG.  3   , the expansion driver  100  is shown in a partially exploded view with the housing  150  revealing an interface of the first driver  110  and the second driver  120  including the first bevel gear  132  and the second bevel gear  133  of the handle  130  which forms a differential for the expansion driver. The first driver  110  has a first end and a second end, with a first gear  111  disposed at the first end of the first driver  110  a second end opposite the first end that is configured to mate with a head of a first actuator  930  of an expandable implant  900 . The second driver  120  includes a first end and a second end, a second gear  121  disposed at the first end, the teeth of which are facing in the opposite direction of the teeth of the first gear  111  of the first driver  110 , with at least a portion of the second end of the second driver  120  extending axially through at least a portion of the first driver  110  and the second end of the second driver  120  configured to mate with a second actuator  940  of the expandable implant  900 . The handle  130  includes a threaded cavity  134  configured to receive at least a portion of the first driver  110  and the second driver  120 , the handle  130  having the first bevel gear  132  and the second bevel gear  133  rotatably attached thereto, the first bevel gear  132  and the second bevel gear  133  each configured to communicate with the first gear  111  and the second gear  121 ; wherein upon a rotation of the handle  130  a rotational torque is configured to be transferred from the handle  130  to the first bevel gear  132  and the second bevel gear  133 , with the first bevel gear  132  and the second bevel gear  133  rotatably secured to the handle  130  and configured to communicate with the first gear  111  and the second gear  121  to rotate at least one of the first driver  110  and the second driver  120 , and thereby configured to adjust an expandable implant  900 . 
       FIG.  4    shows an enhanced view of the differential of the expansion driver formed between the first gear  111  of the first driver  110 , the second gear  121  of the second driver  120 , the first bevel gear  132 , and the second bevel gear  133  which form a differential gear set for the expansion driver  100 . The teeth of the first gear  111  mirror the teeth of the second gear  121 , whereby both the first gear  111  and the second gear  121  can simultaneously communicate with each of the at least one bevel gears  132 ,  133 . 
     As one with skill in the art may appreciate, a rotation of the handle  130  drives the first bevel gear  132  and the second bevel gear  133  to rotate around the axis of the first driver  110  and the second driver  120 . The teeth of the first bevel gear  132  and the second bevel gear  133  communicate with the teeth of the first gear  111  and the teeth of the second gear  121 . Depending on a comparison of an amount of resistance experienced by each of the first driver  110  and the second driver  120  at the first and second actuators  930 , 940 , respectively, of the expandable implant  900 , the first bevel gear  132  and the second bevel gear  133  will rotate whichever of the first driver  110  and the second driver  120  is experiencing the least amount of resistance. In the condition in which the amount of resistance is substantially equal, the first bevel gear  132  and the second bevel gear  133  will drive both the first driver and the second driver equally. 
     In the illustrated embodiment exemplary embodiment, two bevel gears are shown. However as one with skill in the art may appreciate, depending on the needs of a designer, a differential for expansion drivers may be formed by one, two, three, or any number of bevel gear gears. The bevel gear gears may be directly in contact with one or more of the first gear and second gear associated with the output drivers. Other known gearing configurations of known differentials are contemplated herein for use with expansion drivers and the use of which is intended to be incorporated within this disclosure. 
       FIG.  5    shows an exploded view of the expansion driver  100  in accordance with the first embodiment, and illustrates an exemplary method of assembly thereof. The first driver  120  is hollow and has a cannula configured to receive at least a portion of the second driver  110 , therethrough. The first bevel gear  132  and the second bevel gear  133  are configured to communicate with the first gear  111  of the first driver  110  and the second gear  121  of the second driver  120 , while being rotatable disposed within the cavity of the handle  130 . 
     Some or all of the components may be fabricated using known machining and additive manufacturing techniques. The drivers may be fabricated from known biocompatible materials including: aluminum, steel, and titanium. Additionally, the handle may be fabricated from materials including: a polymeric material, carbon fiber, and metals. 
       FIG.  6    shows a side view of a tip of an expansion driver  200  in accordance with an exemplary embodiment. The expansion driver  200  may include some or all of the features from the first embodiment, and is also shown including a first driver  210  and a second driver  220 . The first driver  210  is configured to interface with a first actuator  930  of an expandable implant  900 , and is configured to rotate independently around the second driver  220 . The second driver  220  is configured to interface with a second actuator  940  of the expandable implant  900 , and is configured to rotate independently within the first driver  210 . The second ends of the first driver  210  and the second driver  220  may be profiled or keyed to communicate with a complementary contact surface of one or more of: the first actuator  930  and the second actuator  940  of the expandable implant  900 . 
     The housing  250  of the expansion driver  200  is shown including locking tabs  251  configured to removably secure an expandable implant  900  to the expansion driver  200 . In some embodiments, the expandable implant  900  is removably secured to the expansion driver  200  prior to placement in the intervertebral space of the patient, with the expansion driver  200  configured to insert, place, and adjust a dimension of the expandable implant  900  within the intervertebral space of the patient. 
       FIG.  7    shows a front view of the expansion driver  200 , looking down the axis of the first driver  210  and the second driver  120 . With the first driver  210  annularly disposed around the second driver  220 . The first driver  210  is configured to rotate independently of the second driver  220  to drive the first actuator  930  of the expandable implant  900 . The second driver  220  is configured to rotate independently of the first driver  210 , and configured to adjust the second actuator  940  of the expandable implant  900 . The housing  250  is shown including the two locking tabs  251  configured to removably secure the expandable implant  900  to the expansion driver  200 . 
       FIG.  8    shows a rear perspective view of an embodiment of an expandable implant  900 . The expandable implant  900  includes a first endplate  910 , a second endplate  920 , a first translating member  931  configured to translate along the length of a first actuator  930 , and a second translating  941  member configured to translate along the length of a second actuator  940 , wherein translation of one or more of the first translating member  931  and the second translating member  941  is configured to change at least one of a height and an angle of lordosis of the expandable implant  900 . 
       FIG.  9    shows a rear view of the expandable implant  900 . The first actuator  930  and second actuator  940  are each configured to interface with each of the first driver  220  and second driver  210  of the expansion driver  200  respectively. The first actuator  930  is hollow and configured to receive at least a portion of the second driver  220  there through. The first actuator  930  is configured to communicate with the first driver  210 , and the second actuator  940  is configured to receive and communicate with the second driver  220  to adjust the expandable implant  900 . 
       FIG.  10    shows the expandable implant  900  secured to the expansion driver  200 , with the expandable implant  900  shown being adjusted to an exemplary angle of lordosis. The expandable implant  900  is removably secured to the expansion driver  200  by locking tabs  251 . The expandable implant  900  is shown in  FIG.  10    in a second adjusted configuration being adjusted to some exemplary angle of lordosis. 
     According to one exemplary method of adjusting an expandable implant  900 , the steps may include: preparing an intervertebral disc space of a patient; placing an expandable implant  900  within the prepared intervertebral disk space of the patient; adjusting the expandable implant  900  using an expansion driver  100  having: a first driver  110 , a second driver  120 , and at least one bevel gear  132 ,  133 , wherein the at least one bevel gear  132 ,  133  is configured to rotate at least one of the first driver or the second driver to adjust the expandable implant  900 . 
     To prepare the intervertebral disc space of the patient, the surgeon may first gain access to the intervertebral disc space via one or more of for example: an anterior, a lateral, and a posterior approach. The intervertebral disc may be partially or totally removed from the disc space. The contact surfaces of the adjacent vertebral bodies may be prepared to help promote fusion. 
     The expandable implant  900  may be provided to the disc space by an insertion device, for example: an inserter or the expansion driver  100 . First the expandable implant  900  would be removably secured to the expansion device  100 . Next the expandable implant  900  would be placed within the prepared intervertebral disc space using, for example, an anterior, posterior, transforaminal or lateral approach. If an inserter was used, the inserter would be removed and an expansion driver  100  would then be secured to the implant and used to adjust the expandable implant  900 . Finally, the expandable implant  900  is adjusted to achieve the desired size to restore the intervertebral disc space. 
     As described above, the expandable implant  900  may be designed to be adjusted in one or more of a height, a length, a width and an angle of lordosis of the expandable implant. The expandable implant  900  may be dimensioned according to the size of the patient. The handle  130  of the expansion driver  100  would be rotated, to adjust the expandable implant  900  to the desired height, length, width, and angle of lordosis. Once the surgeon was satisfied with the amount of adjustment the expansion driver  100  can be removed from the expandable implant  900 , and subsequently the patient, whilst leaving the expandable implant  900  adjusted within the intervertebral space of the patient. 
     It may be desirable for the surgeon to pack one or more of the expandable implant and the intervertebral disc space using a bone graft or bone graft substitute material to promote fusion. Fixation plates may be applied to one or more of the vertebral bodies and the expandable implant to secure the expandable implant within the intervertebral disc space. And finally, all placement and expansion instrumentation may be removed and the access hole closed, to allow for the fusion and healing processes to begin. 
     It has been shown above that the incorporation of a differential gear set is useful to achieve even adjustment of an expandable implant having coaxial actuators. But if the expandable implant includes two separate actuators spaced apart at some distance, a splitter attachment  500  for the expansion driver  100  may be utilized. 
       FIG.  11    shows a schematic of an expansion driver  300  in accordance with a third embodiment, the expansion driver  300  shown including: a first driver  310  having a first end and a second end, with a first gear  311  disposed at the first end and the second end configured to mate with a first actuator  930  of an expandable implant  900 ; a second driver  320  having a first end and a second end, a second gear  321  disposed at the first end and configured to oppose the first gear  311  of the first driver  310 , at least a portion of the second end of the second driver  320  extending axially through at least a portion of the first driver  310  and configured to mate with a second actuator  940  of the expandable implant  900 ; and a handle operably  330  connected to the first driver  310  and the second driver  320 , the handle having a rotating carrier  340  attached thereto, the rotating carrier  340  which communicates with the first gear  311  and the second gear  321 ; wherein upon a rotation of the handle  330  a torque is transferred from the handle  330  to the rotating carrier  340 , with the rotating carrier  340  having one or more pinion  341  which communicates and rotates at least one of the first driver  310  and the second driver  320 . 
     The differential gear set of the third embodiment includes a rotating carrier  340 . The rotating carrier  340  has at least one pinion  341 . In this embodiment there are four individual pinions  341  each configured to communicate with the first gear  311  and the second gear  321 . Upon a rotation of the rotating carrier  340  as indicated in  FIG.  12   , the four pinions  341  will rotate at least one of the first gear  311  and the second gear  321 , depending on which is experiencing less input resistance, as discussed above. 
       FIG.  13    shows a splitter attachment  500  for the expansion driver  100 , the splitter attachment  500  is configured to receive at least a portion of the expansion driver  100  in an input  540  thereof. The splitter attachment  500  includes a first output shaft  510  configured to rotate a first actuator  1030  of an expandable implant  1000  in accordance with a second embodiment, and a second output shaft  520  configured to rotate a second actuator  1040  of the expandable implant  1000 . 
       FIG.  14    shows the expansion driver  100  in communication with the splitter attachment  500 . The splitter attachment  500  configured to separate the torque of the first driver  110  and second driver  120  of the expansion driver  100  from a coaxial rotation into two parallel splitter output shafts  510 ,  520  separated by a distance. The splitter attachment  500  enables the expansion driver  100 , to deliver an equal amount of torque and adjustment to an expandable implant  1000  having two non-coaxial actuators separated by a distance. 
       FIG.  15    shows a cross-sectional view of the expansion driver  100  in communication with the splitter attachment  500 . The splitter attachment  500  includes a first coupler gear  511  configured to operably mate with the first driver  110  and rotatably disposed within a housing  530  of the splitter attachment  500 . The splitter attachment  500  also includes a first transfer gear  512  configured to rotate and transfer torque from the first coupler gear  511  to a first splitter output shaft  510 . As one with skill in the art may appreciate additional gears and shafts may be provided in accordance with known methods of stepping up the output torque, stepping down the output torque, and changing the distance separating the first splitter output shaft  510  and the second splitter output shaft  520 . 
     The splitter attachment  500  includes a second coupler gear  521  configured to operably mate with the second driver  120  and rotatably disposed within the housing  530  of the splitter attachment  500 . The splitter attachment  500  also includes a second transfer gear  522  configured to rotate and transfer torque from the second coupler gear  521  to a second splitter output shaft  520 . The first output shaft  510  and second output shaft  520  shown separated by a distance and configured to adjust an expandable implant  1000  having two actuators  1030 , 1040  separated by a distance. As one with skill in the art may appreciate additional gears and shafts may be provided in accordance with known methods of stepping up the output torque, stepping down the output torque, and changing the distance separating the first splitter output shaft  510  and the second splitter output shaft  520 . 
       FIG.  16    shows an expandable implant  1000  having a first endplate  1010 , a second endplate  1020 , a first actuator  1030  and a second actuator  1040 , with the first actuator  1030  and the second actuator  1040  configured to change at least one of a height and an angle of lordosis between the first endplate  1010  relative to the second endplate  1020 . An expansion driver  100  is shown including a splitter attachment  500 , the splitter attachment  500  having a first splitter output shaft  510  configured to rotate the first actuator  1030  and a second splitter output shaft  520  configured to rotate the second actuator  1040 . 
     Similar to the operation of expansion driver  100  described above, when a first amount of resistance from the first actuator  1030  on the first splitter output shaft  510  is less than a second amount of resistance from the second actuator  1040  on the second splitter output shaft  520 , the first bevel gear  132  and the second bevel gear  133  of the expansion driver  100  are configured to rotate the first driver  110  of the expansion driver  100 . The first driver  110  will in tum rotate all the internal gearing of the splitter attachment  500  operably connected between the first driver  110  and first splitter output shaft  510 , and the first splitter output shaft  510  will rotate the first actuator  1030  to thereby adjust the expandable implant  1000 . The second splitter output shaft  520  will not adjust the second actuator  1040  of the expandable implant  1000 , and thus the first actuator  930  will continue to be rotated adjusting the angle of lordosis of the expandable implant  1000  until an equal amount of resistance is observed by the first actuator  1030  and the second actuator  1040 . 
       FIG.  17    shows the expansion driver  100  having a splitter attachment  500 , operably engaged with the expandable implant  1000  to adjust the expandable implant  1000 . For expansion drivers similar to the embodiments described above, a rotation of a handle  130  will in tum rotate one or more of a first driver  110  and a second driver  120  of the expansion driver  100  depending on an amount of resistance thereon. Also as described above, when a splitter attachment  500  is integrated with an expansion driver  100 , a rotation of the first driver  110  will rotate a first splitter output shaft  510  and a rotation of the second driver  120  will rotate a second splitter output shaft  520 . 
     When a first amount of resistance from the first actuator  1030  on the first splitter output shaft  510  is more than a second amount of resistance of the second actuator  1040  on the second splitter output shaft  520 , the first bevel gear  132  and the second bevel gear  133  of the expansion driver  100  are configured to rotate the second driver  120  of the expansion driver  100 . The second driver  120  will in turn rotate all the internal gearing of the splitter attachment  500  operably connected between the second driver  120  and second splitter output shaft  520 , and the second splitter output shaft  520  will rotate the second actuator  1040  to thereby adjust the expandable implant  1000 . The first splitter output shaft  510  will not adjust the first actuator  1030 , and thus the second actuator  1040  will continue to be rotated adjusting the angle of lordosis of the expandable implant  1000  until an equal amount of resistance is observed by the first actuator  1030  and the second actuator  1040 . 
     When a first amount of resistance from the first actuator  1030  on the first splitter output shaft  510  is substantially equal to a second amount of resistance of the second actuator  1040  on the second splitter output shaft  520 , the first bevel gear  132  and the second bevel gear  133  of the expansion driver  100  are configured to rotate both the first driver  110  and the second driver  120 , which in turn rotate the first actuator  1030  and the second actuators  1040  of the expandable implant  1000 . 
       FIG.  18    shows the expandable implant  1000  adjusted to an exemplary angle of lordosis by the expansion driver  100  having the splitter attachment  500 . In the transition from the collapsed configuration of the expandable implant  1000  as seen in  FIG.  16   , to the expanded configuration of  FIG.  18   , it is implied that the amount of resistance experienced on the first end of the expandable implant  1000  was lower than the amount of resistance experienced on the second side of the expandable implant  1000 . This would be similar to forces experienced within an intervertebral disc space of a patient, where a natural lordosis angle could be restored and the expandable implant  1000  subsequently evenly expanded to a desired height. 
     Exemplary embodiments herein have been directed to expandable implants configured for adjustment in height and angle of lordosis. It is contemplated that devices within the scope of this disclosure could be used to adjust expandable implants which are adjustable in height, length, width, angle of lordosis, and any change of dimension. The chosen embodiments should not be construed as limiting and this disclosure is intended to encompass the due bounds as presented in the claims.