INSERTER FOR EXPANDING AN EXPANDABLE INTERBODY FUSION DEVICE
An elongate inserter has a distal end releasably connected to an expandable interbody fusion device and a proximal end including a trigger actuator. The interbody fusion device comprises a superior endplate and an inferior endplate that are movable in an expansion direction relative to each other in the intradiscal space. The inserter includes a lifting platform and an elevator that define cooperatively engaging ramps and ramps surfaces that upon operation of the trigger actuator cause the superior and inferior endplates to move relatively away from each other. A driver is supported by the inserter for pushing an insert into the expanded device between the superior and inferior endplates.
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The subject invention relates generally to the field of spinal implants and more particularly to an inserter for expanding an expandable interbody fusion device and inserting an insert therewithin.
BACKGROUND OF THE INVENTIONSpinal implants such as interbody fusion devices are used to treat degenerative disc disease and other damages or defects in the spinal disc between adjacent vertebrae. The disc may be herniated or suffering from a variety of degenerative conditions, such that the anatomical function of the spinal disc is disrupted. Most prevalent surgical treatment for these conditions is to fuse the two vertebrae surrounding the affected disc. In most cases, the entire disc will be removed, except for a portion of the annulus, by way of a discectomy procedure. A spinal fusion device is then introduced into the intradiscal space and suitable bone graft or bone substitute material is placed substantially in and/or adjacent the device in order to promote fusion between two adjacent vertebrae.
Certain spinal devices for achieving fusion are also expandable so as to correct disc height between the adjacent vertebrae. Examples of expandable interbody fusion devices are described in U.S. Pat. No. 6,595,998 entitled “Tissue Distraction Device”, which issued on Jul. 22, 2003 (the '998 patent), U.S. Pat. No. 7,931,688 entitled “Expandable Interbody Fusion Device”, which issued on Apr. 26, 2011 (the '688 patent), and U.S. Pat. No. 7,967,867 entitled “Expandable Interbody Fusion Device”, which issued on Jun. 28, 2011 (the '867 patent). The '998 patent, the '688 patent and the '867 patent each discloses sequentially introducing in situ a series of elongate inserts referred to as wafers in a percutaneous approach to incrementally distract opposing vertebral bodies to stabilize the spine and correct spinal height, the wafers including features that allow adjacent wafers to interlock in multiple degrees of freedom. The '998 patent, the '688 patent and the '867 patent are assigned to the same assignee as the present invention, the disclosures of these patents being incorporated herein by reference in their entirety.
One issue that has arisen regarding such interbody fusion devices that use inserts or wafers to incrementally expand such devices is the determination of when full expansion has been achieved as a result of ligamentotaxis and no further inserts may be inserted. It is therefore desirable for a surgeon to know when a sufficient number of inserts has been introduced to stabilize the spine and correct spinal height and whether any additional inserts may be introduced.
Accordingly, there is a need for a method and instrument to expand an expandable interbody fusion device and introduce inserts therein and to determine when proper expansion of the device has been achieved and no further inserts may be introduced.
SUMMARY OF THE INVENTIONIt is an object of the invention to provide an inserter for expanding an expandable spinal implant, such as an interbody fusion device and to introduce inserts therein after the implant has been expanded. It is a further object of the invention to also provide a method whereby full expansion of the expandable device may be determined in a manner such that a user may ascertain that no additional inserts may be inserted.
For the purposes of promoting and understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one skilled in the art to which this invention pertains.
Turning now to
The superior endplate 112 is elongate and comprises a hub 116 that is sized and configured to fit within a cavity 118 of the inferior endplate 114 for telescoping movement therewithin upon expansion. The lower surface 120 of the hub 116 includes a shaped configuration defined by insert mating features 122 (see
Details of the interlocking insert 200 are shown in
The insert 200 includes several features for interlocking engagement to the hub 116 and to adjacent inserts 100 in a complementary interlocking mating interface. One particular feature includes a series of locking elements defined by resiliently deflectable prongs 220 that project outwardly above the upper surface 202 of the insert 200 in the direction of expansion of device 100. A complementary series of locking surfaces 222 are defined in the lower surface 204 of the insert 200 for resilient engagement with the prongs 220 as wafers are inserted into device 100 to form a stack. The lower surface 204 of each insert 200 as shown in
Turning again now to
The distal end 12a is shown in exploded detail in
The distal end 12a of barrel 12 supports a lifting platform 24 and an elevator 26. The lifting platform 24 is coupled at its proximal end 24a by a boss 24b or other suitable projection to a lifting platform link 28. The boss 24b is suitably received and retained in opening 28a at the distal end of link 28. The lifting platform 24 is axially translatable relative to elevator 26 upon axial translational movement of link 28 which is coupled to an actuator, such as trigger actuator 14 at its proximal end, as will be described. Link 28 is supported by track 16 for translational movement within a track channel 16a extending axially along track 16. Inserts 200 or movably supported in a linear array on link 28 within the channel 16a. It should be appreciated that actuators other than trigger actuators may be used with the inserter 10 described herein.
Elevator 26 comprises a proximal end 26a and a distal projecting end 26b. The proximal end 26a is suitably affixed to the track 16 and, in the particular arrangement being described, remains in a fixed position relative to lifting platform 24 and inferior endplate 114 as lifting platform is translationally moved. The proximal end 26a defines a channel 26c for receipt of the proximal end 24a of lifting platform 24. The lifting platform 24 and elevator 26 may in one arrangement be a disposable component and replaced by a new unused lifting platform 24 and elevator 26 for subsequent procedures.
The distal projecting end 26b of elevator 26 includes a lower substantially flat surface 26c and an upper surface 26d, generally parallel to lower surface 26c. Projecting end 26b is configured to extend within inferior endplate 114 with lower surface 26c supported by an interior surface 114a (see
Lifting platform link 28 includes thereon an upper surface 28a on which the inserts 200 are movably supported in a linear array. Link 28 includes a spring element 28b having an inclined surface for engaging an insert 200 and moving such insert upwardly into an insertion position from track 16 during axial transit along link 28. A pair of cantilevered spring projections 28d and 28e may be spaced axially along link 20 in a manner to substantially prevent retrograde movement of inserts 200 along link 28.
Barrel 12 further supports a driver 30 for axial translational movement within the barrel 12. The proximal end of driver 30 is coupled to trigger actuator 14 to effect translational movement of the driver, as will be described. The distal end of driver 30 comprises a pushing surface 30a sized and configured to enter into the opening 216 of an insert 200 to engage pushing surface 218 and push the insert 200 into the device 100 upon axial distal movement of driver 30.
Turning now to
Turning now to
Upon operation of trigger actuator 14, lifting platform link 28 is translated proximally causing ramps 24e to engage and ride upwardly along ramp surfaces 26e of elevator 26 thereby causing during such translational movement the lifting platform 24 to move upwardly and away from elevator 26. Such movement lifts insert 200 together with interlocked superior endplate 112 in the direction of expansion an incremental distance slightly greater than the thickness of insert 200a. With the bar linkage mechanism 31 of trigger actuator 14 configured to temporarily hold this position for a certain period of time, continued operation of trigger actuator 14 moves pusher 30 distally until the pushing surface 30a of driver 30 causes the front end 208a of subsequent insert 200a to enter device 100 between lower surface 204 of a previously inserted insert 200 and inferior ledge 114b of the inferior endplate 114, as shown in
It should be appreciated that upon when operation of trigger actuator 14 lifting platform 24 is incapable of physically reaching the desired elevation (which is approximately slightly greater than the thickness of an insert 200 and determined by the bar linkage mechanism 31), further operation of the trigger actuator 14 during any given stroke will be substantially prevented. Such resistance will provide tactile feedback to the surgeon who will recognize that the device 100 has been expanded to its maximum anatomic extent as the spine has reached ligamentotaxis. The surgeon would then terminate the insert insertion procedure releasing handle 36, and then removing the inserter 10 from the expanded device 100 by rotatably removing knob 22 from the proximal end of guide pin 20. As shown in
Having described the inserter 10 and the method of expanding an interbody fusion device 100 and inserting thereinto one or more inserts 200 with reference to device 100 wherein a first insert 200 has been positioned between superior endplate 112 and inferior endplate 114, it should be appreciated that the inserter 10 and method may also be used to introduce insert 200 initially between superior endplate 112 and inferior endplate 114.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected. For instance, while the lifting platform 24 has been described herein as being movable axially relative to a fixed elevator 26, it should be appreciated that lifting platform 24 may be held in a fixed axial position while the elevator 26 is moved axially relative thereto. Also, while the illustrated embodiments have been directed particularly to interbody fusion of the spine, the expandable devices and inserts disclosed herein may be used in other applications that require distraction of tissue surfaces, such as, for example, vertebral compression fracture treatments. Modifications in size may be necessary depending upon the body space being distracted.
Claims
1. An inserter for expanding an expandable spinal interbody fusion device and inserting an insert therewithin, said device including a superior endplate having an outer surface configured to contact a first vertebral body of a spine and an inferior endplate movable relative to said superior endplate in an expansion direction, said inferior endplate having an outer surface configured to contact a second opposing vertebral body of said spine, comprising:
- an elongate barrel having a distal end and a proximal end, said distal end being releasably attachable to said device and comprising a trigger actuator at said proximal end,
- said barrel including at said distal end a lifting platform for engaging said superior endplate and an elevator for engaging said inferior endplate, said lifting platform being movable translationally relative to said elevator in a direction transverse to the direction of expansion of said device to cause during such translational movement said lifting platform to move away from said elevator in the direction of expansion and thereby lift said lifting platform relative to said inferior endplate and expand said device, one of said lifting platform and said elevator being operably coupled to said trigger actuator to cause said translational movement upon operation of said trigger actuator, and
- said barrel movably supporting at least one insert insertable upon operation of said trigger actuator into said device between said superior endplate and said inferior endplate after expansion of said device, said barrel supporting a driver coupled to said trigger actuator for translational movement relative to one of said lifting platform and said elevator, said driver having a distal end defining a pushing surface for engagement with a cooperative pushing surface on said insert.
2. The inserter of claim 1, wherein said lifting platform and said elevator comprise cooperating ramps that upon relative translation of said lifting platform and said elevator cause said ramps to cooperatively engage and move said lifting platform and said elevator relatively away from each other in the direction of expansion.
3. The inserter of claim 2, wherein said lifting platform is coupled to said trigger actuator for translational movement and said elevator is attached to said barrel in a fixed position.
4. The inserter of claim 3, wherein said driver is coupled to said trigger actuator for translational movement relative to said elevator.
5. The inserter of claim 4, wherein said lifting platform includes an upper surface for supporting said insert and a lower opposing surface defining said cooperating ramps.
6. The inserter of claim 5, wherein said driver and said lifting platform are coupled to said trigger actuator to move independently upon operation of said trigger actuator.
7. The inserter of claim 6, wherein said driver and said lifting platform are coupled to said trigger actuator to move independently of each other upon operation of a single stroke of said trigger actuator.
8. The inserter of claim 7, wherein said lifting platform is coupled to said trigger actuator to move before movement of said driver and cause said superior endplate to lift relative to said inferior endplate.
9. The inserter of claim 8, wherein said lifting platform is coupled to said trigger actuator to hold the position of said superior endplate in a lifted position relative to said inferior endplate during operation of said trigger actuator while said driver is moved during such operation to push said insert at least partially between said superior endplate and said inferior endplate.
10. The inserter of claim 9, wherein said lifting platform is coupled to said trigger actuator to retract said lifting platform towards said elevator after said insert is positioned at least partially between said superior endplate and said inferior endplate, said driver being coupled to said trigger actuator to advance said insert thereafter substantially fully between said superior endplate and said inferior endplate.
11. The inserter of claim 10, wherein said lifting movement of said lifting platform relative to said elevator, said translational movement of said driver insert for pushing said insert into said device and said retraction movement of said lifting platform towards said elevator are effected in a single operational stroke of said trigger actuator.
12. The inserter of claim 11, wherein said trigger actuator comprises a linkage mechanism that substantially prevents translational movement of said driver until the lifting movement of said lifting platform is completed.
13. The inserter of claim 12, wherein said barrel movably supports a further insert insertable upon operation of said trigger actuator between said at least first insert and said inferior endplate.
14. An apparatus for use in spinal interbody fusion, comprising:
- an expandable interbody fusion device including an inferior endplate having an outer surface configured to contact a vertebral body of the spine, a superior endplate having an outer surface configured to contact an opposing vertebral body of said spine, said inferior endplate and said superior endplate being movable relative to each other in a direction of expansion, said device including at least one insert insertable into said device between said inferior endplate and said superior endplate upon expansion of said device; and
- an elongate inserter having a distal end and a proximal end, said distal end of said inserter being releasably attached to said device, said inserter including an actuator at said proximal end, said inserter comprising a lifting platform operably coupled to said actuator for engaging and lifting one of said superior endplate and an insert within said device, and a driver operably coupled to said actuator to insert said at least one insert into said device, said inserter including an elongate track linearly supporting a plurality of inserts for sequential insertion into said device one below the other.
15. The apparatus of claim 14, wherein said inserter comprises an elevator at said distal end, said elevator having an upper surface and a lower surface, said lower surface being in engagement with an interior surface of said inferior endplate.
16. The apparatus of claim 15, wherein said lifting platform has a lower surface, the lower surface of said lifting platform and the upper surface of said elevator comprising cooperatively engaging ramps.
17. The apparatus of claim 16, wherein said elevator is disposed in a fixed position relative to said inferior endplate and said lifting platform is coupled to said actuator for translational movement relative to said elevator upon operation of said actuator to cause said ramps to cooperatively engage and thereby move said lifting platform and said elevator relatively away from each other in the direction of expansion.
18. The apparatus of claim 14, wherein said actuator comprises a trigger actuator including a handle and a bar linkage mechanism pivotally coupled thereto.
19. The apparatus of claim 14, wherein said apparatus further comprises a guide pin releasably connected to said device and detachably connected to said inserter.
20. The apparatus of claim 14, wherein said at least one insert comprises a locking structure to interlock said at least one insert to said superior endplate upon insertion into said device.
21. The apparatus of claim 20, wherein said at least one insert comprises a locking structure to interlock said at least one insert to a subsequent insert inserted below said at least one insert.
22-25. (canceled)
26. A method of expanding an expandable spinal interbody fusion implant, in situ, said device including an inferior endplate having an outer surface configured to contact a vertebral body of the spine, a superior endplate having an outer surface configured to contact an opposing vertebral body of said spine, said inferior endplate and said superior endplate being movable relative to each other in a direction of expansion, comprising the steps of:
- releasably attaching a distal end of an inserter to said device, said inserter including an actuator at a proximal end thereof;
- initially operating said actuator to cause said inferior endplate and said superior endplate to move relative to each other in a direction of expansion to expand said device; and
- inserting a first insert movably supported by said inserter into said device after expansion of said device between said inferior endplate and said superior endplate; and then
- further operating said actuator to cause said superior endplate and said first insert to move jointly relative to said inferior endplate to further expand said device, and after said further expansion sequentially inserting a second insert movably supported by said inserter directly between said first insert and said inferior endplate.
27. The method of claim 26, wherein said first insert and said second inserts are supported linearly by said inserter immediately adjacent each other, and wherein after said device is expanded in the initial operating step said first insert is inserted directly between said superior endplate and said inferior endplate.
28. The method of claim 27, further including the step of determining whether said expanded device is capable of receiving a further insert prior to insertion of said further insert between said inferior endplate and said superior endplate.
29. The method of claim 28, wherein said determining step is effected by tactile feedback through said actuator.
30. The method of claim 29, wherein said actuator comprises a trigger actuator including a handle and a linkage mechanism, and wherein the expansion of said device and the insertion of said at least one insert into said expanded device is effected in a single operational stroke of said trigger actuator.
31. A method of expanding an expandable spinal interbody fusion implant, in situ, said device including an inferior endplate having an outer surface configured to contact a vertebral body of the spine, a superior endplate having an outer surface configured to contact an opposing vertebral body of said spine, said inferior endplate and said superior endplate being movable relative to each other in a direction of expansion, comprising the steps of:
- releasably attaching a distal end of an inserter to said device, said inserter including an actuator at a proximal end thereof and an elongate track therebetween supporting a plurality of inserts, each insert having a thickness in the direction of expansion;
- operating said actuator for the individual insertion of said plurality of inserts, during said operation causing the inferior endplate and the superior endplate to move apart relative to each other in the direction of expansion independently of the insertion of each insert and creating for each insert an incremental space in the expanded device of dimension not less than the thickness of an insert; and
- sequentially individually inserting said plurality of inserts into a respectively created incremental space.
32. The method of claim 31, wherein a first incremental space is created directly between said inferior endplate and said superior endplate for the insertion of a first insert.
33. The method of claim 32, wherein a second incremental space is created directly between said inferior endplate and said first insert for the insertion of a second insert, said first insert and said superior endplate having been moved jointly relative to said inferior endplate upon the operation of said actuator.
34. The method of claim 33, further including the step of determining whether said expanded device is capable of receiving a third insert prior to insertion of said third insert between said inferior endplate and said second insert as determined by tactile feedback through said actuator.
Type: Application
Filed: Mar 13, 2013
Publication Date: Sep 18, 2014
Applicant: SPINE WAVE, INC. (Shelton, CT)
Inventors: Spanky Allen Raymond (Uniontown, OH), Scott McLean (Waterbury, CT), Nicola Cullinan (Bethel, CT)
Application Number: 13/799,792
International Classification: A61F 2/46 (20060101);