Patent Application
20090248163
Embodiments of the disclosure relate generally to implants for spinal surgery and more particularly to artificial interbody spinal fusion implants for insertion within implantation spaces formed across the height of disc spaces between vertebral bodies of human spines. Embodiments of the disclosure relate to interbody spinal implants that may be inserted into a patient during surgical procedures including minimally invasive surgical procedures.
Bone may be subject to degeneration caused by trauma, disease, and/or aging. Degeneration may destabilize the affected bone and affect surrounding structures. For example, destabilization of a spine may result in an alteration of the natural spacing between adjacent vertebral bodies. Alteration of the natural spacing between adjacent vertebral bodies may subject the nerves that pass between the vertebral bodies to pressure. Pressure applied to the nerves may cause pain and/or nerve damage. Maintaining the natural spacing between vertebral bodies may reduce the pressure applied to these nerves. A spinal interbody implant may be used to maintain or restore the natural spacing between vertebral bodies.
Spinal implants may be inserted during a vertebral bodies replacement or interbody fusion procedure using a posterior approach as in Posterior Lumbar Interbody Fusion (PLIF) or Transforaminal Lumbar Interbody Fusion (TLIF). Spinal implants may be inserted during a spinal stabilization procedure using an anterior spinal approach as in Anterior Lumbar Interbody Fusion (ALIF). With these and other procedures, spinal implants may also be inserted into implantation spaces between the C2 and S1 vertebral bodies.
Conventional procedures for inserting spinal implants require distracting the adjacent vertebral bodies with a distractor or series of distractors then inserting the spinal implant in the distracted space. These procedures require a number of complex surgical steps and tools that can make the procedures time consuming and complicated.
Embodiments of the present disclosure provide spinal interbody implants that eliminate, or at least substantially reduce, the shortcomings of prior art spinal implants.
One embodiment provides an interbody implant indicated for vertebral body replacement or interbody fusion. The implant may be inserted through an open, or minimally invasive, posterior, anterior, or transforaminal approach into the implantation space to maintain or restore the height of a disc space after a discectomy or other procedure. Fusion of the vertebral bodies may take place over the course of 6-12 months during which it may be desired to maintain an appropriate space between the vertebral bodies. In some embodiments, the implants come in a variety of sizes which may be selected from to match patient anatomy.
One embodiment provides an artificial interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between vertebral bodies of a human spine. The implant can comprise a posterior portion, an anterior portion opposite from the posterior portion and a pair of medial-lateral sidewalls between the posterior portion and the anterior portion. The posterior portion, anterior portion, and side walls can define an implant body having a cephalad surface, a caudal surface, and a fusion promotion cavity extending between the cephalad surface and the caudal surface. According to various embodiments, one or both of the cephalad and caudal surfaces can be convex. At least one of the sidewalls defines a hole from the exterior of the implant to the fusion promotion cavity. The hole can be centered about a primary axis of impact and can be tapered toward the posterior portion of the implant along the axis of impact. For example, the side wall hole can be tear drop shaped or have another tapered shape that is thinner towards the posterior portion of the implant.
Various embodiments of implants can include features to facilitate surgical procedures. For example, according to one embodiment, the anterior portion of the implant can be tapered in the saggital and transverse planes. As another example, one or more of the caudal or cephalad surfaces can include teeth that project along the caudal and cephalad surfaces beyond the fusion promotion cavity. According to further embodiments, the posterior portion of the implant can define a threaded instrument engagement hole for engagement with an instrument for inserting the implant. The posterior portion can further include an engagement notch adjoining the instrument engagement hole. Embodiments of implants can also include fluoroscopy markers. According to various embodiments, a first and second elongated fluoroscopy marker can be located toward the posterior portion of the implant, while a third fluoroscopy marker can be located toward the anterior portion of the implant. According to an embodiment, the third fluoroscopy marker has approximately the same cross sectional area as the first fluoroscopy marker in a first viewing plane and has a different cross sectional area than the first fluoroscopy marker in a second viewing plane orthogonal to the first viewing plane.
Other embodiments can include a surgical kit for surgery on human spines having vertebral bodies and disc spaces having heights between some of the vertebral bodies, the vertebral bodies having an anterior aspect and a posterior aspect and a depth therebetween. According to one embodiment, a surgical kit can comprise a set of different sized artificial interbody spinal fusion implants for insertion within implantation spaces formed across the heights of the disc spaces. Each implant can further comprise a posterior portion of the implant shaped to interface with an insertion tool, an anterior portion of the implant opposite the posterior portion of the implant and a pair of medial-lateral side walls of the implant between the posterior and anterior portions of the implant. The posterior portion, anterior portion, and medial lateral sidewalls can define an implant body having a cephalad surface, a caudal surface and defining a fusion promotion cavity extending between the cephalad surface and the caudal surface. According to an embodiment, at least one of the side walls defines a hole from the exterior of the implant to the fusion promotion cavity, the side wall hole being centered about a primary axis of impact and being tapered toward the posterior portion of the implant along the axis of impact. For example, the side wall hole can be tear drop shaped or have another tapered shape that is thinner towards the posterior portion of the implant.
According to an embodiment, a posterior portion of each implant in a kit defines a threaded instrument engagement hole for engagement with the instrument and an instrument engagement notch adjoining the instrument engagement hole. The instrument engagement hole of each implant has a depth in a direction along the axis of impact, the depth being the same for all sizes in some embodiments.
The cephalad and caudal surfaces of each implant optionally can be convex with each of the cephalad surfaces having a first radius of curvature and each of the caudal surfaces having a second radius of curvature. The first radius of curvature can be the same for all sizes and the second radius of curvature can be the same for all sizes.
According to an embodiment, each implant in the kit can have a posterior portion with a first length from a posterior portion to the fusion promotion cavity. The first length being the same for all sizes of implants in the kit. Similarly, according to and embodiment, each implant can have an anterior portion with a second length from an anterior portion to the fusion promotion cavity. The second length can be same for all sizes.
Each implant can further comprise a first and a second elongated fluoroscopy marker toward a posterior portion of the implant and a third fluoroscopy marker toward an anterior portion of the implant. At least one of the fluoroscopy markers can be a selected distance from one of the ends of the implant. This distance can be the same for all sizes.
Another embodiment can include a method of manufacturing an artificial interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between vertebral bodies of a human spine, the vertebral bodies having an anterior aspect and a posterior aspect and a depth therebetween. The method can comprise forming a posterior portion of the implant shaped to interface with an insertion tool, forming an anterior portion of the implant opposite the posterior portion of the implant, and forming a pair of medial-lateral side walls of the implant between the posterior and anterior portions of the implant. The posterior portion, anterior portion, and medial lateral sidewalls can define an implant body having a cephalad surface, a caudal surface and defining a fusion promotion cavity extending between the cephalad surface and the caudal surface. The method can further comprise forming a hole in at least one of the medial-lateral side walls from the exterior of the implant to the fusion promotion cavity, the side wall hole being centered about a primary axis of impact and being tapered toward the posterior portion of the implant along the axis of impact. For example, the side wall hole can be a tear drop shape or other tapered shape. The method can further include forming a set of teeth into at least one of the cephalad or caudal surfaces. According to one embodiment, the teeth can be formed to extend beyond the cavity toward at least one of the ends of the implant.
According to various embodiments, at least one of the surfaces is convex and has a radius of curvature. The teeth can be formed such that the height of the teeth does not extend beyond the radius of curvature.
Embodiments of the method can further comprise forming at least a first and second marker hole in the implant toward the posterior portion of the implant and a third marker hole toward the anterior portion of the implant and inserting a first marker in the first fluoroscopy marker in the first marker hole, a second fluoroscopy marker in the second marker hole and a third fluoroscopy marker in the third marker hole. According to various embodiments, the third fluoroscopy marker has approximately the same cross sectional area as the first fluoroscopy marker in a first viewing plane and has a different cross sectional area than the first fluoroscopy marker in a second viewing plane orthogonal to the first viewing plane.
Embodiments of the present described herein provide advantages over previous implants. One advantage provided by various embodiments is that the implant can be shaped to better distribute the stress caused by impacts to the implant during the insertion process. Another advantage provided by various embodiments of the implant is that the nose can aid in distraction and can be shaped to move aside nerves during insertion. Yet another advantage provided by embodiments of an implant is that a set of teeth can be provided to reduce the likelihood that the implant can be ejected from the implantation site. Another advantage provided by embodiments disclosed herein is that features of the implant can be more easily manufactured.
These, and other, aspects will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. The following description, while indicating various embodiments and numerous specific details thereof, is given by way of illustration and not of limitation. Many substitutions, modifications, additions or rearrangements may be made within the scope of the disclosure, and the disclosure includes all such substitutions, modifications, additions or rearrangements.
A more complete understanding of the disclosure and the advantages thereof may be acquired by referring to the following description, taken in conjunction with the accompanying drawings in which like reference numbers generally indicate like features and wherein:
Preferred embodiments of the disclosure are illustrated in the FIGURES, like numerals being used to refer to like and corresponding parts of the various drawings. Embodiments of the disclosure provide artificial interbody spinal fusion implants for insertion within implantation spaces formed across the height of a disc spaces between vertebral bodies of human spines.
One embodiment of an implant can comprise a posterior portion, an anterior portion opposite from the anterior portion and a pair of medial-lateral side walls between the posterior portion and the anterior portion. The posterior portion, anterior portion, and side walls can define an implant body having a cephalad surface, a caudal surface and defining a fusion promotion cavity extending between the cephalad surface and the caudal surface. According to various embodiments, one or more of the cephalad and caudal surfaces can be convex. At least one of the sidewalls defines a hole from the exterior of the implant to the fusion promotion cavity. The hole can be centered about a primary axis of impact and can be tapered toward the posterior portion of the implant along the axis of impact. For example, the side wall hole can be tear drop shaped or have another tapered shape that is thinner towards the posterior portion of the implant.
Implant 10 can include a cavity into which bone graft material may be placed to promote fusion of vertebral bodies and may include a hole(s) in one or both of its sidewalls to allow bone cells to migrate into the fusion promotion cavity. The hole can be circular, elongated, tear drop shaped or have some other shape. Implant 10 may define cephalad and caudal surfaces which may be convex to correspond to the anatomical surfaces (of vertebral bodies 14) with which the surfaces abut when implant 10 is in implantation space 18. One or both surfaces may include teeth to prevent expulsion of implant 10 from implantation space 18. In some embodiments, implant 10 may define a threaded posterior hole and adjacent notch or other features to engage corresponding features of instrument 12 to detachably attach and lock implant 10 to instrument 12.
Instrument 12 can include a handle 22 that can be designed for an ergonomic grip. Handle 22 can be detachable from or fixed to other portions of instrument 12 and can be positioned so that the surgeon's hand is out of the line of sight to implant 10. Additionally, handle 22 can be positioned to be out of the way of a slap hammer, mallet, or other device used to drive implant 10 into the body. In this regard, instrument 12 can include a feature to allow an impact to be applied. According to some embodiments, instrument 12 can include an impaction cap for a slap hammer. The impaction cap may be permanently affixed to instrument 1 or may be removably coupled to instrument 12 by threads or other mechanisms. In the example illustrated in
Handle 22 allows surgical personnel to navigate implant 10 through an incision in the patient's body and to the surgical site near vertebral bodies 14. During a procedure, instrument 12 can be used to place the anterior portion of implant 10 between adjacent vertebral bodies 14 (as shown in
In some embodiments, surgical personnel may, instead of unlocking and releasing implant 10, may withdraw implant 10 from implantation space 18 using instrument 12. Surgical personnel can remove implant 10 from instrument 12 and replace it with another implant (perhaps with differing overall dimensions). Surgical personnel can insert replacement implant 10 into implantation space 18. Originally attached implant 10 and replacement implant 10, as well as instrument 12, the mallet, and any extensions or accessories for instrument 12 may be included in a kit.
With reference now to
Implant 100 can be formed of a biocompatible material such as PEEK, titanium, a titanium-aluminum alloy such as Ti6A14-Eli. Implant 100 may define cavity 102 wherein boney material may be placed to promote bone fusion between vertebral bodies 14. In various embodiments, implant 100 includes posterior portion 104, anterior portion 106, and two medial-lateral side walls 108 and 110. Cavity 102 may be generally centered in implant 100 between posterior portion 104, anterior portion 106, and medial-lateral side walls 108 and 110. In some embodiments, cavity 102 is elongated in a direction between posterior and anterior portions 104 and 106. The bone graft material which can be placed in cavity 102 can be natural or synthetic and can include by way of example, but not limitation, autograft bone such as bone from the patient's liliac crest, autograft bone from other locations, synthetic bone or a combination thereof. Furthermore, when the bone graft material is natural it can be gathered from the patient, a donor, or perhaps an animal source such as is the case with bovine bone graft material. In addition to the bone graft material, various carrier materials to retain the bone graft material in cavity 102 can be placed in cavity 102. Other materials, such as bone growth promotion materials, may be included in cavity 102.
With reference again to
As described with respect to
With continuing reference to
As illustrated by
Those skilled in the art will recognize that many other implants of different overall dimensions are possible and within the scope of the disclosure.
In some embodiments, cephalad and caudal surfaces 113 and 115 have radius of curvature r (see
In some embodiments, lengths Ip and Ia of posterior and anterior portions 104 and 106 respectively may vary between implants 100 and between implant sizes as illustrated by
Since patient anatomy varies widely, some embodiments provide a kit of implants 100 of differing heights, widths, and lengths including, but not limited to, those dimensions shown by
As mentioned previously, forming teeth 116 in the body of implant 100 with a depth of dt (See
Posterior portion 104 may define instrument engagement hole 112 and adjoining instrument engagement notch 114 as illustrated in
As shown by
Fluoroscopy markers 120 and 122 may be press fit into corresponding holes 132 and 133 on implant 100. Holes 132 and 133 can be dimensioned such that one or more of fluoroscopy markers 120 and 122 are centered about axis of impact 20 (of
Forces exerted on implant 100 by vertebral bodies (and other sources) can tend to cause implant 100 to move in a posterior direction after it is inserted in the implantation space. To prevent such movement and expulsion of implant 100 from the implantation space, teeth 116 may be formed in cephalad surface 113 (by, in some embodiments, forming grooves in implant 100). By the term “forming teeth in implant 100” it is meant that the teeth do not extend beyond the general contours of cephalad surface 113. This arrangement contrasts with forming teeth on the body of implant 100 by which teeth extend beyond the general contours of cephalad surfaces 113. Forming teeth 116 in the body of implant 100 allows more accurate matching of implant 100 height to implantation space height h then forming teeth 116 on the body of implant 100. Forming teeth 116 in the body of implant 100 also minimizes spinal subsidence after implant 100 is placed in implantation space 18. Implant 100 with teeth formed in the body of implant 100 therefore provides improved recovery and shorter recovery time for the patient. Teeth 116 may be formed into cephalad surface 113 and caudal surface 115. In some embodiments, teeth 116 can be formed by machining, laser, casting, powder metallurgy, etc. In some embodiments, teeth 116 may be added to cephalad surface 113 or otherwise added thereto. Teeth 116 may extend across all, or a portion of, cephalad surface 113. In some embodiments, teeth 116 may lie primarily in the region of cephalad surface 113 near cavity 102 although teeth 116 can extend along cephalad surface 113 beyond the region near cavity 102. Teeth 116 may, in various embodiments, be rounded or sharp, point toward posterior or anterior portions 104 and 106 or a combination thereof.
Side wall hole 118 can be elongated in a direction parallel to the axis of impact 20. Side wall hole 118 can be tear drop shaped with the tapered portion of the tear drop shape pointing toward posterior portion 104 in some embodiments. Regardless of the shape of side wall hole 118, side wall hole 118 can be located at about the center of medial-lateral side walls 108 or 110 or can be located elsewhere on medial-lateral side walls 108 and 110. Side wall hole 118 can be positioned such that (when viewed from the side) the center of side wall hole 118 aligns with axis of impact 20 as shown in
Referring again to
As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, process, article, or apparatus that comprises a list of elements is not necessarily limited only those elements but may include other elements not expressly listed or inherent to such process, process, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
Additionally, any examples or illustrations given herein are not to be regarded in any way as restrictions on, limits to, or express definitions of, any term or terms with which they are utilized. Instead, these examples or illustrations are to be regarded as being described with respect to one particular embodiment and as illustrative only. Those of ordinary skill in the art will appreciate that any term or terms with which these examples or illustrations are utilized will encompass other embodiments which may or may not be given therewith or elsewhere in the specification and all such embodiments are intended to be included within the scope of that term or terms. Language designating such nonlimiting examples and illustrations includes, but is not limited to: “for example”, “for instance”, “e.g.”, “in one embodiment”.
Although embodiments have been described in detail herein, it should be understood that the description is by way of example only and is not to be construed in a limiting sense. It is to be further understood, therefore, that numerous changes in the details of the embodiments and additional embodiments will be apparent, and may be made by, persons of ordinary skill in the art having reference to this description. It is contemplated that all such changes and additional embodiments are within scope of the claims below.
