Patent Grant
9060808
The present disclosure relates generally to orthopedics, an in particular relates to fixation systems and associated surgical methods and procedures for using same.
A variety of fixation devices for the reduction of bone or bone fragments are well known. For instance, external bone fixation devices, or external fixators, are used to reduce fractures of the long bones in the human body. Internal bone fixation devices, such as bone plates, are also commonly used to reduce bone fractures. Spinal fixation devices including intervertebral implants, spinal rods, and the like, are used to replace intervertebral discs, fuse or align adjacent vertebrae, and address other spinal issues.
A large number of fixation devices are attached to underlying bone using bone anchors, which can include screws, pins, nails, and the like. For instance, a typical bone plate includes screw holes that accommodate bone screws which are drilled into underlying bone on opposing sides of a fracture to join bone segments together. A typical cervical spine implant can likewise include screw holes that accommodate screws which are drilled into adjacent vertebral bodies in order to fix the position of the implant. Unfortunately, the attachment of fixation devices to the underlying bone can become compromised if, for instance, the screw becomes dislodged from the bone during normal anatomical function.
What is therefore desirable is an anchor system for use in bone fixation that more reliably fastens a fixation device to underlying bone.
An anchor-in-anchor fixation system includes a first bone anchor including a first shaft and a first head, the first shaft extending along a first longitudinal shaft axis and configured to attach to underlying structure, and the first head defining a bore extending therethrough along a bore axis, wherein the bore axis and the first longitudinal shaft axis define an acute angle. The anchor-in-anchor fixation system further includes a second bone anchor including a second shaft and a second head, the second shaft extending along a second longitudinal shaft axis and configured to attach to underlying structure, the second bone anchor configured to be inserted into the bore.
The foregoing summary, as well as the following detailed description of the preferred embodiments of the application, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the anchor-in-anchor system, there are shown in the drawings preferred embodiments. It should be understood, however, that the application is not limited to the precise arrangements and instrumentalities illustrated in the drawings, in which:
Certain terminology is used in the following description for convenience only and is not limiting. The words “right,” “left,” “top,” and “bottom” designate in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. The words “anterior,” “posterior,” “superior,” “inferior,” and related words and/or phrases designate preferred positions and orientations in the human body to which reference is made and are not meant to be limiting. The terminology includes the above-listed words, derivatives thereof and words of similar import.
With initial reference to
Referring also to
The head 28 includes an annular body 32 that defines a radially inner surface 33, an opposing radially outer surface 35, a proximal, or upper, end 28a and a distal, or lower, end 28b. The annular body 32 can define the shape of a segment of a sphere as illustrated, having a diameter or cross-sectional dimension that is greater at a location between the proximal and distal ends 28a-b than at either of the proximal and distal ends 28a-b. Accordingly, the radially outer surface 35 can be spherical or otherwise convex. Of course, the head 28 can assume any other suitable alternative shape as desired.
The distal end 28b of the head 28 is coupled to the proximal end 26a of the shaft 26, either directly or indirectly via an unthreaded neck 34 that is coupled between the proximal end 26a of the shaft 26 and the distal end 28b of the head 28. The annular body 32 can include a base 37 at the distal end 28b that extends continuously in a circumferential direction about the head 28. The annular body 32 further includes a plurality of circumferentially spaced retention tabs 36 that extend up from the distal end 28b. Thus, the terminal ends of the retention tabs 36 are disposed at the proximal end 28a of the head 28. The retention tabs 36 are configured such that circumferentially adjacent tabs 36 are separated by a slot 38 that extends distally into the proximal end 28a of the head 28 in a direction toward, but not through, the base 37.
The head 28 further defines a bore 40 extending centrally through the annular body 32 along a central bore axis C1. The central axis C1 extends in a direction angularly offset with respect to the longitudinal axis L1. The shaft 26 is coupled to the base 37, and extends radially outward and down from the radially outer surface 35 of the base 37 such that the shaft 26 does not interfere with the bore 40. The head 28 includes a plurality of helical threads 41 in the bore 40 that extend radially inward from the radially inner surface 33 of the annular body 32, including the tabs 36 and the base portion 37. In the illustrated embodiment, the central axis C1 of the bore 40 intersects with the longitudinal axis L1 of the shaft 26 so as to define an acute angle α. The angle α is illustrated as being acute. Thus, in accordance with one embodiment, the angle is between 0° and 90°, for instance between 20° and 60°, for instance between 20° and 40°.
In the illustrated embodiment, the central axis C1 is normal with respect to the proximal and distal ends 28a-b, though it should be appreciated that the proximal and distal ends 28a-b could be configured such that the central axis C1 defines a non-perpendicular angle with respect to one or both of the proximal and distal ends 28a-b. Therefore, with continuing reference to
While the inner surface 33 can include threads 41 extending circumferentially continuously within the bore 40 as illustrated in
Referring now to
The head 44 includes an annular body 48 that defines a radially inner surface 43 an opposing radially outer surface 45, a proximal, or upper, end 44a and a distal, or lower, end 44b. The outer surface 45 extends concentrically about an axis C2, and can define the shape of a frustum as illustrated having an outer diameter OD3 or cross-sectional dimension that increases in a direction from the distal end 44b of the head 44 toward the proximal end 44a. Alternatively, the head can assume any suitable alternative shape as desired, such as a segment of a sphere as illustrated, having a diameter or cross-sectional dimension that is greater at a location between the proximal and distal ends 44a-b than at either of the proximal and distal ends 44a-b. In the illustrated embodiment, the central axis C2 is parallel and coincident or aligned with the longitudinal axis L2 of the shaft 42, though it should be appreciated that the central axis C2 could be angularly offset from the longitudinal axis L2 if desired.
The distal end 44b of the head 44 is coupled to the proximal end 42a of the shaft 42, either directly as illustrated, or indirectly via an unthreaded neck 39 of the type described above with respect to the first bone anchor 22. The head 44 includes helical threads 50 that extend radially out from the outer surface 45 of the annular body 48. It should thus be appreciated that the second bone anchor 24 can provide as a locking screw as illustrated, though it should be appreciated that the second bone anchor can alternatively be provided as a compression screw, a nail, rivet, or pin whose shaft is smooth or ribbed, as desired.
The head 44 further defines a central axis D2 defined by the proximal and distal ends 44a-b. In particular, the central axis D2 extends in a direction normal with respect to the proximal and distal ends 44a-b. Because the central axis C2 head 44 extends parallel to the direction extending between the proximal and distal ends 44a-b in the illustrated embodiment, the axes C2 and D2 are coincident or aligned, and thus extend parallel and coincident or aligned with the longitudinal L2 in the illustrated embodiment. Of course, it should be appreciated that the proximal and distal ends 44a-b could be geometrically configured such that the axes C2 and D2 are angularly offset from each other.
The threads 50 define an outer diameter OD3 that increases in a direction from the distal end 44b of the head 44 to the proximal end 44a of the head 44. Thus, the outer diameter of the threads 50 is greater at the proximal end 44a than at the distal end 44. The inner diameter of the threads 41 of the bore 40 can define an inner diameter that increases in a direction from the distal end 44b toward the proximal end 44a, such that the threads 50 and 41 are configured to mate. It should be appreciated, of course, that the outer diameter of the threads 50 and 41 could be constant across the corresponding proximal and distal ends.
The assembly of the bone fixation system will now be described with respect to FIGS. 1 and 4A-C. In particular, the bore 40 of the first bone anchor 22 is configured to receive the second bone anchor 24, such that the first and second bone anchors 22 and 24 are fastened together. Thus, during use, the surgeon forms an incision to access a targeted area of the underlying bone 21. Next, the first bone anchor 22 is driven, for instance screwed, into the underlying bone 21 such that the threads 30 engage and attach the bone anchor 22 to a select one of the underlying bone segments 21a-b. Either or both of the bone anchors 22 and 24 can be self-tapping, and thus include cutting flutes 25, or a bore can be pre-drilled into the bone 21 prior to insertion of the shaft 26 into the bone 21. The first bone anchor 22 is inserted into the underlying segment such as a bone segment 21a to a sufficient depth, and is rotated until the axis C1 of the bore 40 is aligned with a desired fixation location of a second underlying segment such as a second bone segment 21b. Once the first bone anchor 22 has been fastened to the underlying bone, the second bone anchor 24 is inserted into the underlying bone 21 through the head 28 of the first bone anchor 22. The second bone anchor 24 can be inserted into the underlying bone 21 through the same incision that received the first bone anchor 22, or through a second incision as desired.
In one embodiment, the first bone anchor 22 is fastened to a first fractured segment 21a of the underlying bone 21, which can be a long bone, such as a femur, humorous, tibia, radius, ulna, or any other bone as desired, and the second bone anchor 24 is fastened to second fractured segment 21b of the underlying bone 21. For instance, the first bone anchor 22 can be fastened to the shaft or intramedullary portion of a patient's femur, while the second bone anchor 24 can be fastened to the head portion of the patient's femur. In this regard, the anchor-in-anchor bone fixation system 20 can be used to fix a femoral fracture, though it should be understood that the fixation system 20 and surgical methods of using the fixation system is equally applicable in other surgical procedures in which a surgeon desires to couple one or more bones or bone fragments.
With continuing reference to FIGS. 1 and 4A-C, the outer diameter OD2 of the threads 46 is less than the inner diameter of the bore 40 extending through the head 28 of the first bone anchor 22, such that the shaft 42 can be driven linearly down through the bore 40 as shown in
The bone anchors 22 and 24 can then be rotated with respect to each other to longitudinally advance the shaft 42 into the bone 21, and to longitudinally advance the head 44 inside the head 28 of the first bone anchor 22 at the same rate as the advancement of the shaft 42 into the bone, such that the first and second bone anchors 22 and 24 are locked together. Thus, the second bone anchor 24 can attach to the first bone anchor 22 without compressing the first bone anchor 22 against the underlying bone 21. Alternatively, the head 44 can be devoid of threads, and the inner surface 33 of the head 28 can be devoid of threads, such that the engagement of the head 44 against the head 28 causes the first bone anchor 22 to compress against the underlying bone 22. The radially inner surface 43 of the head 44 can define a hexagonal or any alternatively shaped structure that can be engaged by a screw driving instrument to rotate the head 44 inside the head 28. Alternatively or additionally, a tool can be inserted into the slots 38 disposed between the retention tabs 36 to prevent the first bone anchor 22 from rotating along with the second bone anchor 24.
Generally, the second bone anchor 24 engages the underlying bone 21 prior to engagement of the threads 41 and 50. As the distal end 44b of the head 44 of the second bone anchor 24 engages the proximal end 28a of the head 28 of the first bone anchor 22, the retention tabs 36 can flex radially outward. Once the first and second bone anchors 22 and 24 have been fully mated, the head 44 of the second bone anchor 24 is nested inside the head 28 of the first bone anchor 22, and the proximal end 44a of the head 44 is substantially flush with the proximal end 28a of the head 28. The shaft 26 of the first bone anchor 22 extends oblique with respect to the underlying bone 21, while the shaft 42 of the second bone anchor extends substantially normal with respect to the underlying bone 21, though it should be appreciated that both shafts could alternatively extend in a direction oblique to the underlying bone.
The retention tabs 36 have particular utility when locking the head 28 in an aperture of an auxiliary bone fixation member, such as a bone plate, an intramedullary nail or screw, an intervertebral implant, a pedicle screw, or the like as will be described in more detail below. It should be appreciated that the head 28 can alternatively be circumferentially continuous at and between the proximal and distal ends 28a-b of the head.
In this manner, when locked inside one another, the bone anchors form a stable triangular load bearing plane P defined by the longitudinal axes L1 and L2, and a direction extending between the shafts 24 and 42 (for instance, between the terminal ends of the shafts 24 and 42). The triangular load bearing plane P is better able to withstand higher forces and prevent subsidence or migration of the bone anchor within the bone. That is, because the bone anchors 22 and 24 are angled with respect to each other, each bone anchor resists migration within the bone due, for instance, to longitudinal forces applied to the other bone anchor that would tend to pull the bone anchor out of the underlying bone 21. In this manner, the anchor-in-anchor bone fixation system 20 enables a smaller auxiliary fixation device such as, for example, a plate, an intramedullary nail or screw, an intervertebral implant, or the like, to be used while enabling the surgeon to insert a larger number of bone anchors, such as bone anchors 22 and 24, to withstand anticipated loads.
Referring now to
The thread pitch of the threads 50 can vary from narrow-to-wide-to-narrow as measured along the central axis of the anchor 24 from one end (e.g., the proximal end) to the other end (e.g., the distal end). This thread profile allows the anchor 24 to engage the bore 40 at a selectable angle within a range of angles while maintaining the same degree of contact with the inner threads 41 regardless of the angle chosen, as described in U.S. patent application Ser. No. 11/971,358, filed Jan. 9, 2009, the disclosure of which is hereby incorporated by reference as if set forth it its entirety herein. That is, the angle of the anchor 24 with respect to the central bore axis C1 within the permissible range of angles does not affect the engagement of the threads 50 with the threads 41.
As will be described below, anchor-in-anchor bone fixation systems can be used in long bone applications, shoulder prosthesis, spinal applications, and can be used for stand-alone fixation whereby the bone anchors directly affix underlying bone segments, or can include one or more auxiliary fixation devices such as bone plates, intramedullary nails or screws, intervertebral implants, interspinous spacers, or other spinal implants such as pedicle screws, and shoulder prosthesis. The anchor-in-anchor fixation systems of the type described herein can thus be used in long bone fracture fixation to fix two or more bones or segments, can be used in the spine in a facet or laminoplasty fixation procedure, and shoulder prosthesis. It should be noted that it is not intended for any of the anchor-in-anchor systems as described herein to be limited to the particularly identified procedures and/or applications unless specifically noted.
For instance, referring now to FIGS. 5 and 6A-F, one or more anchor-in-anchor bone fixation systems 20 can be used in combination with an auxiliary fixation device such as a bone plate 52 so as to define an anchor-in-anchor fixation assembly 23 configured to fix of one or more long bones or bone fragments in a patient's body. Thus, the fixation assembly 23 includes at least one, such as a plurality of anchor-in-anchor bone fixation systems, configured to be coupled to an auxiliary fixation device. While various embodiments of the fixation assembly 23 are illustrated with respect to one or both of the fixation systems 20 and 120, it should be appreciated that either or both fixation systems 20 or 120 could be coupled to the auxiliary fixation device unless otherwise indicated. The fixation assembly and its components can be manufactured from any suitable biocompatible material known in the art including but not limited to titanium, titanium alloy such as TAN, stainless steel, reinforced plastics, allograft bone, and the like, unless otherwise indicated.
The bone plate 52 can be configured as desired, and includes an elongate planar plate body 54 defining an inner bone-facing surface 53 and an opposing outer surface 55. One or more, such as a plurality, of bone fixation apertures 56 (a pair of apertures 56 as illustrated) extends through the plate body 54 along a central axis A, which extends perpendicular to the inner and outer surfaces 53 and 55 of the plate body 54. The plate body 54 thus defines a central plate portion 57 that is disposed between the apertures 56 and configured to overlay a fracture F that separates the bone segments 21a-b. The plate body 54 can be planar as illustrated, though it could be curved or shaped as desired so as to conform partially or fully to the underlying bone, depending on the type of bone fixation being performed.
The apertures 56 present a spherical or otherwise convex inner surface 58 that matches the contour of the outer radial surface 35 of the head 28. A plurality of first bone anchors 22 is installed in the bone plate 52 such that each head 28 is disposed in a corresponding aperture 56, the central axis C1 of the bore 40 coincides with the central axis A of the corresponding aperture 56, and the longitudinal axis L1 of the shaft 26 extends down from the plate 52 in a direction that defines the angle α with respect to the axis A of the aperture 56. The second bone anchor 24 is fastened to the first bone anchor 22 in the manner described above, such that the shaft 42 extends down from the plate 52 along the axis A.
The method of attaching the bone plate 52 to underlying bone segments 21a-b will now be described with reference to
Once the bone anchors 22 have been inserted into the underlying bone segments 21a-b at a desired depth as illustrated in
Once the heads 28 have been disposed in the apertures 56, the spherical or convex outer surfaces 35 of the heads 28 and the mating inner surface of the aperture 56 allows the bone anchor 22 to polyaxially rotate with respect to the bone plate 52. Otherwise stated, the bone anchor 22 can be inserted into the aperture 56 at any desired angular orientation so long as the second bone anchor 24 is able to pass through the bore 40 of the head 28 and into underlying bone. The first bone anchor 22 can be inserted into the underlying bone to provide compression of the plate 52 against the bone segments if desired.
Next, referring to
The bone anchor 24 can then be rotated to longitudinally advance the shaft 42 of the second bone anchor 24 into the bone 21, and to longitudinally advance the head 44 inside the head 28 of the first bone anchor 22, such that the threads 50 extending in from the head 28 mate with the threads 41 extending out from the head 44 until the first and second bone anchors 22 and 24 are locked together as illustrated in
As the distal end 44b of the head 44 of the second bone anchor 24 engages the proximal end 28a of the head 28 of the first bone anchor 22, the retention tabs 36 flex radially outward against the inner surface 58 of the aperture 56, thereby causing a frictional fit that secures the position of the first bone anchor 22 with respect to the plate. Otherwise stated, the head 28 expands against the bone plate 52 as the second bone anchor 24 mates with the first bone anchor 22. In particular, the outer surface 45 of the head 44 can taper radially outward in a direction from the distal end 44b toward the proximal end 44a. Accordingly, insertion of the second bone anchor 24 into and through the bore 40 radially expands the head 28 of the first bone anchor 22 against the inner surface 58 of the aperture 56.
Furthermore, as described above, both the radially inner surface 33 of the bone anchor head 28 and the radially outer surface 45 of the bone anchor head 44 are threaded so that the bone anchors 22 and 24 mate with each other when the first bone anchor 22 receives the second bone anchor 24, thereby securing the second bone anchor 24 to both the first bone anchor and furthermore to the bone plate 52. Thus, in use, the anchor-in-anchor bone fixation system 20 includes a first bone anchor 22 having an expandable head 28 and a locking compression screw mechanism to lock a non-parallel second bone anchor in a bone plate 52. Accordingly, the bone fixation system 20 allows the placing of two non-parallel bone anchors in a relatively small plate area so that a higher level of stability can be achieved with respect to a bone plate that receives a single bone anchor in each aperture to affix the bone plate to underlying bone segments. Because one of the bone anchors (the first bone anchor 22 as illustrated) is angularly offset with respect to the vertical direction of the second bone anchor 24, longitudinal forces applied to the second bone anchor that might otherwise cause migration in the bone 21 are translated to the shaft 26 of the first bone anchor 22, which resists the longitudinal forces that would tend to pull the bone anchor 24 out of the underlying bone 21.
Alternatively, the bone plate 52 can be placed against the bone segments 21a-b, and the shafts 26 can be inserted through the apertures 56 prior to affixing the shafts into the underlying bone. In this alternative embodiment, the bone anchors 20 are inserted into the underlying bone to a desired depth, and the plate 52 is brought up against the heads 28. If the slots 38 separating the retention tabs 36 extend significantly into the distal portion 28b of the heads 28, then the tabs 36 can compress radially inward as the plate is brought up over the heads 28. Alternatively the head 28 can include a single slot 38 that extends vertically through the head 28 so as to define a pair of tabs 36 that are separated at only one circumferentially outer end (see slot 138 in
While the bone fixation system 20 and the bone fixation assembly 23 have been illustrated and described in accordance with the first and second bone anchors 22 and 24 constructed in accordance with one embodiment, it is envisioned that bone fixation systems and assemblies can be provided in accordance with numerous alternative embodiments whereby a second bone anchor extends through a bore formed in the head of a first bone, such that the first and second bone anchors join to an underlying structure, segments of an underlying structure, or different structures.
For instance, referring now to
In particular, the proximal end 126a of the shaft 126 is attached to the distal end 128b of the head 128, such that the shaft 126 is centrally disposed with respect to the head 128 and extends longitudinally down from the head 128. Thus, the central axis D1′ that extends normal with respect to the proximal and distal ends 128a-b is parallel and coincides with the longitudinal axis L1 of the shaft 26. It should be appreciated, of course, that the shaft 126 could be offset from the central axis D1 of the head 128. The bore 140 extends through the head 128 along a central axis C1 that is angularly offset with respect to both the longitudinal axis L1 of the shaft 126, and the central axis D1 that extends normal with respect to the proximal and distal ends 128a-b of the head 128. In particular, the central axis C1 of the bore 140 forms an acute angle α with respect to the longitudinal axis L1 and the central axis D1′. Thus, the angle α is between 0° and 90°, such as between 40° and 60°. The head 128 can include retention tabs of the type described above with respect to the head 28 of the bone anchor 22, or the head 128 can be circumferentially continuous at and between the proximal and distal ends 128a-b as illustrated in
Referring now also to
The first bone anchor 22 is inserted into the underlying segment such as a bone segment 21a at a sufficient depth, and is rotated until the axis C1 of the bore 140 is aligned with a desired insertion location of a second underlying segment such as a second bone segment 21b. In this regard, it should be appreciated that the first bone segment 122 can be inserted into the bone segment 21a in a direction normal to the plane defined by the underlying bone 21, or can be inserted in a direction angularly offset with respect to a direction normal to the plane defined by the underlying bone 21.
Once the first bone anchor 122 has been fastened to the underlying bone such that the axis C1 is aligned with a target location for the second bone anchor 124, the second bone anchor 124 is inserted into the underlying bone 21, such as segment 21b, through the head 128 of the first bone anchor 122. The second bone anchor 124 can be inserted into the underlying bone 21 through the same incision that received the first bone anchor 122, or through a second incision as desired. Thus, the first bone anchor 122 can be inserted, for instance, into a fragmented long bone segment 21a, while the second bone anchor 124 can be inserted, for instance, into a non-fragmented long bone segment 21b, thereby securing the fragmented bone segment 21a to the non-fragmented bone segment 21b. As illustrated, the shafts 126 and 142 of the first and second bone anchors 122 and 124 each extend oblique with respect to the underlying bone 21, though one of the shafts could alternatively extend substantially perpendicular with respect to the underlying bone in the manner described above.
While the fixation system 120 has been illustrated and described as being used to secure a free-floating bone fragment to a long bone, it should be appreciated that the anchor-in-anchor fixation systems as described herein can also be used to secure a bone fragment in other parts of the body as well, including but not limited to the cranium, face, hands, feet, pelvis, and the like. The anchor-in-anchor fixation systems of the type described herein can also be used to secure one fragment to another fragment (for instance one bone fragment to another bone fragment), or one structure to another structure (for instance one bone to another bone).
It will also be appreciated that anchor-in-anchor bone fixation systems enable a smaller auxiliary fixation device such as, for example, a plate, an intramedullary nail or screw, an intervertebral implant, or the like, to be used while enabling the surgeon to insert a larger number of bone anchors, such as bone anchors 122 and 124, to withstand anticipated loads. Moreover, when locked inside one another, the bone anchors form a stable triangular load bearing plane P and are thus better able to withstand higher forces and prevent subsidence or migration. That is, because the bone anchors 122 and 124 are angled with respect to each other, each bone anchor resists migration within the bone due, for instance, to longitudinal forces applied to the other bone anchor that would tend to pull the bone anchor out of the underlying bone 21.
Referring now to
Once the first bone anchor 122 has been positioned such that the central axis C1 is aligned with a target location of the second bone anchor 124, the second bone anchor 124 is fastened to the first bone anchor 122 in the manner described above, such that the shaft 142 extends down from the plate 152 in a direction coincident with the central axis C1, so as to define the angle α with respect to the axis A. As illustrated in
Alternatively, the bone plate 152 can be placed against the bone segments 21a-b, and the shafts 126 can be inserted through the apertures 156 prior to affixing the shafts into the underlying bone. In this alternative embodiment, the heads 128 are brought down into the apertures 156 of the bone plate 152. Once the head 144 is coupled to the head 128, the radially outer surface 145 expands radially outward against the bone plate 152 in the manner described above, thereby securely fastening the bone anchors 122 and 124 to the bone plate 152.
Furthermore, while the bone anchors 22, 24, 122, and 124 have been described in accordance with particular illustrated embodiments whereby the threads extend along an entirety of the shaft, for instance at and between the proximal and distal ends of the shaft, the bone anchors used in combination with any of the bone fixation systems described herein can be alternatively constructed.
For instance, referring to
In this manner, the first bone anchor 122 is inserted into the underlying bone and through the aperture 156, the shaft 126 is first inserted through the apertures 156 such that the threads 130 extending out from the head 128 engage the threads in the inner surface 158 to secure the bone anchor 122 to the bone plate 152. In this regard, it should be appreciated that the threaded engagement between the head 128 and the bore 156 fixes the angular position of the first bone anchor 122 relative to the bone plate 152 such that the second bone anchor head 144 need not expand the head 128 against the inner surface 158 in the manner described above. Furthermore, the threaded engagement between the head 128 and the bone plate 152 allows the bone anchors 122 and 124 to attach the plate 152 to the underlying bone without compressing the plate 152 against the underlying bone.
While the bone plate 52 has been illustrated as attached to underlying bone 21 via the fixation systems 20 and the bone plate 152 has been illustrated and described as attaching to underlying bone 21 via the fixation systems 120, it should be appreciated that one or more fixation systems 20 and 120 could be used in combination to attach either of the bone plates 52 and 152 to the underlying bone 21.
Whether the fixation system 120 is provided as a stand-alone construct (i.e., without an auxiliary fixation device) or in combination with an auxiliary fixation device such as the bone plate 152 to provide a fixation assembly 23, the threaded engagement between the second bone anchor 124 and the first bone anchor 122 allows the head 144 of the second bone anchor 124 to be countersunk within the head 128 of the first bone anchor 122, such that the proximal end 128a of the head 128 is substantially flush to provide a low profile and minimize the trauma associated with the fixation system 120.
Alternatively, referring to
Referring to
It should alternatively be appreciated that one or more, up to all of the bone anchors 22, 24, 122, and 124 could be constructed having fully threaded shafts, partially threaded shafts, or shafts that are entirely devoid of threads. For instance,
For instance, referring to
Referring now to
Alternatively still, as illustrated in
While the anchor-in-anchor bone fixation systems 20 and 120 have been described in combination with an elongate plate configured to provide long bone fixation, it should be appreciated that the anchor-in-anchor bone fixation systems of the type described herein could alternatively include bone plates of any suitable size and shape. For instance, referring to
A plurality of longitudinally spaced apertures 256a extends through the first plate section 254a, and a plurality of laterally spaced apertures 256b extends through the second plate section 254b. In one embodiment, it is envisioned that the T-shaped bone fixation plate is configured to attach to a tibia having a fracture that is disposed longitudinally between the plurality of apertures 256a and the plurality of apertures 256b. Either or both of the fixation systems 20 and 120 can be inserted into one or more, up to all, of the apertures 256a-b. As illustrated, the fixation system 20 is inserted into the apertures 256a-b in the manner described above with respect to bone plate 52. It can be appreciated that the shafts 26 of the first bone anchors 22 can be aligned in any angular direction as desired, and can be constructed sufficiently long so as to extend through overlaid bone segment, through the fracture, and into the opposing fractured bone segment.
Referring now to
The apertures 74a can be longitudinally displaced from each other along the length of the rod segment 72a, and can further be angularly displaced from each other about the circumference of the rod segment 72a. Likewise, the apertures 74b can be longitudinally displaced along the length of the rod segment 72b, and can further be angularly displaced from each other about the circumference of the rod segment 72b. The apertures 74a-b can extend centrally through the rod body segments 72a-b coextensive with the diameter of the segments 72a-b, or offset from the center of the segments 72a-b coextensive with a chord of the segments 72a-b. The apertures 74a-b can also define a longitudinal directional component such that one end of a given aperture is longitudinally displaced with respect to the opposing end of the aperture. While the rod 70 is illustrated as substantially cylindrical as illustrated, it should be appreciated that the rod 70 could assume any suitable alternative shape and size as desired.
As illustrated in
In accordance with the illustrated embodiment, the shaft 142 is inserted through the bore 140 and driven into the surrounding bone 21, for instance using a screwing, drilling, hammering, or like mechanism to insert the shaft 142 into the surrounding bone 21. In this regard, it should be appreciated that, as in all embodiments of the of anchor-in-anchor bone fixation systems described herein unless otherwise noted, either or both of the bone anchors 122 and 124 could be provided with threaded heads, unthreaded heads, heads including locking tabs 136 or heads that are circumferentially continuous at and between the proximal and distal ends, fully threaded shafts, partially threaded shafts, or unthreaded shafts defining a smooth radially outer surface or including teeth 47 projecting out from the radially outer surface.
While the first bone anchor 122 is configured to be attached to the rod 70 and the second bone anchor 124 is configured to be attached to the surrounding bone, it should be appreciated that the second bone anchor 124 could alternatively be attached to the rod 70 in the manner described above, and the first bone anchor 122 could be attached to the surrounding bone. In this alternative embodiment, the first bone anchor 22 is driven into the bone 21 such that the central axis C1 of the bore 140 is aligned with one of the apertures 74. The second bone anchor 124 is then inserted through the bore 140 such that the shaft 142 extends through and is coupled to the aligned aperture 74.
It should further be appreciated that while the second fixation system 120 has been illustrated as attached to the intramedullary rod 70 and surrounding bone 21 in the manner described above, the first fixation system 20 could alternatively or additionally attach to the intramedullary rod 70 and surrounding bone. For instance, the first bone anchor 22 could attach to one of the apertures 74 and the second bone anchor could attach to the surrounding bone 21 in the manner described above, or the first bone anchor 22 could attach to the surrounding bone 21, and the first bone anchor could attach to one of the apertures 74 in the manner described above.
Referring also now to
Thus, the fixation systems 20 and 120 can be used alone or in combination to fasten the intramedullary rod 72 to the surrounding bone. It should be further appreciated in all embodiments described herein, unless otherwise, noted, that the fixation systems 20 and 120 can be used in combination when attaching directly to bone as a stand-alone construct, or when affixing an auxiliary fixation device to an underlying structure such as bone, bone-substitutes or bone-spacers, allografts, autografts, synthetic grafts, and metal or titanium grafts. It should be further appreciated that the bone anchors that attach to the intramedullary rod 72 can be rotated to any desired position, such that the other bone anchor can extend into the surrounding bone at any angular orientation as desired.
In the embodiments illustrated, in
Referring now to
As illustrated in
It should be appreciated, alternatively, that the head 128 of the first bone anchor 122 can attach to the bone plate 52 in the manner described above, and the shaft 126 can attach to the bone 21 without passing through the intramedullary rod 170, and that the second bone anchor can pass through the head 128 and attach to one of the apertures 174 of the intramedullary rod 170. Alternatively or additionally, it should be appreciated that the bone fixation system 20 can be used in combination with the bone fixation system 120 or alone to attach the intramedullary rod 170 to the bone plate 52 and the surrounding bone in the manner described herein. It should further be appreciated that the intramedullary rod 70, or any intramedullary rod constructed as desired, can be attached to surrounding bone by one or both of the fixation systems 20 and 120 alone, or in combination with a second auxiliary bone fixation member such as a bone plate. The bone plates of the type described herein can be provided with any thickness as desired. For instance, the bone plates can be constructed sufficiently thin so as to provide an in-between member for suture attachment between a pair of bone anchors provided as screws, for instance, in order to fasten and reposition soft tissue structures such as tendons, ligaments, and muscles.
As illustrated in
Referring now to
The fixation system 20 is installed into the nail 270 by first inserting the bone anchor 22 into the aperture 274 such that the shaft 26 extends into the proximal end of the aperture 274 and is then directed through the distal end of the associated auxiliary aperture 274a. The aperture 274 can define a diameter that is substantially equal to or slightly greater than the outer diameter of the anchor head 28, such that the anchor head is recessed within the aperture 274. It should be appreciated that any of the auxiliary fixation devices could include apertures configured such that the received bone anchor heads are recessed therein. Once the bone anchor 22 has been installed, the secondary bone anchor 24 is inserted into the bore 40 of the anchor head 22 in the manner described above, thereby causing the head 22 to expand and lock against the inner surface of the aperture 274. In particular, the shaft 42 extends into the proximal end of the aperture 274, through the anchor head 28, and through the distal end of the aperture 274. In this manner, the shaft 42 extends substantially normal to the underlying bone, while the shaft 26 extends oblique with respect to the underlying bone. The distal ends of the apertures 274 and auxiliary apertures 274a can be widened greater than the diameter of the respective shafts as desired, or can be provided as elongate slots so as to provide for angular flexibility.
Referring now to
Referring now to
The bone plate body includes a pair of body segments 363 and 365. The body segment 363 includes an inner segment plate 363a and an outer segment plate 363b, and an interior groove 367 disposed between the plates 363a-b that is sized to receive the body segment 365 therein. At least one or both inner surfaces 369 that define the groove 367 include teeth 373 extending out therefrom into the groove 367. Likewise, one or both of the surfaces of the body segment 365 define teeth 371 extending outwardly therefrom and configured to engage the teeth 373. The first body segment 363 defines a threaded locking aperture 375 that is threaded at the outer plate 363b. Accordingly, the shaft 377a of a threaded locking pin 377 can be inserted through the aperture 375 in a direction from the inner surface 353 toward the outer surface 355, and engage the threads of the outer plate 363b so that the head 377b can compress the plates 363a-b against each other, thereby causing the teeth 371 and 373 to engage and prevent relative movement between the body segments 363 and 365.
During operation, the body segment 365 is inserted into the groove 367, and extended or retracted so that the apertures 356 define a desired length therebetween. The second body segment 365 includes a cutout 379 that allows the segment 365 to slide without interfering with the locking pin 377. The locking pin 377 is then rotated within the aperture 375 to advance within the aperture 375 and lock the position of the body segments 365 and 363. In this regard, it should be appreciated that a bone fixation system 20 can be locked within the apertures 356, such that the shafts 26 and 42 of the bone anchors 22 and 24 are inserted into underlying bone in the manner described above. It should be appreciated that once the fixation systems 20 have been attached to the plate 352 and to the underlying bone, the body segment 365 can be retracted within the groove 367 so as to reduce the underlying fracture, or otherwise compress a pair of bones or bone fragments joined to the fixation systems 20 toward each other. Alternatively, the body segment 365 can be extended within the groove so as to further space the bones or bone fragments joined to the fixation systems 20.
Referring now to
During use, the shaft 26 of each first bone anchor 22 is inserted into the target pedicles P of the vertebral body V on opposing sides of the vertebral foramen thereof. The first bone anchors 22 are rotated as desired such that the central axes C1 define insertion trajectories for the shafts 42 of the second bone anchors 24 into desired target location bone segments of an adjacent vertebral body V, such as facets F. The bone plate 352 is then installed onto the heads 28 of the first bone anchors 22 such that the apertures 356 are snapped down over the anchor heads 28 of the first bone anchors 22 in the manner described above. The shafts 42 of the second bone anchors 24 are then inserted through respective heads 28 of the first bone anchors 22 and inserted into the target facets F. The heads 28 of the first bone anchors 22 expand against the bone plate 352 to lock the fixation assembly 23 in place in the manner described above. The forces exerted by the first and second anchors 22 and 24 of the fixation assemblies 20 restrict movement of the vertebral bodies V with respect to each other.
It should be appreciated that in alternative embodiments, the plate 352 can be attached to a fractured long bone in the manner described above, or can be used in combination with a corpectomy, whereby a vertebral body is replaced by a vertebral implant. For instance, referring now to
Once the implant 300 is disposed within the intervertebral space, the fixation systems 20 are affixed to the adjacent vertebral bodies V, for instance in the cervical spine region, via an anterior approach. In particular, both bone anchors 22 and 24 extend into the vertebral body, such that one of the bone anchors extends through the respective vertebral body V and into one of the pedicles P. In accordance with the illustrated embodiment, the shafts 26 of the first bone anchors 22 are inserted through the corresponding vertebral body V and into a target one of the pedicles P. Once each shaft 26 has reached its approximate desired depth in the pedicle P, it is rotated until the central axis C1 is aligned with the vertebral body V at the desired angle of entry. Next, the bone fixation plate 352 is attached to the heads 28 in the manner described above with respect to plate 52. For instance, the apertures 356 are fitted over the heads 28 until the heads 28 are disposed within the apertures 356. Finally, the shafts 42 of the second bone anchors 24 are inserted into respective heads 28 and into the corresponding vertebral bodies V. The shafts 42 have a length sufficient so as to not extend into the vertebral foramen VF.
If desired, the plate 352 can be extended or compressed in the manner described above if it is desired to adjust the spacing between the adjacent vertebral bodies that define the intervertebral space in which the implant 300 is disposed. In this regard, it should be appreciated that the fixation system 23 allows all bone anchors to be inserted into the vertebral bodies V via an anterior approach, and that the angular offset of the bone anchors 22 and 24 define a triangular load bearing plane in the manner described above, and are thus better able to withstand higher forces and prevent subsidence or migration of the bone anchors within vertebral bodies without requiring additional spinal fixation via a posterior approach. The bone anchors 22 can be inserted into vertically aligned pedicles P as illustrated, or can be inserted into pedicles P disposed on opposing sides of the vertebral foramen VF depending on the angular orientation of the central axis C1 of the first bone anchors 22. Alternatively still, a pair of side-by-side apertures could be disposed at opposing longitudinal ends of the bone plate 252, such that a pair of fixation assemblies 20 includes a corresponding pair of bone anchors 24 that extend into both pedicles of the respective vertebra.
Referring now to
For instance, a first fixation system such as system 20 is affixed within the aperture 456 extending through the first segment 454a in the manner described above, such that the shaft 26 of the first bone anchor 22 extends in a direction oblique with respect to the bone plate 452, and the shaft 42 of the second bone anchor 24 extends substantially normal with respect to the plate 452, though it should be appreciated that both shafts 26 and 42 could alternatively extend in a direction oblique with respect to the bone plate 452. A second fixation system such as system 20 is likewise affixed within the aperture 456 that extends through the second segment 454b in the manner described above. Thus, the respective shaft 24 extends in a direction oblique with respect to the bone plate 452 and the shaft 42 extends substantially normal with respect to the bone plate 452, though both shafts 26 and 42 could extend oblique with respect to the plate 452. Before or after the fixation assemblies 20 are affixed to the apertures 456, the second segment 454b can be rotated in the direction of Arrow R within the first segment 454a so as to adjust the longitudinal position of the respective shafts 26 and 42 with respect to the shafts 26 and 42 joined to the aperture 456 extending through the first segment 454a, thereby increasing or decreasing the longitudinal distance between the fixation assemblies 20.
While the fixation system 20 is illustrated as coupled to the plate 452, it should be appreciated that, as with all auxiliary fixation devices described herein, the other fixation system, in this case the second fixation system 120, could alternatively or additionally be coupled to the plate 452.
Referring now to
During operation, the shaft 126 of the first bone anchor 122 is inserted into the underlying sacral spine area and into a vertebral body through the pedicle, or could alternatively be inserted into a facet, lamina, the spinous process, or alternative vertebral structure as desired, so as to affix the first bone anchor 122 at a location offset with respect to the pedicle. The bone anchor 122 is rotated until the central axis C1 is aligned with the pedicle. Next, the shaft 142 of the second bone anchor 124 is inserted through the head 128 and inserted into the pedicle until the head 144 is disposed in the head 128 in the manner described above. The lower opening 410 is then fitted over the head 128 so as to operatively couple the fixation system 120 to the fixation rod 404. The angular offset of the shafts 126 and 142 define a triangular load bearing plane in the manner described above, and are thus better able to withstand higher forces and prevent subsidence or migration of the pedicle screw 140 within the vertebral body. As illustrated in
Referring now to
The backing plate 502 defines a backing plate body 506 that presents a concave insert-engaging surface 508 and an opposing convex surface 510. A pair of spaced apertures 512 extends through the body 506 along respective central axes A. A pair of cylindrical extensions 514 projects down from the opposing surface 510 at a location aligned with the apertures 512, and each define aperture extensions 512a. A radial projection 516 extends inward from the inner surface of each cylindrical extension, and assists in affixing the insert 504 to the backing plate 502. A lip 518 projects radially inward from the distal end of each cylindrical extension 514, and presents a mounting surface for the respective fixation systems 120.
The fixation systems 120 are attached to the backing plate 502 and to underlying bone by first inserting the shaft 126 of the first bone anchor 122 into underlying scapular bone in the manner described above. Next, the shaft 142 of the second bone anchor 124 is inserted through the head 128 and into the underlying scapular bone such that the head 144 is disposed inside the head 128 in the manner described above. Next, the backing plate 502 is placed down over the head 128 such that the lips 518 snap over the respective heads 128 and lock the heads 128 therein. The shafts 126 can be aligned with the axis A of the aperture 512, and the shafts 142 can be angulated with respect to the axis A, though it should be appreciated that both shafts 126 and 142 could be angulated with respect to the axis A.
The insert 504 defines a bearing surface 520 that is concave so as to provide an artificial or prosthetic glenoid, and an opposing surface 522. A pair of locking pegs 524 project down from the opposing surface 522 at locations aligned with the apertures 512. The pegs 524 define a circumferential recess 526 that receive the projections radial projections 516 to attach the insert 504 to the backing plate 504, at which point the artificial glenoid 520 provides an articulation surface for a humeral implant.
While the concavity of the bearing surface 520 is suitable to provide an artificial or prosthetic glenoid as described above, it should be appreciated that the bearing surface 520 can be provided with any curvature as desired. For instance, the concavity of the bearing surface 520 can be constructed so as to provide a hip cup usable as a ball-and-socket joint, usable for instance in hiparthroplasty.
Referring now to
In an alternative embodiment, as illustrated in
Referring now to
Referring now to
As illustrated in
The shaft 126 of the first bone anchor 122 of the second fixation system 120 is inserted into the base of the spinous process SP of the vertebral body V on the opposing side of the spinous process SP, in proximity to the second of the fractures FR. The shaft 126 of the first bone anchor 122 of the second fixation system 120 is rotated such that the central axis C1 defines an insertion trajectory for the shaft 142 of the second bone anchor 124 of the second fixation system 120 through the second fracture FR and into a corresponding second pedicle P of the vertebral body V. The shaft 142 of the second bone anchor 124 of the second fixation system 120 is inserted through the head 128 of the first bone anchor 122 of the second fixation system 120 and into the second pedicle P in the manner described above. The forces exerted by the first and second bone anchors 122 and 124 of the first and second fixation systems 120 compress the spinous process SP against the corresponding pedicles P, thereby reducing the fractures FR.
With reference now to
The shaft 126 of the first bone anchor 122 of the second fixation system 120 is inserted into the allograft bone extension A in a proximity to the second of the fractures FR. The shaft 126 of the first bone anchor 122 of the second fixation system 120 is rotated such that the central axis C1 defines an insertion trajectory for the shaft 142 of the second bone anchor 124 the second fixation system 120 through the second fracture FR and into the lamina L of the vertebral body V. The shaft 142 of the second bone anchor 124 of the second fixation system 120 is inserted through the head 128 of the first bone anchor 122 of the second fixation system 120 and into the lamina L. The forces exerted by the first and second bone anchors 122 and 124 of the first and second fixation systems 120 compress the allograft bone extension A between the spinous process SP and the lamina L, thereby reducing the fractures FR.
Referring now to
It should be appreciated that any combination of the above-described laminoplasty procedures can be used either alone or in combination with any of the above-described facet fixation procedures. It should be appreciated that the relative positions of the bone anchors 22, 122, 24, and 124 of the anchor-in-anchor systems 20 and 120 as illustrated in
Referring now to
In particular, the anchor-in-anchor fixation assembly 23 illustrated in
It should be appreciated that the plate 52 can be omitted from the above-described lumbosacral fixation procedure if desired, and that the relative positions of the bone anchors 22 and 24 of the fixation assemblies 20 as illustrated in
Referring now to
It should be appreciated that the relative positions of the bone anchors 22 and 24 of the anchor-in-anchor system 20 as illustrated in
Referring now to
The body 602 further includes upper and lower edges 602d and 602e respectively, defined where the upper and lower surfaces 602b and 602c intersect with the lateral surface 602a of the implant body 602. The implant body 602 may have a bore 604 defined within the lateral surface 602a and extending into the body 602 in a direction away from the lateral surface 602a. The inner surface of the bore 604 may be configured to receive an anchor from the anchor-in-anchor fixation systems 20 and/or 120. For example, the inner surface of the bore 604 may have complimentary threads formed therein configured to engage with the threads formed on the shaft 26 of the first bone anchor 22 of the anchor-in-anchor fixation system 20.
The body 602 may further include a groove 606 formed in the upper edge 602d and proximate to the bore 204, the groove 606 configured to receive a portion of the shaft 42 of the second bone anchor 24 when the shaft 42 of the second bone anchor 24 is inserted into the head 28 of the first bone anchor 22 and into a desired fixation location. It should be noted that the groove 606 may be formed in the upper edge 602d (as illustrated) to receive the shaft 42 of the second anchor 24 when securing the implant 600 to the lower, or caudal, surface of an adjacent vertebral body, or alternatively the groove 606 may be formed in the lower edge 602e to receive the shaft 42 of the second bone anchor 24 when securing the implant 600 to the upper, or cranial, surface of an adjacent vertebral body.
During use, the shaft 26 of the first bone anchor 22 is engaged in the bore 604 of the implant body 602. The implant 600 is disposed in an intervertebral space and positioned as desired. The first bone anchor 22 is oriented such that the central axis C1 is aligned with a desired insertion trajectory of the second bone anchor 24 into a target vertebral body V of the adjacent vertebral bodies. Thereafter, the shaft 42 of the second bone anchor 24 is inserted through the head 28 of the first bone anchor 22 in the manner described above, and the shaft 42 of the second bone anchor 24 is inserted into a target vertebral body bone segment of the target vertebral body V, for example the cortical rim and/or the cancellous bone of the target vertebral body V. It is possible to gain compression on the implant 600 through tightening of the second bone anchor 24. The intervertebral implant system 27 can be used in combination with posterior unilateral spinal fixation constructs to provide enhanced stability to such constructs. It should be noted the intervertebral implant 600 can be used in combination with the anchor-in-anchor fixation system 20 as depicted and described herein, the anchor-in-anchor fixation system 120, or any combination thereof.
Alternative embodiments of the intervertebral implant system 27 can include an intervertebral spacer configured to receive more than one anchor-in-anchor fixation system 20 and/or 120. For instance, as illustrated in
The body 702 further includes upper and lower perimeter edges 702d and 702e respectively, defined where the upper and lower surfaces 702a and 702b intersect with the sides of the implant body 702. The body 702 of the implant 700 can have mounting structures formed therein to facilitate coupling an anchor plate 708, carrying a pair of anchor-in-anchor assemblies 20, to the body 702. For example, retention slots 704, formed in the upper and lower perimeter edges 702d and 702e, are configured to releasably receive mating clips 716 extending from the anchor plate 708. It should be noted that the retention slots 704 are merely example mounting structures for use in coupling the anchor plate 708 to the implant 700, and any other mounting structures may be utilized as desired to couple the anchor plate 708 to the implant 700. The body 702 can further include grooves 706, formed for example in the upper and lower edges 702d and 702e, the grooves 706 configured to receive portions of the shafts 26 and/or 42 of the first and second anchors 22 and 24, respectively, when the anchor-in-anchor assemblies 20 are disposed within the anchor plate 708 and the anchor plate 708 is mated to the body 702.
The anchor plate 708 includes a generally rectangular shaped body 710 having upper, lower, and lateral surfaces 710c, 710d, and 710e defined between a proximal end 710a and an opposing distal end 710b. The outer perimeter geometry of the body 710, as defined along the upper, lower, and lateral surfaces 710c, 710d, and 710e, can be defined to substantially match the outer perimeter geometry of the body 702 of the implant 700. One or more, such as a plurality, of apertures 712 (e.g., a pair of apertures 712 as illustrated) extends through the anchor plate body 710 perpendicular to the proximal and distal ends 710a and 710b. The anchor plate body 710 can be generally planar as illustrated, though it could be curved or otherwise shaped as desired so as to conform partially or fully to corresponding geometry of the implant 700.
The apertures 712 include spherical or otherwise convex inner surfaces that match the contour of the outer radial surfaces of the heads 28 of the first bone anchors 22. A plurality of first bone anchors 22 can be installed in the anchor plate 708 such that each head 28 is disposed in a corresponding aperture 712, with the shafts 26 of the first bone anchors 22 received in corresponding grooves 706 in the implant 700. The second bone anchors 24 are fastened to the first bone anchors 22 in the manner described above, such that the shafts 42 of the second bone anchors 24 are received in corresponding grooves 706 in the implant 700. It should be noted that while the illustrated embodiment depicted in
The body 710 of the anchor plate 708 includes an attachment aperture 714 defined in the proximal end 710a, the attachment aperture configured to releasably engage with an attachment, such as an insertion tool used to dispose the intervertebral implant system 27 into an intervertebral space within a patient. The body 710 can further include one or more mounting structures for coupling the anchor plate 708 to the implant 700. For example, as illustrated, a pair of mating clips 716 extend outwardly from the upper and lower surfaces 710c and 710d at the distal end 710b of the body 710. The mating clips 716 are configured to releasably engage with the retention slots 704 of the implant 700, thereby coupling the anchor plate 708 to the implant 700. It should be noted that the mating clips 716 are merely example mounting structures for use in coupling the anchor plate 708 to the implant 700, and any other mounting structures may be utilized as desired to couple the anchor plate 708 to the implant 700.
During use, an intervertebral implant 700 appropriate to the procedure being performed is selected and an anchor plate 208 is coupled thereto, for example by snapping the mounting clips 716 of the anchor plate 708 into position within the retention slots 704 of the implant 700. The intervertebral implant system 27 is then disposed within an intervertebral space within a patient, for example with the use of an insertion tool engaged within the attachment aperture 714 of the anchor plate 708. Once the implant 700 is disposed within the intervertebral space, the fixation systems 20 are affixed to the adjacent vertebral bodies V, for instance in the lumbar spine region, via a direct lateral approach, or in the cervical spine region, via an anterior approach. In particular, both sets of bone anchors 22 and 24 extend into target vertebral body bone segments of the adjacent vertebral bodies V. In accordance with the illustrated embodiment, the shafts 26 of the first bone anchors 22 of the pair of anchor-in-anchor assemblies 20 are inserted through the apertures 712 of the anchor plate 708, received within the grooves 706 of the implant 700, and inserted into target vertebral body bone segments of respective adjacent vertebral bodies V such that the heads 28 of the first bone anchors 22 are received in the apertures 712. Target vertebral body bone segments can include a cortical rim, cancellous bone, and the like of a respective target vertebral body.
In the illustrated embodiment, the shaft 26 of the first bone anchor 22 of the first fixation system 20 is inserted into one of the apertures 712 along a generally cranial trajectory so as to engage the adjacent vertebral body V directly above the implant 700, while the shaft 26 of the first bone anchor 22 of the second fixation system 20 is inserted into the other aperture 712 along a generally caudal trajectory so as to engage the adjacent vertebral body V directly below the implant 700. It should be noted that the shafts 26 of the first bone anchors 22 may be inserted in any alternative configuration as desired, for example by reversing the cranial and caudal insertion trajectories described above, by inserting both of the first bone anchors 22 along generally caudal insertion trajectories, or inserting both of the first bone anchors 22 along generally cranial insertion trajectories.
The first bone anchors 22 are oriented such that the central axes C1 determine insertion trajectories for the shafts 42 of the second bone anchors 24 into target vertebral body bone segments of the respective adjacent vertebral bodies V. Thereafter, the shafts 42 of the second bone anchors 24 are inserted through the heads 28 of the first bone anchors 22 in the manner described above, received in the corresponding grooves 706, and inserted into the target vertebral body bone segments of the respective adjacent vertebral bodies V. It should be noted that the intervertebral implant 700 and the anchor plate 708 can be used in combination with the anchor-in-anchor fixation system 20 as depicted and described herein, the anchor-in-anchor fixation system 120, or any combination thereof.
Referring now to
The body 802 further includes a pair of generally opposing apertures 804a and 804b formed therein, the apertures 804a and 804b configured to receive the anchor-in-anchor assembly 20. The apertures 804a and 804b can be defined as circular, slot shaped, or any other geometry as required, in order to receive the first and second anchors 22 and 24 of the anchor-in-anchor assembly 20. The inner surfaces of the apertures 804a and 804b may be smooth, or may have threads formed therein configured to engage complimentary threads on the shafts 26 and 42 of the first and second anchors 22 and 24. Additionally, the aperture 804a may be countersunk or otherwise defined within the body 802 of the interspinous spacer 800 such as to receive the head 28 of the first bone anchor 22 nestably therein. It should be noted that the interspinous spacer 800 can be configured to be used in combination with more than one anchor-in-anchor assemblies 20 and/or 120, for example to achieve varying anchoring configurations for securing the interspinous spacer 800 to a target vertebral body V.
During use, the interspinous spacer 800 is disposed within an interspinous space between the spinous processes SP of adjacent vertebral bodies within a patient. With the spacer 800 disposed within the interspinous space, the fixation systems 20 are affixed to target vertebral body bone segments of an adjacent target vertebral body V, for instance in the lumbar spine region, via a direct posterior approach. In particular, both the first and second bone anchors 22 and 24 are inserted through the apertures 804a and 804b and into target vertebral body bone segments of the adjacent target vertebral body V. Target vertebral body bone segments may include spinous processes, laminae, pedicles, facets, and the like. In accordance with the illustrated embodiment, the shaft 26 of the first bone anchor 22 of the anchor-in-anchor assembly 20 is inserted through the apertures 804a and 804b of the interspinous spacer 800 and driven into a first target bone segment of the target vertebral body V such that the head 28 of the first bone anchor 22 is received in the aperture 804a. The first bone anchor 22 is oriented such that the central axis C1 is aligned with the desired insertion trajectory for the second bone anchor 24 into a second target bone segment of the target vertebral body V. Thereafter, the shaft 42 of the second bone anchor 24 is inserted through the head 28 of the first bone anchor 22 in the manner described above, and into the second target bone segment of the target vertebral body V. It should be noted that the interspinous spacer 800 can be used in combination with the anchor-in-anchor fixation system 20 as depicted and described herein, the anchor-in-anchor fixation system 120, or any combination thereof.
It should be appreciated that a kit can be provided that includes one or more bone fixation assemblies 23 or components thereof as described above. The components of the kit can be configured the same or differently. For instance, bone anchors 22 and 24 can be provided having different lengths and outer diameters of the shafts 42 and 26, differently constructed shafts and threads depending on the needs of the surgeon and the surgical procedure being performed, and different angles α defined between the shafts and heads. The kit can further include one or more auxiliary fixation devices of the type described above.
Although the invention has been described with reference to preferred embodiments or preferred methods, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. For instance, it should be appreciated that the structures and features of the various bone fixation assemblies and systems described herein and their components can be incorporated into any of the other bone fixation assemblies and systems described herein and their components, unless otherwise indicated. Furthermore, although the invention has been described herein with reference to particular structure, methods, and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all structures, methods and uses that are within the scope of the present invention, along with kits having one or more fixation systems, assemblies, or components thereof as described herein. Those skilled in the relevant art, having the benefit of the teachings of this specification, may effect numerous modifications to the invention as described herein, and changes may be made without departing from the scope and spirit of the invention, for instance as recited in the appended claims.
This application is a continuation in part of U.S. patent application Ser. No. 12/631,293, filed Dec. 4, 2009. U.S. patent application Ser. No. 12/631,293 claims the benefit of U.S. Patent Application Ser. No. 61/120,138, filed Dec. 5, 2008. U.S. patent application Ser. No. 12/631,293 and 61/120,138 are incorporated herein by reference in their entirety.
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