INTERBODY SPACER
An interbody spacer includes concave lateral surfaces extending at an angle with respect to the longitudinal axis. In one aspect, the interbody spacer includes upper and lower convex surfaces defined by an arc extending from a center point offset from the spacer midpoint. In another aspect, lateral edges of the upper and lower surfaces are also defined by convex arcs extending from a center point offset from the spacer midpoint.
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The present invention relates to devices adapted for spacing between two adjacent vertebrae.
It is known that if an intervertebral disc is damaged, it can be removed and the resulting space between the two adjacent vertebrae may be filled with a bone growth inducing substance to promote a honey fusion across the disc space. Fixation devices external to the disc space have been utilized to maintain the position of the adjacent vertebrae while the intervening material fuses with adjacent bone to form a honey bridge. As an alternative or in conjunction with fixation devices, load bearing spacers, such as artificial devices or bone grafts, may be placed in the empty disc space. These spacers transmit the loading from one adjacent vertebra to the other adjacent vertebra during the healing process. Such spacers may be provided in a variety of forms.
A need exists for improvements to existing interbody spacers and the present invention is directed to such need.
SUMMARY OF THE INVENTIONThe present invention provides an improved interbody fusion device adapted for spacing two adjacent vertebral bodies. In one preferred aspect but without limitation to embodiments incorporating alternative features, the spacer includes lateral surfaces that extend at an angle with respect to the longitudinal axis. In another preferred aspect, the spacer includes upper and lower convex surfaces adapted for engagement with adjacent vertebrae. Preferably, the convex surfaces are defined by an arc with a center point offset from the device midpoint, thereby establishing a spacer that may induce angulation when positioned in the disc space between adjacent vertebrae. In still a further preferred aspect, the lateral edges of the upper and lower surfaces are convex. Still more preferably, the center point for the arc defining the lateral edges is offset from the midpoint of the device.
The present invention also provides an inserter for use in combination with an interbody spacer. In a preferred embodiment, the inserter has a gripping end with a length approximately the length of the implant and, a width and height equal to or less than the width and height of the implant.
The present invention also provides a method for manufacturing an improved interbody spacer. In one preferred aspect of the method, one or more radiopaque markers is positioned in the spacer material and is shaped to conform to the exterior geometry of the implant.
These and other aspects and advantages of the present invention will become apparent to those skilled in the art from the description of the preferred embodiments set forth below.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
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Each of the top surface 22 and the bottom surface 24 include a series of projections 32 and 34, respectively. Each projection is rounded to eliminate an abrupt surface feature that may have a tendency to engage or tear soft tissue during insertion. In a preferred aspect, each projection peak has a convex radius R3 and a trough radius R2 extending between projections. In a preferred aspect, R3 is approximately 0.25 millimeters and R2 is approximately 0.8 millimeters.
Implant 20 is provided with a series of radiopaque markers to accommodate visualization of the implant during and after insertion into an intervertebral disc space when the implant is formed of substantially radiolucent material. Radiopaque markers 40 and 42 are positioned at the front or anterior portion of the device at the transition point between front portion 26 and top surface 22 and bottom surface 24, respectively. Radiopaque markers 44 and 46 are positioned on the top surface 22 and the bottom surface 24, respectively, adjacent posterior end 28. In a preferred aspect, radiopaque markers 40, 42, 44 and 46 are pins inserted into the implant material prior to formation of the exterior geometry. As illustrated in
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The above described implant has included a variety of improved features. While all of these features have been disclosed with reference to the described embodiment, it will be appreciated that one or any combination of features may be utilized with an improved interbody spacer. Further, while specific dimensions were disclosed suitable for spinal anatomy in the lumbar spine of some patients, a spacer may be configured with other dimensions suitable for interbody spacers at various levels, lumbar, thoracic, and cervical, of the spine for a variety of patient populations. For example, in an average patient population the anterior height of the device may range from 4 millimeters to 18 millimeters. Similarly, the posterior height of the device may range from 2 millimeters to 16 millimeters. Within this range, the longitudinal offset of the center point defining the arc of the top and bottom surfaces may be adjusted to create lordotic angulations ranging from 0° to 20°. Further, while a radius of approximately 75 millimeters has been shown for the purpose of illustrating the convex arc of the top and bottom surfaces, alternative radii lengths ranging from 120 millimeters to 30 millimeters may be used. It is anticipated that such radii may approximate a wide range of spinal anatomies. A radius of approximately 60 millimeters may be useful for implantation in smaller disc spaces.
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While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. One of ordinary skill will be able to effect various alterations, substitutions of equivalents and other changes without departing from the broad concepts imparted herein. It is, therefore, intended that the letters patent issued hereon be limited only by the definition contained in the appended claims and equivalents thereof.
Claims
1-36. (canceled)
37. An interbody spacer, comprising:
- a body extending along a longitudinal axis between a first end and a second end, the body comprising a top surface and an opposing bottom surface each extending between the first and second ends, the body comprising a first lateral surface and an opposite second lateral surface each extending between the top and bottom surfaces and between the first and second ends,
- wherein the top and bottom surfaces each include a series of spaced apart projections extending transverse to the longitudinal axis, the projections each extending between and connecting the first and second lateral surfaces, and
- wherein opposite ends of each projection are tapered from an adjacent one of the first and second lateral surfaces to a crest of the projection to facilitate rotation of the body about the longitudinal axis.
38. An interbody spacer as recited in claim 37, wherein the body is rounded between the top surface and the first and second lateral surfaces and between the bottom surface and the first and second lateral surfaces
39. An interbody spacer as recited in claim 37, wherein at least a portion of each of the first and second lateral surfaces is concavely curved between the top and bottom surfaces.
40. An interbody spacer as recited in claim 37, wherein the top and bottom surfaces are each continuously convexly curved between the first and second ends.
41. An interbody spacer as recited in claim 37, wherein:
- the first end defines a nose that is convexly curved between the top and bottom surfaces and between the first and second lateral surfaces; and
- the second end defines a planar end surface extending perpendicular to the longitudinal axis.
42. An interbody spacer as recited in claim 37, wherein the body is free of any openings extending into the top and bottom surfaces and the first and second lateral surfaces.
43. An interbody spacer, comprising:
- a body extending along a longitudinal axis between a first end and a second end, the body comprising a top surface and an opposing bottom surface each extending between the first and second ends, the top and bottom surfaces being continuously curved between the first and second ends, the body comprising a first lateral surface and an opposite second lateral surface each extending between the top and bottom surfaces and between the first and second ends,
- wherein the body is rounded between the top surface and the first and second lateral surfaces and between the bottom surface and the first and second lateral surfaces,
- wherein at least a portion of each of the first and second lateral surfaces is concavely curved between the top and bottom surfaces.
44. An interbody spacer as recited in claim 43, wherein the top and bottom surfaces each comprise a series of spaced apart projections, each of the projections extending perpendicular to the longitudinal axis.
45. An interbody spacer as recited in claim 44, wherein the projections each include a crest that is rounded.
46. An interbody spacer as recited in claim 43, wherein:
- the body has a length defined by a distance between the first and second ends;
- the body defines a midlength plane extending perpendicular to the longitudinal axis that is equidistant from each of the first and second ends; and
- the top and bottom surfaces are each convexly curved between the first and second ends such that the body has a maximum height defined by a distance between the top and bottom surfaces at a location that is offset from the midlength plane.
47. An interbody spacer as recited in claim 46, wherein:
- the first end defines a leading end and the second end defines a trailing end, the leading end having a maximum width defined by a distance between the first and second lateral surfaces that is greater than that of the trailing portion; and
- the location is positioned closer to the leading end than the trailing end.
48. An interbody spacer as recited in claim 43, wherein the first and second lateral surfaces are each continuously convexly curved between first and second ends.
49. An interbody spacer as recited in claim 43, wherein:
- the body has a length defined by a distance between the first and second ends;
- the body defines a midlength plane extending perpendicular to the longitudinal axis that is equidistant from each of the first and second ends; and
- the first and second lateral surfaces are each convexly curved between first and second ends such that the body has a maximum width defined by a distance between the first and second lateral surfaces at a location that is offset from the midlength plane.
50. An interbody spacer as recited in claim 49, wherein:
- the first end defines a leading end and the second end defines a trailing end, the leading end having a maximum width defined by a distance between the first and second lateral surfaces that is greater than that of the trailing portion; and
- the location is positioned closer to the leading end than the trailing end.
51. method for positioning an interbody spacer between vertebrae, comprising:
- providing an interbody spacer comprising a body extending along a longitudinal axis between a first end and a second end, the body comprising a top surface and an opposing bottom surface each extending between the first end and the second end, the top and bottom surfaces each comprising a series of spaced apart projections, the body comprising a first lateral surface and an opposite second lateral surface each positioned between the top surface and the bottom surface;
- positioning the interbody spacer between the vertebrae such that one of the first and second lateral surfaces faces a superior vertebra and the other of the first and second lateral surfaces faces an adjacent inferior vertebra; and
- rotating the interbody spacer between the vertebrae such that the projections of one of the top and bottom surfaces engage the superior vertebra and the projections on the other of the top and bottom surfaces engages the inferior vertebra.
52. A method as recited in claim 51, wherein:
- the body is rounded between the top surface and the first and second lateral surfaces and between the bottom surface and the first and second lateral surfaces; and
- each of the first and second lateral surfaces is concavely curved between the top and bottom surfaces.
53. A method as recited in claim 51, wherein:
- the body has a length defined by a distance between the first and second ends;
- the body defines a midlength plane extending perpendicular to the longitudinal axis that is equidistant from the first and second ends; and
- the top and bottom surfaces are each convexly curved between the first and second ends such that the body has a maximum height at a location that is offset from the midlength plane.
54. A method as recited in claim 53, wherein opposite ends of each projection are tapered from an adjacent one of the first and second lateral surfaces to a crest of the projection to facilitate rotation of the body about the longitudinal axis.
55. A method as recited in claim 51, wherein the first and second lateral surfaces are each smooth and free of any projections.
56. A method as recited in claim 51, wherein the body comprises PEEK.
Type: Application
Filed: Sep 26, 2013
Publication Date: Jan 30, 2014
Applicant: WARSAW ORTHOPEDIC, INC. (WARSAW, IN)
Inventors: Peter McCombe (Brisbane), B. Thomas Barker (Bartlett, TN), William Sears (St. Leonards), David Warmbold (Collierville, TN), Russell Powers (Collierville, TN)
Application Number: 14/037,730
International Classification: A61F 2/44 (20060101);