Interbody spinal fusion device

A spinal fusion implant includes a leading end, an opposite trailing end, an upper portion extending between the leading and trailing ends, a lower portion extending between the leading and trailing ends, and opposed first and second side portions extending between the leading and trailing ends. The upper portion includes at least two rails extending between the leading and trailing ends, the at least two rails including a first rail and a second rail spaced apart from one another, the first rail of the upper portion including a bone-contacting surface being at least partially smoothened. The lower portion includes at least two rails extending between the leading and trailing ends, the at least two rails including a first rail and a second rail spaced apart from one another, the first rail of the lower portion including a bone-contacting surface being at least partially smoothened.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an interbody spinal fusion device for insertion into a disc space between adjacent vertebral bodies. More specifically, the present invention relates to an interbody spinal fusion device having an upper portion and a lower portion configured to facilitate ease of insertion into a disc space between adjacent vertebral bodies. More specifically, the present invention relates to an interbody spinal fusion device including rails provided on each of an upper portion and a lower portion of the implant, the rails extending above and below surfaces of the upper portion and the lower portion to contact adjacent vertebral bodies to facilitate ease of insertion of the implant into a disc space between the adjacent vertebral bodies.

Description of the Prior Art

Some of the degenerative conditions that affect the spine of a patient may be so severe as to require surgical intervention. Oftentimes, the degenerative conditions are such that a spinal implant is required to restore the height of a disc space between adjacent vertebral bodies. Such spinal implants are insertable into the disc space between the adjacent vertebral bodies of adjacent vertebrae of the patient. Oftentimes, such spinal implants are configured for push-in insertion into the disc space, and require fastening or holding features to maintain the positions thereof in the disc space. However, such fastening or holding features can serve in resisting push-in insertion of the spinal implants into the disc space. Therefore, there is a need for a spinal implant that includes fastening or holding features, and also includes features facilitating insertion into the disc space.

SUMMARY OF THE INVENTION

The present invention in one preferred embodiment contemplates a spinal fusion implant including a leading end, an opposite trailing end, an upper portion extending between the leading and trailing ends, and a lower portion extending between the leading and trailing ends, the upper portion including a first portion positioned adjacent the leading end, a second portion positioned adjacent the trailing end, and at least two rails extending between the first and second portions of the upper portion, the lower portion including a first portion positioned adjacent the leading end, a second portion positioned adjacent the trailing end, and at least two rails extending between the first and second portions of the lower portion, the at least two rails of the upper portion including a first rail including a bone-contacting surface being at least partially smoothened and a second rail including a bone-contacting surface, and the at least two rails of the lower portion including a first rail including a bone-contacting surface being at least partially smoothened and a second rail including a bone-contacting surface, where the first rail of the upper portion and the first rail of the lower portion facilitate insertion of the implant into a disc space between adjacent vertebrae, and the second rail of the upper portion and the second rail of the lower portion serve in holding the implant in position between the adjacent vertebrae.

The present invention in another preferred embodiment contemplates a spinal fusion implant including a leading end, an opposite trailing end, an upper portion extending between the leading and trailing ends, a lower portion extending between the leading and trailing ends, a first side portion extending between the leading and trailing ends, and a second side portion extending between the leading and trailing ends, the first and second side portion being opposite from one another, the upper portion including a first portion adjacent the leading end, a second portion adjacent the trailing end, and first, second, and third rails spaced apart from one another and extending between the first and second portions of the upper portion, the lower portion including a first portion adjacent the leading end, a second portion adjacent the trailing end, and first, second, and third rails spaced apart from one another and extending between the first and second portions of the lower portion, the first rail of the upper portion being positioned between the second and third rails of the upper portion, the first rail of the lower portion being positioned between the second and third rails of the lower portion, the second rails of the upper and lower portions being positioned adjacent the first side portion, and the third rails of the upper and lower portions being positioned adjacent the second side portion, where the first rails of the upper and lower portions include bone-contacting surfaces being at least partially smoothened, and where the second and third rails of the upper and lower portions include bone-contacting surfaces.

The present invention in yet another preferred embodiment contemplates a spinal fusion implant including a leading end, an opposite trailing end, an upper portion extending between the leading and trailing ends, a lower portion extending between the leading and trailing ends, and opposed first and second side portions extending between the leading and trailing ends, the upper portion including at least two rails extending between the leading and trailing ends, the at least two rails including a first rail and a second rail spaced apart from one another, the first rail of the upper portion including a bone-contacting surface being at least partially smoothened, the lower portion including at least two rails extending between the leading and trailing ends, the at least two rails including a first rail and a second rail spaced apart from one another, the first rail of the lower portion including a bone-contacting surface being at least partially smoothened.

These and other objects of the present invention will be apparent from review of the following specification and the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An implant according to the present invention is generally indicated by the numeral10inFIGS. 1-8. The implant10is a spinal interbody fusion implant. As discussed below, the implant10is configured for insertion into a disc space between adjacent vertebrae, and is configured to allow bone growth therethrough between endplates of the adjacent vertebrae.

As depicted inFIGS. 1-8, the implant10includes a first end generally indicated by the numeral12and a second end generally indicated by the numeral14. The first end12and the second end14are opposite from one another. Furthermore, the implant10includes a hollow cavity16positioned between the first end12and the second end14. As discussed below, the hollow cavity16can be filled with bone growth promoting substances. Together with the configuration of the implant10, the bone growth promoting substances can promote growth of bone through the implant10between the endplates of the adjacent vertebrae and onto the surfaces of the implant, particularly the roughened surfaces.

The first end12is the leading end of the implant10, and the second end14is the trailing end of the implant10. As depicted inFIGS. 1-4, the first end12is configured to facilitate insertion of the implant10into the disc space, and the second end14is configured to facilitate engagement of an insertion instrument (not shown) used to insert the implant10into the disc space. To that end, the first end12includes a nose portion20facilitating the insertion of the implant10into the disc space, and the second end14includes various tool engaging apertures/slots facilitating engagement with the insertion instrument. For example, the nose portion20has a rounded wedge shape configuration, and the configuration of the nose portion20affords introduction of the implant10into the disc space via slidable engagement with and separation of the adjacent vertebrae. Furthermore, the second end portion14can include a threaded aperture22and slots26facilitating engagement with the insertion instrument, and the engagement therebetween allows manipulation of the implant10using the insertion instrument.

As depicted inFIGS. 1 and 2, the implant includes an upper portion30, a lower portion32, a first side portion34, and a second side portion36. The first side portion34and the second side portion36each include portions extending adjacent the upper portion30and the lower portion32between the first and second ends12and14. Furthermore, the first side portion34and the second side portion36each include a horseshoe-shaped surface40and an aperture42communicating with the hollow cavity16. The hollow cavity16and the apertures42define a passage through the implant10between the first side portion34and the second side portion36.

The upper portion30and the lower portion32each extend between the first and second ends12and14. The upper portion30includes a forward portion50adjacent the first end12, and a rearward portion52adjacent the second end14. The forward portion50and the rearward portion52each include surfaces for engaging the endplate of the upper of the adjacent vertebrae. The upper portion30also includes first, second, and third rails54,56, and58.

The first, second, third rails54,56, and58extend between the forward portion50and the rearward portion52, and serve in joining the forward portion50and the rearward portion52together. The first, second, and third rails54,56, and58are also for engaging the endplate of the upper of the adjacent vertebrae. The first rail54is positioned between the second rail56and the third rail58, the second rail56is positioned adjacent the first side portion34, and the third rail58is positioned adjacent the second side portion36. Various cross members60A,62A, and64A extend between the first rail54and the second rail56to join these rails together, and various cross members60B,62B, and64B extend between the first rail54and the third rail58to join these rails together.

Various apertures66,68,70,72,74,76,80, and82are formed in the upper portion30, and these apertures are bordered by at least two of the forward portion50, the rearward portion52, the first rail54, the second rail56, the third rail58, and the cross members60A,60B,62A,62B,64A, and64B. The apertures66,68,70,72,74,76,80, and82extend through the upper portion30, and communicate with the hollow cavity16. The apertures66,68,70,72,74,76,80, and82facilitate growth of bone from the upper of the adjacent vertebrae therethrough and into the hollow cavity16.

The first aperture66is at least bordered by the forward portion50, the first rail54, the second rail56, and the cross member60A. The second aperture68is at least bordered by the forward portion50, the first rail54, the third rail58, and the cross member60B. The third aperture70is at least bordered by the first rail54, the cross member60A, and the cross member62A. The fourth aperture72is at least bordered by the first rail54, the cross member60B, and the cross member62B. The fifth aperture74is at least bordered by the second rail56, the cross member62A, and the cross member64A. The sixth aperture76is at least bordered by the third rail58, the cross member62B, and the cross member64B. The seventh aperture80is at least bordered by the rearward portion52, the first rail54, and the cross member64A. The eighth aperture82is at least bordered by the rearward portion52, the first rail54, and the cross member64B.

As depicted inFIG. 1, the first rail54has a smoothened upper surface. Furthermore, although both are depicted as being at least partially serrated inFIG. 1, the second rail56can have a smoothened and/or a serrated upper surface, and the third rail58can have a smoothened and/or a serrated upper surface. When provided therewith, the smoothened upper surface of the first rail54serves in aiding the insertion of the implant10into the disc space between the adjacent vertebrae. When the upper surfaces of the second and third rails56and58are at least partially smoothened, the second and third rails56and58can serve in aiding the insertion of the implant10into the disc space. Moreover, when the upper surfaces of the second and third rails56and58are at least partially serrated, the second and third rails56and58can serve in resisting movement of the implant10after positioning thereof in the disc space.

The lower portion32includes a forward portion90adjacent the first end12, and a rearward portion92adjacent the second end14. The forward portion90and the rearward portion92each include surfaces for engaging the endplate of the lower of the adjacent vertebrae. The lower portion32also includes first, second, and third rails94,96, and98.

The first, second, and third rails94,96, and98extend between the forward portion90and the rearward portion92, and serve in joining the forward portion90and the rearward portion92together. The first, second, and third rails94,96, and98are also for engaging the endplate of the lower of the adjacent vertebrae. The first rail94is positioned between the second rail96and the third rail98, the second rail96is positioned adjacent first side portion34, and the third rail98is positioned adjacent the second side portion36. Various cross members100A,102A, and104A extend between the first rail94and the second rail96to join these rails together, and various cross members1006,102B, and104B extend between the first rail94and the third rail96to join these rails together.

Various apertures106,108,110,112,114,116,120,122are formed in the lower portion32, and these apertures are bordered by at least two of the forward portion90, the rearward portion92, the first rail94, the second rail96, the third rail98, and the cross members100A,1006,102A,102B,104A, and104B. The apertures106,108,110,112,114,116,120,122are formed and extend through the lower portion32, and communicate with the hollow cavity16. The apertures106,108,110,112,114,116,120,122facilitate growth of bone from the lower of the adjacent vertebrae therethrough and into the hollow cavity16.

The first aperture106is at least bordered by the forward portion90, the first rail94, the second rail96, and the cross member100A. The second aperture108is at least bordered by the forward portion90, the second rail96, and the cross member1006. The third aperture110is at least bordered by the first rail94, the cross member100A, and the cross member102A. The fourth aperture112is at least border by the first rail94, the cross member1006, and the cross member102B. The fifth aperture114is at least bordered by the second rail96, the cross member102A, and the cross member104A. The sixth aperture116is at least bordered by the third rail98, the cross member102B, and the cross member104B. The seventh aperture120is at least bordered by the rearward portion92, the first rail54, and the cross member104A. The eighth aperture122is at least bordered by the rearward portion92, the first rail94, and the cross member104B.

As depicted inFIG. 2, the first rail94has a smoothened lower surface. Furthermore, although both are depicted as being at least partially serrated inFIG. 2, the second rail96can have a smoothened and/or a serrated lower surface, and the third rail98can have a smoothened and/or a serrated lower surface. When provided therewith, the smoothened lower surface of the first rail94serves in aiding the insertion of the implant10into the disc space between the adjacent vertebrae. When the lower surfaces of the second and third rails96and98are at least partially smoothened, the second and third rails96and98can serve in aiding the insertion of the implant10into the disc space. Moreover, when the lower surfaces of the second and third rails96and98are at least partially serrated, the second and third rails96and98can serve in resisting movement of the implant10after positioning thereof in the disc space.

During insertion of the implant10into the disc space between adjacent vertebrae, the nose portion20of the first end12, the forward portion50of the upper portion30, and the forward portion90of the lower portion32first engage the adjacent vertebrae. In doing so, the nose portion20engages the upper and lower vertebrae, the forward portion50engages the upper vertebra, and the forward portion90engages the lower vertebra. Because of the rounded wedge shape of the nose portion20, and because the forward portions50and52are angled with respect to one another, the adjacent vertebrae are wedged apart from one another as the nose portion20, the forward portion50, and the forward portion90are pushed into engagement thereto.

As the implant is pushed further into the disc space, the first rail54of the upper portion30and the first rail94of the lower portion32engage the upper and lower vertebrae, respectively. Portions of the upper surface of the first rail54and portions of the lower surface of the first rails94are raised above and below, respectively, the remainder of the upper portion30and the lower portion32. Thus, given that the upper and lower surfaces of the first rails54and94are smoothened, the implant10slides on the first rails54and94during insertion of the implant10into the disc space. In other words, the upper surface of the first rail54and the lower surface of the first rail94provide mediums on which the implant10can slide during entry thereof into the disc space. When the upper surfaces of the second and third rails56and58and the lower surfaces of the second and third rails96and98are at least partially smoothened, these surfaces can also serve in aiding the insertion of the implant10into the disc space.

Once positioned in the disc space, the upper surfaces, if serrated, of the second and third rails56and58, and the lower surfaces, if serrated, of the second and third rails96and98serve in resisting movement of the implant10. If serrated, much of the upper surfaces of the second and third rails56and58would be positioned below the upper surface of the first rail54, and, if serrated, much of the lower surfaces of the second and third rails56and58are positioned above the lower surface of the first rail94. That is, when looking atFIGS. 3 and 4(i.e., the right and left side elevational views of the implant10), the first rail54has a larger profile than the second and third rails56and58due to the serrations, and the first rail94has a larger profile than the second and third rails96and98due to the serrations. The first rails54and94can also be configured to have larger or smaller profiles than the second rails56and96and/or the third rails58and98.

The endplates of the upper and lower vertebrae are generally concave between the anterior and posterior portions thereof and between the lateral sides thereof. Thus, when the implant10is inserted anteriorly or posteriorly and positioned between the endplates, the first rail54can be contacted to a more upper portion of the upper endplate than the portions of the upper endplate contacted by the second and third rails56and58, and the first rail94can be contacted to a more lower portion of the lower endplate than the portions of the lower endplate contacted by the second and third rails96and98. As discussed above, when provided with serrations, contact of the serrations of the second rails56and96and the third rails58and98serve in resisting movement of the implant10after implantation into the disc space.

The implant10can be manufactured using Additive Manufacturing Methods. Using Additive Manufacturing Methods, the various surfaces of the implant10can be provided with different textures, and these textures can be used to afford ease of insertion of the implant10into the disc space, or used to facilitate bone growth into the implant10. An example of Additive Manufacturing Methods is Direct Metal Laser Sintering. For example, portions of the nose portion20, the first, second, and third rails54,56, and58, and the first, second, third, rails94,96, and98can be manufactured to include smoothened surfaces as depicted inFIG. 9, and the remainder of the implant10can be manufactured to include roughened surfaces as depicted inFIG. 9. The reference to smoothened and roughened surfaces denotes a relative difference between the textures of these surfaces. As such, the smoothened surfaces can be somewhat rough, but be considerably smoother than the roughened surfaces

The smoothened surfaces can be provided to facilitate insertion of the implant10into the disc space, and the roughened surfaces can be provided to facilitate bone growth onto the implant10. Thus, the various surfaces afforded by the use of Additive Manufacturing Methods facilitates (via smoothened surfaces) entry of the implant10into the disc space, and facilitates (via roughened surfaces) integration of the implant10into the upper and lower vertebrae. Additionally, the various surfaces of the implant10can be smoothened using a polishing process.

The location of the smoothened surfaces of the implant10are generally indicated by the numeral130and are represented by stippling inFIGS. 1-8. The remainder of the surfaces of the implant10can be roughened. For example, the cross members60A,60B,62A,62B,64A, and64B and the cross members100A,100B,102A,102B,104A, and104B, as well as rearward portions52and92, can have roughened upper surfaces and roughened lower surfaces, respectively, that serve in resisting movement of the implant10after positioning thereof in the disc space. Settling of the implant10into the bone of the adjacent vertebrae causes increased contact with these roughened surfaces to increase resistance of the implant10to movement.

Additionally, as depicted inFIGS. 1-4, smoothened surfaces132can be provided on the surfaces40around the edges of apertures42and on the interior surfaces of the apertures42. The smoothened surfaces132can provide smoothened edges at the transition of the surfaces40into the apertures42.

It is also noted that the edges of the implant10can be rounded to minimize any potential harm to sensitive tissues during implantation of the implant10. For example, in addition to the nose portion20, the transitions between the upper portion30and the first and second side portions34and36, and the transitions between the lower portion32and the first and second side portions34and36can also be rounded.