Unitarily formed expandable spinal implant and method of manufacturing and implanting same

A unitarily formed expandable spinal implant for insertion in a disc space between two adjacent vertebrae. The unitarily formed expandable spinal implant is moveable from an unexpanded configuration to an expanded configuration, and can be manufactured by a 3-dimensional printer. The unitarily formed expandable spinal implant includes an upper portion, a lower portion, a proximal wall, a first distal wall portion, a second distal wall portion, and a separator connected by at least one point of attachment to the spinal implant. A separation tool breaks the separator free from the at least one point of attachment, and moves the separator within the implant to force expansion thereof from the unexpanded configuration to the expanded configuration.

BACKGROUND OF THE INVENTION

The present invention relates to a unitarily formed expandable spinal implant for use in spinal surgery. More particularly, the present invention relates to a unitarily formed expandable spinal implant for implantation into a disc space between two adjacent vertebrae, and movable from an unexpanded configuration to an expanded configuration. More specifically, the present invention relates to a unitarily formed expandable spinal implant including a component fixed as a unitary part thereof, which is configured, following implantation of the implant into a disc space between two adjacent vertebrae, to be broken free by an insertion tool, and moved within the implant to force expansion of the implant. The present invention further relates to a unitarily formed expandable spinal implant manufactured using a 3-dimensional printer.

DESCRIPTION OF THE RELATED ART

Expandable spinal implants are known in the art. Such expandable spinal implants can be configured to ultimately have lordotic, tapered configurations to assist in the restoration or enhancement of spinal lordosis. The expandability of such implants allows placement thereof into a corresponding surgically-enhanced disc space between two adjacent vertebrae through a relatively small surgical opening in a patient's body. Thereafter, expansion of the implants provides the advantage of increasing the heights thereof within the disc space to assist in the restoration or enhancement of spinal lordosis. The related art expandable fusion implants, however, have certain disadvantages.

The related art implants are typically manufactured with multiple parts, using traditional manufacturing methods, requiring the use of an excessive amount of material, e.g., titanium, to manufacture all of the components. For example, a significant portion of extra manufacturing material is milled away to configure the various necessary components that define the implant. The need to remove such extra manufacturing material both increases the manufacturing cost, and, for the sake of efficiency, requires the manufacture of the various components of the implants in bulk quantities.

The related art implants further are not unitarily formed expandable spinal implants configured to, after implantation into the disc space, be converted to multiple-part implants by breaking one part free from the remainder of the implant and expanding the implant with that one part.

SUMMARY OF THE INVENTION

In accordance with the invention, a unitarily formed expandable spinal implant is configured to be inserted into a disc space between two adjacent vertebrae.

The unitarily formed expandable spinal implant includes an upper portion having a proximal end and an opposite distal end, an upper portion exterior surface and an upper portion interior surface, the upper portion exterior surface and the upper portion interior surface extending from at least adjacent the proximal end to at least adjacent the distal end of the upper portion, the upper portion exterior surface configured to contact one of the two adjacent vertebrae, the upper portion interior surface at least in part declining between the upper portion proximal end and the upper portion distal end, and at least one opening being provided in the upper portion between the upper portion interior surface and the upper portion exterior surface.

The unitarily formed expandable spinal implant includes a lower portion having a proximal end and an opposite distal end, a lower portion exterior surface and a lower portion interior surface, the lower portion exterior surface and the lower portion interior surface extending from at least adjacent the proximal end to at least adjacent the distal end of the lower portion, the lower portion exterior surface configured to contact the other of the two adjacent vertebrae, the lower portion interior surface at least in part declining between the lower portion proximal end and the lower portion distal end, and at least one opening being provided in the lower portion between the lower portion interior surface and the lower portion exterior surface.

The unitarily formed expandable spinal implant further includes a chamber between portions of the upper portion and the lower portion.

The unitarily formed expandable spinal implant further includes a proximal wall having an exterior surface and an interior surface, the proximal wall extending between the upper portion and the lower portion, the proximal wall having a maximum height, and an aperture provided in the proximal wall between the interior surface and the exterior surface thereof, the aperture provided in the proximal wall communicating with the chamber.

The unitarily formed expandable spinal implant further includes a first distal wall portion and a second distal wall portion, the first distal wall portion being attached to the upper portion at the distal end thereof, the second distal wall portion being attached to the lower portion at the distal end thereof, the first distal wall portion and the second distal wall portion having a first height less than the maximum height of the proximal wall.

The unitarily formed expandable spinal implant further includes a separator having a leading portion, the separator being unitarily formed with one of the upper portion interior surface, the lower portion interior surface, and the interior surface of the proximal wall. The separator is configured to be separated by an insertion tool inserted through the aperture in the proximal wall and into contact with a trailing portion of the separator from at least one point of attachment to the remainder of the spinal implant, thereby converting the implant into a multiple-part implant. The insertion tool is further configured to force the separator toward the distal end of the spinal implant, and, in doing so, force the upper portion and the lower portion apart from one another to expand the spinal implant in the disc space into an expanded configuration, the first distal wall portion and the second distal wall portion having a second height in the expanded configuration greater than the maximum height of the proximal wall.

In accordance with another aspect of the present invention, a method of manufacturing a unitarily formed expandable spinal implant for implantation in a disc space between two adjacent vertebrae is provided. The method includes utilizing a 3-dimensional printer to lay down sequential layers of an upper portion having a proximal end and an opposite distal end, the upper portion having an upper portion exterior surface and an upper portion interior surface, the upper portion exterior surface and the upper portion interior surface extending from at least adjacent the upper portion proximal end to at least adjacent the upper portion distal end, the upper portion exterior surface being configured to contact one of the two adjacent vertebrae, the upper portion interior surface at least in part declining between the upper portion proximal end and the upper portion distal end, and at least one opening being defined between the upper portion interior surface and the upper portion exterior surface; utilizing the 3-dimensional printer to lay down sequential layers of a lower portion having a proximal end and an opposite distal end, the lower portion having a lower portion exterior surface and a lower portion interior surface, the lower portion exterior surface and the lower portion interior surface extending from at least adjacent the lower portion proximal end to at least adjacent the lower portion distal end, the lower portion exterior surface being configured to contact the other of the two adjacent vertebrae, the lower portion interior surface at least in part inclining between the lower portion proximal end and the lower portion distal end, and at least one opening being defined between the lower portion interior surface and the lower portion exterior surface; utilizing the 3-dimensional printer to lay down sequential layers of a proximal wall having an exterior surface and an interior surface, the proximal wall extending between the upper portion and the lower portion, the proximal wall having a maximum height, and an aperture provided in the proximal wall between the interior surface and the exterior surface thereof, the aperture provided in the proximal wall communicating with a chamber formed between portions of the upper portion interior surface and the lower portion interior surface; utilizing the 3-dimensional printer to lay down sequential layers of a first distal wall portion and a second distal wall portion, the first distal wall portion being attached to the upper portion at the distal end thereof, the second distal wall portion being attached to the lower portion at the distal end thereof, the first distal wall portion and the second distal wall portion having a first height less than the maximum height of the proximal wall; and utilizing the 3-dimensional printer to lay down sequential layers of a separator including a leading portion, the separator being unitarily formed with one of the upper portion interior surface, the lower portion interior surface, and the interior surface of the proximal wall by at least one point of attachment; wherein the separator is configured to be separated from the at least one point of attachment, and be moved along at least a portion of the lower portion interior surface and at least a portion of the upper portion interior surface toward the first distal wall portion and the second distal wall portion to move the upper portion and the lower portion apart from one another into an expanded configuration, the first distal wall portion and the second distal wall portion having a second height in the expanded configuration greater than the maximum height of the proximal wall.

In accordance with yet another aspect of the present invention, a method of implanting a unitarily formed expandable spinal implant into a disc space between two adjacent vertebrae is provided. The method includes utilizing the unitarily formed expandable spinal implant including: an upper portion having a proximal end, an opposite distal end, an upper portion exterior surface, and an upper portion interior surface, the upper portion exterior surface and the upper portion interior surface extending from at least adjacent the upper portion proximal end to at least adjacent the upper portion distal end, the upper portion exterior surface being configured to contact one of the two adjacent vertebrae, the upper portion interior surface at least in part declining between the upper portion proximal end and the upper portion distal end, and at least one opening being defined between the upper portion interior surface and the upper portion exterior surface; a lower portion having a proximal end, an opposite distal end, a lower portion exterior surface, and a lower portion interior surface, the lower portion exterior surface and the lower portion interior surface extending from at least adjacent the lower portion proximal end to at least adjacent the lower portion distal end, the lower portion exterior surface being configured to contact the other of the two adjacent vertebrae, the lower portion interior surface at least in part declining between the lower portion proximal end and the lower portion distal end, and at least one opening being defined between the lower portion interior surface and the lower portion exterior surface; a proximal wall having an exterior surface and an interior surface, the proximal wall extending between the upper portion and the lower portion, the proximal wall having a maximum height, and an aperture provided in the proximal wall between the interior surface and the exterior surface thereof; a chamber formed between portions of the upper portion interior surface, the lower portion interior surface, and the interior surface of the proximal wall, the aperture formed in the proximal wall communicating with the chamber; a first distal wall portion and a second distal wall portion, the first distal wall portion being attached to the upper portion at the distal end thereof, the second distal wall portion being attached to the lower portion at the distal end thereof, the first distal wall portion and the second distal wall portion having a first height less than the maximum height of the proximal wall; and a separator including a leading portion, the separator being unitarily formed with one of the upper portion interior surface, the lower portion interior surface, and the interior surface of the proximal wall by at least one point of attachment; wherein the separator is configured to be separated from the at least one point of attachment and be moved along at least a portion of the lower portion interior surface and at least a portion of the upper portion interior surface toward the first distal wall portion and the second distal wall portion to move the upper portion and the lower portion apart from one another into an expanded configuration, the first distal wall portion and the second distal wall portion having a second height in the expanded configuration greater than the maximum height of the proximal wall; inserting the spinal implant into the disc space; inserting an insertion tool through the aperture defined in the proximal wall and into contact with the separator; applying force to the separator with the insertion tool to break the at least one point of attachment; and forcing the separator along the upper portion interior surface and the lower portion interior surface toward the first distal wall portion and the second distal wall portion to move the upper portion and the lower portion apart from one another into the expanded configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the present invention, a first embodiment of a unitarily formed expandable spinal implant10is depicted inFIGS. 1-9, In accordance with the present invention, a second embodiment of a unitarily formed expandable spinal implant110is depicted inFIGS. 10-13, and a third embodiment of a unitarily formed expandable spinal implant210is depicted inFIGS. 14-17. As discussed below, each of the spinal implants10,110, and210are formed as a single part/component. Similar numerals are used to describe similar features of the unitarily formed expandable spinal implants10,110, and210.

The spinal implants10,110, and210can be used as fusion implants, and are configured for placement in a disc space between two adjacent vertebrae. The spinal implants10,110, and210can be packed with fusion promoting materials to facilitate their use as spinal fusion cages. To that end, the spinal implants10,110, and210include interior cavities (or chambers) C for receiving the fusion promoting materials therein. Furthermore, as discussed below, the spinal implants10,110, and210can be moved from an unexpanded configuration to an expanded configuration. In doing so, the implants10,110, and210can be used in producing an angular relationship between the two adjacent vertebrae corresponding to naturally occurring physiologic lordosis.

As depicted inFIGS. 1-3, the spinal implant10includes a proximal end12and a distal end14opposite from one another, and a mid-longitudinal axis X-X extending through the proximal end12and the distal end14. The spinal implant10includes an upper portion20having a proximal end22, a distal end24opposite the proximal end22, an upper portion exterior surface26, an upper portion interior surface28, and a plurality of apertures29provided between the upper portion exterior surface26and the upper portion interior surface28. Furthermore, the spinal implant10includes a lower portion30having a proximal end32, a distal end34opposite the proximal end32, a lower portion exterior surface36, a lower portion interior surface38, and a plurality of apertures39provided between the lower portion exterior surface36and the lower portion interior surface38.

The upper portion interior surface28and the lower portion interior surface38in part define the interior cavity (or chamber) C of the spinal implant10. As depicted inFIG. 3, the upper portion interior surface28declines from adjacent the proximal end22to adjacent the distal end24, and the lower portion interior surface38inclines from adjacent the proximal end32to adjacent the distal end34. The upper portion exterior surface26and the lower portion exterior surface36can include surface roughenings27and37, respectively. The surface roughenings27and37can be used to engage the adjacent vertebrae to inhibit movement of the spinal implant10after implantation thereof in the disc space.

As depicted inFIG. 1, the spinal implant10includes a proximal wall40at the proximal end12thereof. The proximal wall40extends between the upper portion20and the lower portion30. The proximal wall40includes an upper edge portion42to which the proximal end22of the upper portion20is attached, and a lower edge portion44to which the proximal end32of the lower portion30is attached. The proximal wall40also includes an exterior surface46and an interior surface47. The proximal wall40has a height H1(FIG. 8), and aperture48defined therein positioned between the upper edge42and the lower edge44. The aperture48extends between the exterior surface46and the interior surface47, and the interior surface47(with the upper portion interior surface28and the lower portion interior surface38) in part define the interior cavity C of the spinal implant10.

The spinal implant10, as depicted inFIG. 2, includes a first distal wall portion50and a second distal wall portion52at the distal end14thereof. The first distal wall portion50is attached at the distal end24of the upper portion20, and the second distal wall portion52is attached at the distal end34of the lower portion30. The first distal wall portion50depends downwardly from the upper portion20, and the second distal wall portion52depends upwardly from the lower portion30. The second distal wall portion52includes side portions54and55defining a notch56therebetween. The notch56is sized to receive the first distal wall portion50therein when the spinal implant10is in the unexpanded configuration.

As depicted inFIG. 8, the first distal wall portion50and the second distal wall portion52together have a height H2. The height H2corresponds to the unexpanded configuration of the spinal implant10. The height H2is less than the height H1of the proximal wall40, and thus, the implant10has an overall tapered wedge profile in the unexpanded configuration thereof. The overall tapered wedge profile facilitates insertion of the spinal implant10into the disc space.

The spinal implant10includes a separator60initially attached as a unitary part of the spinal implant10. As depicted inFIG. 8, the separator60is initially attached to the remainder of the spinal implant10proximate the proximal wall40. For example, the separator60can be attached to one of the upper portion interior surface28, the lower portion interior surface38, and the interior surface47of the proximal wall40. The separator60is attached to and suspended from the upper portion interior surface28of the upper portion20by at least one stem. One or more stems68can be used for attachment to and suspension from the upper portion interior surface28, or alternatively or in addition thereto, one or more stems68can be used for attachment to and suspension of the separator60from the lower portion interior surface38and/or the interior surface47of the proximal wall40.

As discussed below, the two stems68can be broken so that the separator60can be separated from the upper portion interior surface28. Thereafter, the separator60can be moved along the upper portion interior surface28and the lower portion interior surface38. Given the inclinations of the upper portion interior surface28and the lower portion interior surface38, movement of the separator60towards the distal end14of the spinal implant10forces the upper portion20and lower portion30away from one another. In doing so, the spinal implant10can be moved from the unexpanded configuration (FIG. 8) to an expanded configuration (FIG. 9).

The separator60includes a trailing portion62and a leading portion64. The trailing portion62is positioned proximate the proximal wall40, and the leading portion64projects from upper and lower ends of the trailing portion62toward the first distal wall portion50and the second distal wall portion52. As depicted inFIG. 3, the trailing portion62is flattened, and the leading portion64is partially cylindrical. Furthermore, the trailing portion62includes a threaded aperture65therein. Also as depicted inFIG. 3, an extension portion66projects from the leading portion64toward the first distal wall portion50and the second distal wall portion52. The present invention, however, is not limited to a separator60having the above-described configuration. For example, the separators160and260used in association with the spinal implants110and210, respectively, have different configurations.

As depicted inFIGS. 1, 2, 3, 8, and 9, the upper portion20and the lower portion30further include a generally concave depression70defined in the upper portion interior surface28and the lower portion interior surface38proximate the first distal wall portion50and the second distal wall portion52. The shape of the generally concave depression70can be complementary to the shape of the leading portion64of the separator60. As such, receipt of the leading portion64in the generally concave depression70can be used to inhibit further movement of the separator60toward the distal end14of the spinal implant10. Furthermore, receipt of the extension portion66in the notch56between the side portions54and55of the second distal wall portion52can be used to inhibit side-to-side movement of the separator60when the leading portion64is received in the generally concave depression70. Thus, the separator60can be moved toward the distal end14to move the spinal implant10from the unexpanded configuration to the expanded configuration, and ultimately be moved into seating engagement in the generally concave depression70and the notch56to maintain the spinal implant10in the expanded configuration.

As depicted inFIG. 9, the first distal wall portion50and the second distal wall portion52together have a height H3. The height H3corresponds to the expanded configuration of the spinal implant10. The height H3is greater than the height H1of the proximal wall40. As such, the spinal implant10can be inserted into the disc space having an overall tapered wedge profile (unexpanded configuration), and thereafter the distal end14can be expanded from the height H2to the height H3to produce an angular relationship between the two adjacent vertebrae corresponding to naturally occurring physiologic lordosis.

An insertion tool80is provided to facilitate insertion of the spinal implant10into the disc space between the two adjacent vertebrae, and to facilitate expansion of the spinal implant10from the unexpanded configuration to the expanded configuration after insertion thereof. Furthermore, after implantation of the implant10into the disc space, the configuration of the insertion tool80affords breakage of the separator60from the stems68(which attach the separator60to the implant10), and movement of the separator60along the upper portion interior surface28and the lower portion interior surface38toward the distal end14of the spinal implant10. As discussed above, such movement of the separator60serves in expanding the implant10by forcing the upper portion20and the lower portion30apart from one another.

The insertion tool80includes a handle portion82configured to be held by a surgeon, and an operational portion84configured to cooperate with the separator60. The operational portion84defines an axis Y-Y that is oriented generally transverse to the handle portion82. As depicted inFIGS. 8 and 9, when the insertion tool80is applied to the spinal implant10, the axis Y-Y of the operational portion84is generally coaxial with the axis X-X of the spinal implant10.

As depicted inFIG. 4, operational portion84includes a proximate end86and a distal end87opposite from one another. Furthermore, the operational portion84includes a body portion88, a knob portion90, an elongated shaft portion92, and an elongated rod portion94moveable with respect to the shaft portion92. As depicted inFIG. 4, the knob portion90includes the proximal end86and extends from the body portion88towards the proximal end86, and the shaft portion92includes the distal end87and extends from the body portion88towards the distal end87. The rod portion94extends from the body portion88towards the distal end87and is extendable beyond the distal end87. The shaft portion92includes an aperture95for receiving the rod portion94therethrough that extends from the body portion88towards the distal end87. Prior to inserting the knob portion90into the body portion88, the rod portion94is advanced into engagement with the spinal implant10either manually or via another tool (not shown).

The shaft portion92is partially split along the axis Y-Y, and includes a first arm portion96with a first flange97and a second arm portion98with a second flange99. The first and second flanges97and99are provided at the distal end87of the operational portion84. The first and second arm portions96and98(and the first and second flanges97and99) are biased toward the axis Y-Y, and the first and second flanges97and99are moveable from a disengaged position to an engaged position.

The rod portion94extends from the aperture95between the first and second arms96and98towards the distal end87. Movement of the rod portion94within the shaft portion92towards the distal end87moves the two flanges97and99apart from one another. In doing so, the first and second flanges97and99can be moved from the disengaged position to the engaged position. As depicted inFIG. 5, when in the disengaged position, the first and second flanges97and99can be received through the aperture48formed in the proximal wall40. Thereafter, movement of the first and second flanges97and99from the disengaged position to the engaged position serves in expanding the flanges97and99apart from one another and into contact with the sides of the aperture48. As depicted inFIG. 6, such contact serves in holding the spinal implant10on the distal end87of the operational portion84of the insertion tool80. The rod portion94includes an end portion100with threads102provided thereon, and the threads102move into engagement with the separator60. In doing so, the end portion100and threads102, as depicted inFIGS. 8 and 9, are received in the threaded aperture65in the trailing portion62of the separator60and rotated into engagement. As depicted inFIG. 7, with the spinal implant10being held by the insertion tool80with the knob portion90engaged to the body portion88, the insertion tool80can be used to insert the spinal implant10into the disc space between the two adjacent vertebrae.

With the knob portion90engaged to the body portion88, movement of the knob portion90serves in manipulating the rod portion94. For example, rotation of the knob portion90linearly advances the rod portion94, and movement of the knob portion90along axis Y-Y results in movement of the rod portion along axis Y-Y.

Further movement of the knob portion90can result in further motion of the rod portion94along axis Y-Y. Such motion of the rod portion94exerts pressure against the separator60, and such pressure applied to the separator60can break the separator60free from its attachment to the remainder of the spinal implant10. For example, such pressure can break the two stems68to release the separator60from its attachment to and suspension from the upper portion interior surface28. Once separated from the remainder of the spinal implant10, the separator60can be moved by the rod portion94(via movement of the knob portion90) along the upper portion of interior surface28and the lower portion of interior surface38toward the distal end14. As discussed above, such movement forces the upper portion20and lower portion30away from one another, so that the spinal implant10can be moved from the unexpanded configuration (FIG. 8) to an expanded configuration (FIG. 9). Ultimately, the separator60is moved by the rod portion94into seating engagement in the generally concave depression70and the notch56to maintain the spinal implant10in the expanded configuration.

After the spinal implant10has been implanted, moved from the unexpanded position to the expanded position via movement of the separator60, and the insertion tool80is detached from the spinal implant10, the interior cavity C can be packed with fusion promoting materials to facilitate its use as a spinal fusion cage. For example, the fusion promoting materials can be inserted through the aperture48in the proximal wall40into the interior cavity C.

As discussed above, the second embodiment of a unitarily formed expandable spinal implant110is depicted inFIGS. 10-13, and the third embodiment of a unitarily formed expandable spinal implant210is depicted inFIGS. 14-17. Numerals similar to those used to describe the features of the spinal implant10are also used to describe the features of the spinal implants110and210. Like the spinal implant10, the spinal implants110and210can be moved from an unexpanded configuration (FIGS. 12 and 16) to an expanded configuration (FIGS. 13 and 17).

The present invention further includes a method of manufacturing the unitarily formed expandable spinal implants10,110, and210having the structural features described above using a 3-dimensional printer. The method includes forming sequential layers of each of the above-described components of the unitarily formed expandable spinal implants10,110, and210by selectively sintering layers of titanium powder, with a laser, to create sequential layers of each component. The titanium powder is applied, and successive layers sintered, until each respective complete component, and eventually the complete unitarily formed expandable spinal implants10,110, and210, configured as disclosed above, is manufactured. Preferably, the titanium powder is provided by a powder dispensing mechanism, and the laser is controlled by a computer, preprogrammed with CAD data depicting the configuration of each part of the unitarily formed expandable spinal implants10,110, and210, as described above. One complete exemplary description of the manufacturing process used by the 3-dimensional printer is disclosed in U.S. Pat. No. 5,639,070, the contents of which are incorporated herein by reference.