Growing Spine Model

Abstract

A spinal surgery modeling system includes a spine model and a spine movement device. The spinal surgery modeling system provides a three-dimensional hands-on model that can be configured to have any desired variation of spinal alignment of the spine model by hydraulic actuation of the spine movement device to simulate the biomechanical feel and behavior of a patient's spine. The spine model may include various vertebral body or disc conditions and allows a clinician to examine and/or adjust the model and observe the three-dimensional outcome of such adjustments.

Claims

1. A spinal construct comprising: a plurality of screws; and an adjustable rod including: a hollow member defining a bore therethrough; and a first end member including a first segment in direct slidable engagement with the bore of the hollow member and a second segment securable to at least one screw of the plurality of screws, the first segment having a first shape and the second segment having a second shape different from the first shape, and the bore of the hollow member having a complementary geometry to that of the first segment.

2. The spinal construct according to claim 1, wherein the first segment of the first end member is rotationally fixed relative to the hollow member.

3. The spinal construct according to claim 1, wherein the first shape of the first segment of the first end member is an I-beam shape.

4. The spinal construct according to claim 1, wherein the second shape of the second segment of the first end member is a compound shape.

5. The spinal construct according to claim 4, wherein the compound shape includes an elongate round portion, an elongate head portion, and a neck portion connecting the elongate round portion with the elongate head portion.

6. The spinal construct according to claim 3, wherein the bore of the hollow member has an I-beam shape.

7. The spinal construct according to claim 1, wherein the hollow member has a fixed axial length and the bore extends longitudinally through the fixed axial length, and the bore is open at the first and second ends of the hollow member.

8. The spinal construct according to claim 1, wherein the first end member is freely extendable and retractable relative to the hollow member.

9. The spinal construct according to claim 1, wherein the adjustable rod further includes a second end member including a third segment engageable with the bore of the hollow member and a fourth segment securable to at least one screw of the plurality of screws.

10. The spinal construct according to claim 9, wherein the third segment of the second end member has a third shape different from a fourth shape of the fourth segment of the second end member.

11. The spinal construct according to claim 9, wherein the first and second end members are axially movable relative to the hollow member.

12. The spinal construct according to claim 11, wherein the first and second end members are freely extendable and retractable relative to the hollow member.

13. The spinal construct according to claim 9, wherein the second end member has a different range of travel relative to the hollow member than the first end member.

14. The spinal construct according to claim 9, wherein the third segment of the second end member has a third shape that is different from the first shape of the first segment of the first end member.

15. The spinal construct according to claim 14, wherein the first segment of the first end member and the third segment of the second end member are each in direct slidable engagement with the bore of the hollow member.

16. A spinal construct comprising: a plurality of screws; and an adjustable rod including: a hollow member defining a bore therethrough; and a first end member including a first segment in direct slidable engagement with the bore of the hollow member and a second segment securable to at least one screw of the plurality of screws, the first segment having an I-beam shape and the second segment having a compound shape including an elongate round portion, an elongate head portion, and a neck portion connecting the elongate round portion with the elongate head portion, wherein the bore of the hollow member has an I-beam shape.

17. The spinal construct of claim 16, wherein the adjustable rod further includes a second end member including a third segment engageable with the bore of the hollow member and a fourth segment securable to at least one screw of the plurality of screws.

18. The spinal construct of claim 17, wherein the first and second end members are axially movable relative to the hollow member.

19. The spinal construct of claim 16, wherein the first segment of the first end member is rotationally fixed relative to the hollow member.

20. The spinal construct of claim 16, wherein the second end member has a different range of travel relative to the hollow member than the first end member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is a front, perspective view of a spinal surgery modeling system in accordance with an embodiment of the present disclosure;

[0028] FIG. 2 is a back, perspective view of the spinal surgery modeling system of FIG. 1;

[0029] FIG. 3 is a front, perspective view of a spine movement device of the spinal surgery modeling system of FIG. 1;

[0030] FIG. 4 is a back, perspective view of the spine movement device of FIG. 3;

[0031] FIG. 5 is an exploded view of the spine movement device of FIG. 3;

[0032] FIG. 6A is a side view of the spine movement device of FIG. 3 in a first position;

[0033] FIG. 6B is a side view of the spine movement device of FIG. 3 in a second position;

[0034] FIG. 7A is a side view of the spinal surgery modeling system of FIG. 1 in a first position;

[0035] FIG. 7B is an enlarged view of a portion of a spine model of the spinal surgery modeling system, shown in the area of detail 7B identified in FIG. 7A;

[0036] FIG. 8A is a front view of the spinal surgery modeling system of FIG. 7A;

[0037] FIG. 8B is an enlarged view of a portion of a spine model of the spinal surgery modeling system, shown in the area of detail 8B identified in FIG. 8A;

[0038] FIG. 9A is a side view of the spinal surgery modeling system of FIG. 1 in a second position;

[0039] FIG. 9B is an enlarged view of a portion of a spine model of the spinal surgery modeling system, shown in the area of detail 9B identified in FIG. 9A;

[0040] FIG. 10A is a front view of the spinal surgery modeling system of FIG. 9A;

[0041] FIG. 10B is an enlarged view of a portion of a spine model of the spinal surgery modeling system, shown in the area of detail 10B identified in FIG. 10A;

[0042] FIG. 11A is a front, perspective view of a spinal construct of the spinal surgical modeling system of FIG. 1;

[0043] FIG. 11B is an exploded view of the spinal construct of FIG. 11A;

[0044] FIG. 12A is a side view of a central member of the spinal construct of FIG. 11A;

[0045] FIG. 12B is a cross-sectional view of the central member of FIG. 12A, taken along line 12B-12B of FIG. 12A;

[0046] FIG. 13A is a side view of an end member of the spinal construct of FIG. 11A;

[0047] FIG. 13B is a cross-sectional view of the end member of FIG. 13A, taken along line 13B-13B of FIG. 13A;

[0048] FIG. 13C is a cross-sectional view of the end member of FIG. 13A, taken along line 13C-13C of FIG. 13A;

[0049] FIG. 14A is a front, perspective view of a spinal construct for use with the spinal surgery modeling system of FIG. 1 in accordance with another embodiment of the present disclosure;

[0050] FIG. 14B is an exploded view of the spinal construct of FIG. 14A;

[0051] FIG. 15A is a side view of a central member of the spinal construct of FIG. 14A;

[0052] FIG. 15B is a cross-sectional view of the central member of FIG. 15A, taken along line 15B-15B of FIG. 15A;

[0053] FIG. 16A is a perspective view of a polyaxial pedicle screw;

[0054] FIG. 16B is an exploded, perspective view of the polyaxial pedicle screw of FIG. 16A;

[0055] FIG. 16C is a perspective view of a set screw usable with the polyaxial pedicle screw of FIGS. 16A and 16B;

[0056] FIG. 17A is an end view of a spinal construct including a taper lock screw and an adjustable rod in accordance with another embodiment of the present disclosure;

[0057] FIG. 17B is a partial cross-sectional view of a portion of the taper lock screw of FIG. 17A shown in a partially locked position; and

[0058] FIG. 17C is an end, cross-sectional view of the taper lock screw of FIG. 17A in an unlocked position with the adjustable rod.

[0059] Corresponding reference characters indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

[0060] Detailed embodiments of the present disclosure are disclosed herein; however, it is understood that the following description and each of the accompanying figures are provided as exemplary embodiments of the present disclosure. Thus, the specific structural and functional details provided in the following description are non-limiting, and various modifications may be made without departing from the spirit and scope of the present disclosure.

[0061] In this disclosure, the term clinician refers to a doctor, nurse, or other care provider and may include support personnel. As used herein, the term proximal refers to the portion of a structure closer to a clinician, while the term distal refers to the portion of the same structure further from the clinician. The term cephalad indicates a direction toward a patient's head, whereas the term caudad indicates a direction toward a patient's feet. The term lateral indicates a direction toward a side of the body of a patient, i.e., away from the middle of the body of the patient, whereas the term medial refers to a position toward the middle of the body of a patient. The term posterior indicates a direction toward a patient's back, and the term anterior indicates a direction toward a patient's front. Additionally, in the drawings and in the description that follows, terms such as front, rear, upper, lower, top, bottom, and similar directional terms are used simply for convenience of description and are not intended to limit the disclosure.

[0062] As shown in FIGS. 1 and 2, a spinal surgery modeling system 10 includes a spine model 20, a spine movement device 30, and optionally, one or more spinal constructs, such an adjustable rod 60 and screws 70. The spine model 20 and the spine movement device 30 may each be removably or fixedly attached to a base 12, and the adjustable rod 60 and screw 70 may be affixed to the spine model 20. The spine model 20 may be a cadaveric or synthetic anatomically and mechanically correct spine model of a pediatric, adult, or geriatric spine which may exhibit any of a variety of spine pathologies.

[0063] Turning now to FIGS. 3-6B, in conjunction with FIGS. 1 and 2, the spine movement device 30 includes a main frame 32 including a back plate 34 having a proximal surface 34a, a distal surface 34b, a threaded central aperture 34c, and a plurality of openings 34d disposed around the central aperture 34c. Cylinders 36 are positioned through the openings 34d of the back plate 34. Each cylinder 36 includes an elongated body 36a defining a bore 36b which may have a substantially consistent diameters along the length thereof, a proximal end 36c including an inlet 36d and a catch 36e that engages the proximal surface 34a of the back plate 34, and a distal end 36f including an outlet 36g. The outlets 36g of each cylinder 36 is fluidly connected to a tube or tubing 38 that is fluidly connected to an inflation member 40, such as a balloon.

[0064] An intermediate plate 42 includes a central aperture 42a and a plurality of openings 42b disposed around the central aperture 42a that are sized and positioned to correspond with the openings 34d of the back plate 34. The intermediate plate 42 is placed adjacent to the proximal surface 34a of the back plate 34, with openings 42b aligned with openings 34d and the catch 36e of each cylinder 36 positioned between the intermediate plate 42 and the back plate 34. The intermediate plate 42 is secured to the back plate 34 with fixation members 44, such as screws.

[0065] Pistons 46 include an elongated body 46a that may be the length of the elongated body 36a of the cylinders 36, a proximal end 46b that is secured to a front plate 48, and a distal end 46c that is dimensioned to frictionally engage the bore 36b of the cylinders 36. The front plate 48 includes a proximal surface 48a, a distal surface 48b, and a central aperture 48c extending through the proximal and distal surfaces 48a, 48b. The distal surface 48b includes a plurality of recesses 48d that are aligned with the openings 34d of the back plate 34 and mechanically engage and lock the proximal end 46b of the pistons 46 thereto. The front plate 48 is positioned in spaced relation with respect to the back plate 34 with the distal ends 46c of the pistons 36 disposed within the bore 36b of the cylinders 36.

[0066] A linear actuating member 50, such as a threaded screw, includes an elongated body 50a having a proximal end 50b and a distal end 50c. The elongated body 50a of the linear actuating member 50 is positioned through the central apertures 34c, 42a, and 48c of the back, intermediate, and front plates 34, 42, and 48, respectively. A handle 52 is secured to the proximal end 50b of the linear actuating member 50 and a nut 54 is disposed on the distal end 50c of the linear actuating member 50 adjacent the distal surface 34b of the back plate 34 to secure the components of the device 30 together.

[0067] Rotation of the handle 52 rotates the linear actuating member 50, which in turn imparts linear motion to the linear actuating member 50 as linear actuating member 50 engages the threaded central aperture 34c of the back plate 34. The linear motion thereby causes the front plate 48 to move proximally or distally with respect to the back plate 34, and in turn, causes the pistons 46 to move proximally or distally within the bores 36b of the cylinders 36. A fluid (not shown), such as a liquid or gas, is disposed within the bores 36b of the cylinders 36 such that distal movement of the pistons 46 displaces the fluid and hydraulically inflates/expands the inflation members 40, and proximal movement of the pistons 46 draws the fluid back into the bores 36b of the cylinders 36, hydraulically deflating the inflation members 40. The amount of fluid contained within each of the cylinders 36 may be the same or different.

[0068] In an exemplary method of use, each inflation member 40 is positioned within the disc space between each of the vertebral bodies 22 of the spine model 20, as shown in FIGS. 7A-8B. A user rotates the handle 52 of the spine movement device 30 to drive the linear actuating member 50 distally thereby displacing fluid from the cylinders 36 into the inflation members 40. As shown in FIGS. 9A-10B, expansion of the inflation members 40 increases the distance between the vertebral bodies 22 simulating, for example, growth of a spine.

[0069] The vertebral bodies 22 of the spine model 20 are freely accessible to a user of the system 10. Accordingly, various spinal constructs, such as a rod 60 and screws 70, may be placed on the vertebral bodies 22 to allow the user to practice methods of placing such spinal constructs on a spine and/or to observe the interaction of the spinal constructs with a spine.

[0070] As shown in FIGS. 11A-13C, in conjunction with FIGS. 7A-10B, an adjustable rod 60 may include a center member 62 and end members 64. Each end member 64 includes a first segment 64a which slidably engages an interior surface 62a of the center member 62 that includes a complementary geometry to that of the first segment 64a. While the interior surface 62a of the center member 62 is shown as a continuous, closed square-shaped surface, it should be understood that the interior surface 62a may have any shape suitable for slidably engaging end members 64, such as tubular, ovular, elliptical, or rectangular, for example, among other shapes that are complementary to the shape of the first segment 64a of the end members 64. As another example, the interior surface 62a of a center member 62 of an adjustable rod 60 may be a semi-continuous surface, having, for example, a c-shaped profile, as shown in FIGS. 14A-15B. Each end member 64 also includes a second segment 64b that includes a connecting portion 64c that may be secured to a screw 70.

[0071] It is contemplated that adjustable rod 60, center member 62, and end members 64 may be used outside of the disclosed spine model 20 and used, in situ, as a standalone spinal implant. In use as a spinal implant, adjustable rod 60 may be configured as follows. Center member 62 may include one or more stops that function to control the expansion and/or contraction of the adjustable rod 60. In particular, one end member 64 may be fixed relative to center member 60, while the other end member 64 is slidable between a minimum amount of extension and a maximum amount of extension with respect to center member 62. Alternatively, both end members 64 may be slidable with respect to center member 62 between a minimum amount of extension and a maximum amount of extension. Further, one end member 64 may have a different range of travel as compared to the other end member 64. Further still, one or both end members 64 may be free to expand and inhibited from contracting relative to center member 62.

[0072] Each end member 64 is shown having a combination configuration with a portion having an I-beam shape (e.g., first segment 64a) and a portion with a compound shape (e.g., second segment 64b). The compound shape includes an elongate round portion, an elongate head portion, and a neck portion connecting the elongate round portion with the elongate head portion. It is contemplated that the entire length of one or both end members 64 has the compound shape and that center member 62 may be configured to receive the compound shape instead of the I-beam shape as shown in FIGS. 11A and 11B. It is also contemplated that center member 62 may receive one end member 64 with an I-beam shape and another end member 64 having a compound shape. It is also within the scope of the present disclosure that adjustable rod 60 may be used with the components and/or instruments (e.g., rod reducers, rod benders, bone screws, etc.) disclosed in U.S. patent application Ser. No. 13/636,416, filed on Nov. 8, 2012 and which published as U.S. Patent Application Publication No. 2013/0144342, and in U.S. Pat. No. 8,882,817, both of which are herein incorporated by reference in their entireties.

[0073] An embodiment of a screw usable with the end members 64 is shown in FIGS. 16A-16C, generally, as a polyaxial pedicle screw 70 including a housing 72, a compression ring or cap 74, an anvil 76, a bone screw member 78, and a set screw 80. The housing 72 includes opposing walls 72a and 72b that define a U-shaped channel 71 therebetween. The internal surfaces of opposing walls 72a and 72b include threaded portions 75 that are threadably engagable with external threads 82 of the set screw 80 (FIG. 16C) to facilitate the securement of an end member 64 of an adjustable rod 60 and 60 (see e.g., FIGS. 11A and 14A) within the channel 71 of the housing 72 adjacent the anvil 76. The housing 72 includes a collar 77 extending therefrom that is adapted to facilitate the securement of the compression ring or cap 74 to the housing 72 once the bone screw member 78 is secured to the housing 72. The collar 77 has a cut out 77a that provides a recess for the reception of a portion of the bone screw member 78, namely a neck 78a, and facilitates the positioning of the bone screw member 78 within the housing 72 from a distal end of the housing 72.

[0074] The bone screw member 78 includes a head 78b and a threaded shaft 78c extending from the head 78b. The bone screw member 78 may be a self-starting fastener or self-tapping fastener. The compression ring or cap 74 may be slid over the threaded shaft 78c of the bone screw member 78 and affixed to the collar 77 of the housing 72 to further secure the bone screw member 78 to the housing 72. Once inserted, the bone screw member 78 is selectively positionable at plurality of angles relative to the housing 72 and may be fixedly securable relative to the housing 72 at a cone angle in the range of 60 to 80 degrees, preferably 70 degrees, from the longitudinal axis L extending through the polyaxial pedicle screw 70. The anvil 76 is positionable within the housing 72 adjacent the head 78b of the bone screw member 78 to facilitate the securement of the end member 64 within the housing 72. The set screw 80 is positionable within the housing 72, e.g., via threading engagement, to secure the end member 64 within the housing 72 adjacent the anvil 76.

[0075] As assembled, the pedicle screw 70 is fastenable to a bone structure (e.g. vertebra) and the housing 72 is repositionable in a plurality of directions with respect to the bone screw member 78 as discussed above. To this end, the housing 72 is rotatable about the longitudinal axis L extending through the polyaxial pedicle screw 70 as well as pivotable relative to the longitudinal axis L and the bone screw member 78. A connecting portion 64c of an end member 64 (see e.g., FIG. 13B) is positionable in the U-shaped channel 71 of the housing 72 and is nested against the anvil 76. The end member 64 is then secured to the pedicle screw 70 using the set screw 80.

[0076] Another embodiment of a screw usable with the end members 64 is shown in FIGS. 17A-17C, generally, as a multi-planar taper lock screw 70 including a dual layered housing 72 and a screw shaft 74 having a spherically configured screw head 76 rotatably coupled with housing 72. The taper lock screw 70 enables manipulation of the screw shaft 74 about multiple axes, whereby the taper lock screw 70 is capable of releasably securing an end member 64 of an adjustable rod with taper lock screws 70 on multiple vertebral bodies that are aligned in the spinal column on different planes due to the natural curvature of the spine.

[0077] Dual layered housing 72 includes an outer housing 72a and an inner housing 72b. Outer housing 72a can be selectively positioned relative to inner housing 72b to fully lock screw head 76 and end member 64 in position within inner housing 72b (FIG. 17A), or alternatively to selectively partially lock screw head 76 and/or end member 64 in position while permitting a sliding and/or rotating motion of the end member 64 relative to screw head 76, and the screw head 76 relative to the housing 72, respectively (FIG. 17B). Specifically, outer housing 72a is configured such that at least a portion of an inner surface of outer housing 72a is capable of sliding over a portion of an outer surface of inner housing 72b in upward and downward directions along the longitudinal axis of taper lock screw 70. When outer housing 72a is slid upward in relation to inner housing 72b an inner surface of outer housing 72a causes inner housing 72b to impart compressive force radially inward to secure end member 64 at least partially disposed therein.

[0078] Inner housing 72b defines a connecting rod slot 78 that is configured and dimensioned to accommodate and retain the end member geometry of end member 64 in the inner housing 72b without impairing the locking ability of the taper lock screw 70. Inner walls that define connecting rod slot 78 imparts compressive force to end member 64 disposed in connecting rod slot 78, whereby the inner walls serve to securely lock and hold end member 64 in its relative position to inner housing 72b. This required forced is provided by the operational engagement of a locking device (not shown) with the taper lock screw 70 that results in an upward sliding motion of the outer housing 72a relative to the inner housing 72b. Inner housing 72b further defines a screw head articulation recess 71 in a lower portion of inner housing 72b that has a complementary surface configuration to the generally spherical shape of screw head 76 to facilitate multi-planar rotational articulation of screw head 76 within articulation recess 71. The lower-most portion of inner housing 72b defines a screw shaft exit portal 73 that is sized small enough to retain the spherical screw head 76 within screw head articulation recess 71, but that is large enough to allow multi-directional movement of screw shaft 74 that extends exterior to inner housing 72b.

[0079] One suitable taper lock screw is commercially available from K2M, Inc. (Leesburg, Va.) under the trade name MESA. In addition, suitable multi-planar taper lock screws are shown and described in U.S. Patent Application Publication No. 2008/0027432 and in U.S. Patent Application Publication No. 2007/0093817, both of which are herein incorporated by reference in their entireties. It is contemplated that other types of screws such as, e.g., a fixed screw in which the head of the screw has no movement relative to the screw shaft, a mono-axial screw such as that disclosed in U.S. Patent Application Publication No. 2009/0105716, and a uni-axial screw such as that disclosed in U.S. Patent Application Publication No. 2009/0105769 may be utilized. Suitable mono-axial and uni-axial screws are also commercially available under the trade name MESA.

[0080] With reference again to FIGS. 7A-10B, in conjunction with FIGS. 11A-13C, in use, the screws 70 are implanted, in spaced relation from each other, into vertebral bodies 22 of the spine model 20. As the spine movement device 30 is actuated and the distance between the vertebral bodies 22 increases (for example, during movement from the first position of FIGS. 7A-8B to the second position of FIGS. 9A-10B), a force is exerted on the screws 70 moving them away from each other, which in turn moves the end members 64 relative to the center member 62.

[0081] A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure.