Polyaxial spinal rod

Abstract

A spinal device includes a spinal rod (10) including a head (12) from which extends a shaft (14). The head (12) has an outer spherical contour and is formed with an internal spherical dome (18). The internal spherical dome (18) is completely open at a first side (20), and at a fastener abutment side (22), which is opposite to the first side (20), an elongate aperture (24) is formed.

Description

POLY AXIAL SPINAL RODFIELD OF THE INVENTION

[0001] The present invention relates generally to surgical devices used in spinal surgery, and particularly to a fusion rod that provides a wide range of polyaxial mounting positions, which is particularly useful between two different levels of vertebra.BACKGROUND OF THE INVENTION

[0002] Spinal ailments in the lumbosacral region (L4, L5, and SI) are well known. Through disease or injury, the laminae, spinous process, articular processes, facets and / or facet capsules of one or more vertebral bodies along with one or more intervertebral discs can become damaged which can result in a loss of proper alignment or loss of proper articulation of the vertebrae. This damage can result in anatomical changes, loss of mobility, and pain or discomfort.

[0003] Spinal fusion may be used to join two or more vertebrae. This procedure can be performed at any level in the spine (cervical, thoracic, lumbar, or sacral) and prevents any movement between the fused vertebrae. Fusion often involves joining vertebrae at two different levels, one level being cephalad, that is, anatomically closer to the head of the person, and the other level being caudal, that is, anatomically closer to the tail bone or feet of the person. For example, fusion may be performed at one or more levels between the LI and SI vertebrae.

[0004] The TOPS ™ device of Premia Spine Ltd. is a non-fusion, posterior arthroplasty system that offers an alternative solution to spinal fusion surgery for patients with moderate to severe lumbar spinal stenosis, degenerative spondylolisthesis and related spinal conditions. The system maintains stability and preserves motion. The implant device replaces bony and soft tissues removed during spinal decompression surgery. The ProMIS ™ System is a posterior open or MIS (minimally invasive surgery) fusion system for multiple spine pathologies.

[0005] In both fusion and non-fusion systems, spinal rods are often used to connect devices and / or pedicle screws from one vertebral level to another. If a device has been implanted between adjacent vertebrae, and another device is required to be implanted at yet another level adjacent to one of the levels already coupled by a fusion or non-fusionsystem, the previous spinal rods and devices or pedicle screws must be removed and repositioned, which can be detrimental to the anatomical structure of the spine.SUMMARY

[0006] The present invention seeks to provide a subwoofer assembly that has a novel construction, as described in detail below. In the subwoofer of the invention, the spider and the surround are directly attached to the same attachment plane.

[0007] There is provided in accordance with a non-limiting embodiment of the invention a spinal device including a spinal rod including a head from which extends a shaft, the head having an outer spherical contour and being formed with an internal spherical dome, wherein the internal spherical dome is completely open at a first side, and at a fastener abutment side, which is opposite to the first side, an elongate aperture is formed.BRIEF DESCRIPTION OF DRAWINGS

[0008] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0009] Figs. 1A and IB are simplified posterior (coronal) and sagittal view illustrations, respectively, of spinal devices implanted in a spine, using spinal rods in accordance with a non-limiting embodiment of the invention.

[0010] Fig. 2 is a simplified posterior (coronal) view of the spinal rod.

[0011] Figs. 3A, 3B and 3C are sagittal view illustrations of the spinal rod, in different sagittal angles of installation, respectively, in the cephalad, horizontal and caudal sagittal directions.

[0012] Fig. 4 is a coronal-plane illustration of the spinal rod, in different coronal angles of installation.

[0013] Fig. 5 is a side-view illustration of the spinal rod.

[0014] Fig. 6 is a bottom view illustration of the spinal rod.

[0015] Figs. 7A and 7B are sagittal and axial sectional views, respectively, of the spinal rod coupled to a tulip of a pedicle screw, in accordance with a non-limiting embodiment of the invention.DETAILED DESCRIPTION

[0016] Reference is now made to Figs. 1A and IB, which illustrate spinal devices implanted in a spine, using spinal rods 10, in accordance with a non-limiting embodiment of the invention. Any spinal device which uses bone screws can be used with the invention. A non-limiting example of a spinal device is a non-fusion, posterior arthroplasty device 2, such as the TOPS ™ device of Premia Spine Ltd. The posterior arthroplasty device 2 is shown installed between the L4 and L5 vertebrae, by means of a cephalad set of pedicle screws 3 and 4 and a caudal set of pedicle screws 5 and 6, respectively secured to the pedicles or spinal processes or other bone at the L4 and L5 levels. Spinal rods 1 connect the two sets of pedicle screws at the medial and lateral sides of the spine. The spinal rods 1 are secured to the tulips of the pedicle screws with set screws.

[0017] Another device is required to be implanted at yet another level, such as at the SI level; in the illustrated example, pedicle screws 8 and 9 must be secured to bone at the SI level and spinal rods must be used to couple the set of pedicle screws 5 and 6 to the set of pedicle screws 8 and 9. In the prior art, this would require removing spinal rods 1, and possibly repositioning the set of pedicle screws 5 and 6, which could be detrimental to the anatomical structure of the spine.

[0018] The present invention provides a novel spinal rod 10 that enables coupling the set of pedicle screws 5 and 6 to the set of pedicle screws 8 and 9 without repositioning the set of pedicle screws 5 and 6, as is explained below.

[0019] Reference is now made to Figs. 2-6. Spinal rod 10 may include a head 12, from which extends a shaft 14. As seen in Figs. 2, 4 and 6, head 12 may be formed with opposing flat faces 16, for grasping with a wrench, for example. Without limitation, the distance F between the flat faces 16 may be in the range of 10-25 mm. Head 12 has an outer spherical contour. As seen in Fig. 6, head 12 may be formed with an internal spherical dome 18, with a diameter D smaller than the distance F such as but not limited to, 2-3 mm less than distance F. The internal spherical dome 18 is completely open at a first side 20 of spinal rod 10, and at an opposite side 22 (20 and 22 are shown in Fig. 5) an elongate aperture 24 (Fig. 6) is formed. Side 22 is also referred to as fastener abutment side 22 (as explained below with reference to Figs. 7A and 7B). The elongate aperture 24may have curved ends and straight sides, for example. The longitudinal axis of elongate aperture 24 may be coaxial with shaft 14. The elongate aperture 24 may have a width E, which may be without limitation, in the range of 6-10 mm.

[0020] As seen in Fig. 5, the length L of shaft 14 may be without limitation, in the range of 40-60 mm. When side 20 is horizontal (as in Fig. 5), shaft 14 may be tilted from the horizontal by an angle T, which may be without limitation, in the range of 0-10°. The head can pivot around a circle that has a diameter PD, which may be without limitation, in the range of 15-25 mm.

[0021] Figs. 3 A, 3B and 3C are sagittal view illustrations of the spinal rod 10, in different sagittal angles of installation, respectively, in the cephalad (sagittal angle SGI), horizontal (sagittal angle = 0°) and caudal (sagittal angle SG2) sagittal directions. The spinal rod is attached to a tulip 30 of pedicle screws 5 or 6 with a set screw 32 (or other suitable threaded fastener 32).

[0022] The spherical shape of the internal spherical dome allows for a wide range of polyaxial movement. Without limitation, in the sagittal plane, SGI may be 34° and SG2 may be -12°, giving a total range of 46° angular movement.

[0023] Fig. 4 is a coronal-plane illustration of the spinal rod, in different coronal angles CORI and COR2 of installation. Without limitation, when spinal rod 10 is at -12° in the sagittal plane (worst case), the range of movement in the coronal plane may be -34° (COR2) to +28° (CORI). The range is even larger at higher positive sagittal angles.

[0024] Reference is now made to Figs. 7A and 7B, which are sagittal and axial sectional views respectively of the spinal rod 10 coupled to tulip 30 of pedicle screw 5 or 6. It is seen that set screw 32 mates with a threaded fastener 36 of the pedicle screw assembly. Fastener 36 passes through elongate aperture 24. The overall height Hl from the top of set screw 32 to the bottom of tulip 30 may be without limitation, in the range of 18-32 mm. The height H2 from the top of set screw 32 to the top of tulip 30 may be without limitation, in the range of 6-10 mm.

[0025] It is seen that set screw 32 abuts against fastener abutment side 22. In the sagittal plane (Fig. 7A) the set screw 32 abuts against fastener abutment side 22 on only one side of elongate aperture 24; in the axial plane (Fig. 7B) set screw 32 abuts against fastenerabutment side 22 on both sides of elongate aperture 24. Where set screw 32 abuts against fastener abutment side 22 depends on the angular orientation of head 12.

[0026] Reference is made again to Fig. 1A. Accordingly, with the present invention, pedicle screws 8 and 9 may be secured to bone at the SI level without removing and repositioning pedicle screws 5 and 6. The surgeon simply removes the existing set screws from pedicle screws 5 and 6, and places the head 12 of spinal rod 10 on the corresponding pedicle screw 5 or 6, swivels the spinal rod 10 angularly so that one end of shaft 14 can be secured to pedicle screw 8 or 9, and tightens the set screw on head 12 at the chosen angular orientation. The procedure is quick and easy.

Claims

CLAIMSWhat is claimed is:

1. A spinal device comprising: a spinal rod (10) comprising a head (12) from which extends a shaft (14), said head (12) having an outer spherical contour and being formed with an internal spherical dome (18), wherein said internal spherical dome (18) is completely open at a first side (20), and at a fastener abutment side (22), which is opposite to said first side (20), an elongate aperture (24) is formed.

2. The spinal device according to claim 1, wherein a longitudinal axis of said elongate aperture (24) is coaxial with said shaft (14).

3. The spinal device according to claim 1 or claim 2, wherein said head (12) is formed with opposing flat faces (16), and wherein a distance between said opposing flat faces (16) is larger than a diameter of said internal spherical dome (18).

4. The spinal device according to any one of claims 1-3, wherein said elongate aperture (24) has curved ends and straight sides.

5. The spinal device according to any one of claims 1-4, wherein said spinal rod (10) is coupled to a tulip (30) of a pedicle screw (5) with a threaded fastener (32), and a portion of said pedicle screw (5) passes through said elongate aperture (24) and said threaded fastener (32) abuts against said fastener abutment side (22).

6. The spinal device according to claim 5, wherein in a sagittal plane, said spinal rod (10) is tiltable through at least 45° of angular movement with respect to said tulip.

7. The spinal device according to claim 5, wherein in a coronal plane, said spinal rod (10) is tiltable through at least 60° of angular movement with respect to said tulip.

8. The spinal device according to claim 5, wherein in one plane said threaded fastener (32) abuts against said fastener abutment side (22) on only one side of said elongate aperture (24).

9. The spinal device according to claim 5, wherein in one plane said threaded fastener (32) abuts against said fastener abutment side (22) on both sides of said elongate aperture (24).

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