Flexible spinal fusion rod

Abstract

A spinal rod assembly includes a flexible spinal fusion rod (10), the flexible spinal fusion rod (10) including connecting members (12) that are hinged to each other so that the rod (10) can be formed into a bent orientation. A locking mechanism (40) is coupled to the connecting member (12) and can lock the connecting member (12) so that the rod (10) is maintained in the bent orientation.

Description

Technical Field

[0001] The present invention relates generally to spinal fusion rods and, more particularly, to flexible spinal fusion rods. Background Art

[0002] Degenerative spinal diseases, such as degenerative disc disease, spinal stenosis, spondylolisthesis, etc., are often treated by spinal decompression. The main purpose of decompression is to reduce the pressure in the spinal canal and on the nerve roots by removing certain tissues of the spine, thereby reducing or eliminating the pressure and the pain caused by the pressure. If spinal tissue is removed, the pain is reduced, but the spine is weakened. Therefore, fusion surgery is often necessary to stabilize the spine after decompression surgery.

[0003] Spinal fusion is a procedure that involves joining two or more adjacent vertebrae with a bone fixation device so that they can no longer move relative to each other. Spinal fixation devices typically include a spinal fixation element, such as a relatively rigid fixation rod, that is connected to adjacent vertebrae by attaching the element to various anchoring devices, such as hooks, bolts, wires, or screws. Summary of the invention

[0004] The present invention is directed to providing an improved flexible spinal fusion rod, which will be described in more detail below. The present invention allows the rod to be flexible during the insertion process (eg, into the tulip head of a pedicle screw).

[0005] Therefore, according to an embodiment of the present invention, a spinal rod assembly is provided, which includes a flexible spinal fusion rod, the flexible spinal fusion rod including connecting members hinged to each other so that the rod can be formed into a bent orientation; and a locking mechanism connected to the connecting members and configured to lock the connecting members so that the rod remains in the bent orientation.

[0006] The locking mechanism may include a flexible, slender member that passes through the lumen of the connecting member from one portion of the rod to another portion, and a fastener that is configured to press the flexible, slender member against an inner wall of at least one of the lumens to lock the flexible, slender member in place.

[0007] The flexible elongate member may pass through the lumen of the connecting member from one end of the rod to the other end.

[0008] The rod may include at least one chamfered end.Each connecting member may include a tenon projecting from the body portion and received in a mortise of an adjacent connecting member.

[0009] The tenon may include a distal projection extending laterally to the lateral projections on opposite sides of the longitudinal axis of the rod. The tenon may taper proximally from each lateral projection to an inflection point located on opposite sides of the longitudinal axis. The tenon may taper to a narrowest point on a concave path on opposite sides of the longitudinal axis. The tenon may taper to a main body portion in a concave shape. The concave mortise may be shaped to complement the shape of the distal projection, the lateral projections, the concave path, and the concave shape of the tenon.

[0010] There may be a gap between the outer edge of each lateral projection and the adjacent inner wall of each female mortise.

[0011] The rod may include one or more markings.The rod may include a covering. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be more fully understood and appreciated from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0013] Figure 1 is a simplified illustration of a flexible spinal fusion rod mounted on a pedicle screw on a patient's vertebrae in accordance with a non-limiting embodiment of the present invention;

[0014] Figure 2 is an end view of a flexible spinal fusion rod;

[0015] Figure 3 is an enlarged view of two connecting components of a flexible spinal fusion rod;

[0016] Figure 4 is a simplified schematic diagram of further connecting components of a flexible spinal fusion rod, wherein the rod is in a bent, flexed orientation;

[0017] Figure 5 and Figure 6 is a simplified schematic diagram of a flexible spinal fusion rod in respective contracted and expanded linear orientations;

[0018] Figure 7 is a simplified diagram of one pattern of connecting members for a fusion rod;

[0019] Figure 8 is a simplified diagram of another mode of connecting member for a fusion rod;

[0020] Fig. 9 is a simplified diagram of a bent orientation of a fusion rod according to a non-limiting embodiment of the present invention;

[0021] Fig.10 is a simplified diagram of a covering (eg, a polymer covering) for a fusion rod;

[0022] Fig.11Simplified diagram of the double - bending orientation of a fusion rod according to a non - limiting embodiment of the present invention;

[0023] Fig.12 Simplified diagram of an irregular or non - repeating pattern of a connecting member for a fusion rod;

[0024] Fig.13 Simplified diagram of a locking mechanism for locking a flexible spinal fusion rod in one orientation (single - bending orientation);

[0025] Fig.14 Simplified cross - sectional view of the locking mechanism;

[0026] Fig.15 Partial enlarged view of the locking mechanism; and

[0027] Fig.16 Simplified diagram of a locking mechanism for locking a flexible spinal fusion rod in another orientation (double - bending orientation). Detailed Description

[0028] Now refer to Figure 1 which illustrates a flexible spinal fusion rod 10 mounted on pedicle screws 11 of a patient's vertebrae according to a non - limiting embodiment of the present invention. In Figure 1 two such rods 10 are installed in a patient (left rod and right rod). The flexible rod 10 can be installed during a minimally invasive surgery (MIS) procedure and can be used during fixation, for example, in the lumbar and sacral regions (e.g., the L3 to S1 region).

[0029] In one aspect, the flexible rod 10 is capable of articulation. The rod can be fixed to two or more pedicle screws 11 and remains non - rigid. The rod 10 has a connecting member that allows the rod 10 to have variable flexibility depending on the direction of movement. For example, the rod 10 can have more flexion than extension. The rod can be changed to have the same or variable bending, the same or variable left - relative - to - right bending, and the same or variable left and right rotation. The flexibility of the rod enables easy installation of the rod from one screw to another in single - segment fusion or multi - level segmental fusion. This solves the problem of aligning the rod even when the screws are not necessarily aligned due to the patient's anatomy.

[0030] In another aspect, as described below, the rod 10 can be locked in any desired straight or bent orientation.

[0031] Now refer to Figures 2 to 3, which illustrates the structure of a flexible spinal fusion rod 10. The rod 10 includes interlocking connecting members 12 made of a surgically safe material, such as but not limited to a cobalt-chromium alloy, a stainless steel alloy, a titanium alloy, or a polymer. In the illustrated embodiment, the connecting members 12 have a circular (round) perimeter, but may also have other shapes. Each connecting member 12 has a lumen 14. Adjacent connecting members 12 are connected to each other by male and female puzzle connecting members.

[0032] Therefore, if Figure 3 As shown, each connecting member 12 includes a tenon 16 that protrudes from a main body portion 18 and is received in a concave mortise 20 of an adjacent connecting member 12. The tenon 16 includes a distal protrusion 22 (distal means away from the main body portion 18 along the longitudinal axis 24 of the rod 10) that extends laterally to a lateral protrusion 26 on opposite sides of the longitudinal axis 24. The tenon 16 tapers proximally (i.e., toward the main body portion 18) from each lateral protrusion 26 to an inflection point 28 located on opposite sides of the longitudinal axis 24. An inflection point means that the curvature changes from convex to concave. The tenon 16 then gradually narrows to a narrowest point 29 on a concave path on opposite sides of the longitudinal axis 24. The tenon 16 then gradually widens in a concave shape to the main body portion 18. Therefore, the tenon 16 is narrower at the inflection point 28 than at the lateral protrusion 26, but the inflection point is not at the narrowest width of the tenon. The radius of curvature of the distal projection 22 is not necessarily the same as (and may typically be greater than) the radius of curvature of the lateral projections 26. The shape of the female mortise 20 is complementary to the shape of the tenon 16 (ie, the "negative" of the tenon shape).

[0033] There is a gap 30 between the outer edge of each lateral projection 26 and the adjacent inner wall 32 of the mortise 20. The size of the gap 30 determines the amount of axial rotation of the connecting members relative to each other (i.e., about Figure 2 The bending or rotation of the axis 25 or the axis 27 in the middle, both of which are perpendicular to the longitudinal axis 24; the axis 24 is perpendicular to the longitudinal axis 24; Figure 2 ). The size of gap 30 also determines the amount of lateral or longitudinal linear movement of the connecting members relative to each other. The size of gap 30 can be selected to control the range of motion of each degree of freedom. In biomechanical terms, this degree of freedom allows spinal flexion and extension movement.

[0034] Now refer to Figure 4 , which illustrates the connecting member 12 of the flexible spinal fusion rod 10 in a bent, flexed orientation.

[0035] Now refer to Figure 5 and Figure 6 .exist Figure 5 In the embodiment, the connecting member 12 of the fusion rod 10 is in a retracted orientation; Figure 6 , it is in an extended linear orientation.

[0036] Now refer to Figure 7 , which illustrates a straight orientation of the connecting members 12 of the rod 10. In this embodiment, the connecting members interlock with each other over the entire length of the rod 10. The rod 10 has a tapered or chamfered end 19. In all embodiments of the present invention, the rod 10 may have one or more markings 23 for orienting the rod 10 in a desired orientation within the tulip-shaped portion of the pedicle screw.

[0037] Now refer to Figure 8 , which illustrates another form of rod in a straight orientation, wherein the connecting member 12 extends over only a portion of the length of the rod 10.

[0038] Now refer to Fig. 9 , which illustrates Figure 7 The connecting component 12 of the rod 10 is in a bent or angled orientation.

[0039] Now refer to Fig.10 , which illustrates a covering 34 (eg, a polymer covering) for a fusion rod 10. The covering 34 can protect the rod from body fluids and protect body tissue from being trapped in the gaps between the connecting members.

[0040] Now refer to Fig.11 , which illustrates a double curved orientation of the fusion rod 10. The types of curved shapes that can be used with the present invention are virtually unlimited.

[0041] Now refer to Fig.12 , which illustrates a non-regular or non-repeating pattern of connecting members 12 for a fusion rod 10. Any pattern is possible, and the type of pattern determines the bend shape of the rod.

[0042] Now refer to Figures 13 to 16 , which illustrates a locking mechanism 40 for locking a flexible spinal fusion rod 10. The locking mechanism 40 may include, but is not limited to, a flexible, elongated member 42 that passes through the lumen 14 of the connecting member 12 from one portion of the rod 10 to another portion. For example, the flexible, elongated member 42 may extend from one end of the rod to the opposite end of the rod to lock the entire length of the rod in a desired orientation. Alternatively, the flexible, elongated member 42 may extend from a portion of the rod that is not at the end to another portion (again, not necessarily at the opposite end of the rod) to lock only a portion of the length of the rod in a desired orientation, leaving the remainder of the rod for flexion.

[0043] As with rod 10, flexible elongated member 42 may be made of a surgically safe material such as, but not limited to, cobalt-chromium alloys, stainless steel alloys, titanium alloys, or polymers, or an elastic material such as a superelastic material (e.g., nitinol). Flexible elongated member 42 may have a stop 44 at one or both ends thereof. Locking mechanism 40 may also include a fastener 46 ( Fig.14 and Fig.15 ), such as but not limited to a set screw, which presses the flexible elongated member 42 against the inner wall of the lumen 14 to lock the flexible elongated member 42 in place after the flexible elongated member 42 is inserted from end to end through the lumen 14. The fastener 46 may be located at the chamfered end 19 or at other locations in the rod 10.

[0044] exist Fig.13 In FIG. 4 , the locking mechanism 40 locks the fusion rod 10 in a single curved orientation. Fig.16 In the embodiment of the present invention, the locking mechanism 40 locks the fusion rod 10 in the bi-flexed orientation.

[0045] Other locking mechanisms may be used, such as, but not limited to, ratchets, pawls, detents, etc.

Claims

1. A spinal rod assembly, the spinal rod assembly include: A flexible spinal fusion rod (10), the flexible spinal fusion rod (10) comprising connecting members (12) that are hinged to each other so that the rod (10) can be formed into a curved orientation; as well as a locking mechanism (40) coupled to the connecting member (12) and configured to lock the connecting member (12) such that the rod (10) is maintained in a bent orientation, The locking mechanism (40) comprises: a flexible elongated member (42) passing through the lumen (14) of the connecting member (12) from one part of the rod (10) to another part; and a fastener (46) configured to press the flexible elongated member (42) against the inner wall of at least one lumen in the lumen (14) to lock the flexible elongated member (42) in place, and The flexible elongated member (42) comprises a first stopper at a first end thereof and a second stopper at a second end opposite to the first end, and wherein the first stopper and the second stopper are each sized so as not to enter the lumen of the connecting member.

2. The spinal rod assembly according to claim 1, in, The flexible elongated member (42) passes through the lumen (14) of the connecting member (12) from one end of the rod (10) to the other end.

3. The spinal rod assembly according to claim 1, in, The flexible elongated member (42) does not extend from one end of the rod (10) to the other, but rather locks only a portion of the length of the rod (10) in a desired orientation, leaving the remainder of the rod (10) available for flexion.

4. The spinal rod assembly according to claim 1, in, The first stopper and the second stopper are unequal in size.

5. The spinal rod assembly according to claim 1, in, The rod (10) comprises at least one chamfered end (19).

6. The spinal rod assembly according to claim 5, in, The fastener (46) is located in the at least one chamfered end (19).

7. The spinal rod assembly according to claim 1, in, Each of the connecting members (12) includes a tenon (16) that projects from a body portion (18) and is received in a mortise (20) of an adjacent connecting member (12).

8. The spinal rod assembly according to claim 7, in, The tenon (16) includes a distal protrusion (22) extending laterally to a lateral protrusion (26) on opposite sides of a longitudinal axis (24) of the rod (10), and the tenon (16) tapers proximally from each of the lateral protrusions (26) to an inflection point (28) located on opposite sides of the longitudinal axis (24), and the tenon (16) gradually narrows to a narrowest point (29) on a concave path on opposite sides of the longitudinal axis (24), and the tenon (16) gradually widens to the main body (18) in a concave shape, and the concave mortise (20) is shaped to complement the distal protrusion (22), the lateral protrusions (26), the shape of the concave path, and the concave shape of the tenon (16).

9. The spinal rod assembly according to claim 8, in, There is a gap (30) between the outer edge of each of the lateral protrusions (26) and the adjacent inner wall (32) of each of the recessed mortises (20).

10. The spinal rod assembly according to claim 1, in, The rod (10) comprises one or more markings (23).

11. The spinal rod assembly according to claim 1, in, The rod (10) includes a covering (34).

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