Fixation system for spinal instrumentation

Abstract

A fixation system for spinal instrumentation comprising a cap (1), which houses the head of a screw (2), the end of said screw (2) projecting through a lower opening of said cap (1). A coupling element (3) having two tabs (33) on both side ends rests on the upper part of the head of said screw (2). Said coupling element (3) houses therein an adjusting ring (4) secured to a series of tabs (7), by which means the movement of the head of said screw (2) can be limited.

Claims

1. A fixation system for spinal instrumentation comprising: a cap having an upper, inner part comprising threading, and a lower inner part comprising two slots extending about a perimeter of the lower inner part of the cap, in which an end of each of the two slots has a hole and a central opening; a screw having a head with four slots and a body having a first end connected to the head and a second end; a coupling element, and two opposing radial tabs extending from a periphery of the coupling element, the coupling element resting on an upper part of the head of the screw, such that the opposing radial tabs engage the holes of the cap; an adjusting ring comprising a plurality of radially extending tabs received by radial apertures of the coupling element, wherein the plurality of tabs limit movement of the head of the screw; a closing lid comprising a circumferential perimeter threading complementary to the upper inner part threading of the cap, wherein the closing lid is connected to the cap via the circumferential perimeter threading engaging the upper inner part threading of the cap; a reducing bar, wherein the reducing bar is located between the coupling element and the closing lid; a screwdriver for polyaxial fixation of the screw; a screwdriver for uniaxial coronal fixation of the screw; a screwdriver for uniaxial sagittal fixation of the screw; and a screwdriver for complete locking of the screw wherein the cap houses the head of the screw, and the second end of the screw projects through the central opening of the cap.

2. The fixation system for spinal instrumentation according to claim 1, wherein: a diameter of the head of the screw is greater than a diameter of the central opening of the cap; the screw having a spherical head with a series of four slots, the series of four slots each separated by 90 degrees, and wherein a centermost part of the screw has a hollow area in a five-pointed star shape; and the screw comprising a cannulated interior, and a screw hole connected to the hollow area of the screw, enabling passage of a guide wire.

3. The fixation system for spinal instrumentation according to claim 1, wherein the adjusting ring fits inside of the coupling element and the extending tabs of the adjusting ring are secured to a series of slots separated by 90 degrees.

4. The fixation system for spinal instrumentation according to claim 1, further comprising a tertiary hollow in a shape of a five-pointed star in a center thereof.

5. The fixation system for spinal instrumentation according to claim 1, wherein the screwdriver comprises an end with a handle, the end of the handle further comprising a threaded disc around a perimeter; a rotatable cap having a lug in a shape of a five-pointed star in a center thereof, secured to the end of the handle allowing the placement of the screw without displacing the tabs of the adjusting ring, leaving the head of the screw unlocked, for the polyaxial fixation of the screw.

6. The fixation system for spinal instrumentation according to claim 1, wherein the screwdriver for uniaxial coronal fixation of the screw comprises an end with a handle, the end of the handle comprising a threaded disc around a perimeter; a rotatable cap having a lug in a shape of a five-pointed star in a center thereof, and two horizontal blades with respect to the five-pointed star secured to the end of the handle, whereby when the screwdriver is locked to the screw, and to the cap, the blades being forced downwards, such that the tabs of the adjusting ring engage the slots of the screw head, allowing movement of the screw, in relation to the cap, in only one direction for the uniaxial transverse fixation of the screw.

7. The fixation system for spinal instrumentation according to claim 1, wherein the screwdriver for uniaxial sagittal fixation of the screw comprises an end with a handle, the end of the handle comprising a threaded disc around a perimeter; a rotatable cap having a lug in a shape of a five-pointed star in a center thereof, and two vertical blades with respect to the five-pointed star secured to the end of the handle, the two vertical blades being placed perpendicular to the screwdriver for uniaxial coronal fixation of the screw, such that the vertical blades descend and the tabs of the adjusting ring engage the slots of the head of the screw, allowing movement of the screw in relation to the cap in one direction and perpendicular to an axis for the uniaxial sagittal fixation of the screw.

8. The fixation system for spinal instrumentation according to claim 1, wherein the screwdriver for complete locking of the screw comprises an end with a handle, the end of the handle further comprising a threaded disc around a perimeter; a rotatable cap having a lug in a shape of a five-pointed star in a center thereof, and four blades separated by 90 degrees secured to the end of the handle for the complete locking of the screw.

Description

DESCRIPTION OF THE DRAWINGS

(1) As a complement to the description provided herein, and for the purpose of helping to make the characteristics of the invention more readily understandable, the present specification is accompanied by a series of figures constituting an integral part of the same, which, by way of illustration and not limitation, represent the following:

(2) FIG. 1 is an exploded perspective view of the fixation system for spinal instrumentation.

(3) FIG. 2 are views of the set of assembled parts of the fixation system for spinal instrumentation.

(4) FIG. 3 is a transverse cross section view of the fixation system for spinal instrumentation.

(5) FIG. 4 are transverse cross section views of the fixation system for spinal instrumentation.

(6) FIG. 5 are views of the cap of the fixation system for spinal instrumentation.

(7) FIG. 6 are views of the screw of the fixation system for spinal instrumentation.

(8) FIG. 7 are views of the coupling element of the fixation system for spinal instrumentation.

(9) FIG. 8 are views of the coupling element, along with the adjusting ring and the secured tabs of the fixation system for spinal instrumentation.

(10) FIG. 9 are views of the adjusting ring of the fixation system for spinal instrumentation.

(11) FIG. 10 are views of the closing lid of the fixation system for spinal instrumentation.

(12) FIG. 11 are views of the fixation system for spinal instrumentation, with an example for polyaxial fixation of the screw.

(13) FIG. 12 are views of the fixation system for spinal instrumentation, with an example for uniaxial fixation of the screw.

(14) FIG. 13 are views of the fixation system for spinal instrumentation, with an example for uniaxial fixation of the screw.

(15) FIG. 14 are views of the fixation system for spinal instrumentation, with an example for the complete locking of the screw.

(16) FIG. 15 is a partial cross section perspective view of the total assembly of elements that form the fixation system for spinal instrumentation (during the fixation process).

(17) FIG. 16 is a partial cross section perspective view of the total assembly of elements that form the fixation system for spinal instrumentation (once the fixation process has finished).

PREFERRED EMBODIMENT OF THE INVENTION

(18) As can be observed in the attached figures, the fixation system for spinal instrumentation is comprised of a cap (1), which houses the head of a screw (2), the end of said screw (2) projecting through a lower opening of said cap (1).

(19) A coupling element (3) having two tabs (33) on both side ends rests on the upper part of the head of said screw (2).

(20) Said coupling element (3) houses therein an adjusting ring (4) secured to a series of tabs (7), by which means the movement of the head of said screw (2) can be limited.

(21) The reducing bar (5) is located between said coupling element (3) and the closing lid (6).

(22) Said cap (1) has threading (8) on its upper, inner part for the fixation of said closing lid (6).

(23) Said cap (1) has slots (13) on its inner part that start at the bases of the side openings of said cap (1) and end in holes (14) wherein the tabs (33) of said coupling element (3) fit.

(24) The diameter of the head of said screw (2) will always be greater than the diameter of the hole of the lower outlet of said cap (1).

(25) Said screw (2) has a spherical head with a series of slots (9) separated by 90 degrees, also having in the centermost part thereof a hollow area (11) in the shape of a five-pointed star.

(26) Said screw (2) is cannulated in its interior to enable the passage of the guide wire, the hole of said cannulated screw continues from said hollow (11).

(27) Said coupling element (3) has a secondary hollow (10) corresponding to the geometry of said adjusting ring (4) and the secured tabs (7) thereof, said secondary hollow (10) formed by a ring secured to a series of slots separated by 90 degrees.

(28) Said closing lid (6) has perimeter threading and a tertiary hollow (12) in the shape of a five-pointed star in the center thereof.

(29) A screwdriver (100) on the end of the handle (101) has a threaded disc (102) around its perimeter.

(30) A rotatable cap (103) that incorporates a lug (104) in the shape of a five-pointed star in the center thereof is secured to the end of said handle (101) for the polyaxial fixation of the screw (2).

(31) A screwdriver (200) on the end of the handle (201) has a threaded disc (202) around its perimeter.

(32) A rotatable cap (203) that incorporates a lug (204) in the shape of a five-pointed star in the center thereof and two horizontal blades (205) with respect to said five-pointed star is secured to the end of said handle (201) for the uniaxial fixation of said screw (2).

(33) A screwdriver (300) on the end of the handle (301) has a threaded disc (302) around its perimeter.

(34) A rotatable cap (303) that incorporates a lug (304) in the shape of a five-pointed star in the center thereof and two vertical blades (305) with respect to said five-pointed star is secured to the end of said handle (301) for the uniaxial fixation of said screw (2).

(35) A screwdriver (400) in the end of the handle (401) has a threaded disc (402) around its perimeter.

(36) A rotatable cap (403) that incorporates a lug (404) in the shape of a five-pointed star in the center thereof and four blades (405) separated by 90 degrees with respect to said lug (404) is secured to the end of said handle (401) for the complete locking of said screw (2).

(37) Examples of use of the fixation system for spinal instrumentation:

(38) For the polyaxial fixation of the screw (2), when it is required that the cap (1) be moved in any direction to search for the reducing bar (5) (without forcing the vertebra towards that direction).

(39) For the uniaxial fixation of the screw (2), when it is required that the screw (2) be only able to move in a sagittal direction and not in other directions; for example, when it is adapted to a curve in the sagittal plane in kyphosis and we would like the head to be able to move on this plane but we do not want movements of the screw (vertebra) on the transverse plane.

(40) For the uniaxial fixation of the screw (2), when it is required that the screw (2) be able to move in a transverse but not sagittal direction; for example, when there is a purely transverse movement but it is not on the sagittal plane.

(41) For the complete fixation of the screw (2), when it is required that the vertebra remains fixed at a point without moving on any plane, we want the reducing bar (5) to search for the screw and not vice versa.

(42) In general, all of these movements are already possible with the screws existing on the market, however, for each one of these situations we would need a different screw. Here, we have the opportunity to achieve this with only one screw being able to determine in advance or even a priori how we want it to act.

(43) Having sufficiently described the nature of the present invention, in addition to an example of implementation, it must be added that the shape and materials of said invention may be modified, provided that it does not imply altering the characteristics claimed below.