CUSTOMIZED POSTERIOR ATLANTOAXIAL REDUCTION FIXATORWITH SCREWS AND RODS

Abstract

A customized posterior atlantoaxial reduction fixator with screws and rods, including two supporting-screws, two pulling-screws, two variable cross section fixing rods, a bracing beam, two lock nuts and two pressing rod nuts. Each of the supporting-screws includes a first head and a first body, and each of the pulling-screws includes a second head and a second body; tips of both the first body and the second body are provided with a tapered thread; both the first head and the second head are provided with nail grooves inside, with U-shaped grooves on the sides; each of the a plurality of nail grooves is provided with an internal thread inside; the second head is provided with a long arm nail groove, with an annular recess configured on the middle part of an outer wall.

Claims

1. A customized posterior atlantoaxial reduction fixator comprising: two supporting-screws, two pulling-screws, two variable cross section fixing rods, a bracing beam, two lock nuts and two pressing rod nuts; wherein each of the two variable cross section fixing rods is configured to connect one of the two supporting-screws and one of the two pulling-screws; the bracing beam is configured to connect the two supporting-screws on the two variable cross section fixing rods; wherein each of the two supporting-screws comprises a first head and a first body, and each of the two pulling-screws comprises a second head and a second body; both the first head and the second head are provided with a plurality of nail grooves, and a plurality of U-shaped grooves on sides; wherein each of the plurality of nail grooves is provided with an internal thread inside, so that a lock nut can be connected to the internal thread of the nail groove of the first head, and a pressing rod nut can be connected to the internal thread of the nail groove of the second head; each of the variable cross section fixing rods passes through the plurality of U-shaped grooves and is fastened by the lock nut; a plurality of bottoms of the nail grooves of the supporting-screws are 2-6 mm higher than the bottoms of the plurality of nail grooves of the pulling-screws; wherein each of the variable cross section fixing rods is provided with an anti-rotation joint portion matched with the plurality of U-shaped grooves; the anti-rotation joint portion is located on one end of a universal round bar of the variable cross section fixing rod; the cross section of the anti-rotation joint portion includes a curved part and a rectangular part; wherein the curved part is a semicircle, with a radius being equal to that of the round bar; wherein a length of a long side of the rectangular part is equal to a diameter of the curved part, and a length of a short side of the rectangular part is equal to a radius of the round bar.

2. The customized posterior atlantoaxial reduction fixator according to claim 1, wherein, both ends of the anti-rotation joint portion are 2-3 mm longer than both ends of the U-shaped groove respectively.

3. The customized posterior atlantoaxial reduction fixator according to claim 1, wherein, the second head is provided with a long arm nail groove, with an annular recess configured on a middle part of an outer wall.

4. The customized posterior atlantoaxial reduction fixator according to claim 3, wherein, the second head is separated into upper and lower portions through the annular recess, a ratio of a height of the upper portion to a height of the lower portion is N/1, wherein N≥1.

5. The customized posterior atlantoaxial reduction fixator according to claim 1, wherein, the pulling-screw is a polyaxial screw, with the second head connected to the second body having a tapered thread tip.

6. The customized posterior atlantoaxial reduction fixator according to claim 1, wherein, the first body of the supporting-screw is a single-axial screw fastened to the first head, having the tapered thread tip; or the first body of the supporting-screw is a polyaxial screw fastened to the first head, having the tapered thread tip.

7. The customized posterior atlantoaxial reduction fixator according to claim 1, wherein, both sides of the bracing beam are provided with a plurality of transverse openings, each of the plurality of transverse openings is an approximative rectangle, with two curved short sides; one end of the lock nut is connected to the first head through a thread, an other end of the lock nut is fastened by a screw cap after the other end passes through one of the plurality of transverse openings.

8. The customized posterior atlantoaxial reduction fixator according to claim 7, wherein, a ring slider is clamped on each of the plurality of transverse openings, an inner wall of the plurality of transverse opening is provided with a sliding slot, an external wall of the ring slider is provided with a projecting part configured to be inserted into the sliding slot; wherein, the ring slider is provided with a gap, one end of the lock nut passes through the ring slider.

9. The customized posterior atlantoaxial reduction fixator according to claim 8, wherein, the external wall of the lock nut comprises a head thread connected with the first head and a screw cap thread connected with a screw cap; a diameter of the head thread is greater than that of the screw cap thread, and is greater than that of the ring slider; a diameter of the screw cap thread is less than that of the ring slider, a diameter of the external wall of the screw cap is greater than that of the ring slider; a through-hole with a hexagonal cross section is provided at a center of the lock nut.

10. The customized posterior atlantoaxial reduction fixator according to claim 1, wherein, the bracing beam is a straight plate or a curved plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings:

[0025] FIG. 1 shows a schematic diagram of the integral structure of the customized posterior atlantoaxial reduction fixator with screws and rods according to the present invention;

[0026] FIG. 2 shows a schematic diagram of the structure of a traditional screw and a supporting-screw according to the present invention; wherein 2-1 represents the traditional screw, and 2-2 represents the supporting-screw;

[0027] FIG. 3 shows a schematic diagram of the structure of a traditional pulling-screw and a pulling-screw according to the present invention; wherein C′ represents the pulling-screw, and C represents the traditional pulling-screw; wherein 3-1 represents a nut, C-1 represents a short arm, and C′-1 represents a long arm;

[0028] FIG. 4 shows a schematic diagram of the pulling-screws according to the present invention, it shows the second head with different specifications;

[0029] FIG. 5 shows a structural schematic diagram of a variable cross section fixing rod according to the present invention;

[0030] FIG. 6 shows a cross-section view of an anti-rotation joint portion of a variable cross section fixing rod according to the present invention;

[0031] FIG. 7 shows a front view of a bracing beam according to the present invention;

[0032] FIG. 8 shows a side view of a bracing beam according to the present invention;

[0033] FIG. 9 shows a connection relationship diagram of a lock nut, a bracing beam and a screw cap according to the present invention;

[0034] FIG. 10 shows a top view of a lock nut according to the present invention;

[0035] FIG. 11 shows a view of reduction effects with different pulling-screws, wherein the left image shows a traditional pulling-screw with a short arm, which needs pressing rod treatment in use; wherein the right image shows a pulling-screw with a long arm according to the present invention, without the need of pressing rod treatment in use; wherein D represents the direction of lifting, C-1 represents a short arm, C′-1 represents a long arm, E represents a normal axis, and A represents an atlas in dislocation;

[0036] FIG. 12 shows a view of effects before and after reduction with traditional supporting-screws; in the case of serious dislocation, limited height of reduction leads to undesired effects after reduction; wherein D represents the direction of lifting, E represents a normal axis, and A represents an atlas in dislocation; and

[0037] FIG. 13 shows a view of effects before and after reduction with the supporting-screws according to the present invention; wherein the supporting-screws with height-increased nail groove result in desired effects after reduction, with greater lifting height; wherein D represents the direction of lifting, E represents a normal axis, and A represents an atlas in dislocation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout.

[0039] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” or “has” and/or “having” when used herein, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

[0040] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0041] Hereinafter, certain exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0042] As shown in FIGS. 1-12, a customized posterior atlantoaxial reduction fixator with screws and rods, comprising two supporting-screws 1, two pulling-screws 2, two variable cross section fixing rods 3, two lock nuts 4, two pressing rod nuts 5 and a bracing beam 6. Each of the variable cross section fixing rods 3 is configured to connect a supporting-screw 1 and a pulling-screw 2, the bracing beam 6 is configured to connect the supporting-screws 1 on the variable cross section fixing rods 3. Each of the supporting-screws 1 comprises a first head 11 and a first body 12, and each of the pulling-screws 2 comprises a second head 21 and a second body 22; both the first head 11 and the second head 21 are provided with nail grooves, with U-shaped grooves on the sides; wherein each of the nail grooves is provided with internal thread inside, so that the lock nut 4 can be connected to the internal thread of the nail groove of the first head 11, and the pressing rod nut 5 can be connected to the internal thread of the nail groove of the second head 21. Each of the variable cross section fixing rods 3 passes through the U-shaped grooves and is fastened by the lock nut 4 and the pressing rod nut 5. The bottoms of the nail grooves of the supporting-screws 1 are 2-6 mm higher than the bottoms of the nail grooves of the pulling-screws. As shown in FIG. 2, h represents the height of the bottom of the nail groove. Specifically, 2-1 represents the traditional screw with a height h1, and 2-2 represents the supporting-screw with a height h2, wherein the specific value of h2 could be selected in accordance with different situations. In the production of the products, the specific value of h2 could be multiples of 1 mm, and the abovementioned height adjustment can obtain the effect of lifting height of supporting-screws, thus improving the capacity of spondylolisthesis reduction of a screw-rod system. As shown in FIG. 11, the view shows the reduction effects comparison, we can see that a spondylolisthesis reduction system with the pulling-screws with long arms according to the present invention possesses much better effects of spondylolisthesis reduction than a spondylolisthesis reduction system with traditional pulling-screws with short arms.

[0043] Preferably, as shown in FIG. 5, each of the variable cross section fixing rods 3 is provided with an anti-rotation joint portion 31 matched with the U-shaped grooves. The anti-rotation joint portion 31 is located on one end of the universal round bar of the variable cross section fixing rod 3. The cross section of the anti-rotation joint portion 31 includes a curved part and a rectangular part (see FIG. 6); wherein the curved part is a semicircle, with a radius being equal to that of the round bar; wherein the length of a long side of the rectangular part is the same as the diameter of the curved part, and the length of a short side of the rectangular part is the same as the radius of the round bar. Compared to a routine fixing rod without any anti-rotation portion, the anti-rotation joint portion 31 can achieve good effects of anti-rotation. Additionally, unlike an oval anti-rotation structure, there is no need to modify the structure of a screw, there is no need to adjust accompanying tools (e.g. a rod bending tool). Furthermore, the oval anti-rotation fixing rod is less compatible with existing screws and accompanying tools, wherein it needs screws with deeper U-shaped groove. In contrast, the variable cross section fixing rod 3 according to the present invention has both excellent effects of anti-rotation and good compatibility.

[0044] Preferably, as shown in FIG. 3, the second head 21 is provided with a long arm nail groove, with an annular recess 23 configured on the middle part of the outer wall. When a fixing rod is placed into the long arm nail groove, a doctor can tighten the nut directly, without a pressing rod device or a lifting the screw and pressing the rod device.

[0045] Accordingly, compared to short arm screw, the long arm nail groove is easy to be applied in reduction operation, without pressing the rod, and the needless upper portion can be broken off at the annular recess 23 after the completion of reduction (see FIG. 12).

[0046] More preferably, the second head 21 is separated into upper and lower portions through the annular recess 23, the height ratio of the upper portion to the lower portion is Nil, wherein N≥1. FIG. 4 shows a schematic diagram of the pulling-screws with N=1, 2 and 3.

[0047] Preferably, the pulling-screw is a polyaxial screw, with the second head 21 connected to the second body 22 which has a tapered thread tip. The first body 12 of the supporting-screw 1 is a single-axial screw which is fastened to the first head 11, having a tapered thread tip or a polyaxial screw which is fastened to the first head 11, having a tapered thread tip. It is noted that the connection fashion of a polyaxial screw could be as follows: to drill a hole at the bottom of the nail groove of the first head 11 or the second head 21, and let the polyaxial screw pass through the hole.

[0048] As shown in FIGS. 7 and 8, both sides of the bracing beam 6 are provided with transverse openings 61, each of which is an approximative rectangle, with two curved short sides. One end of the lock nut 4 is connected to the first head 11 through thread, the other end of the lock nut 4 is fastened by a screw cap 7 after the other end passes through one of the transverse openings 61. A ring slider 62 is clamped on each of the transverse openings 61, the inner wall of the transverse opening 61 is provided with a sliding slot, the external wall of the ring slider 62 is provided with a projecting part configured to insert into the sliding slot; wherein the ring slider 62 is provided with a gap, one end of the lock nut 4 passes through the ring slider 62.

[0049] As shown in FIGS. 9 and 10, the external wall of the lock nut 4 comprises a head thread 41 connected with the first head 11 and a screw cap thread 42 connected with the screw cap 7. The diameter of the head thread 41 is greater than that of the screw cap thread 42, and is also greater than that of the ring slider 62; the diameter of the screw cap thread 42 is less than that of the ring slider 62, the diameter of the external wall of the screw cap 7 is greater than that of the ring slider 62. Moreover, a through-hole with hexagonal cross section is configured in the center of the lock nut 4.

[0050] Preferably, the bracing beam 6 could be a straight plate or a curved plate, depending on various situations.

[0051] The following description is intended to illustrate the use procedure of the customized posterior atlantoaxial reduction fixator according to the present invention. In use, firstly, the supporting-screws 1 with higher nail grooves are screwed into a normal axis in accordance with the degree of dislocation, the pulling-screws 2 are screwed into an atlas in dislocation; after that, an anti-rotation joint portion 31 of each of the variable cross section fixing rods 3 is placed into a U-shaped groove of the first head 11, the other end passes through a U-shaped groove of the second head 21, then a lock nut 4 is fastened to the first head 11 through a head thread 41, so that the variable cross section fixing rod 3 is fastened, avoiding rotation. Secondly, a tool is utilized to screw the pressing rod nut 5 into the U-shaped groove of the second head 21, and the variable cross section fixing rod 3 is gradually pressed down to the bottom of the second head 21 during the screwing process; simultaneously, under the lifting force of the variable cross section fixing rod 3, the vertebral body in dislocation gradually restores the normal position, after the completion of screwing, the upper portion of the second head 21 is broken off at the annular recess 23. Thirdly, a ring slider 62 of the bracing beam 6 passes through the screw cap thread 42 of a lock nut 4 on the supporting-screw 1. Finally, the other end of the lock nut 4 is fastened by a screw cap 7, and the process of reduction and fixation is completed.

[0052] The above descriptions are only the preferred embodiments of the invention, not thus limiting the embodiments and scope of the invention. Those skilled in the art should be able to realize that the schemes obtained from the contents of the specification and drawings of the invention are within the scope of the invention.