Anti-distracting head and fixation screw for spinal fixation

Abstract

A fork prevention system has a base, first and second arms, first and second locking channels. Each of the first and second locking channels is formed in a respective one of the arms from a proximal opening to a proximal bottom at or adjacent a proximal start of an internal thread in the arm. The system can alternatively or also include a set screw having a drive portion, a body portion, an external thread extending from the body portion, and an intermediate locking member rotatably connected to the body portion. The intermediate locking member and the locking channels are configured such that the locking member can be moved to a fixed position in the locking channel during operation of the system and, when in the fixed position, secures both arms against forkage. The technology also includes methods for manufacturing the system or components thereof.

Description

Technical Field

[0001] The present technology generally relates to spinal fixation systems and methods, and more particularly to anti-forking and fixation screw placement. Background Art

[0002] Surgical screws and rods are commonly used to surgically correct spinal abnormalities. Pedicle screw assemblies are used to facilitate the placement and attachment of spinal rods relative to the spine. Such pedicle screw assemblies include at least a bone screw segment or anchor and at least one receiver portion attached to the bone screw. The bone screw segment is anchored to the vertebra during the surgical procedure.

[0003] The receiver portion has arms between which the various sections of the spinal rod are received. The arms are typically configured with internal threads that correspond to the threads on the set screw. After the screw is anchored in the bone and the rod is placed between the arms of the receiver, the set screw is threaded between the arms to secure the rod in the receiver.

[0004] The receiver portion of a typical pedicle screw can be angled or fixedly positioned relative to the screw section to facilitate the desired attachment of the spinal rod between the vertebrae.

[0005] Over time after implantation, outward forces on the receiver arms will attempt to cause the arms to diverge. One way to limit divergence is by configuring the receiver and set screw threads with angled thread flanks, such that the set screw holds the arms inwardly against the set screw.

[0006] Other attempted solutions for forking include the use of a cover that may be mounted over at least a portion of the exterior of the receiver arms to prevent the arms from moving away from each other.

[0007] These and other previous efforts to avoid bifurcation have suffered from various drawbacks, including undesirable cost, form factors (eg, size of the implant or fit within the patient), and strength over time. Summary of the Invention

[0008] The systems, methods, and techniques of the present disclosure generally relate to anti-fork opening and set screw arrangements.

[0009] In one aspect, the present disclosure provides an anti-split system. The system includes a receiver having a base, a first arm, a second arm, a first locking channel, and a second locking channel. The first arm and the second arm each extend from the base to define a rod-receiving cavity between the arms. The first and second arms include first and second internal threads formed on respective inner surfaces of the first and second arms. The first locking channel is formed in the inner surface of the first arm and extends from a proximal opening to a proximal bottom at or adjacent to the first proximal end of the first internal thread. The second locking channel is formed in the inner surface of the second arm and extends from a proximal opening to a proximal bottom at or adjacent to the second proximal end of the second internal thread.

[0010] Additionally in this aspect, the system includes a set screw having a drive portion, a body portion, external threads extending from the body portion, and an intermediate locking member rotatably connected to the body portion.

[0011] The intermediate locking member of the set screw and the locking channel of the receiver are configured so that the locking member can be moved to a fixed position in the locking channel during operation of the system and, when in the fixed position, the two arms are secured from spreading apart.

[0012] The intermediate locking member is rotatably connected to the main body portion intermediate the driving portion and the external thread of the set screw.

[0013] The locking member includes opposing lateral ends sized and shaped to correspond to the size and shape of the locking channel for mating engagement therebetween.

[0014] A first lateral end of the lateral ends includes an opposing shoulder sized and shaped to engage an opposing shoulder of a first locking channel of the locking channel.

[0015] The lateral ends include first and second lateral ends, and the connecting member includes first and second arms connecting the first and second lateral ends to the ring, respectively.

[0016] The depth of the locking channel is approximately twice the height of the locking end or less.

[0017] The locking member comprises a ring surrounding a portion of the set screw body. Where the ring surrounds the body, the body has a reduced diameter.

[0018] In another aspect, the system further includes a bone anchor connectable to the receiver and the spinal rod.

[0019] In yet another aspect, the technology includes a method of making any of the above-described anti-splitting systems or anti-splitting components.

[0020] The details of one or more aspects of the disclosure are set forth in the following drawings and description. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 shows a perspective view of a partially exploded anti-split system according to an embodiment of the present disclosure, the system including an anti-split receiver and an anti-split set screw;

[0022] Figure 2 For the Figure 1 A cross-sectional view of the anti-split fixing screw taken along the section line 2-2;

[0023] Figure 3 for Figure 1 A side view of the anti-fork opening system;

[0024] Figure 4 is a perspective view of the anti-strapping set screw as it is lowered for insertion into the receiver;

[0025] Figure 5 for Figure 4 A perspective view of the embodiment of the present invention with the anti-split set screw threaded into its final position within the anti-split receiver;

[0026] Figure 6 Bottom view of the fixing screw to prevent it from being split;

[0027] Figure 7 To prevent forking, a top view of the receiver;

[0028] Figure 8 for Figure 7 a top view of the device with the anti-split set screw inserted into the anti-split receiver; and

[0029] Figure 9 For the Figure 1 A cross-sectional view of the assembled anti-split system taken along section line 9-9. DETAILED DESCRIPTION

[0030] Turning now to the drawings, and in particular the first drawing, Figure 1 A perspective view of components of an anti-split system, generally indicated by reference numeral 100 , is shown.

[0031] According to an embodiment of the present disclosure, system 100 includes an anti-split head or receiver 110 and an anti-split set screw 120 .

[0032] The receiver 110 has arms 112 extending upwardly or proximally from a base 113. The arms 112 define a rod cavity 114 therebetween for receiving a spinal fusion rod. Figure 3 and 8 Schematically shown in FIG. 1 is a rod 300 positioned in the cavity 114 .

[0033] Set screw 120 extends from a driving or proximal end having a drive portion 122. Drive portion 122 includes a drive port 123. Drive port 123 may be a cavity sized and shaped to correspond to any available set screw driver (shown).

[0034] The set screw 120 further includes a shaft or body 125 extending to a distal end of the screw 120. In contemplated embodiments, the drive portion 122 can be integrally or monolithically formed with or within the body 125 of the set screw 120.

[0035] The body 125 has a threaded exterior 126. The threaded surface 126 corresponds in size and shape to the threads 116 of the receiver 110 for threading into the receiver.

[0036] The fixing screw 120 further includes a locking member 124. The locking member 124 is rotatably connected to the body 125, as shown in FIG. Figure 1 Indicated by the arrow in .

[0037] In various embodiments, the locking member 124 is connected to the body 125 intermediate the drive portion 122 and the threads 126. In such cases, the locking member 124 may be referred to as an intermediate locking member, an in-screw locking member, or the like.

[0038] although Figure 1 The arrow in indicates a first rotational direction, but in various embodiments, the connection features are configured such that the locking member 124 can be rotated in both directions or only in one direction or the other.

[0039] The locking member 124 extends between opposite ends 128. The ends 128 of the locking member 124 are connected by a central connector 130. In various embodiments, the connector is formed as a ring 130. The ring 130 surrounds a portion of the body 125 that extends up to the drive portion 122, just as Figure 2 In various embodiments, the body 125 has a reduced diameter to accommodate a ring, such as Figure 2 shown.

[0040] The connection in various embodiments includes features that facilitate relative rotation between the ring 130 and the body 125, such as ball bearings or medical lubricant.

[0041] End 128 may extend through arm 127 , connecting end 128 to a central connecting structure 130 , such as a connecting ring 130 .

[0042] With further reference to the anti-split receiver 110, each arm 112 has an internal thread set 116. Figure 1 As shown, each thread set 116 is interrupted or separated by an anti-split or locking channel 118 at the proximal end of the receiver threads 116. The threads 116 oppose each other across the cavity 114 and may be referred to as opposing threads or thread segments.

[0043] Each locking channel 118 is opened from the proximal opening 117 (refer to Figure 1 ) extends distally to a distal stop or bottom. In operation of the system 100, the anti-split set screw 120 is screwed into the anti-split receiver 110 until the locking member 124 enters the locking channel 118. The screwing can be performed until the locking member 124 is engaged with the channel stop 119 ( Figure 7 ) engages and / or the distal end of the body with the spinal rod 300 ( Figure 3 and 8 ) engagement. In most embodiments, engaging the rod is a priority.

[0044] The size and shape of the locking channel 118 and the size and shape of the anti-split set screw 120 are set so that the set screw 120 extends distally when threaded into the receiver 110 until the rod is contacted through the distal end of the rod. At this point, or after a small amount of further threading, such as a quarter turn, half turn, or full turn of the screw 120, the locking member 124 bottoms out at the stop 119 of the channel 118. In some embodiments, the system 100 is designed and the rod is sized so that the locking end 128 fully enters the channel 118 even without bottoming out.

[0045] The locking channel must be deep enough. If the locking channel 118 is not deep enough, the locking member 124 will bottom out at the stop 119 before the set screw 120 can be fully threaded into the receiver 110.

[0046] In various embodiments, the stop 119 is at or adjacent the top of the corresponding internal thread 116. For example, the stop 119 can be at or adjacent the first, second, or third level of the internal thread 116. Figure 1 In the example of , the channel extends from the top or opening 117 through a single layer of internal threads, wherein the stop 119 is generally at the beginning of the second layer of internal threads starting from the top or opening 117. These areas including the first or several threads can be generally referred to as the proximal beginning of the internal threads.

[0047] In various embodiments, the channel depth is at least equal to the height of the locking member 124 or the height of the end 128 of the locking member 124 .

[0048] In contemplated embodiments, system 100 or a kit in which the system is provided includes any of the components mentioned. The system or kit may include any suitable components for performing a surgical procedure, including, but not limited to, implantable components and instruments for performing the procedure. System 100 may include, for example, any of anti-split receiver 110, anti-split set screw 120, and rod 300. System 100 or the kit may include the drivers mentioned but not shown. System 100 or the kit may include any number and size of these components, including multiple anti-split set screws 120 and receiver 110.

[0049] Turning to the second accompanying figure, Figure 2 Shown along Figure 1 FIG. 1 is a cross-sectional view of the fixing screw 120 taken along line F2 - F2.

[0050] In system 100( Figure 1 ), the surgeon or the surgical robot aligns the locking member 124 with the locking channel 118 of the receiver 110. When the anti-split set screw 120 is screwed into the receiver 110, the surgeon or the robot rotates the driver (or driving instrument; not shown) against the driving portion 220 of the driving portion 122, and the locking member 124 enters the channel 118.

[0051] Figure 3 for Figure 1 1 and 12. A side view of the anti-split receiver 110 and the anti-split set screw 120. The rotatability of the locking member 124 relative to the set screw body 125 is again indicated by the arrow.

[0052] Figure 3 Also schematically shown is an end view of the rod 300 positioned within the cavity 114 of the receiver 110 .

[0053] Figure 4 A perspective view of the anti-split set screw 120 as it is lowered for insertion into the anti-split receiver 110. This movement is generally determined by Figure 4 Indicated by the arrow in .

[0054] exist Figure 4 Prior to removal of the vertebra, the receiver 110 is secured to the patient's vertebra by a bone screw connected to the receiver 110. The bone screw (not shown) can be of any conventional or available type. The receiver 110 can be configured for top loading or bottom loading of the bone screw into the receiver 110. The receiver 110 can be easily connected or connectable to a bone anchor in such a manner as to be readily accessible during the normal course of surgery.

[0055] The anti-splitting receiver 110 and the anti-splitting bone screw 120 can be further configured to allow desired relative motion, such as uniaxial or multiaxial motion. In some embodiments, the bone screw and receiver 110 are fixed together by being integrally or monolithically formed or fixedly connected to each other.

[0056] In operation of the anti-split system 100 , care is taken to align the locking end 128 of the locking member 124 with the anti-split channel 118 of the arm 112 of the receiver 110 before and / or as the setscrew 120 moves toward the receiver 110 .

[0057] The anti-split channel 118 accommodates the end 128 of the locking member 124. In various embodiments, the locking member 124 is sized so that the end extends laterally further than the maximum diameter of the screw body 125, and in some cases, further than the maximum diameter of the threads 126, as shown and best seen in FIG. Figure 2 .

[0058] Figure 5 1 and 2 show the final position in which the anti-split set screw 120 has been screwed into the anti-split receiver 110. In this position, the locking member 124 will rest against the rod 300, as shown in FIG. Figure 3 and 8 The screwing motion that causes the fixing screw 120 to transition toward the final position is as shown in FIG. Figure 5 Indicated by the arrow in .

[0059] Figure 6 The bottom view of the fixing screw 120 is to prevent the fixing screw from being split apart. The relative rotatability between the fixing screw body 125 and the locking member 124 is as follows: Figure 6 and Figure 1 Indicated by the arrow in .

[0060] End 128 of locking member 124 is configured so that when engaged with arms 112 of receiver 110, it slides into anti-split channel 118 to prevent arms 112 from moving away from each other. The connection prevents each arm 112 from moving away from the other, i.e., prevents arms 118 from splitting apart.

[0061] The end 128 of the locking member 124 includes a first engagement or locking feature 600, such as a shoulder. The shoulder 600, which may be referred to as an outer shoulder, corresponds to a second engagement or locking feature 700 ( Figure 7 The shoulder 600 of the locking member 124 may be referred to as an outer shoulder, which corresponds to the inner shoulder 800 of the receiver 110 .

[0062] The configuration of each end 128 may be referred to as a double dovetail, corresponding to the opposing shoulders 600 .

[0063] In contemplated embodiments (not shown in detail), the locking or engagement features can be configured in any of a variety of other ways. These features can include a locking member 124 having opposing inner shoulders at each end 128. In this case, the inner shoulders of the locking member 124 form a locking member void to engage, for example, opposing outer shoulders of a projection extending from or on the inner surface of each arm 112 of the receiver 110. In this case, the locking member 124 is aligned so that when the inner shoulders of the locking member 124 slide downwardly along the outer shoulders of the projections of the receiver arms 112, the projections of the receiver arms 112 are received in the voids of the locking member 124.

[0064] Figure 7 A plan view of the anti-split receiver 110 is shown. The view shows a top or approximate view of the receiver including the anti-split channel 118.

[0065] Figure 8 for Figure 7 1, wherein the anti-splitting set screw 120 is inserted into the anti-splitting receiver 110 to produce the assembled anti-splitting system 100. The complete assembly in some embodiments includes the anti-splitting set screw 120 and the receiver 110 connected to the bone anchor (not shown).

[0066] The rod 300 is shown positioned within the anti-split receiver 110. The rod 300 is secured in place by the receiver 110 and the anti-split set screw 120 threaded into the receiver 110, with the end 128 of the locking member 124 secured within the anti-split channel 118 of the receiver 110.

[0067] It should be understood that the various aspects disclosed herein may be combined in combinations other than those specifically presented in the detailed description and figures. It should also be understood that, depending on the instance, certain actions or events in any process or method described herein may be performed in a different order, added, combined, or omitted entirely (e.g., not all described actions or events are required to implement the described technology).

[0068] Unless the present disclosure or claims expressly require such limitation, any disclosure or claim herein that refers to a direction is not intended to limit the interpretation of the present disclosure. For example, references herein to upward or downward movement are not limited to movement in any particular direction during a surgical procedure or system assembly, as the surgical procedure or assembly can be performed in any of a variety of directions or in any suitable frame of reference.

[0069] Additionally, while certain aspects of the present disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of the present disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0070] Unless otherwise specifically defined herein, all terms should be given their broadest possible interpretation, including the meaning implicit from the specification and the meaning understood by those skilled in the art and / or the meaning as defined in dictionaries, treatises, etc. It must also be noted that, unless otherwise specified, the singular forms "a", "an", and "the" used in the specification and the appended claims include plural referents, and the terms "comprises" and / or "comprising" when used in this specification specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0071] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be interpreted as limiting, but should only be used as an illustration of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. An anti-split system, comprising: a receiver having a base, a first arm, a second arm, a first locking channel, and a second locking channel, the first arm and the second arm each extending from the base to define a rod receiving cavity therebetween, the first arm and the second arm including first and second internal threads formed in respective inner surfaces of the first and second arms, the first locking channel being formed in the inner surface of the first arm and extending from a proximal opening to a proximal bottom at or adjacent to a first proximal end of the first internal thread, and the second locking channel being formed in the inner surface of the second arm and extending from the proximal opening to a proximal bottom at or adjacent to a second proximal end of the second internal thread; and a set screw having a drive portion, a body portion, external threads extending from the body portion, and an intermediate locking member rotatably connected to the body portion, wherein the intermediate locking member is rotatably connected to the body portion intermediate the drive portion and the external threads of the set screw; The intermediate locking member of the set screw and the locking channel of the receiver are configured so that the locking member can be moved to a fixed position in the locking channel during operation of the system, and when in the fixed position, the two arms are fixed to prevent them from crossing.

2. The system of claim 1 , wherein the locking member includes opposing lateral ends sized and shaped to correspond to the size and shape of the locking channel for mating engagement between the locking member and the locking channel.

3. The system of claim 2, wherein a first lateral end of the lateral ends includes an opposing shoulder sized and shaped to engage an opposing shoulder of a first locking channel of the locking channel.

4. The system of claim 2, wherein the lateral end comprises first and second lateral ends, and the first and second lateral ends are connected by a central connector.

5. The system of claim 2, wherein the depth of the locking channel is approximately twice the height of the locking end or less.

6. The system of claim 1, wherein the locking member comprises a ring surrounding a portion of the set screw body.

7. The system of claim 6, wherein the body has a reduced diameter at the location where the ring surrounds the body.

8. An anti-split system comprising: bone anchors; spinal rods; a receiver configured to couple with the bone anchor, the receiver having a base, a first arm, a second arm, a first locking channel, and a second locking channel, the first arm and the second arm each extending from the base to define a rod receiving cavity therebetween, the first arm and the second arm including first and second internal threads formed in respective inner surfaces of the first and second arms, the first locking channel formed in the inner surface of the first arm and extending from a proximal opening to a proximal bottom at or adjacent to a first proximal end of the first internal thread, and the second locking channel formed in the inner surface of the second arm and extending from the proximal opening to a proximal bottom at or adjacent to a second proximal end of the second internal thread; and a set screw for securing the rod in position in the receptacle in a portion of the system, the set screw having a drive portion, a body portion, external threads extending from the body portion, and an intermediate locking member rotatably connected to the body portion, wherein the intermediate locking member is rotatably connected to the body portion intermediate the drive portion and the external threads of the set screw; The intermediate locking member of the set screw and the locking channel of the receiver are configured so that the locking member can be moved to a fixed position in the locking channel during operation of the system, and when in the fixed position, the two arms are fixed to prevent them from crossing.

9. The system of claim 8, wherein the locking member includes opposing lateral ends sized and shaped to correspond to the size and shape of the locking channel for mating engagement between the locking member and the locking channel.

10. The system of claim 9, wherein a first lateral end of the lateral ends includes an opposing shoulder sized and shaped to engage an opposing shoulder of a first locking channel of the locking channel.

11. The system of claim 9, wherein the lateral end comprises first and second lateral ends, and the first and second lateral ends are connected by a central connector.

12. The system of claim 11, wherein the depth of the locking channel is approximately twice the height of the locking end or less.

13. The system of claim 8, wherein the locking member comprises a ring surrounding a portion of the set screw body.

14. The system of claim 13, wherein the body has a reduced diameter at the location where the ring surrounds the body.

15. A method for manufacturing an anti-split system, comprising: forming a receiver configured for connection to a bone anchor, the receiver having a base, a first arm, a second arm, a first locking channel, and a second locking channel, The first arm and the second arm each extend from the base and define a rod-receiving cavity therebetween, the first arm and the second arm comprising first and second internal threads formed in respective inner surfaces of the first and second arms, the first locking channel formed in the inner surface of the first arm and extending from a proximal opening to a proximal bottom at or adjacent to a first proximal end of the first internal thread, and the second locking channel formed in the inner surface of the second arm and extending from the proximal opening to a proximal bottom at or adjacent to a second proximal end of the second internal thread; providing a set screw for securing the rod in position in a receiver in a portion of the system, the set screw having a drive portion, a body portion, external threads extending from the body portion, and an intermediate locking member rotatably connected to the body portion and having opposing locking ends, wherein the intermediate locking member is rotatably connected to the body portion intermediate the drive portion and the external threads of the set screw, The intermediate locking member of the set screw and the locking channel of the receiver are configured so that the locking member can be moved to a fixed position in the locking channel during operation of the system, and when in the fixed position, the two arms are fixed to prevent them from crossing.

16. The method of claim 15, wherein the intermediate locking member comprises a central ring connected to the locking end.

17. A method of forming an anti-split system, comprising: providing a set screw for securing a rod in position in a receiver in a portion of the system, the set screw having a drive portion, a body portion, external threads extending from the body portion, and an intermediate locking member rotatably connected to the body portion and having opposing locking ends, The locking member comprises a central ring and opposite lateral ends connected to the ring, and the central ring surrounds a portion of the body extending up to the driving portion.

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