Patent Application
20220183722
Not Applicable.
Not Applicable.
Not Applicable.
The present application relates to a pedicle tract stabilization system for fixing a pedicle screw into a vertebra. The pedicle tract stabilization system is also known as a pedicle tract stabilization device or apparatus. More particularly, the present application relates to a bone anchor of the pedicle tract stabilization system for stabilizing the vertebra during surgical instrumentation of the spine as well as a fixation mechanism of the pedicle tract stabilization system for fixing the bone anchor in place during the surgical instrumentation.
There have been revolutionary advancements in spinal neuronavigational technology in the last few decades. Computed Tomography (CT) guided imaging techniques and integration with robotics have optimized accuracy of pedicle screw placement. Currently, methods of eliminating motion artefacts into a navigational system are available; However, the current methods cannot prevent motion occurring during pedicle screw preparation and insertion. Furthermore, cancellation of the motion artefacts does not ensure that an intended screw trajectory is preserved. In fact, a real screw trajectory may be deviated from the intended screw trajectory and may require revisions during pedicle screw insertion.
In order to resolve these problems, the present application introduces a pedicle tract stabilization system for preparing and inserting a pedicle screw in a vertebra, which would have applications in spinal operations, including minimally invasive surgery (MIS). The pedicle tract stabilization system also inherently enables an automated or manually operated drill/screwdriver to detect a potential breach in the pedicle cortex (e.g. the breach is determined by indirect measures of a change in resistance of the pedicle cortex), thereby informing the surgeon to revise the current trajectory. Furthermore, the proposed pedicle tract stabilization system could also provide a channel for insertion of an ultrasound device to visualize walls of the pedicles which can help to optimize the planned trajectory for pedicle tract preparation and screw insertion and potentially eliminate the need for intraoperative radiation required in neuronavigational techniques. In addition, the proposed pedicle tract stabilization system may also have other advantages, including being a lightweight system, easy to operate and cost-effective.
In view of the foregoing background, it is therefore an object of the non-limiting exemplary embodiment(s) to provide a pedicle tract stabilization system. These and other objects, features, and advantages of the non-limiting exemplary embodiment(s) are provided by a first aspect, wherein the present application discloses a bone anchor for stabilizing the vertebra when the pedicle screw and preparation instruments (such as awl, pedicle probe and tap screw) are inserted into the vertebra. The bone anchor comprises a gripping mechanism for securing the bone anchor to the vertebra and a central body for coupling the gripping mechanism. In particular, the gripping mechanism is configured to form an aperture (also known as lumen) for the pedicle screw and other instruments to pass through the gripping mechanism. For example, an awl is attached at an end of a stylet or a slender probe which is inserted through the aperture to reach a pre-determined location in the vertebra, such as a drilled facet, an inferior articular process or a lateral mass.
The gripping mechanism optionally comprises a tapered screw with a plurality of screw threads for securing the bone anchor to the surrounding vertebral cortex. The screw threads may have various depths to provide better purchase with the vertebral cortex surrounding the tapered screw for reducing or even eliminating any likelihood of pullout and advancement of the bone anchor from a fixed position in the vertebral cortex.
The tapered screw optionally has an inner side with an inner angle and an outer side with an outer angle. The inner side and the outer side face the aperture and the vertebral cortex, respectively. The screw threads are optionally coupled to the outer side of the gripping means for providing better anchorage with the surrounding vertebral cortex. In particular, the inner angle is larger than the outer angle, since the inner angle is designed to accommodate a wide range of screw trajectories while the outer angle aims to facilitate acceptance of the bone anchor when the bone anchor is screwed into a decorticated edge of the drilled facet, the inferior articular process or the lateral mass.
The inner side and the outer side of the tapered screw are configured to form a sharp edge for cutting through underlying cancellous bone of the vertebral cortex for preparing a screw trajectory in the vertebra. The profile of the tapered screw can either be a conical-cutting configuration or crown-cutting configuration. The conical-cutting configuration has a fixed inner angle and thus a fixed screw depth which permits only a maximum inner angle for the screw to rest. While the crown-cutting configuration has a variable inner angle which provides a greater degree of angulation for the screw to rest and also provides a greater screw depth. Therefore, the crown-cutting configuration is more advantageous as it provides a wider range of possible screw trajectories and also greater screw depth for better integration into surrounding cancellous bones.
The central body may further comprise a base coupled to the tapered screw for mechanically supporting the tapered screw. The base is opposed to the sharp edge of the tapered screw. The base is also used to couple the tapered screw to other parts of the pedicle tract stabilization system. The bone anchor optionally further comprises an adjustable head movably coupled to the base. In some implementations, the base has a first hinge or a first movable joint movably coupled to the adjustable head for enabling greater rotation of the adjustable head. Therefore, the first hinge allows the pedicle screw or other surgical instruments to be orientated in a certain direction through the aperture. The adjustable head is configured to form an internal cavity aligned with the aperture for the pedicle screw or other surgical instruments to pass through the adjustable head, the base and the tapered screw.
Within the internal cavity and the aperture, the bone anchor is optionally configured to form a screw trajectory along which the pedicle screw or other surgical instruments are inserted into the pedicle cortex. In particular, the screw trajectory is configured to adjust in a certain range in the internal cavity and the aperture. The certain range is determined by two factors, firstly widths of the internal cavity and the aperture; and secondly the inner angle of the tapered screw. Hence, the wider the internal cavity and the aperture are, and the larger the inner angle is, the larger the range of available screw trajectories there will be.
The adjustable head is configured to form a side aperture for a bar to laterally pass through. In this way, multiple bone anchors loaded at different vertebral levels on one side of the spinal column are assembled together by inserting the bar laterally through their side apertures for thereby forming a stable screw-rod fixation construct. In particular, the bar may have a curved configuration for matching a curved profile of the spinal column. If one of the bone anchors is accidently not stabilized, the rest bone anchors could help fix the unstable bone anchor via the bar.
The adjustable head optionally comprises a threaded end for coupling to a fixation mechanism. For example, the adjustable head has a threaded end opposed to the tapered screw; while the fixation mechanism has complementary threads matching the threaded end; and thus the adjustable head is firmly assembled with the fixation mechanism at the threaded end.
The bone anchor may further comprise a stylet coupled to the base for stabilizing the bone anchor when the bone anchor is screwed into decorticated facet in the vertebral cortex. In some implementations, the stylet has a first stylet arm and a second stylet arm coupled to a left side and a right side of the base of the bone anchor, respectively. For example, the base has a first hole and a second hole on the left side and the right side for receiving the first stylet arm and the second stylet arm, respectively.
The bone anchor may further comprise a locking nut superimposed onto the bar within the adjustable head for securing the bar to the bone anchor. The locking nut (also known as locknut, lock nut, self-locking nut or stiff nut) could resist loosening under vibrations and torque when the bone anchor is inserted into the vertebra vortex. In some implementations, the locking nut comprises a prevailing torque nut or an elastic stop unit of which some portion deforms elastically to provide locking action.
The pedicle screw optionally comprises a polyaxial screw which is easily aligned correctly with the screw trajectory, since the polyaxial screw could be adjusted to multiple axes directing to the screw trajectory without hindrance. The polyaxial screw may further comprise a polyaxial screw base configured to load on the base; and a screw shaft movably coupled to the screw chassis. In particular, the screw shaft is configured to form an acute angle with the screw base.
As a second aspect, the present application discloses a fixation mechanism for fixing a bone anchor. The fixation mechanism comprises a frame coupled to the bone anchor. In particular, the frame is configured to form an internal passage for a pedicle screw and other surgical instruments (such as pedicle tract preparation instruments) to pass through. Therefore, the frame, the adjustable head, the base and the tapered screw are configured to form a through channel for the pedicle screw and other surgical instruments to pass through. In some implementations, the frame comprises a flute having a hollow cylindrical configuration which matches the adjustable head in size.
The fixation mechanism may further comprise an internal stabilizing component (also known as internal stabilizer) coupled within the frame for minimizing buckling of the bone anchor in operation by allowing rotatory movement of the bone anchor only. Therefore, excessive motions of surgical instruments (i.e. pedicle probe, tap screw and pedicle screw) are minimized or even eliminated in automated or manually-performed stages of pedicle tract preparation and screw insertion when they are advanced through the cancellous medium of the pedicle and vertebral body. In some implementations, the internal stabilizer is coupled within a mid-section of the frame for minimizing or even eliminating buckling of surgical instruments during the stages of pedicle tract preparation and screw insertion. The fixation mechanism may further comprise an inset coupled within the frame for supporting the internal stabilizer. The inset has a small size than the internal stabilizer such that the inset would not block the surgical instruments to advance within the internal passage of the frame.
The internal stabilizer optionally has a plurality of stabilizing teeth which complement the bolt threads of a threaded bolt attached to an expanded portion of the surgical instruments for stabilizing their advancement through the pedicle and vertebral body. In other words, the internal stabilizing component and the surgical instruments are tightly engaged together by the stabilizing teeth and the bolt teeth for resisting external turbulences during automated or manually-performed stages of spinal instrumentation.
As a third aspect, the present application discloses a pedicle tract stabilization system. The pedicle tract stabilization system comprises one or more bone anchors for stabilizing one or more vertebra; and a fixation mechanism movably attached to the one or more bone anchors. In particular, the bone anchors and the fixation mechanism are configured to form a through channel for a pedicle screw and surgical instruments (such as pedicle tract preparation instruments) to pass through.
The pedicle tract stabilization system may further comprise an external clamping mechanism for clamping the bone anchor and the fixation mechanism to a stationary object (such as a surgical table); and a linking mechanism for movably coupling the fixation mechanism and the external clamping mechanism. The stationary object is firmly secured to the ground for preventing any motion of the pedicle tract stabilization system during surgery. In some implementations, the stationary object comprises a surgical table where a patient to be operated on during surgery is also laid.
The linking mechanism may further comprise a circular frame coupled to the fixation mechanism, an external arm having a proximal end and a distal end and a cuboidal clamp. The circular frame and the cuboidal clamp are movably coupled (such as via a hinge mechanism) to the proximal end and the distal end of the external arm, respectively. The circular frame would pass through the channel for stabilizing the fixation mechanism. The cuboidal clamp is movably coupled to the distal end and the external clamping mechanism for coupling the linking mechanism and the external clamping mechanism. In some implementations, the external arm further comprises a first sub-arm and a second sub-arm adjoined by a sliding-hinge mechanism for enabling the external arm to extend or contract along a single axis. In some implementations, the cuboidal clamp may further comprise a ball and a socket joint movably coupled together for providing a greater degree of maneuverability. For example, the ball could rotate substantially within the socket joint.
In some implementations, the external clamping mechanism comprises a supporting means (such as a rod) movably coupled to the cuboidal clamp and a clamping means coupled to the supporting means and the stationary object. For example, the clamping means comprises a table clamp hinged to the stationary object (such as the surgical table) for easy operation during the surgery. Therefore, the pedicle tract stabilization system as a whole would serve to annul any motion induced during the surgery and also preserve the pedicle tract trajectory at all stages of the surgery by locking the bone anchor with the fixation mechanism and clamping system.
The pedicle tract stabilization system may further comprise a reference frame for accurately locating and orientating the bone anchor head and an attached frame. For example, the reference frame is loaded onto an adjacent vertebra around a targeted vertebra onto which the bone anchor and frame would be secured. An external sensor detects the relative positions of optical (such as reflective) markers located on both the reference frame and the frame (such as flute), thereby enabling them to be mapped out in 3D space. The mappings can be superimposed on an intraoperative CT image of the spine which can then be used to correctly orientate the bone anchor and attached frame (such as flute) in a real-time trajectory with the planned trajectory from the CT.
As a fourth aspect, the present application discloses a surgical process with the pedicle tract stabilization system. Firstly, a patient is positioned and prepped in a standard fashion for pedicle screw fixation procedure. Pedicle screws may be inserted under open or MIS techniques. Once facet joints are exposed, a facetectomy is performed using bone rongeurs or a high-speed drill. A reference frame is attached to a specified spinous process of a vertebra above or below the levels of intended spinal fixation. An intraoperative computed tomography (CT) scan is performed to serve as a neuronavigational guide.
Secondly, a bone anchor with suitable dimensions to a specific spinal level is loaded onto a frame with an egg handle attached thereto. The bone anchor is screwed into the facetectomised cortex on one side of a specified vertebra until good purchase is achieved. The frame is then stabilized with an external clamping mechanism in a specific position and orientation, determined either using ultrasound techniques or neuronavigational guidance. For example, the ultrasound techniques use a tubular ultrasound scanner which can be passed through the central axis along length of the frame (such as the flute) into the aperture of the bone anchor. During manually positioning the frame (such as the flute), an ultrasound transducer at the tip of the device would scan the contour of the pedicle and thus help to optimize the final position of the frame (such as the flute). Alternatively, the frame (such as the flute) may be correctly positioned by neuronavigational guidance by aligning the real-time trajectory that is based on neuronavigational markers located on the frame (such as the flute) in relation to the reference frame on a spinous process of an adjacent vertebra with the planned trajectory. The position of the frame (such as the flute) is adjusted by theta degrees in a cross-sectional view and alpha degrees in a lateral view such that the real time trajectory coincides with the planned trajectory determined using the intraoperative computed tomography. Therefore, the neuronavigational guidance for positioning the frame (such as the flute) is used as an alternative technique to the ultrasound techniques.
Once the frame (such as the flute) is correctly positioned and orientated, the entire pedicle tract stabilization system is locked. The pedicle is prepared with a pedicle probe followed by a tap screw or reamer. The pedicle screw is then inserted. In both pedicle preparation and screw insertion processes, the surgical instruments are stabilized by the complementary teeth of the threaded bolt of the surgical instrument and the internal stabilizer contained within the mid-section of the frame for minimizing micro-movements and also maintaining a same trajectory.
Thirdly, the processes above are repeated for other vertebral levels and also on the contralateral side of the spine. The frame and external clamping mechanism are removed. Once all the pedicle screws are inserted into the vertebra, a rod is passed through the apertures on both sides of each bone anchor, thereby interconnecting the bone anchors of adjacent vertebral levels. Finally, locking nuts are applied to the adjustable head of each bone anchor in order to secure the rod in place.
Therefore, the pedicle tract stabilization system can stabilize a specified vertebra during pedicle screw preparation and insertion; preserve a planned trajectory during all stages of pedicle screw preparation and insertion in order to optimize the accuracy of pedicle screw placement; eliminate motion artefact and hence providing accurate visual feedback to a surgeon; discard the need for methods of eliminating computational artefact employed by other spinal neuronavigational systems; and minimize trajectory and screw revision, which will be both cost effective and less time consuming.
Furthermore, an automated drill screwdriver system may be utilized in conjunction with the bone anchor and external clamping system of the subject application. The automated drill screwdriver system may be further coupled to an integrated pressure-sensing mechanism to detect potential pedicle cortex breach. The automated drill screwdriver system can be used by including an external rectangular frame with two sets of perpendicularly running platforms joined to the surgical table. This frame system with two sets of perpendicularly running platforms is operated robotically and thus transports the automated drill-screwdriver system between a box-set of pedicle screws and each individual frame (such as the flute). The movements of the motorized platform and alignment of the automated drill-screwdriver system are stereotactically governed by the pre-determined trajectories from the frame (such as the flute) and the position of the box-set of pedicle screws relative to the reference frame. The reference frame serves as an origin with a (0,0,0) landmark for neuronavigation based on a 3D Cartesian coordinate system (x,y,z).
There has thus been outlined, rather broadly, the more important features of non-limiting exemplary embodiment(s) of the present disclosure so that the following detailed description may be better understood, and that the present contribution to the relevant art(s) may be better appreciated. There are additional features of the non-limiting exemplary embodiment(s) of the present disclosure that will be described hereinafter and which will form the subject matter of the claims appended hereto.
The novel features believed to be characteristic of non-limiting exemplary embodiment(s) of the present disclosure are set forth with particularity in the appended claims. The non-limiting exemplary embodiment(s) of the present disclosure itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:
Those skilled in the art will appreciate that the figures are not intended to be drawn to any particular scale; nor are the figures intended to illustrate every non-limiting exemplary embodiment(s) of the present disclosure. The present disclosure is not limited to any particular non-limiting exemplary embodiment(s) depicted in the figures nor the shapes, relative sizes or proportions shown in the figures.
The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which non-limiting exemplary embodiment(s) of the present disclosure is shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the non-limiting exemplary embodiment(s) set forth herein. Rather, such non-limiting exemplary embodiment(s) are provided so that this application will be thorough and complete, and will fully convey the true spirit and scope of the present disclosure to those skilled in the relevant art(s). Like numbers refer to like elements throughout the figures.
The illustrations of the non-limiting exemplary embodiment(s) described herein are intended to provide a general understanding of the structure of the present disclosure. The illustrations are not intended to serve as a complete description of all of the elements and features of the structures, systems and/or methods described herein. Other non-limiting exemplary embodiment(s) may be apparent to those of ordinary skill in the relevant art(s) upon reviewing the disclosure. Other non-limiting exemplary embodiment(s) may be utilized and derived from the disclosure such that structural, logical substitutions and changes may be made without departing from the true spirit and scope of the present disclosure. Additionally, the illustrations are merely representational are to be regarded as illustrative rather than restrictive.
One or more embodiment(s) of the disclosure may be referred to herein, individually and/or collectively, by the term “non-limiting exemplary embodiment(s)” merely for convenience and without intending to voluntarily limit the true spirit and scope of this application to any particular non-limiting exemplary embodiment(s) or inventive concept. Moreover, although specific embodiment(s) have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiment(s) shown. This disclosure is intended to cover any and all subsequent adaptations or variations of other embodiment(s). Combinations of the above embodiment(s), and other embodiment(s) not specifically described herein, will be apparent to those of skill in the relevant art(s) upon reviewing the description.
References in the specification to “one embodiment(s)”, “an embodiment(s)”, “a preferred embodiment(s)”, “an alternative embodiment(s)” and similar phrases mean that a particular feature, structure, or characteristic described in connection with the embodiment(s) is included in at least an embodiment(s) of the non-limiting exemplary embodiment(s). The appearances of the phrase “non-limiting exemplary embodiment” in various places in the specification are not necessarily all meant to refer to the same embodiment(s).
Directional and/or relationary terms such as, but not limited to, left, right, nadir, apex, top, bottom, vertical, horizontal, back, front and lateral are relative to each other and are dependent on the specific orientation of an applicable element or article, and are used accordingly to aid in the description of the various embodiment(s) and are not necessarily intended to be construed as limiting.
If used herein, “about,” “generally,” and “approximately” mean nearly and in the context of a numerical value or range set forth means±15% of the numerical.
If used herein, “substantially” means largely if not wholly that which is specified but so close that the difference is insignificant.
The conical tapered screw 102 is imaginarily divided into a left portion 110 and a right portion 150 in the cross-sectional view. Accordingly, the base 104 is also imaginarily divided into a left portion 140 and a right portion 180 in the cross-sectional view for connecting the left portion 110 and the right portion 150 of the conical tapered screw 102, respectively. It is clearly shown that the conical tapered screw 102 has a tapering inner profile and a tapering outer profile from the top to the bottom; and a sharp edge (not shown) is formed at the bottom. As a result, both the left portion 110 and the right portion 150 have a triangle shape in the cross-sectional view; and the sharp edge is reduced to a left sharp point 116 and a right sharp point 156 at the left portion 110 and the right portion 150, respectively. The base 104 has an expanding inner profile and a vertical outer profile from the top to the bottom. In other words, the left portion 140 has a left inner face 146 opposed from the left hinge 142; and the right portion 180 also has a right inner face 186 opposed from the right hinge 182. As a result, both the left portion 140 and the right portion 180 have a trapezoid shape in the cross-sectional view. In particular, an internal cavity 202 is formed in the adjustable head 200 and the internal cavity 202 further forms a through channel with the aperture 106 in a vertical direction for the pedicle screw to pass through the bone anchor 100. A side aperture 208 is also formed in the adjustable head 200 in a lateral direction perpendicular to the internal cavity 202. In the cross-sectional view, the side aperture 208 is shown as a left aperture 210 and a right aperture 212 above the left concave structure 204 and the right concave structure 206, respectively. A rod (not shown) may pass through the hollow hole 208 for connecting multiple bone anchors 100 in series. In addition, the adjustable head 200 has a threaded end 210 opposed to the concave structures 204, 206 for connecting to a fixation mechanism (not shown).
Similarly, the right portion 150 also has a triangular configuration in the cross-sectional view with a right inner side 152 and a right outer side 154, both of which forms a right sharp point 156. The right portion 150 also has a four right screw tips 158-164 coupled on the right outer side 154. To provide better purchase with the surrounding vertebra cortex, the right screw tips 158-164 may also have various depths which may vary in a range of 1 millimeter (mm) to 4 millimeters (mm), depending on a specific bone of the spinal column the bone anchor 100 is applied to. The right screw threads 158-164 may be flexibly distributed on the left outer side 154. As shown in
In the application, unless specified otherwise, the terms “comprising”, “comprise”, and grammatical variants thereof, intended to represent “open” or “inclusive” language such that they include recited elements but also permit inclusion of additional, non-explicitly recited elements.
As used herein, the term “about”, in the context of concentrations of components of the formulations, typically means+/−5% of the stated value, more typically +/−4% of the stated value, more typically +/−3% of the stated value, more typically, +/−2% of the stated value, even more typically +/−1% of the stated value, and even more typically +/−0.5% of the stated value.
Throughout this disclosure, certain embodiments may be disclosed in a range format. The description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.
While non-limiting exemplary embodiment(s) has/have been described with respect to certain specific embodiment(s), it will be appreciated that many modifications and changes may be made by those of ordinary skill in the relevant art(s) without departing from the true spirit and scope of the present disclosure. It is intended, therefore, by the appended claims to cover all such modifications and changes that fall within the true spirit and scope of the present disclosure. In particular, with respect to the above description, it is to be realized that the optimum dimensional relationships for the parts of the non-limiting exemplary embodiment(s) may include variations in size, materials, shape, form, function and manner of operation.
The Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above Detailed Description, various features may have been grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiment(s) require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed non-limiting exemplary embodiment(s). Thus, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter.
The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiment(s) which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the above detailed description.
