Reinforced cannulated screw assembly systems and methods

A reinforced cannulated screw assembly includes a cannulated screw and a reinforcing rod coupled to the cannulated screw. The cannulated screw includes a channel formed therethrough that is defined by an inner wall having at least one set of grooves formed therein. The reinforcing rod is configured for insertion into the channel. The reinforcing rod includes a set of protrusions configured to engage the at least one set of grooves.

BACKGROUND

The present disclosure relates generally to systems and methods of neutralizing a bone fracture and other orthopedic reconstruction procedures, and, more specifically, to systems and methods of utilizing a reinforced cannulated screw assembly during an orthopedic procedure.

Orthopedic procedures often demand the application of significant forces in specific ways and/or directions, or combinations thereof. The details of the injury and anatomy being treated dictate how the procedure is performed and generally do not tailor themselves to the skill of the surgeon or the ease of use of the available equipment.

One factor that contributes to a surgeon's challenges is precise placement of orthopedic or surgical screws in a patient's bone. Precise placement, location and angle, is important because the surgeon does not want to crack or weaken the bone by putting the screw too close to the edge of the bone or in a part of the bone which is too shallow.

Therefore, at least some known surgical screws have been cannulated, i.e., made with a longitudinal bore (“cannula”) for a guide wire. The cannulated screw is guided into place by the guide wire. Then the screw is threaded into the bone. However, due to cannulation, such a screw is significantly weaker than a solid screw.

Cannulated screws have broad application and may need to be in place for decades while being subject to dynamic loading. Therefore, it is desirable to improve the strength of a cannulated screw. Moreover, surgical screws may at some point need to be removed. For example, screws used in children may need to be removed subsequently in view of impending bone growth, or screws that are later determined to be improperly placed, break, cause pain, irritation, infection or other problems usually need to be removed. It is good medical practice to ensure that any screws and other fixation implants are capable of being removed if necessary. Additionally, stripping of threads on the screw may occur either during insertion or removal. Removal of a stripped screw may be more difficult.

Accordingly, a system for reinforcing a cannulated screw and/or a system that eliminates or minimizes the chances of stripping of the cannulated screw and enables easy removal of the cannulated screw is desirable.

BRIEF DESCRIPTION

In one aspect, a reinforced cannulated screw assembly is provided. The reinforced cannulated screw assembly includes a cannulated screw and a reinforcing rod coupled to the cannulated screw. The cannulated screw includes an inner wall defining a channel therethrough. The inner wall includes at least one set of grooves formed therein. The reinforcing rod is configured for insertion into the channel. The reinforcing rod includes a set of protrusions configured to engage the at least one set of grooves.

In another aspect, a reinforced cannulated screw system is provided. The reinforced cannulated screw system includes a reinforced cannulated screw assembly including a cannulated screw and a reinforcing rod coupled to the cannulated screw. The cannulated screw includes an inner wall defining a channel therethrough. The inner wall includes at least one set of grooves formed therein. The reinforcing rod is configured for insertion into the channel. The reinforcing rod includes a set of protrusions configured to engage the at least one set of grooves. The reinforced cannulated screw system also includes a torque tool configured to engage at least one of the cannulated screw and the reinforcing rod to facilitate insertion of the reinforced cannulated screw assembly into a substrate.

In yet another aspect, a method of using a reinforced cannulated screw assembly is provided. The method includes inserting a cannulated screw into a substrate. The cannulated screw includes an inner wall defining a channel formed therethrough. The inner wall includes at least one set of grooves formed therein. The method also includes inserting a reinforcing rod into the channel. The reinforcing rod includes a set of protrusions configured to engage the at least one set of grooves. The reinforcing rod is then rotated with respect to the cannulated screw such that the plurality of protrusions engage at least one set of grooves.

DETAILED DESCRIPTION

FIG. 1illustrates a side view of an exemplary cannulated surgical screw100,FIG. 2is a cross-sectional view of screw100, andFIG. 3is a top view of screw100. In the exemplary embodiment, screw100includes a first end, or head102, an opposite second end, or tip104, and a body portion106extending therebetween. As described in further detail below, tip104is configured to be inserted into a patient during surgery and head102is engaged by a tool to rotate screw100and complete insertion.

In the exemplary embodiment, screw100includes at least one set of external threads. More specifically, screw100includes a first set of threads108proximate head102and a second set of threads110proximate tip104. Threads108extend along body106a first length L1that is shorter than a second length L2of threads110. Further, threads108include a first pitch angle α with respect to a longitudinal axis112, and threads110includes a second pitch axis β that is less than pitch angle α. As such, threads108and110compress any bone portions joined by screw100. Alternatively, screw100may not include threads108and only includes threads100proximate tip104. Generally, screw100may be any type of cannulated screw used in any type of bone fragment fixation or other surgical procedure.

As shown inFIG. 2, screw100includes a channel114defined therethrough that extends between head102and tip104along axis112. More specifically, channel114includes a body portion116and a counter-bore118. Counter-bore118is defined by a substantially cylindrical inner wall120that extends a third length L3into body106from an outer radial surface122of screw100and that includes a first diameter D1. Similarly, channel body116is defined by a substantially cylindrical inner wall124that extends a fourth length L4from an inner radial surface126of counter-bore118and includes a second diameter D2that is smaller that first diameter D1.

In the exemplary embodiment, screw100includes a first set of grooves128formed in inner wall124. More specifically, grooves128include a pair of oppositely-oriented grooves formed in wall124that extend a fifth length L5from inner radial surface126along channel body116. Grooves128are substantially straight, that is, parallel to longitudinal axis112. As described in further detail below, grooves128are configured to receive a tool that applies torque to screw100to drive screw100into the patient's bone.

Screw100also includes a second set of grooves130formed in inner wall124. More specifically, grooves130include a pair of symmetrical grooves formed in wall124that extend a sixth length L6from inner radial surface126along channel body116. Grooves130are helical in shape such that grooves130are spirally wound around channel body116, as best seen inFIG. 2. As described in further detail below, grooves130are configured to receive protrusions formed on a reinforcing rod as it is inserted into channel114.

In the exemplary embodiment, helical grooves130intersect axial grooves128at least one time over a predetermined length of channel body116. Further, helical grooves130wind around channel body116such that at least a portion of grooves128and130overlap along channel body116. Additionally, axial grooves128are oriented approximately 90 degrees from helical grooves130on radial surface126, as best shown inFIG. 3, to facilitate insertion of the tool and the reinforcing rods at different orientations. Alternatively, axial grooves128are aligned with helical grooves130on radial surface126. In the exemplary embodiment, axial grooves128extend a distance into inner wall124that is shorter than the distance helical grooves130extend into inner wall124. As such, helical grooves130are deeper than axial grooves128, and accordingly, the reinforcing rod cannot be removed without rotation, as described in further detail below.

FIG. 4is a side view of reinforcing rod200that may be used with cannulated screw100(shown inFIG. 1),FIG. 5is a top view of rod200, andFIG. 6is a perspective view of reinforcing rod200partially inserted into cannulated screw100. The combination of screw100and rod200form a reinforced cannulated screw assembly300. In the exemplary embodiment, rod200includes a first end, or head202, an opposite second end, or tip204, and a body portion206extending therebetween. As described in further detail below, tip204is configured to be inserted into channel body116of screw100and head102is configured to be seated within screw counter-bore118. As such, when rod200is fully inserted within screw100, rod200increases the overall strength of screw100such that the resulting strength of screw100is comparable to the strength of a solid screw.

In the exemplary embodiment, rod200includes at least one length determination feature208that enables a surgeon to select a length of rod200that can be accommodated within a particular screw100. More specifically, rod200includes a plurality of features208axially spaced along a length of body portion206. In the exemplary embodiment, features208include a plurality of circumferential grooves formed in rod body206. Alternatively, features208are a plurality of score lines. Generally, length determination features208are any feature that indicates a predetermined length to the surgeon and enables the surgeon to select the length of rod200. For example, screw100may be manufactured in a variety of different lengths for use in different procedures, and rod200may be manufactured in a single length that includes length determination features208such that the surgeon can reduce the overall length of rod200to correspond to a length of the selected screw. Length determination features208may be formed on rod200to correspond to known common screw lengths.

Rod body206includes a third diameter D3that is slightly smaller than second diameter D2of channel body116to enable insertion of rod body206into channel body116. Similarly, rod head202includes a fourth diameter D4that is slightly smaller than first diameter D1of counter-bore118to enable insertion of rod head202into counter-bore118. When rod200is inserted into screw100, as shown inFIG. 6, a radial surface210of rod head202contacts radial surface126of screw100such that rod200is prevented from further insertion. Surfaces210and126may include a bevel or chamfer to facilitate seating of rod200and screw100. Similarly, tip204includes a bevel or is rounded to facilitate entry of tip204into channel114. In the exemplary embodiment, when rod200is fully inserted into screw100, an end surface212of rod head202is substantially flush with outer surface122of screw100. Alternatively, rod head202may be seated slightly within counter-bore118such that surfaces212and122are not flush. End surface212also includes a recess214that receives a tool inserted by the surgeon to enable rotation of rod200. In one embodiment, recess214is hexagonal in shape, although other shapes of recess214are contemplated.

In the exemplary embodiment, rod200also includes a pair of protrusions216that extend radially outward from rod body206proximate rod head202. Protrusions216are configured to engage helical grooves130of screw100to enable insertion of rod200into screw100by rotation of rod200. As such, helical grooves130and protrusions216act as a worm gear that enables rod200to be smoothly inserted into channel114of screw100while reducing the occurrence of stripping grooves130or protrusions216during insertion or removal or rod200. As described above, axial grooves128extend a distance into inner wall124that is shorter that the distance helical grooves130extend into inner wall124. As such, helical grooves130are deeper than axial grooves128and the reinforcing rod cannot be removed without rotation. For example, the deeper helical grooves130ensure alignment of protrusions216with grooves130and prevent the surgeon from attempting insertion of protrusions216into shallower axial grooves128. Further, once the surgeon seats rod200into screw100, the difference in the depth of grooves128and130prevent removal of rod200even when protrusions216are aligned with axial grooves128. That is, rod200is removable via rotation and cannot be removed with a purely axial force.

FIG. 7is a perspective view of a portion of a reinforced cannulated screw system400illustrating a torque tool500arranged for engagement with cannulated screw100. Tool500includes a handle502, a shaft504coupled to handle502, and an engaging portion506extending from shaft504. Engaging portion506includes a tip508and a pair of symmetrical flanges510that extend axially between shaft504and tip508. In the exemplary embodiment, flanges510are oppositely-oriented on engaging portion506and are shaped to correspond with axial grooves128in screw100to enable insertion of tool engaging portion506into screw grooves128. In use, engaging portion506is inserted into screw100a distance of L%, which is as deeply as axial grooves128permit. The surgeon may then rotate tool500to torque screw100along most if not substantially all of the length of screw100, thus sharply reducing the chance of stripping and/or slipping and making both the insertion and removal of screw100easier and more reliable.

FIG. 8is a perspective view of a portion of cannulated screw system400at a work site illustrating insertion of a guide wire600into a first bone portion602and a second bone portion604that are separated by a bone fracture606.FIG. 9is a perspective view of cannulated screw system400at the work site illustrating cannulated screw100coupling bone portions602and604. In operation, bone fracture606is to be repaired using at least one reinforced cannulated screw assembly300(shown inFIG. 6). The surgeon makes an incision, and advances a drill sleeve608or drill sleeve assembly through the soft tissue to the bone surface of first bone portion602contacting as shown. Guide wire600is then inserted through drill sleeve608to the desired depth and position such that a guide wire tip610extends through both first and second bone portions602and604that are to be joined. The position of guide wire600may be checked by removing drill sleeve608and/or by x-ray. Depending upon how many screw assemblies300are to be used, the same or similar procedures may be followed at the other locations as appropriate.

In the exemplary embodiment, the surgeon uses a cannulated drill bit (not shown) to drill a pilot hole for screw assembly300a desired length into bone portions602and604. Alternatively, screw100is a self-tapping screw that does not require a pilot hole. However, in embodiments where screw100is self-tapping, it may still be helpful to drill through the bone cortex. If screw100is to be countersunk, e.g., to avoid soft tissue being irritated by screw head102, then a cannulated countersink tool (not shown) may be used.

Drill sleeve608is then replaced by a protection sleeve612, and a measuring device (not shown) may be used to measure the depth of the drilled hole to determine the required length of screw100. Screw100is then threaded onto guide wire600, as shown inFIG. 9, and inserted through protection sleeve612. Torque tool500having first engaging portion506is then inserted into channel114(shown inFIG. 2), such that flanges510(shown inFIG. 7) engage axial grooves128(shown inFIG. 2) of screw100. The surgeon applies torque to tool500to rotate screw100into bone portions602and604until screw tip104meets guide wire tip610.

Guide wire600may then be removed from bone portions602and604to enable reinforcing rod200to be inserted into screw100, as shown inFIG. 6. In the exemplary embodiment, the surgeon utilizes length determination features208(shown inFIG. 4) to modify a length of rod200to correspond to the selected size of screw100. Rod200is inserted into screw such that protrusions216(shown inFIG. 4) engage helical grooves130(shown inFIG. 2) of screw100. In the exemplary embodiment, the first engaging portion506on tool500is replaced by a second engaging portion507that is configured to correspond to recess214in rod200. Alternatively, a different tool with engaging portion507may be used. The surgeon then engages recess214(shown inFIG. 5) with engaging portion507and applies torque to tool500to rotate rod200and cause rod to seat into screw100. As such, when rod200is fully and properly seated within screw100, rod200reinforces screw100such that the strength of screw100is increased comparable to that of a solid core screw. In embodiments where screw100and/or rod200require removal, the surgeon simply uses engaging portions506and507to rotate screw100and/or rod200in a direction opposite of the threading direction. As such, screw assembly300provides a reinforced cannulated screw that joins two bone portions and enables easy removal with a reduced risk of stripping. Alternatively, screw assembly300may be used in any type of surgical procedure and is not limited to only joining two bone portions.

The above described reinforced cannulated screw assemblies and systems facilitate efficient methods of reinforcing a cannulated screw. Specifically, in contrast to many known cannulated screw assemblies, the cannulated screw assemblies described herein include a cannulated screw having a channel formed therethrough that is defined by an inner wall. The inner wall includes a set of axial groves and a set of helical grooves formed therein. The axial grooves are configured to be engaged by a torque tool to drive the cannulated screw into a bone. The cannulated screw assemblies described herein also include a reinforcing rod configured for insertion into the screw channel. The reinforcing rod includes a set of protrusions that engage the helical grooves such that the protrusions are configured to move along the helical grooves and advance the reinforcing rod into the cannulated screw. As such, the reinforcing rod provides addition strength to the cannulated screw such that the cannulated screw assembly has comparable strength to a solid core screw.

The interaction of the rod protrusions and the helical grooves between the cannulated screw and the reinforcing rod reduces the chances of stripping the coupling mechanism or slipping. Additionally, the different methods of advancing the torque tool and the reinforcing rod into the cannulated screw further reduce the chances of stripping or slipping when inserting or removing the cannulated screw and/or reinforcing rod.

Exemplary embodiments of methods, systems, and apparatus for using a reinforced cannulated screw assembly are not limited to the specific embodiments described herein, but rather, components of systems and steps of the methods may be utilized independently and separately from other components and steps described herein. For example, the reinforced cannulated screw assembly may be used in combination with other application environments and in other surgical procedures, and is not limited to practice with only the bone joining surgical system and methods as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other applications, equipment, and systems that may benefit from the advantages described herein.

Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and claimed in combination with any feature of any other drawing.