Bone graft material loading assembly and associated devices, systems, and methods

A bone graft loading device includes a syringe comprising a nozzle at a distal portion of the syringe and an opening at a proximal portion of the syringe, and a plunger configured to force bone graft material from the reservoir through the nozzle. The plunger comprises a plunger body positioned at least partially within the syringe and defining a lumen. A tamp is positioned within the lumen of the plunger body and is configured to protrude distally of the plunger through the nozzle. The plunger mates with an inner wall of the syringe and the tamp to block passage of the bone graft material into the lumen of the plunger body. The plunger can be rotated to guide the bone graft material into the cannula, and the tamp can be periodically actuated to clear clogs that form at or near the nozzle.

TECHNICAL FIELD

The present disclosure relates generally to assemblies and devices for loading and delivering biological material to a patient. More specifically, the present disclosure provides assemblies and devices for loading bone graft material into an injection cannula.

BACKGROUND

One important surgical tool in the treatment of bone-related medical issues is to provide bone graft material to anatomical structures affected during surgical procedures to aid in the bone regeneration process and to promote healing. It is desirable to be precise and accurate in the delivery of the bone graft site. However, bone graft materials may not be easily workable. For example, bone graft materials may be heterogenous mixtures of tissue and fluids that are not easily compressed or moved by injection. In some instances, an injection tube or cannula is used to inject the bone graft material with a higher degree of control and precision. Loading the bone graft material into the injection tube can be an imprecise and difficult process. If too much force is applied to the bone graft material when it is being loaded into the injection tube, the fluids of the bone graft material mixture can be expressed, which adversely affects the qualities and workability of the material. Further, bone graft material may be prone to clogs or stoppages, particularly when the bone graft material is being moved into a tube or reservoir of a smaller cross-sectional size.

SUMMARY

The present application provides devices, assemblies, and associated methods for loading bone graft material into a bone graft injection cannula. In one embodiment, a bone graft loading device comprises a syringe, a threaded plunger configured to force bone graft material toward a nozzle of the syringe, and a tamp configured to protrude out a distal end of the plunger to force the bone graft material through the nozzle and into a cannula coupled to the nozzle of the syringe. The tamp is coupled to the plunger and the syringe such that the tamp can move independently of the plunger. In an exemplary embodiment, a physician can use the threaded plunger as the main mechanism to guide the bone graft material into the cannula, and may periodically switch to the tamp to clear clogs that form at or near the nozzle.

According to one embodiment, a bone graft loading device includes a syringe defining a reservoir, the syringe comprising a nozzle at a distal portion of the syringe and an opening at a proximal portion of the syringe, and a plunger configured to force bone graft material from the reservoir through the nozzle. The plunger comprises a plunger body positioned at least partially within the syringe and defining a lumen; a handle coupled to a proximal end of the plunger body and positioned outside the reservoir; and a tamp positioned within the lumen of the plunger body and configured to protrude distally of the plunger through the nozzle. An outer surface of the plunger mates with an inner wall of the syringe, and an inner surface of the plunger mates with the tamp to block passage of the bone graft material into the lumen of the plunger body.

In some embodiments, the plunger comprises a stopper coupled to a distal end of the plunger body. In some embodiments, the stopper comprises: the outer surface of the plunger mating with the inner wall of the syringe; and the inner surface of the plunger mating with the tamp. In some embodiments, the plunger body comprises a threaded portion and a distal portion coupled to the threaded portion, wherein at least the distal portion extends within the syringe. In some embodiments, in a retracted position, at least part of the threaded portion is positioned outside of the syringe. In some embodiments, the distal portion of the plunger body comprises a flange.

In some embodiments, the bone graft loading device further comprises a spring coupled to the tamp and the plunger, wherein the spring is configured to bias the tamp in a proximal direction relative to the plunger. In some embodiments, the tamp comprises a widened section and a distal section, a cross-sectional size of the widened section is greater than a cross-sectional size of the distal section, the plunger body comprises a first retention feature around the lumen of the plunger body, and the spring is positioned around the distal section of the tamp and extends between the first retention feature of the plunger body and the widened section of the tamp. In some embodiments, the plunger comprises a second retention feature proximal of the first retention feature, and wherein second retention feature is configured to abut a surface of the widened section of the tamp to retain the tamp within the lumen of the plunger body. In some embodiments, the syringe comprises a finger grip feature protruding from an external surface of the syringe. In some embodiments, the tamp is configured to advance distally relative to the plunger by a first distance, and wherein a distal end of the tamp is spaced from the nozzle by a distance greater than the first amount when the plunger is in a first position relative to the syringe. In some embodiments, the first distance is between 1.0 in. and 2.0 in. In some embodiments, a proximal section of the tamp extends proximally of the lumen of the plunger body, and wherein a tamp cap is coupled to the proximal section of the tamp. In some embodiments, the tamp cap is positioned proximally of the handle of the plunger and is movable independently of the handle.

According to another embodiment of the present disclosure, a method for loading a bone graft injection cannula includes: coupling the cannula to a syringe defining a reservoir, the syringe comprising a nozzle at a distal portion of the syringe and an opening at a proximal portion of the syringe; placing bone graft material within the reservoir; providing a plunging assembly that comprises: a plunger body defining a lumen; a handle coupled to a proximal end of the plunger body; a tamp extending within the lumen of the plunger body, wherein the tamp is movable relative to the plunger body, and wherein the tamp is biased proximally relative to the plunger body; coupling the plunging assembly to the syringe such that the plunger body is positioned within the reservoir through the opening at the proximal portion, wherein an outer surface of the plunger is configured to form a first sliding seal with the reservoir wherein an inner surface of the plunger is configured to form a second sliding seal with the tamp; rotating the handle of the plunger assembly to move the bone graft material toward the nozzle; and pushing the tamp toward the nozzle such that a distal end of the tamp protrudes distally of the plunger body to force the bone graft material through the nozzle and into the cannula.

According to another embodiment of the present disclosure, a bone graft loading device includes: a syringe defining a reservoir, the syringe comprising a nozzle at a distal portion of the syringe and an opening at a proximal portion of the syringe, wherein the syringe comprises a first cylindrical portion comprising a first diameter, and wherein the nozzle comprises a second cylindrical portion comprising a smaller second diameter; and a plunger configured to force bone graft material from the reservoir through the nozzle. The plunger comprises: a plunger body positioned at least partially within the syringe and defining a lumen; a handle coupled to a proximal end of the plunger body and positioned outside the reservoir; and a tamp positioned within the lumen of the plunger body and configured to protrude distally of the plunger into the second cylindrical portion comprising the smaller second diameter.

DETAILED DESCRIPTION

FIG.1is a perspective view of a bone graft delivery assembly50, according to one embodiment of the present disclosure. The bone graft delivery assembly50includes a bone graft loading device100and an injection cannula180. In the illustrated embodiment, the bone graft loading device100is configured to load a bone graft material (e.g., allograft) into the cannula180for delivery to an operation site of a patient. As described further below, the cannula180may be detached from the loading device100and coupled to an injection device (e.g., injection device190,FIG.2.) for delivery to the operation site.

The loading device100includes a syringe body or portion110, a threaded cap120coupled to a proximal end of the syringe body110, a plunger or plunger body130comprising a handle136and a threaded portion132positioned within the syringe body110, and a tamp140positioned within a lumen of the plunger130. The loading device100shown inFIG.1includes two distinct actuation mechanisms for loading bone graft material into the cannula180: a threaded screw mechanism for advancing the plunger130distally within the syringe body110, and a retractable tamping mechanism for pushing or forcing portions of the bone graft material through a distal opening112of the syringe body110and into the cannula180. In that regard, the threaded portion132of the plunger130engages corresponding threads in a central opening of the threaded cap120such that rotating the handle136advances the plunger130and the tamp140distally toward the opening112of the syringe body110. The handle is coupled to a proximal end of the plunger130such that the handle136is positioned outside the syringe body110. Additionally, the tamp140is configured to be advanced distally within the lumen of the plunger130such that a distal end of the tamp140protrudes from an opening in a stopper134of the plunger130toward the opening112such that it protrudes at least partially within the cannula180. These two loading mechanisms can provide both bulk movement and higher force to move the bone graft material into the cannula180and a more concentrated tamping mechanism in the event of a clog or stoppage of the bone graft at the distal end of the syringe body110.

The syringe body110includes an integrally formed (e.g., injection molded) hollow body that includes finger grips114and the distal opening112. The syringe body110also includes external threads on a proximal end configured to engage with corresponding threads of the threaded cap120. The syringe body110comprises a polymer material and defines a cylindrical or substantially cylindrical reservoir for a bone graft material. It will be understood that any suitable polymer may be used for the syringe body, including polycarbonate, nylon, polyethylene, polypropylene, acrylonitrile butadiene styrene (ABS), polyether ether ketone (PEEK), DELRIN®, or any other suitable material. Further, in some embodiments, the syringe body110comprises a metallic material, such as stainless steel, aluminum, brass, or any other suitable metallic material.

The threaded cap120is configured to couple to the threads of the syringe body110. As described further below, the threaded cap120includes a second set of central threads configured to engage the threaded portion132of the plunger130. In the illustrated embodiment, the threaded body120comprises a polymer material. It will be understood that any suitable polymer may be used for the threaded body120, including polycarbonate, nylon, polyethylene, polypropylene, ABS, polyether ether ketone (PEEK), DELRIN®, or any other suitable material. Further, in some embodiments, the syringe body110comprises a metallic material, such as stainless steel, aluminum, brass, or any other suitable metallic material. In some aspects, it may be advantageous for the threaded cap120to include a softer material than the syringe body110and/or the threaded portion132of the plunger130in order to reduce particulates created by friction between the syringe body110, threaded cap120, and/or plunger130. For example, in an exemplary embodiment, the syringe body110and the threaded portion132of the plunger130comprise polycarbonate, and the threaded cap120comprises polypropylene.

FIG.2is a perspective view of an injection device190coupled to the cannula180. In that regard, once the cannula180has been loaded with bone graft by the loading device100, the cannula180can be attached to the injection device190to deliver the bone graft to an operation site of the patient. The injection device190comprises a handle192and a trigger194configured to advance a plunger196into the lumen of the cannula180. In the illustrated embodiment, actuating the trigger194causes the plunger196to advance forward into the cannula180. In some embodiments, actuating the trigger194causes the plunger to move forward in increments or steps. In that regard, an articulating member may engage threads or grooves on the plunger196to move the plunger forward by a controlled amount.

FIG.3illustrates an exploded view of the bone graft injection assembly50shown inFIG.1. Starting at a proximal portion of the assembly50, a cap142is coupled to a proximal end of the tamp body140, which includes a distal portion144and a widened portion146. In the illustrated embodiment, tamp140comprises a single body such that the widened portion comprises an integral part of the tamp140. However, in other embodiments, the widened portion146may comprise a cylindrical body or sheath positioned over the cylindrical tamp body140. The widened portion146is configured to engage a proximal end of a spring such that a distal shelf or end of the widened portion146is configured to compress the spring, as further described below. The proximal shelf or end of the widened portion146engages a retention feature of the handle136such that the tamp140is retained within the lumen of the threaded portion132of the plunger/handle136. The tamp140and the spring are inserted into the lumen of the threaded portion132of the plunger130. In that regard, it will be understood that the proximal end of the tamp140may be inserted into the threaded portion through the distal opening of the threaded portion132such that the proximal end of the widened portion abuts the retention feature of the handle136, as further described below.

The threaded portion132is at least partially inserted into the central opening of threaded cap120by engaging internal threads of the threaded cap, as further described below. A distal portion138or body of the plunger130is partially inserted into a distal opening of the threaded portion132of the plunger130. Accordingly, rotating the handle136of the plunger130relative to the threaded cap120advances the threaded portion132and the distal portion138of the plunger138relative to the threaded cap120. The distal portion138includes a retention lip or flange135comprising a circular projection and configured to retain the distal portion from being withdrawn from an interior of the syringe body through the threaded cap120, as further shown below. In that regard, a cross sectional size or diameter of the flange135is larger than a cross sectional size or diameter of the central opening (124,FIG.4) of the threaded cap120.

In the illustrated embodiment, the handle136and the threaded portion132of the plunger130form single, integral component or body. For example, the threaded portion132and the handle136may be formed by an injection molding process. In other embodiments, the handle136and the threaded portion132comprise separate components that may be fused, adhered, welded, screwed, or otherwise coupled to one another. Further, in some embodiments, the distal portion138and the threaded portion132comprise a single, integrally formed component.

The distal portion138of the plunger130includes a stopper coupling feature131configured to couple to and engage the stopper134. More specifically, the stopper coupling feature131includes at least one projection or lip and at least one groove sized, shaped, and structurally configured to engage a corresponding at least one groove and at least one projection or lip of the stopper134. The stopper134comprises an elastomeric material, such as a silicone rubber, thermoplastic elastomer (TPE), or any other suitable material that can be resiliently deformed to fit over the stopper coupling feature131. The stopper134is sized, shaped, and structurally arranged to form a sliding seal with an inner wall of the syringe body110. In that regard, an outer surface of the stopper134of the plunger130is configured to remain in contact with the inner wall of the syringe body110around its circumference. Accordingly, the stopper134maintains the bone graft material within the portion of the syringe body110that is between the stopper134and the distal opening112while the stopper134is advanced distally within the syringe body110.

The syringe body110comprises a first cylindrical portion or section111having a larger first diameter. The syringe body110further comprises a nozzle113that includes a tapered section114and a second cylindrical portion or section115having a smaller second diameter. The second cylindrical section115of the syringe body110includes internal threads116configured to engage corresponding external threads182of the cannula180. Accordingly, the cannula180is attached to the loading device100by inserting the threads182into the distal opening112and rotating the cannula180relative to the syringe body110, or vice versa. The syringe body110includes a volume marking101to indicate that a particular volume (e.g., 10 mL, 20 mL) of bone graft material is present within the syringe body110. The volume marking101may comprise a projection or raised feature integrally formed (e.g., by injection molding) with the syringe body110. In other embodiments, the volume marking101may comprise visible ink markings printed on the outer surface of the syringe body110. In some embodiments, no volume markings are used. In other embodiments, multiple volume markings corresponding to different volumes are used.

Assembly of the loading device100can be performed as follows. The tamp140is inserted through the distal opening of the threaded portion132and moved proximally relative to the threaded portion132until the widened portion146of the tamp140abuts the retention feature (e.g.,133,FIG.4) of the handle136. The tamp cap142is positioned over the proximal end of the tamp140, aligning the flat surface with a corresponding flat surface of the cap142. The spring150is positioned over the distal portion144of the tamp140within the lumen of the threaded portion132. The threaded cap120is twisted on to the distal end of the threaded portion132. The distal portion or body138of the plunger130is inserted into the distal opening of the threaded portion132, enclosing the spring within an annular space defined by the distal portion144of the tamp140and the inner wall of the threaded portion132. The stopper134is coupled to the distal portion138of the plunger130by positioning the stopper134over the retention feature131. As further shown below, when the distal portion138of the plunger130is attached to the threaded portion132, a distal end of the tamp140protrudes through an opening139of the stopper134. An inner surface around the opening139of the stopper134is sized, shaped, and structurally arranged to form a second sliding seal between the stopper134and the distal portion of the tamp140. In this manner, the tamp140may be advanced and retracted relative to the stopper134while maintaining a seal to prevent bone graft material from escaping into the lumen of the distal portion138of the plunger130. Thus, the stopper134provides two sliding seals: a first sliding seal between the stopper134and the inner wall of the syringe body110, and a second sliding seal between the stopper and the outer surface of the distal portion144of the tamp140.

At this stage, the bone graft material may be introduced into the syringe body110through the proximal end of the syringe body110, as further described below with respect toFIG.7. In some instances, the cannula180may be coupled to the syringe body110at this stage, or at another stage, either before or after. The partially assembled portion of the loading device that comprises the tamp140, plunger130, and threaded cap120is coupled to the syringe body110by positioning the distal portion138and stopper134of the plunger130within the syringe body110and engaging the inner threads122of the threaded cap120with corresponding external threads118of the syringe body110.

As described further below, the distal portion or section144of the tamp140comprises a first diameter149. The first diameter149may be sized such that it can protrude through the smaller diameter of the second cylindrical section115and into the lumen of the cannula180. In some embodiments, the diameter149of the tamp140is approximately equal to the lumen diameter of the cannula180. In other embodiments, the diameter149of the tamp140is smaller or larger than the diameter149of the tamp140.

FIG.4shows a longitudinal cross-sectional view of the loading device100shown inFIGS.1and3, according to an embodiment of the present disclosure. In particular,FIG.4shows additional details related to the two loading mechanisms described earlier. In the illustrated embodiment, the syringe body110defines an inner reservoir having a first cylindrical section111. The first cylindrical section111has a first inner diameter117. The first inner diameter117may range from approximately 0.5 in. to approximately 2.0 in., including values such as 0.75 in., 1.0 in., 1.25 in., 1.5 in., or any other suitable value, but larger and smaller. The length of the syringe body110may range from approximately 2.0 in. to approximately 8.0 in., including values such as 3.0 in., 4.0 in., 5.0 in., 6.0 in., 7.0 in., or any other suitable value, both larger and smaller. The threaded cap120is coupled to the syringe body110such that the inner threads122of the threaded cap120engage corresponding external threads118of the syringe body110. The threaded portion132of the plunger130is positioned within a central opening124of the threaded cap120and engages corresponding internal threads126within the central opening124of the threaded cap120. The retention lip135of the plunger130abuts an internal surface of the threaded cap120such that the distal portion138of the plunger130is retained distal of the threaded cap120. By rotating the handle136relative to the threaded cap120and syringe body110, the plunger130advances distally further into the syringe body110. In some aspects, the rotational loading mechanism effected by the threaded plunger130and the cap120may be used for bulk movement or compacting of the bone graft material to the nozzle113and through the distal opening112of the syringe body110. However, as described above, because the second inner diameter119is smaller than the first inner diameter117, the bone graft material may be susceptible to clogs and blockages at or near the nozzle113. Accordingly, the tamp140can be used as described below to break up the clogs and force portions of the bone graft material into the cannula180.

Referring now to the tamping mechanism, the tamp140extends through a lumen of the plunger130and a distal end of the tamp140extends through a central opening139of the stopper134. In some embodiments, the distal end of the tamp140is tapered or rounded. The tamp140is sized and shaped to be inserted into the second cylindrical section115of the syringe body110, which has the smaller second diameter119, through the distal opening112of the syringe body110, and into the cannula180(seeFIG.5b). In some embodiment, the tamp140is sized and shaped to match a size and shape of the lumen of the cannula180. For example, in some embodiments, the outer diameter of the tamp140is approximately equal to an inner diameter of the cannula180, which may be equal to, smaller than, or larger than the second diameter119. In some embodiments, the cross-sectional size of the tamp140is slightly smaller than the cross-sectional size of the cannula180. In some embodiments, the diameter of the tamp140ranges from approximately 0.1 in. to about 0.5 in., including values such as 0.125 in., 0.2 in., 0.25 in., 0.3 in., or any other suitable value, both greater or smaller.

The spring150is positioned within an annular space defined by the threaded portion132of the plunger130and the tamp140. The spring150extends from the widened portion146of the tamp140to the proximal end of the distal portion138of the plunger130. In the illustrated embodiment, the spring150is partially compressed and the tamp is maintained in place by the retention feature133of the handle136. Accordingly, the tamp140is configured to longitudinally move or translate relative to the syringe body110by an amount of travel. In some embodiments, the amount of travel the tamp140may travel is at least partially defined by the length of the annular space in which the spring150is positioned when the widened portion146of the tamp140is resting against the retention feature133of the plunger130. In that regard, the tamp140may extend distally by compressing the spring150until the pitch of the coil spring150is closed such that the spring150is fully compressed. In the illustrated embodiment, the total travel of the tamp140is approximately 1 inch. However, the travel of the tamp140may comprise values between approximately 1.0 in. and approximately 2.0 in, or any other suitable amount, including 0.5 in., 0.75 in., 1.25 in., 1.5 in., 1.75 in., 2.25 in., 2.5 in., 3.0 in., 5 in., 6 in., 9 in., or any other suitable value, both larger and smaller. The travel of the tamp140may be configured such that, when the plunger130is in the position shown inFIG.4relative to the syringe body110, the tamp140can be advanced to protrude through the distal opening112and partially within the proximal end of the cannula180. In other embodiments, the tamp140can be configured to extend further within the cannula180than what is shown inFIGS.1-4. For example, in some embodiments, the arrangement of the tamp140is such that its travel is sufficient to extend through an entire length, or a majority of the length, of the cannula180. In that regard, in some embodiments the tamp140can be used to inject or deliver the bone graft material to the predetermined location in the patient's body.

InFIG.4, the plunger130is shown in a fully retracted position whereby the retention lip135is abutting the inner surface of the threaded cap120. The plunger130is configured to be advanced distally within the syringe body110until the stopper134abuts the inner surface of the nozzle113of the syringe body110. The shape of the distal surface of the stopper134at least partially conforms to the shape of the nozzle113of the syringe body110. The convex shape of the stopper134may facilitate improved loading because there is less open space remaining when the plunger130is fully advanced within the syringe body110. In some embodiments, the plunger130may have approximately the same amount of travel relative to the syringe body110as the tamp140has relative to the plunger130. In some embodiments, the amount of travel afforded to the tamp140and/or the plunger130may differ from what is shown inFIG.4. For example, in some embodiments, the tamp140has a sufficient amount of travel to extend further within the cannula180when the plunger130is fully retracted. In some embodiments, the tamp140and/or the plunger130has less travel than that shown inFIG.4.

FIGS.5aand5billustrate the loading device100having bone graft material added within the syringe body110with the plunger130and the tamp140in different loading positions. InFIG.5a, both the plunger130and the tamp140are fully retracted such that the stopper134of the plunger130and the distal end of the tamp140are at a first position141. InFIG.5bthe plunger130is partially advanced to a second position143and the tamp140is fully extended relative to the plunger130to a third position145such that the tamp140extends partially within the cannula180. The bone graft material160may be at least partially compressible. In that regard, inFIG.5a, bone graft material160may be in an uncompressed state such that there are pockets of empty space within the bone graft material. When the plunger130and tamp140are in the first position141, the travel of the tamp140is not sufficient to reach the distal opening112or the cannula180. The plunger130can be advanced distally to compress the bone graft material and force the bone graft material through the distal opening into the cannula180. However, as mentioned above, the heterogenous nature of the bone graft material160may cause it to be susceptible to clogs at the nozzle113of the syringe body110. If too much compressing force is applied on the bone graft material160by the plunger130, the liquid within the bone graft material160may be expressed, which undesirably affects the characteristics and workability of the material160. Accordingly, the tamp140can be used to clear clogs in the distal opening and force a smaller amount of bone graft material into the cannula180.

FIG.5bshows the loading device100with the plunger130partially advanced by rotating the handle relative to the threaded cap and syringe body. The tamp140is fully advanced by its full travel distance147such that the spring is fully compressed and the distal end of the tamp140extends through the opening112and into the lumen of the cannula180. The lumen of the cannula180comprises a diameter184. In some embodiments, the travel distance147is between approximately 0.25 in., and 6 in. For example, the travel distance147may be 0.5 in., 0.75 in., 1.0 in., 1.12 in., 1.25 in., 1.5 in., 2.0 in., 3.0 in., 4.0 in., or any other suitable distance, both greater and smaller. The diameter of the tamp140(see149,FIG.4) is sized such that it fits within the diameter184of the cannula180. The spring-loaded action of the tamp140allows for a separate force mechanism to move the bone graft material into the cannula180. Accordingly, each force mechanism can be applied independently using different structural features. In that regard, the threaded plunger130can be advanced relative to the syringe body by rotating the handle136relative to the syringe body and/or threaded cap. When the handle136is rotated, the tamp140moves distally with the plunger130but does not advance distally relative to the plunger. Additionally, the tamp140can be advanced distally by pressing on the cap142to control the spring-loaded motion of the tamp relative to the plunger130and the syringe body110. When the tamp140is fully extended, as shown inFIG.5b, the distal end of the tamp140protrudes through the distal opening112of the syringe body110and into the cannula180. In that regard, the syringe body110includes a first cylindrical section having a first diameter.

It will be understood that a number of modifications to the loading device100and/or the cannula180shown inFIGS.1-5bcan be made without departing from the scope of the original disclosure.FIG.6illustrates a loading device200and a cannula280according to another embodiment of the present disclosure. The loading device200may include components similar to the loading device100illustrated inFIGS.1-5b. For example, the loading device200comprises a syringe body210, a threaded cap220, a tamp240, a handle236, and a tamp cap242. In the embodiment ofFIG.6, an auger-style mechanism230is used instead of the threaded plunger described above. In that regard, rotating the handle236of the auger230causes the auger230to rotate, but does not move the auger230longitudinally relative to the syringe body210. In some aspects, the auger style mechanism230works with gravity and the inner wall of the syringe body210to move bone graft material distally toward the distal opening212. The tamp240is positioned through a central lumen of the auger230and can be advanced distally into the cannula280to force bone graft material at or near the opening212into the cannula280. Further, in the embodiment ofFIG.6, the finger grips221are directly attached to the threaded cap220instead of the syringe body210. At the distal opening212of the syringe body210, the threads216are on the outside of the syringe body210and on the inside of the cannula280. In some embodiments, the loading device200may include a component within the syringe body210that is prevented from rotating within the syringe body210, but is configured to advance distally within the syringe body210as the mechanism230rotates to move the bone graft material distally toward the distal opening212.

It will be understood that various modifications can be made to the loading devices and/or cannulas described above without straying from the scope of the present disclosure. For example, the syringe body may comprise various shapes and/or cross-sectional profiles other than the cylindrical body shown inFIGS.1-6. In some embodiments, the syringe body comprises a rectangular cross-section, an elliptical cross-section, a triangular cross-section, a polygonal cross-section, or any other suitable shape. The syringe body may comprise various lengths and internal volumes to support various amounts of bone graft material. For example, the syringe body may be sized, shaped, and structurally arranged to contain 5 milliliters (mL) of bone graft material, 10 mL, 20 mL, 30 mL, 50 mL, 100 mL, 200 mL, or any other suitable amount of bone graft material, both greater and smaller. In some embodiments, the syringe includes graduated markings to indicate a volume of material present in the syringe body. In some embodiments, the syringe body110can include other openings other than those shown inFIGS.1-6.

In some embodiments, the plunger body may comprise more or fewer components than shown in the embodiments ofFIGS.1-6. For example, in some embedment's, the plunger130comprises a single integral structure. In some embodiments, the threads of the plunger130extend along a greater or smaller portion of the length of the plunger, including an entirety of the length of the plunger. In some embodiments, the plunger130includes one or more O-rings to create seals between the plunger130and the syringe body110, and/or between the plunger130and the tamp140. In some embodiments, the plunger130includes one or more O-rings in lieu of the stopper134. In an exemplary embodiment, the syringe body110and the plunger130comprise a same material, such as polycarbonate plastic. However, in other embodiments, the plunger130may comprise a different material than the syringe body110. For example, the plunger130may comprise a metallic material, a plastic material, an elastomeric material, a ceramic material, or any other suitable type of material. Similarly, in some embodiments, the plunger130may comprise a different material than the threaded cap120. For example, the threaded cap120may comprise a soft plastic material, a metallic material, an elastomeric material, a ceramic material, or any other suitable type of material. In some embodiments, no threaded cap120is included in the loading device100. For example, the syringe body may include internal threads to engage external threads of the threaded plunger130.

The threaded engagements described herein may vary in some respects. For example, in some embodiments, the threads of the plunger, threaded cap, and/or the cannula comprise right-handed threads. In some embodiments, the threads of the plunger, threaded cap, and/or the cannula comprise left-handed threads. In some embodiments, the threads comprise single lead threads. In some embodiments, the threads comprise double lead threads. While the spring150of the loading device100is a coil spring, other types of springs may be used for the spring-loaded tamp140. For example, elastomeric strands may be used to bias the tamp140proximally to rest on the retention lip133. In some embodiments, the stopper134may comprise various shapes and/or profiles, including semi-spherical, conical, flat, or any other suitable shape. In some embodiments, the cannula180forms an interference fit with the syringe body110. In some embodiments, the threaded cap forms a locking connection with the syringe body110.

FIG.7is a flow diagram illustrating a method300for loading a bone graft material into an injection device using a bone graft loading device. It will be understood that one or more steps of the method may be performed using the devices and/or assemblies described above, including the loading devices100,200and/or the cannulas180,280. In step310, a cannula is coupled to a syringe defining a reservoir, the syringe comprising a nozzle at a distal portion of the syringe and an opening at the proximal portion of the syringe. In step320, bone graft material is placed within the reservoir. In some embodiments, the bone graft material is added to the reservoir through the opening at the proximal portion of the syringe. In step330, a plunging assembly is provided that includes a plunger body defining a lumen, a handle coupled to a proximal end of the plunger body, and a tamp extending within the lumen of the plunger body. The tamp is movable relative to the plunger body and biased proximally relative to the plunger body. In step340, the plunging assembly is coupled to the syringe such that the plunger body is positioned within the reservoir through the opening at the proximal portion. An outer surface of the plunger is configured to form a first sliding seal with the reservoir, and an inner surface of the plunger is configured to form a second sliding seal with the tamp. In step350, the handle of the plunger assembly is rotated to move the bone graft material toward the nozzle. In step360, the tamp is pushed distally toward the nozzle such that a distal end of the tamp protrudes distally of the plunger body to force the bone graft material through the nozzle and into the cannula. In some embodiments, the tamp is spring-loaded to create the proximal bias. In some embodiments, the tamp is pushed distally using a tamp cap that is positioned proximal of the handle. Accordingly, the tamp and the plunger body are independently movable to provide two different loading mechanisms, as described above.