Threaded syringe for delivery of a bone substitute material

The present invention relates to a threaded syringe. More specifically, the present invention relates to syringes used to deliver bone replacement material.

Injectable bone replacement materials are used for orthopedic repair and augmentation of fractures and defects. Bone replacement materials can also be used in some diagnostic or therapeutic procedures required for the formation of cavities in bone mass. This procedure can also be used to treat bones that have been fractured, for example due to osteoporosis, vascular necrosis, cancer, or trauma, or that are prone to compression fractures or collapse. If not adequately treated, these conditions can lead to malformations, chronic complications and a general adverse effect on quality of life.

Moreover, as is known, during surgery, a relatively large amount of bone replacement material is injected at a relatively low pressure, followed by a relatively high amount of a small amount of material without applying substantially enhanced force. It may be necessary to inject with pressure. However, especially for highly viscous or solid and flexible cement compositions, the material is extruded through the outlet opening of the syringe by applying axial pressure to the plunger of the syringe with a standard extruded syringe. It is often difficult to generate the pressure required for the. Another serious problem is that after applying sufficient pressure to the plunger, it is difficult to precisely control the amount of material that is extruded through the outlet opening of the outer cylinder, and the material is extraosseous (ie, small bone). It will flow (outside the cavity).

Various types of devices have been used to deliver bone replacement materials such as bone cement. For example, injector guns with a trigger mechanism with a lever-shaped trigger have been used. A standard extruded syringe with an outer cylinder and plunger can also be used for this purpose.

A bone cement gun with a trigger mechanism having first and second mechanical benefits in response to a trigger stroke is disclosed in US Pat. No. 5,638,997. U.S. Pat. No. 4,338,925 discloses a trigger gun that utilizes a trigger mechanism with a constant mechanical benefit that facilitates high pressure from the first mechanical benefit.

However, trigger guns generally lack the improved tactile feedback obtained using a syringe device. Such improved tactile feedback is important to inform the surgeon if there is an obstruction or blockage that prevents the material from exiting the delivery device, or in performing sensory procedures such as vertebral repair.

A type of injector or syringe for injecting bone cement into a surgically prepared bone cavity is described in European Patent No. B1-006430. This bone cement injector consists of a piston and a cylindrical tube to which a nozzle element with a nozzle tube having a relatively small cross section is attached. These injectors are constructed so that pasty bone cement can be mixed and extruded in a simple manner. In this regard, the nozzle tube is made as a two-part member with a relatively small cross section.

Other types of syringes for bone cement are disclosed in US Pat. No. 4,576,152. The injector is provided with an injection nozzle at the bottom of the cylinder tube for low pressure operation to deliver large amounts of bone cement. The nozzle element can be releasably attached to the cylinder tube for injection at high pressure. This nozzle element is removed for low pressure injections and attached for high pressure injections.<patcit num="1"><text>U.S. Pat. No. 5,638,997</text></patcit><patcit num="2"><text>U.S. Pat. No. 4,338,925</text></patcit><patcit num="3"><text>European Patent No. B1-006430</text></patcit><patcit num="4"><text>U.S. Pat. No. 4,576,152</text></patcit>

<p> The present invention relates to a syringe for delivery of a bone substitute material. The syringe comprises an outer cylinder for holding material, a plunger that is acceptable within the outer cylinder and has a threaded portion, and an engaging member that includes a threaded through hole that is coaxially arranged with the outer cylinder. The threaded portion of the plunger is movable through the threaded through hole of the outer cylinder by pushing the plunger in the axial direction and rotating the plunger.</p><p> Preferred engaging members are C-shaped and include slots that extend radially through the engaging member. In addition, the preferred engaging member is radially expandable. In one embodiment, the size of the cross section of the through hole is variable. In another embodiment, the through hole comprises an inner surface that makes full contact with the plunger as the plunger moves through the through hole.</p><p> In another preferred embodiment, when the plunger is pushed distally, the material is ejected from the outer cylinder under a first pressure, and when the plunger advances by rotation, the material is outside under a second pressure. Taken out of the cylinder. Preferably, when the plunger is pushed axially, it produces audible noise as the threaded portion of the plunger passes through the engaging member. Preferably, a predetermined amount of material is extruded from the outer cylinder for each audible click sound. Further, as the outer cylinder advances with the rotation of the plunger, a predetermined amount of material is pushed out of the outer cylinder.</p><p> Preferably, the syringe also comprises a coupling member configured to receive a portion of the package containing the material to facilitate transfer of the material from the package to the outer cylinder. A preferred coupling member comprises a funnel member that pours the material into the outer cylinder.</p><p> Preferably, the syringe also comprises a finger grip coupled to an outer cylinder at the proximal end, with the engaging member housed within the finger grip. In one embodiment, the finger grip comprises a pair of hemishells. In a preferred embodiment, the engaging member can advance the plunger in a finger grip with a first position in which the plunger can be advanced by pushing the plunger axially and by rotating the plunger. It is movable to and from the second position. A preferred engaging member comprises an extension arm that contacts the inner wall of the finger grip when the engaging member is in the first position. Preferably, the engaging member engages with the seat to prevent the engaging member from expanding when the engaging member is in the second position.</p><p> The present invention also relates to a method of discharging material from a syringe having an outer cylinder, an engaging member and a plunger. A preferred method is to move the plunger in the outer cylinder by pushing the plunger through the engaging member and to move the plunger in the outer cylinder by rotating the plunger through the engaging member. including.</p>

With general reference to FIGS. 1 and 2, a first embodiment of the syringe 10 made according to the present invention comprises a cylindrical body or outer cylinder 12, an engaging member 13, and a threaded plunger 14. This syringe is used for the delivery of drugs, preferably materials that facilitate recovery from bone trauma or disease. Examples of suitable materials applicable to bone treatment include polymethylmethacrylate (PMMA), Norian Corporation of Cupertino, and Norian Calcium Phosphate Bone Cement available from CA. Calcium Phosphate Cement, Calcium Sulfate Cement, Desalted Includes amount of bone suspension, or other bone filler material or bone substitute. In a preferred embodiment, the syringe 10 delivers a material that is relatively viscous or solid and flexible, or a material that has a relatively low ratio of liquid to solid, such as a paste.

The outer cylinder 12 comprises a central channel or hole 16 extending from the proximal end 20 to the distal end 22 along the longitudinal axis 18 of the outer cylinder 12. It is preferred that the interior of the hole 16 is substantially cylindrical and has a diameter D of about 0.625 inches. When using the syringe 10, the outlet channel 24 is in fluid communication with the hole 16 at the distal end of the hole 16 and from the diameter of the hole 16 for discharging the contents of the outer cylinder 12 through the hole 16. Also has a small diameter. The inner wall of the hole 16 tapers at the distal end at a reduction angle of 26 and transitions to a smaller diameter exit channel 24. In a preferred embodiment, the reduction angle 26 is about 90 ° to allow the material to move out of the hole 16 into the exit channel 32. The outer cylinder 12 has a generally cylindrical outer surface 28, preferably at least one circular flange 30 extending radially beyond the outer surface 28 at the proximal end 20. A pair of flat finger grip attachments 33 extend radially outwardly from the proximal end 20 of the outer cylinder 12 and beyond the proximal end 20 in the longitudinal direction to support the finger grip 34.

The needle attachment portion 36 is formed at the distal end 22 of the syringe 10. The needle mounting portion 36 includes a central cylinder 38 extending distally from the distal end of the outer cylinder 12 and defines an outlet channel 32 inside the central cylinder 38. A pair of fins 40 extends from the distal end of the outer cylinder 12 to the distal end 22 of the syringe 10. At least one flange 42 is located at the distal end of the needle attachment portion 36 to facilitate attachment of the needle or the like to the distal end 22 of the syringe 10.

The finger grip 34 is coupled to the finger grip attachment 33 at the proximal end 20 of the syringe 10 and is configured to accommodate the user's fingers when using the syringe. In a preferred embodiment, the finger grip 34 comprises a pair of half-shells 44 fitted onto a mounting portion 33 and mounted together in a pairing relationship, such as by ultrasonic welding. Preferably, the distal portion of the finger grip 34 abuts the circular flange 30 to transfer all the force proximally applied to the finger grip 34 to the outer cylinder 12 when using the syringe. And vice versa. A part of the inside of the finger grip 34 abuts or comes into contact with the mounting portion 33 to transmit all the rotational force transmitted to the finger grip 34 to the outer cylinder 12 and vice versa. The exterior of the finger grip 34 comprises a central cylindrical portion 46 having a diameter slightly larger than the diameter of the outer cylinder 12 and a pair of finger portions 48 oriented parallel to the longitudinal axis 18 of the outer cylinder 12. .. The inside of the finger grip 34 is at least partially hollow, in which the engaging member 13 is housed. In a preferred embodiment, the engaging member 13 expands freely in the radial direction and moves axially within the central cylindrical portion 46. In an alternative embodiment, the engaging member 13 can be housed in the outer cylinder 12 or formed integrally with the outer cylinder 12.

Referring to FIGS. 2 and 3, the engaging member 13 includes a threaded through hole 50 that is located adjacent to the proximal end 20 of the outer cylinder 12 and has a thread 52 on its inner surface 54. The thread 52 of the engaging member 13 is complementary to the thread of the plunger 14. In a preferred embodiment, the engaging member 13 is C-shaped and has an outer diameter that generally corresponds to the diameter of the circular flange 30 described above. The slot 56 extends radially from the through hole 50 to the outer surface 58 of the engaging member 13 to allow the engaging member 13 to expand radially, as indicated by the arrow 60 in FIG. In a preferred embodiment, the engaging member 13 and the threaded through hole 50 are arranged within the finger grip 34 so as to be axially aligned with the central hole 16 of the outer cylinder 12. The slot 56 aligns and engages with one of the finger grip attachments 33, and a portion of the outer surface 58 of the engaging member 13 abuts the other finger grip attachment 33. The engaging member 13 is axially movable inside the finger grip 34. The engaging member 13 is located at the first position on the distal side of the finger grip 34 where the engaging member abuts or contacts the outer cylinder 12, as shown in FIG. 11A, and as shown in FIG. 11B. It is movable to and from a second position on the proximal side of the finger grip 34, where the engaging member abuts or contacts the inner wall of the finger grip. When the engaging member 13 is engaged with the finger grip mounting portion 33, the slot 56 prevents the engaging member 13 from rotating. The engaging member 13 contacts the inner wall of the finger grip 34 when the engaging member is in the first position, providing an easily identifiable feature of the engaging member and assisting in proper assembly of the syringe 10. The extension arm 62 is provided.

Referring to FIG. 4, the plunger 14 has a proximal end 72, a distal end 74, a threaded stem 76, an unthreaded distal tip 78, and an integrally formed handle-shaped head 80. .. The outer thread 82 of the threaded stem 76 is configured to complement and pair with the inner thread 52 of the engaging member 13. The outer diameter of the thread 82 of the threaded stem 76 is approximately the same as the inner diameter D of the central hole 16 of the outer cylinder 12, but slightly smaller, with the threaded stem 76 having a slight tolerance. It is designed to slide in the central hole 16. In a preferred embodiment, the pitch of the threads 82 of the threaded stem 76 is about 0.10 inches, or about 10 threads per inch. It is preferable that the flank angles 84 and 86 of the screw thread 82 are not symmetrical. As can be seen in FIG. 5, the advancing flank surface 88 of each thread 82 of the threaded stem 76 has an advancing flank angle 84. In a preferred embodiment, the advancing flank angle is about 60 degrees. However, the preferred advancing flank angle 84 is from about 45 degrees to about 75 degrees. On the chasing side flank surface 90, the chasing side flank angle 86 is about 0 to about 10 degrees, preferably 0 degrees, respectively. A preferred flank angle is one that extrudes the material from the syringe 10 to help prevent the plunger 14 from being pushed or forced proximally during use. The contour of the screw described above clearly deviates from the contour of the acme screw and has a modified configuration. Readers should refer to Machinery's Handbook. See Industrial Press Incorporated, New York, NY, 24th Edition for a more detailed description of the terms used herein to describe threads and their components. Many of the definitions contained in the description describing the threaded portion are incorporated herein by reference.

The outer diameter of the unthreaded tip 78 is the inner diameter of the central hole 16 to prevent the material from flowing back between the threads of the threaded stem 76 as the material advances into the outer cylinder 12. It is roughly the same as, but slightly smaller, with the unscrewed tip 78 sliding within the central hole 16 with a slight tolerance. The unthreaded tip 78 also has an annular recess to receive a suitable size O-ring (not shown) to provide a more effective seal on the inner surface of the central hole 16. The distal end 74 of the unthreaded tip 78 has an angled tip surface 92 that facilitates the discharge of the maximum amount of material out of the syringe 10. In one preferred embodiment, the angle 94 of the plunger at the distal end of the tip 78 is about 95-145 degrees, more preferably about 105-135 degrees, most preferably about 120 degrees. It has also been determined that it is desirable that the plunger angle 94 is not equal to the reduction angle 26. It is also preferred that the plunger angle 94 be greater than the reduction angle 26 so that the maximum amount of material can be ejected from the syringe.

The plunger 14 can be pushed or rotated axially through the engaging member 13 to advance in the outer cylinder 12. The plunger 14 is movable along the longitudinal axis 18 of the outer cylinder 12 through the threaded through hole 50 of the engaging member 13 by pushing the plunger axially. The plunger 14 can also be moved along the longitudinal axis of the outer cylinder 12 by rotating the plunger so that the thread 82 of the threaded stem 76 of the plunger 14 is threaded through the threaded through hole 50. It is designed to engage with 52.

With reference to FIGS. 6-9, in one preferred embodiment, the coupling member 110 can be attached to the proximal end 20 of the outer cylinder 12 to facilitate insertion of the material into the outer cylinder 12. The coupling member 110 is adapted to fit into a package or tube 96 having a coupler 98, facilitating the transfer of material held within the tube 96 to the syringe.

One preferred coupling member 110, shown in FIG. 7, includes an inverted central funnel member 112 having a relatively thin cylindrical nose 114 extending upward from a relatively wide opening 116 at its bottom. The screw engaging fingers 118 are spaced apart from the opening 116 and are configured to engage the thread 52 of the engaging member 13. A pair of release arms 120 extend radially outward from the top of the nose 114 and insert the coupling member 110 into the proximal end 20 of the outer cylinder 12 for easy removal. As can be seen in FIG. 8, after inserting the coupling member 110 into the proximal end 20 of the outer cylinder 12, the coupler 98 of the tube 96 engages the coupling member 110 and the nose 114 is inside the coupler 98. Extend. With the tube 96 engaged to the outer cylinder 12, the material in the tube 96 can be easily moved from the tube 96, for example by tightening the tube 96. Once the material enters the outer cylinder 12, the reverse funnel 112 of the coupling member 110 favorably deflects the material through the engaging member 13 and protects the engaging member 13 from contact with the material during material transfer. .. Keeping the engaging member out of contact with the material is desirable to allow the engaging member to move freely during operation of the syringe. Referring to FIG. 9, after sufficient material has been transferred to the outer cylinder 12, the coupling member 110 and the tube 96 can be easily removed from the syringe 10 by accessing the release arm 120 and releasing the finger 118 from the thread 52. Can be removed.

Next, referring to FIG. 10, after the material is placed in the outer cylinder 12, the plunger 14 is inserted into the proximal end 20 of the outer cylinder 12 via the engaging member 13 and is inserted into the central hole of the outer cylinder 12. Extends within 16. If desired, the material can be released under low pressure and high pressure. For example, low pressure is suitable for releasing large amounts of material, and high pressure is suitable, for example, when the material must be poured into a closed cavity or when penetration into the cancellous bone is desired. In some embodiments, injecting the therapeutic material at a sufficient rate should result in about 100 psi to about 500 psi. It should be noted that it is desirable for the user to receive tactile feedback during material insertion and deliver the material under optimal pressure, depending on the required treatment.

By pushing the plunger 14 axially, the material can be released under low pressure. As mentioned above, the flank angles 84, 86 of the thread 82 are not symmetrical and have a leading flank surface 88 with a leading flank angle 84. Thus, when the plunger is advanced or pushed axially, this advancing flank angle 84 guides the engaging member 13 to a region within the finger grip 34, where it is as indicated by arrow 60 in FIG. , The engaging member 13 elastically expands in the radial direction. In this regard, when each thread 82 of the plunger passes through the through hole 50, the size of the cross section of the through hole 50 changes with the expansion and contraction of the engaging member 13. This allows the engaging member 13 to act like a ratchet with minimal resistance when the plunger advances distally. In a preferred embodiment where the trailing flank angle is approximately 0 degrees, after the thread 82 has advanced distally through the engaging member, the plunger is not rotated counterclockwise, i.e. screw the plunger. Without loosening, the thread is prevented from returning proximally through the engaging member. In a preferred embodiment, the inner surface 54 of the through hole 50 surrounds the plunger 14, preferably plans when Ja moves through the through hole 50, in contact with the plunger 14 and the entire surface. It is preferable to make an audible click sound at the same time each time the thread 82 completely passes through the engaging member. By adjusting the pitch of the threads 82 to the size of the cross section of the outer cylinder 12, this clicking sound indicates the individual volume of material extruded from the syringe. In a preferred embodiment with a diameter of 0.625 inches and a thread pitch of 0.10 inches, a one-click sound indicates 0.5 cc of material extruded from the syringe. This provides the user with a method of determining the volume delivered.

By rotating the head 80 of the plunger 14 in the clockwise direction with respect to the outer cylinder 12, the material can be released under high pressure. When this head is rotated, the distal end 74 of the plunger 14 gradually advances into the central hole 16 of the outer cylinder 12. The threaded through hole 70 and the threaded stem 76 work together to apply a rotational external force applied to the head 80 to the bone cement material contained within the outer cylinder 12 via the distal end 74 of the plunger 16. Converts to longitudinal force. The use of a threaded plunger can help the user generate the force required within the outer cylinder 12 to push the material out of the distal end 22 of the outer cylinder 12 under relatively high pressure. It will be understood by those skilled in the art. Note that the shape of the head 80 also allows the user to effectively rotate the plunger 16 with minimal hand and wrist rotation. The enlarged head 80 has a shape that is easy for the user to grasp and operate. In particular, when a highly viscous or solid and flexible bone cement composition is present in the outer cylinder 12, the plunger 16 is advanced into the outer cylinder 12 by rotating the plunger 16 with respect to the outer cylinder 12. Those skilled in the art should understand that significant pressure can be generated in the outer cylinder 12 when it is forced to. In this regard, in one preferred embodiment, the mechanical benefit provided by the use of the threaded plunger is preferably about 5 to 1. Further, the number of revolutions (or fractions thereof) of the plunger 14 relative to the outer cylinder 12 provides a means of measuring the amount of material discharged from the distal end 22 of the syringe 10. In one preferred embodiment, including a screw pitch of 0.10 inches, each full rotation of the head 80 (eg, 360 degrees) would push the plunger 14 out of 0.5 cc of material from the distal end 22 of the outer cylinder 12. Advance in the longitudinal direction by a sufficient distance.

Referring to FIG. 11B, in a preferred embodiment, the plunger is rotated clockwise and then the engaging member 13 is moved proximally to engage the seat 126 within the proximal interior of the finger grip 34. Match. The seat 126 preferably surrounds or captures at least a portion of the outside of the engaging member 13 to prevent the engaging member from expanding radially. This favorably provides rigid support to the engaging member, allowing the engaging member to act like a threaded nut, transforming the rotational movement of the plunger 14 into axial movement.

One of ordinary skill in the art will consider numerous modifications and modifications to the invention disclosed herein. All of these amendments are intended in the true spirit and scope of the claimed claims.

<figref num="1">The perspective view which shows the syringe device made by this invention.</figref><figref num="2">Front view of the syringe of FIG. 1, showing a cross-sectional view of the finger grip.</figref><figref num="3">The perspective view which shows the engaging member of FIG.</figref><figref num="4">The perspective view which shows the screwed plunger of FIG.</figref><figref num="5">Longitudinal partial cross-sectional view showing the threads of the threaded plunger of FIG.</figref><figref num="6">An exploded perspective view showing the attachment of a tube of material to the syringe of FIG.</figref><figref num="7">The perspective view which shows the coupling member of FIG.</figref><figref num="8">Front sectional view showing transfer of material to the syringe of FIG. 1.</figref><figref num="9">FIG. 5 is a perspective view showing the tube of FIG. 6 removed from the syringe of FIG.</figref><figref num="10">The perspective view which shows the insertion of the plunger of FIG. 4 into the outer cylinder of FIG.</figref><figref num="11">11A and 11B are partial cross-sectional views of the finger grip of FIG. 1 showing engaging members in first and second positions, respectively.</figref>