Abstract:
A steroid delivery system including a mixing syringe having a first chamber and a second chamber and at least one hypodermic needle is provided. The first chamber of the mixing syringe contains a pre-measured volume of a local anesthetic and the second chamber contains a pre-measured volume of a corticosteroid. An improved mixing syringe and a method for treating pain using the steroid delivery system of the present invention is also provided herein. The improved syringe achieves mixing without the introduction or elimination of air and without puncturing or rupturing of a membrane, diaphragm or other material. The kit concept improves the speed of the procedure, sterility, accuracy of dosing, and immediate availability of disparate items to implement the procedure in a variety of medical practice settings.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to pain management systems, and more specifically, a steroid delivery system for the treatment of localized musculoskeletal or neurogenic pain. Most specifically, the present invention relates to a prepackaged orthopedic steroid delivery system including an improved mixing syringe pre-filled with local anesthetic and corticosteroid, a variety of needles, local antiseptics, and ethyl chloride, if used. 
     BACKGROUND OF THE INVENTION 
     Steroid injections are often used to treat localized musculoskeletal or neurogenic pain. In practice, the corticosteroid is often mixed with a local anesthetic and injected into a patient&#39;s joint, tendon sheath, or adjacent to a painful ligament or inflamed nerve. The corticosteroid acts over several days to manage inflammation and pain, while the local anesthetic works immediately, but only temporarily. If the injection is properly placed, the local anesthetic will instantly numb the patient&#39;s pain, and the practitioner can be reasonably assured that the corticosteroid will be injected in the proper area to effectively manage pain. A successful local treatment of musculoskeletal or neurogenic pain improves the patient&#39;s function and decreases the need for systemic medications and even surgery, in some cases. 
     In the current state of the art, the preparation of such an injection requires a practitioner to gather a variety of supplies including the corticosteroid and anesthetic, a syringe and needles, and local anesthetic, among other things. The length of time it takes to prepare the injection can depend on the availability and accessibility of the supplies and the efficiency and organization of the medical office and staff. Lack of even one item, whether it is misplaced, out of stock, outdated, contaminated or in another area, can extend preparation time. The entire process can be very time consuming and can be a limiting factor in the number of such treatments a practitioner can administer in one day. 
     One example of a device that attempts to address these problems is disclosed in U.S. Pat. No. 7,100,771 B2 to Massengale et al. The Massengale patent relates to a pain management kit containing the primary medical supplies for performing a continuous nerve block procedure. The kit comprises sterile field supplies, local anesthetic supplies and continuous nerve block supplies in a single, sterile container. Inside the container, the supplies are organized within a series of compartmentalized trays which hold each of the included supplies. The particular anesthetic drug is omitted from the kit. 
     One disadvantage of this kit, however, is that the desired infusion drug and several other necessary supplies, such as nerve simulator and an infusion pump, are not contained within the kit. Therefore, the practitioner would still have to gather additional supplies, in addition to the kit, in order to perform the nerve block procedure. If any of these supplies are out of stock, misplaced, in another room, or in use by another practitioner, the procedure will be delayed. 
     Another factor which greatly affects the time to prepare an injection for pain management as described at the outset is that the practitioner must manually measure and mix the corticosteroid and anesthetic from separate vials immediately before use. This has several significant disadvantages. First, this can again add considerable time to the overall length of the procedure, depending on the dexterity and experience of the doctor. Even if all of the materials are within the practitioner&#39;s reach, he/she still must take the time to draw separate volumes of both the corticosteroid and anesthetic. Second, certain safety risks are associated with manually preparing the injection for each administration. Not only can human error play a role when manually measuring the two solutions, but also sterility is an issue when the vials of corticosteroid and anesthetic are reused to prepare several injections often by different practitioners at the same site. Third, the vials of corticosteroid and anesthetic have a limited shelf-life once they punctured, so if they are not completely used within the allotted time, they must be discarded, which can be costly. In fact, a practitioner that would not normally administer enough of these injections to avoid wasting opened vials of the pre-mixed corticosteroid or anesthetic may choose not to perform these types of procedures altogether. 
     However, in the current state of the art, corticosteroid premixed with local anesthetic is not readily commercially available. Many steroid preparations are suspensions of particles, which settle to the bottom of their glass vials within minutes of no motion. These particles can stick firmly to the glass vial and require vigorous shaking to re-suspend. 
     Furthermore, mixing syringes currently known in the field have the disadvantage of introducing air into the mixed solution. For example, in U.S. Pat. No. 7,101,354 to Thorne, Jr. et al., a small amount of air is contained in the chambers  120 ,  130  to aid in the creation of a negative pressure across the valved stopper  110 . Any air within the chamber must be removed before injecting the mixed solution into a patient, which again can lengthen the time of a procedure. 
     Prior art mixing syringes also have the disadvantage of requiring the puncturing or rupturing of a membrane, diaphragm or other material separating the two injection solutions. When this rupturing or puncturing occurs, minute fragments of the separating material may be mixed into the injection. These materials may have an adverse effect when injected into the human body with the injection mixture. 
     What is desired, therefore, is a pre-packaged, sterile pain management kit which contains all of the instruments and supplies necessary to treat localized musculoskeletal or neurogenic pain. It is further desired to have a syringe containing pre-measured volumes of corticosteroid and local anesthetic in separate compartments that can be quickly mixed into a homogeneous chemical mixture immediately prior to use, without rupturing or puncturing of a separating material and without introducing air into the mixture. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a sterile steroid delivery system which contains all of the instruments and supplies necessary for a pain management treatment. 
     It is a further object of the present invention to provide a method for treating pain using the corticosteroid delivery system of the present invention. 
     It is still a further object of the present invention to provide an improved mixing syringe for mixing corticosteroid and local anesthetic immediately prior to use for pain management in conjunction with the corticosteroid delivery system of the present invention. 
     These and other objectives are achieved by providing a steroid delivery system comprising a mixing syringe having a first chamber and a second chamber, the first chamber containing a pre-measured volume of a local anesthetic and the second chamber containing a pre-measured volume of a corticosteroid, and at least one hypodermic needle. The mixing syringe and at least one needle may be sealed within said sterile package. The local anesthetic may be chosen from the group consisting of: lidocaine, xylocaine, ropivacaine, marcaine, or similar. Further, the corticosteroid may be chosen from the group consisting of betamethasone, triamcinolone, and methylprednisolone. In other embodiments, the steroid delivery system further comprises at least one 22 gauge hypodermic needle, at least one 25 gauge hypodermic needle, a local surface anesthetic, and a local antiseptic. In yet further embodiments of the present invention, the volume of local anesthetic varies based on the intended treatment area and desired effect and the volume of corticosteroid varies based on the intended treatment area and desired effect. Moreover, the ratio of the volume of local anesthetic to the volume of corticosteroid may vary based on the intended treatment area and desired effect. 
     Other objects of the present invention are achieved by provision of a method for treating pain and inflammation comprising the steps of: providing a steroid delivery system having a mixing syringe having a first chamber and a second chamber and at least one hypodermic needle; combining said pre-measured volume of local anesthetic and pre-measured volume of corticosteroid within the mixing syringe into an injection mixture prior to injection, and injecting said injection mixture into an intended treatment area. The first chamber of the syringe contains a pre-measured volume of local anesthetic and the second chamber contains a pre-measured volume of corticosteroid. In some embodiments, the method further comprises the step of choosing the volume of local anesthetic based on the intended treatment area and desired effect. In other embodiments, the method further comprises the step of choosing the volume of corticosteroid based on the intended treatment area and desired effect. In further embodiments, the method further comprises the step of choosing the ratio of the volume of local anesthetic to the volume of corticosteroid based on the intended treatment area and desired effect. 
     Still other objects of the present invention are achieved by provision of a mixing syringe comprising a first chamber adapted for containing an injectable material, a second chamber in axial alignment with the first chamber and adapted for containing an injectable material, a cannula having an end open to said first chamber and having a lateral opening spaced apart from the end thereof, a mixing assembly disposed between the first and second chambers, said mixing assembly supporting the cannula for axial movement and covering the lateral opening when the cannula is in an inoperative position, a retracting element attached to the cannula, axial movement of the retracting element causing corresponding axial movement of the cannula such that the cannula is retracted from the inoperative position to an operative position where the lateral opening lies within the second chamber, so that the second chamber is in fluid communication with the first chamber. 
     In some embodiments, the mixing assembly comprises a first sealing element slidably disposed between the first chamber and second chamber and a second sealing element at least partially disposed within the first chamber and second chamber. The first may have sealing element has an axial hole therethrough for slidably receiving the second sealing element therein. In further embodiments, the syringe further comprises a hollow barrel having an inner surface, an open proximal end and a distal end, the barrel distal end being adapted to receive a hypodermic needle. The first chamber of the syringe is defined by the barrel inner surface between the barrel proximal end and the mixing assembly. In other embodiments, the retracing element comprises a flange. In yet other embodiments, the retracting element comprises a lever, hingedly affixed to the cannula. 
     Other objects of the invention and its particular features and advantages will become more apparent from consideration of the following drawings and accompanying detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of one embodiment of the steroid delivery system of the present invention. 
         FIG. 2  is a perspective view of one embodiment of the improved mixing syringe for use in the steroid delivery system of the present invention. 
         FIG. 3 a    is a side view of one embodiment of a syringe barrel for use in the steroid delivery system of the present invention. 
         FIG. 3 b    is a side view of the stopper, vial, and retracting assembly for use in the steroid delivery system of the present invention. 
         FIG. 3 c    is a side view of the cannula and for use in the steroid delivery system of the present invention. 
         FIG. 4  is a detailed partial side view of one embodiment of the improved mixing syringe for use in the steroid delivery system of the present invention. 
         FIG. 5  is a side view of one embodiment of the improved mixing syringe for use in the steroid delivery system of the present invention. 
         FIG. 6  is a side view of one embodiment of the improved mixing syringe for use in the steroid delivery system of the present invention. 
         FIG. 7  is a side view of one embodiment of the improved mixing syringe for use in the steroid delivery system of the present invention. 
         FIG. 8  is a side view of one embodiment of the improved mixing syringe for use in the steroid delivery system of the present invention. 
         FIG. 9  is a perspective view of one embodiment of the improved mixing syringe for use in the steroid delivery system of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of the steroid delivery system  10  of the present invention is shown in  FIG. 1 . The steroid delivery system  10  consists of a kit  12  containing all of the medical supplies necessary to administer a corticosteroid and anesthetic treatment including, but not limited to, an improved mixing syringe  14  prefilled with a volume of local anesthetic and corticosteroid, a variety of hypodermic needles  16 , local antiseptic wipes (e.g. povidine, isopropyl alcohol)  18 , an antiseptic swab  20  and a local surface anesthetic (not shown), such as ethyl chloride, if used. All of the desired items for administering the treatment are contained within a sterile package  22  so that the items may be removed and immediately used. As stated above, the time it currently takes to administer this treatment is highly dependent on the availability and accessibility of all of the necessary supplies. By bundling all of the supplies into one kit, the preparation time will be greatly reduced and increase the likelihood that such an injection can be achieved on short notice. 
     Furthermore, the prepackaged kit  12  can be produced in a variety of corticosteroid to anesthetic ratios and quantities, for the treatment of pain in different areas of the body, such as a joint, a tendon sheath, a ligament, or a nerve. One having skill in the art is familiar with the particular volumes and strengths of both the anesthetic and corticosteroid that are safe and effective for the relief of pain and inflammation in certain areas of the body. In addition, by providing a variety of hypodermic needles  16  of different lengths and gauges, one kit  12  may be used to treat a variety of areas. For example, at least one 25 gauge needle, and at least one 22 gauge needle may be provided in one kit  12 . Moreover, the needles can be provided in varying lengths, such a spinal-length needle. 
     Referring now to  FIGS. 2 and 3A-3C , the improved mixing syringe  14  for use in the corticosteroid delivery system  10  of the present invention, having a proximal end  24  and a distal end  26 , comprises a hypodermic needle  28  having a neck  30 , a barrel  32 , a mixing assembly  34  and a retracting assembly  36 . Hypodermic needle  28  would be provided separately of the syringe  14  within the sterile kit  12  and would be connected by the practitioner immediately before administration. Barrel  32  is a conventional syringe barrel known in the art, having a nozzle  38  for accepting a hypodermic needle, a fluid dispensing orifice  40 , a hollow cylinder  42  and a grip  44 . Distal end  46  of barrel  32  has is contoured to maximize effluent flow and to minimize fluid retained in barrel  32  as a plunger or stopper is displaced to abut the distal end. Prior to use and during the mixing phase, orifice  40  is closed and sealed by a removable cap  48 . 
     Mixing assembly  34  comprises stopper  50 , cannula  52 , flange projection  54 , elongate plug  56  and vial  58 . Slidably disposed within hollow cylinder  42  of barrel  32  between distal end  46  and grip  44 , stopper  50  defines a first chamber  60  for containing a first injectable material. Stopper  50  is sufficiently close fitting with hollow cylinder  42  to be fluid tight and has a generally convex distal end  62  that corresponds to distal end  46  of barrel  32 . Vial  58  is received within proximal portion  66  of channel  64  of stopper  50  and rests on ledge  68 . Again, vial  58  is sufficiently close fitting with the proximal portion  66  of channel  64  to be fluid tight. While not necessary, vial  58  may be affixed within channel  64  of stopper  50  with an adhesive. 
     Elongate plug  56  is slidably disposed within distal portion  70  of stopper  50 . The diameter of distal portion  70  is approximately the same as the diameter of inner surface  72  of vial  58 . Thus, plug  56  is fluid tight with both the internal surface  72  of vial  58  and the distal portion  70  of stopper  50 . Cannula  52 , having a lateral opening  78  and a distal opening  80  and a solid segment  81  proximal of the lateral opening  78 , is slidably received within internal passage  76  of plug  56 . Cannula  52  is hollow from distal opening  80  to the solid segment  81 . Thus, with cannula  52  received in passage  76 , plug  56  defines a second chamber  74  within vial  58  for containing a second injectable material. 
     Referencing  FIG. 3B , retracting assembly  36  comprises a connecting portion  82  having a lip  84 , struts  86 , lever arms  88  and a plunger  90 . Together, connecting portion  82 , struts  86 , plunger  90 , and stopper  50  are similar in function and structure to a plunger stem of basic syringes known in the art. When assembled, lip  84  of connecting portion  82  is inserted into groove  92  of stopper  50  and shoulder  94  of vial  58  rests against ridge  96  of struts  86 . 
     Lever arms  88  are hingedly affixed at a proximal end  98  to plunger  90  and at a distal end  100  to disk  102 . Head  106  of cannula  52  is engaged with disk  102 . Preferably, lever arms  88  are formed as one continuous piece and hinge at elbow  104 . However, each lever arm  88  may be formed of two separate pieces of plastic and hingedly connected at elbow  104 . To allow lever arms  88  to hinge at elbows  104  and the connections at proximal  98  and distal  100  ends, arms  88  are preferably formed of a molded plastic that is robust, yet has some flex to it, such as a low density polyethylene (LDPE), high density polyethylene (HDPE), or polypropylene (PP). Moreover, lever arms may be integrally formed with plunger  90  and disk  102 . As is depicted in  FIG. 3B , elbows  104  are positioned slightly lower (more distal) than disk  102 , the utility of which will be described below. A detailed view of the assembled mixing assembly  34  and its connection to the retracting assembly  36  is shown in  FIG. 4 . 
       FIG. 5  depicts mixing syringe  14  in an inoperative position  107  in which lateral opening  78  of cannula  52  is sealed by plug  56 . Thus, while distal opening  80  of cannula  52  is open to first chamber  60 , second chamber  74  is not in communication with first chamber  60 . In this inoperative position  107 , plug  56  extends partially into first chamber  60  and flange projection  54  is spaced apart both from distal end of cannula  52  and plug  56 . Further, lever arms  88  are in an open position  108 . This is how mixing syringe  14  would be provided in the sterile kit  12 . 
     As stated above, the improved mixing syringe  14  contains separate, pre-measured volumes of two injectable materials, preferably a corticosteroid and a local anesthetic. Additionally, the syringe is designed so that the two component medications can be quickly combined into a homogeneous chemical mixture just prior to use. In operation, as shown in  FIG. 6 , to mix the injectable materials in first chamber  60  and second chamber  74 , a practitioner squeezes lever arms  88  in the direction of arrow A. This squeezing is a simple motion and will be familiar to practitioners in the art and intuitive to less frequent practitioners. Due to the hinged connections at proximal end  98 , distal end  100 , and elbows  104 , and the orientation of disk  102  with respect to elbows  104  causes disk  102  to move proximally in the direction of arrow B. As cannula  52  is engaged with disk  102 , it is also drawn in the direction of arrow B. Mixing syringe  14  is in an operative position  110  when lateral opening  78  lies fully within second chamber  74 , causing second chamber  74  to be in fluid communication with first chamber  60  and allowing the respective injectable materials contained therein to mix. Further, as cannula  52  was drawn in the direction of arrow B, flange projection  54  was moved into abutment with plug  56 . 
     As the user continues to squeeze lever arms  88  in the direction of arrow A, cannula  52  continues to be drawn in the direction of arrow B. Now, because flange projection  54  was moved into abutment with plug  56 , plug  56  is also drawn proximally in the direction of arrow B and into second chamber  74 . Plug  56  is drawn into chamber  74  until its proximal end abuts the inner surface of shoulder  94  of the vial  58 , fully expelling substantially all of the injectable material contained in second chamber  74  into first chamber  60  through opening  80 . The injectable mixture is now fully contained within first chamber  60 . Notably, the total volume of the first  60  plus the second  74  chambers remains constant from the beginning and throughout the mixing process. Moreover, no air is introduced into either of the chambers and no separating material is ruptured or punctured in the mixing process. 
     After the injectable materials are mixed, the user would then connect a hypodermic needle  28  to nozzle  38  of syringe barrel  32  in preparation for administration. As can be seen in  FIG. 7 , when lever arms  88  are in a closed position  112 , they are folded in, hinged at elbows  104 , and lie completely within the profile of the struts  86 . Therefore, when plunger  90  is depressed in the direction of arrow C, as shown in  FIG. 8 , the struts  86  and arms  88  fit within hollow cylinder  42  of barrel  32 . The injectable mixture is then expelled out of barrel  32  through fluid dispensing orifice  40  (and through needle  28 ) as plunger  90  is depressed. All of the fluid is expelled once convex distal end  62  of stopper  50  abuts distal end  46  of barrel  32 . 
     The mixing syringe  14  may be used in conjunction with the steroid delivery system of the present invention, for the purpose of treating musculoskeletal or neurogenic pain. In this embodiment, the first injectable material contained within the first chamber  60  is preferably a local anesthetic, which may be lidocaine, xylocaine, ropivacaine, or marcaine. The second injectable material contained within the second chamber  74  is preferably a corticosteroid, which may contain particles settled in the suspension. The corticosteroid may be betamethasone, triamcinolone, or methylprednisolone, or others. By placing the corticosteroid in the second chamber, any particles that have settled to the bottom of the chamber will be dispersed throughout the solution when the local anesthetic from the first chamber is introduced. The corticosteroid and anesthetic may be reversed when there is no particle suspension. 
     The mixing syringe  14  of the present invention may also be used in any instance where it is desirable to administer two injectable solutions at one time, but where the two solutions must be kept separate prior to injection. Therefore, the first and second chambers may be pre-filled with any desired injectable solutions, particulate suspensions, powders, etc. 
     An alternative embodiment of the improved mixing syringe  114  for use in the steroid delivery system of the present invention is shown in  FIG. 9 . Like elements are labeled the same. This embodiment of syringe  114  functions the same as syringe  14 , except that the lever arms  88  and disk  102  of the retracting assembly  36  are replaced with a flange  116 , which is connected to the proximal end of the cannula  52 . In operation, a user merely grasps flange  116  and pulls it in the proximal direction to move syringe  114  from an inoperative position  107  to an operative position  110 . Other embodiments of retracting assembly  36 , including a threaded mechanism wherein a user would twist the retracting assembly and cause it to draw the cannula proximally, are also contemplated. 
     It should be understood that the foregoing is illustrative and not limiting, and that obvious modifications may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, reference should be made primarily to the accompanying claims, rather than the foregoing specification and relative dimensions shown and described therein, to determine the scope of the invention.