Patent Publication Number: US-2007118068-A1

Title: Method and apparatus for use of a vacuum package for allograft material

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a divisional of U.S. patent application Ser. No. 10/634,468, filed on Aug. 5, 2003, the disclosure of which is incorporated by reference. 
    
    
     FIELD OF THE INVENTION  
      The present invention is generally related to an allograft packaging apparatus and packaging and delivery methods, and more particularly to a method and apparatus for packaging and reconstituting allograft using a vacuum system to assist the reconstitution.  
     BACKGROUND OF THE INVENTION  
      The natural joints and bones of the body often undergo degenerative changes due to a variety of etiologies. When these degenerative changes become advanced and irreversible, it may ultimately become necessary to replace or repair a damaged bone or joint. When such a procedure becomes necessary, the bone may be repaired with an implant secured with allograft material such as de-mineralized bone material or bone chips. Other uses of allograft material include repairing or mending bone fractures or shattered bones that may occur from extreme trauma. Allograft may also be used to fill bone screw holes made during an orthopedic medical procedure or chips in teeth.  
      When a surgical procedure requires the use of bone particles as a filler material or to promote bone growth, the surgeon may recycle bone particles from the patient (autograft), or use donor bone particles (allograft). Allograft is frequently used due to the lack of quality or quantity of autograft. Bone particles may be freeze-dried and stored for later use. Typically, it is desirable to store these freeze-dried particles under a negative pressure in order to prolong their shelf-life. In order to implant allograft that has been freeze-dried into a surgical site, the allograft must be reconstituted using a liquid such as patient blood, platelet concentrate, or saline. Platelet concentrate (from the patient, centrifuged during surgery) and patient blood are desirable to prevent the bone from rejecting the graft and can be harvested during surgery.  
      Typical methods for reconstituting allograft involve soaking the allograft in a liquid. This method relies primarily on the capillary action of the liquid in the pores of the allograft. Blood has been found to exhibit poor capillary action when compared to thinner liquids, such as saline or water. This deficiency in capillarity may result in a prepared allograft that has not been thoroughly wetted. Thus, prior art methods require time to adequately wet the capillaries, or pores, of allograft particles. While allograft can be reconstituted prior to use, the need for more allograft than expected may prolong a surgical procedure.  
      What is needed is an improved apparatus and packaging system to more expediously reconstitute allograft with various liquids and deliver the reconstituted allograft to a surgical site, while ensuring a thorough wetting of allograft particles.  
     SUMMARY OF THE INVENTION  
      In accordance with the teaching of the present invention, a method and apparatus for packaging and delivering allograft is disclosed.  
      The present invention provides methods of hydrating and/or delivering an allograft or substrate to a surgical area. A first container is positioned within a second container and a negative pressure is maintained on a chamber as formed by the first container and a sealing device. The sealing device is engaged with a reconstituting fluid delivery device. The reconstituting fluid is injected into the chamber having an allograft or substrate therein, while preventing the introduction of significant amounts of gases into the first container.  
      Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
       FIG. 1  illustrates an allograft packaging system or kit of the present invention;  
       FIG. 2  illustrates an assembled apparatus as provided in the allograft packaging system of  FIG. 1 ;  
       FIG. 3  illustrates the delivery of allograft using a container shown in  FIG. 1 ;  
       FIG. 4  is another embodiment of the allograft packaging system according to the teachings of the present invention;  
       FIG. 5  illustrates the allograft packaging system of  FIG. 3  in an exploded view; and  
       FIG. 6  illustrates a step in reconstituting the allograft contained within the allograft packaging system of  FIG. 4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The following description of the embodiments of a method and apparatus for packaging, reconstituting, and delivering an allograft is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Moreover, while the present invention is described in detail with reference to an allograft material, it will be appreciated by those skilled in the art that the present invention is not limited to an allograft material, but may also be used with any other material that requires reconstitution or wetting and could benefit from reconstitution under a vacuum. It should also be appreciated that the reconstituting liquid may be platelet concentrate, blood, aspirate, or other liquids capable of reconstituting the allograft material.  
       FIG. 1  illustrates an allograft packaging system  10  wherein an outer container  12  encloses a first container  14  and a second container  16 , such as a syringe. Outer container  12  is preferably configured to maintain first container  14  and second container  16  in a sterile environment under a negative pressure and, as an example, may be a flexible vacuum bag. In this regard, the first container  14  and second container  16  are placed in outer container  12  and a vacuum is drawn in the outer container  12 .  
      First container  14  includes a barrel  20  having a proximal end  22 , an outlet end  24 , a plunger  26 , a plunger seal  28 , and a valve  30 . Valve  30  includes a female leur fitting  32  adapted to couple in fluid communication with barrel  20 , and a leur fitting  34  adapted to couple with second container  16 . Valve  30  is removably coupled to outlet end  24  of barrel  20  with leur fitting  32 . Optionally, valve  30  is a one-way vented valve that is operable to respond to a differential pressure and allow fluids to flow out of first container  14 , and may be selectively opened. Collectively, barrel  20 , plunger seal  28 , and valve  30  define a chamber  36 . Chamber  36  may be prepackaged with an allograft  38 . The allograft  38  includes bone chips or de-mineralized bone material (DBM) that has been freeze-dried for preservation, although chamber  36  could also be packed with other porous, bone substitute materials, autograft, synthetic materials such as ceramics, or combinations thereof. The chamber  36  is pulled to a vacuum before first container  14  is positioned in outer container  12 . Plunger  26  is fitted with a removeable clip  44  that interferes with proximal end  22  to prevent movement of plunger  26  toward outlet end  24 . While first container  14  may be a conventional syringe, first container  14  can also be a Maxxim Medical Part No. 193221 syringe with dosage control that includes an integral member to limit travel of plunger  26 , thus eliminating the need for clip  44  can be any other appropriate container. In this manner, allograft  38  can be stored in an environment that is favorable for long or short term preservation. Second container or second container  16  includes a barrel  50  having an outlet end  52 , a plunger  54 , and a leur fitting  56  positioned at outlet end  52 . Second container  16  can be a conventional syringe such as VWR Scientific Part No. BD309604 or any appropriate syringe or container generally having a barrel, a plunger, and a connector.  
      In manufacture, all components of allograft packaging system  10  are maintained in a sterile environment. First container  14 , with plunger  26  inserted therein, is filled with a predetermined amount of allograft  38 . Valve  30 , in an open position, is removably coupled to barrel  20 . Clip  44  is attached to plunger  26 , and a vacuum is drawn on allograft  38  within chamber  36  via valve  30 . Valve  30  is then closed and removed from the vacuum source. First container  14  and the second container  16  are positioned in outer container  12 , and outer container  12  is sealed with a negative pressure therein. The negative pressure within outer chamber  12  is comparable to the negative pressure within chamber  36 . Thus provided, the negative pressure within outer chamber  12  can reduce differential pressure stresses on plunger  26 , plunger seal  28 , valve  30 , and clip  44 . In this manner, allograft  38  can be provided at a negative pressure within first container  14  that is packaged within an outer container that protects the seals of first container  14 .  
      It would be appreciated that first container  14  may be evacuated by connecting a vacuum source to leur fitting  34  and that multiple first containers  14  may be evacuated simultaneously with the use of a manifold attachment to the vacuum source. It would also be appreciated that valve  30  may be a vent valve and that a plurality of first containers  14  can be evacuated in a vacuum chamber with the vent valve(s) in the vent position. When the vacuum chamber is opened, the vacuum within chamber(s)  36  will be maintained by the integral vent of the vent valve.  
      When fully assembled, first container  14  and second container  16  are sealed in outer container  12  such that the allograft packaging system  10  provides a sterile, convenient means to provide an allograft implantation system at a surgical site as discussed below.  
      Referring now to  FIG. 2 , in preparing allograft  38  for delivery, outer container  12  is opened and first container  14  and a second container  16  are dumped into a sterile field. Second container  16  is used to collect a reconstituting liquid  60  such as platelet concentrate, patient blood, saline, or bone marrow aspirate, etc. Leur fitting  56  of second container  16  is connected to leur fitting  34  of valve  30 . Valve  30  is opened by turning leur fitting  34  relative to leur fitting  32  and the reconstituting liquid  60  is introduced into first container  14 . It would be appreciated that plunger  54  of second container  16  may be depressed in order to inject the reconstituting liquid  60  into first container  14 , or that the vacuum within first container  14  may draw the reconstituting liquid  60  from second container  16  into first container  14 . In this manner, the vacuum within the pores of allograft  38  draws the reconstituting liquid  60  directly therein regardless of the orientation of second container  16  to first container  14 .  
      It would be appreciated that the use of a vacuum to draw the reconstituting liquid  60  into the voids or pores of allograft  38  will aid the natural capillary action. When the reconstituting liquid  60  has fully wetted the allograft  38 , leur fitting  32  can be removed from barrel  20 , thus exposing chamber  36  to atmospheric pressure. It would be appreciated that any residual vacuum in chamber  36  would serve to drive more reconstituting liquid  60  into the pores of allograft  38  as the pressure in chamber  26  rises to atmospheric pressure.  
      Prior to allograft deposition into a surgical site, clip  44  is removed from plunger  26  to allow plunger  26  to force allograft  38  into the surgical site. Thus provided, allograft packaging system  10  allows an allograft  38  to be reconstituted and delivered within the same container thereby minimizing contamination and waste that is associated with a multi-container allograft delivery system.  
       FIG. 3  illustrates a bone  70  with apertures  72 . Apertures  72  may be voids in bone  70  resulting from a trauma or a surgical procedure, such as temporary support screw holes or an area of recision for an implant. Outlet end  24  of first container  14 , with leur fitting  32  removed, is placed adjacent bone  70  such that allograft  38  can be deposited into aperture  72 . A surgeon can depress plunger  96  in order to deliver allograft  38  into aperture  72 . It would be appreciated that while  FIG. 3  illustrates the delivery of allograft  38  into an aperture  72  with leur fitting  32  removed from first container  14 , a reducer or similar device, if desired, may be attached to outlet end  24  to direct allograft into a narrow or remote aperture  72 .  
      FIGS.  4  illustrates an alternate embodiment of allograft packaging system  90  including a sterile tray  92 , a third container  94 , a plunger  96 , and an allograft reconstituting apparatus  100 . In the embodiment shown, an exterior portion of allograft reconstituting apparatus  100  is defined by an outer container  102 . Outer container  102  encloses a delivery container  104 . The outer container  102  defines an opening  106 . In the embodiment shown, outer container  102  is a glass bottle, although outer container  102  could be constructed of an equivalent material, such as stainless steel. Additionally, delivery container  104  is shown to be a syringe barrel, although it is anticipated that delivery container  104  could be other suitable containers.  
      Delivery container  104  has a proximal end  110  defining a plunger opening  112 , a delivery end  114  defining a delivery opening  116 , a barrel  118  and finger flange  120 . A membrane cap  130  is removably attached to delivery end  114  of delivery container  104  covering delivery opening  116 . Membrane cap  130  defines at least one aperture  132 . A membrane  136  is interposed between membrane cap  130  and delivery end  114  such that membrane  136  covers aperture  132 . Membrane  136  may be constructed of Gore-tex™, available from W. L. Gore and Associates, Newark, Del. to provide a seal that passes air or vents and inhibits fluid from passing.  
      Proximal end  110  has a sealing member  140  attached thereto that is adapted to maintain a negative pressure within delivery container  104 . Delivery container  104  has an outer seal  142 , adjacent proximal end  110 . Outer seal  142  is adapted to seal delivery container  104  with opening  106  of outer container  102 . Although outer seal  142  is preferably a modified bottle stopper, it would be appreciated that outer seal  142  could also be a flexible overmolded portion of delivery container  104  that is configured to sealingly engage opening  106 . The delivery container  104  has a plunger seal  150  located therein. Plunger seal  150  has at least one seal aperture  152  located therein.  
      Allograft packaging system  90  is shown in  FIGS. 4 and 5  to further include plunger  96  that is adapted for insertion within plunger opening  112  of delivery container  104 . Allograft packaging system  90  also includes a screw cap  162  within internal threads  164  formed therein. Screw cap  162  is adapted to cover opening  106 . The outer container  102  includes external threads  168  formed adjacent opening  106  that are configured to mate with internal threads  164  of the screw cap  162 .  
      During assembly of the allograft reconstituting apparatus  100 , outer seal  142  is positioned in delivery container  104  such that outer seal  142  and finger flange  120  are in contact. Membrane  136  is inserted in membrane cap  130  and membrane cap  130  is removably affixed to delivery container  104 . Allograft  38  is loaded into delivery container  104  and plunger seal  150  is inserted into delivery container  104 . Sealing member  140  is removably attached to delivery container  104  and delivery container  104  is partially inserted into outer container  102  just until outer seal  142  contacts outer container  102 .  
      This intermediate apparatus is then placed into a vacuum chamber under a moveable press. The vacuum chamber is evacuated to a desired negative pressure and the moveable press is actuated such that delivery container  104  and outer seal  142  are fully inserted into outer container  102 . When the intermediate apparatus is removed from the vacuum chamber, screw cap  162  is threaded onto outer container  102  to produce allograft reconstituting apparatus  100 . Allograft reconstituting apparatus  100  is then packaged with a plunger  96  and third container  94  in a sterile tray  92  to form an allograft packaging system  90  as shown in  FIG. 4 . In the embodiment shown, third container  94  is a syringe; although it would be appreciated that third container  94  can be any container suitable to deliver a reconstituting liquid  60 .  
      In preparing allograft  38  for delivery, screw cap  162  is removed from outer container  102 . As seen in  FIG. 6 , a reconstituting liquid  60  is loaded into a third container  94  having a hypodermic needle  182  attached thereto. The hypodermic needle  182  is used to pierce sealing member  140  and the reconstituting liquid  60  is injected into delivery container  104 . The liquid  60  is pulled into delivery container  104  due to the vacuum contained therein and is drawn through seal aperture  152  of plunger seal  150 . As the liquid  60  is injected into delivery container  104 , a localized pressure increase is experienced. The vacuum contained in the outer container  102  and the interstitial voids of allograft  38  draws the liquid  60  through allograft  38  and into the pores of allograft  38 . Membrane  136  inhibits the liquid  60  from passing through delivery container  104 . In this manner, a negative pressure and associated lack of air molecules is utilized to introduce the liquid  60  into allograft  38  to prepare allograft  38  for implantation. While  FIG. 6  illustrates hypodermic needle  182  piercing sealing member  140  for delivery of reconstituting liquid  60  to delivery container  104 , it would be appreciated that any coupling means between third container  94  and delivery container  104  that accomplishes the delivery of liquid  60 , such as a leur fitting, could also be used.  
      In contrast, methods of reconstituting allograft that are performed at a constant pressure rely on capillary action for a liquid  60  to enter the allograft pores. While the height of liquid  60  within the allograft does provide some pressure differential across the allograft particles, air molecules within the allograft pores resist the introduction of liquids. This resistance is overcome by the capillarity of the liquid. It should also be noted that while prior art methods require time for the reconstitution of porous materials, or require that a liquid be (washed) several passes through a porous material, the method of the present invention is capable of essentially an instantaneous reconstitution.  
      As best seen in  FIG. 6 , a pre-determined amount of liquid  60  is injected into delivery container  104  until allograft  38  is sufficiently reconstituted. Sealing member  140  is then removed from allograft packaging system  90 . Upon removal of sealing member  140 , the internal pressure of delivery container  104  returns to atmospheric. Plunger  96  is inserted into delivery container  104 , and delivery container  104  is then removed from outer container  102 . Membrane cap  130  and membrane  136  are removed from delivery container  104  and allograft  38  is delivered to a surgical site by fully inserting plunger  96  into delivery container  104 . It would be appreciated that allograft  38  should be surrounded by the liquid  60  prior to allowing the pressure within delivery container  104  to rise to atmospheric in order to take full advantage of the negative pressure within allograft  38 .  
      When using an allograft  38  consisting of bone chips and a platelet concentrate as the reconstituting liquid  60 , exemplary results are achieved when using an allograft packaging system  90  that is pulled to between about 28-29 inches of water vacuum and supplied with about 5 cc of bone chips. A physician injects about 3 cc of platelet concentrate into delivery container  104  and then pauses to ensure that the platelet concentrate percolates toward the membrane cap  130 . An additional 3 cc of platelet concentrate is injected, and sealing member  140  is removed. It would be appreciated that while this method is successful for larger allograft particle sizes, any dry, particulate material, including powdered allograft, can be reconstituted with this method. When performing the method with small particulate or powdered allograft, or bone cement, exemplary results are achieved when liquids are introduced into delivery container  104  with a slower rate of injection so as to prevent the formation of a saturated layer of powder that could effectively act as a dam and seal dry areas of powder from the liquid  60 . For smaller particles, exemplary results are experienced with a slow rate of liquid injection.  
      The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.