Abstract:
The invention provides for dispensing a bone substitute material, comprising: an elongated body having an outer wall, a front opening, and a rear opening, with the outer wall defining a longitudinally extending interior space therein. The invention also includes a cover for the front opening having a sealable opening therein to allow substances to pass through the opening. A plunger sized to slide within the longitudinally extending cavity divides the cavity into first and second portions. The plunger preferably has a small opening therein to allow passage of fluids (including gases), from the longitudinally extending interior space without permitting solids to pass therethrough. A detachable handle connects to the plunger for sliding the plunger toward or away from the front opening.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to devices for implantation of bone replacement materials, and more particularly to a syringe which can mix and dispense solid bone substitutes and fluid additives, such as gels, suspensions or solutions of blood or its components, or natural or recombinant bone growth factors.  
         BACKGROUND OF THE INVENTION  
         [0002]    Several materials have been developed to fill a void in a bone or to cause a fusion between adjacent bones or segments of bone. Such a void may exist because a diseased portion of the bone has been surgically removed or has been damaged in an accident. The surgeon may desire to fill the space with a temporary or permanent bone substitute material, as well as with one or more agents which help to promote healing.  
           [0003]    For example, U.S. Pat. No. 4,976,736 (Shors and White), entitled “Coated BioMaterial and Methods for Making Same” discloses a bone repair material which includes a phase which rapidly breaks down to allow tissue ingrowth, as well as a phase which resorbs more slowly. Such a material, sold commercially as Interpore 500R, often gets used as an implant material to fill bone voids or other spaces during orthopedic surgery. In granular form, it may be implanted either with or without a fluid which includes, for example, a gel, suspension, or solution of blood or its components, or natural or recombinant growth factors, for example. Mixing and handling the solid, dry granules and the fluid or gel can be difficult, particularly during an actual procedure.  
           [0004]    Untied U.S. Pat. No. 4,769,011 (Swaniger), discloses several plunger-type syringes for the surgical implantation of granular ceramic substances including hydroxyapatite during alveolar ridge augmentation and repairs. The barrels of the syringes have various lengths and radii of curvature and various degrees of tip beveling, such that the surgeon can select the most appropriate barrel configuration for the area undergoing repair.  
           [0005]    It would be desirable therefore to have a device which could help the surgeon dispense the granules or other particles into the desired cavity with the necessary control over the volume dispensed. Further, it would be desirable for the dispenser to have the ability to mix a porous or non-porous bone repair material (whether in block, granule, or particle form) with a liquid or gel which may contain the bone repair promoting agent.  
         SUMMARY OF THE INVENTION  
         [0006]    The objects of the invention can be achieved and the disadvantages of the prior art may be overcome through the present invention. The invention provides a syringe assembly for dispensing a bone substitute material, comprising: an elongated body having an outer wall, a front opening, and a rear opening, with the outer wall of the elongated body defining a longitudinally extending interior space therein. The invention also includes a cover for the front opening having a sealable opening therein to allow substances to pass through the opening. A plunger sized to slide within the longitudinally extending cavity divides the cavity into first and second portions. The plunger preferably has a small opening therein to allow passage of fluids (including gases), from the longitudinally extending interior space without permitting solids to pass therethrough. A detachable handle connects to the plunger for sliding the plunger toward or away from the front opening.  
           [0007]    The invention also provides a kit for use in mixing a fluid with a porous or non-porous solid bone substitute material. The kit comprises a syringe assembly as discussed in the foregoing paragraph, and may also include a container having a solid or porous particulate or granular bone repair material, such as an optional vial or container of a bone promoting agent. The solid material may be hydroxyapatite granules, for example. The bone repair promoting agent may be in solid or liquid form, and may include (for example) blood or a component thereof, or natural or recombinant bone growth factors, or other agents useful for stimulating bone repair or growth. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    Further features, objects, and advantages of the invention will become apparent upon review of the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings in which:  
         [0009]    [0009]FIG. 1 is a perspective view of the syringe assembly of the present invention showing the piston handle disconnected from the piston;  
         [0010]    [0010]FIG. 2 is a partial cross-sectional view of a syringe barrel the syringe assembly of FIG. 1 shown with the rear cap removed from the piston;  
         [0011]    [0011]FIG. 3 is a front elevational view partially broken away of the syringe barrel shown in FIG. 2;  
         [0012]    [0012]FIG. 4 is a top view of the piston handle of the syringe assembly of the present invention;  
         [0013]    [0013]FIG. 5 is a side elevational view, partially in section, of the piston handle taken along line  5 - 5  in FIG. 4;  
         [0014]    [0014]FIG. 6 is a cross-sectional view of the handle taken along line  6 - 6  in FIG. 4;  
         [0015]    [0015]FIG. 7 is a top view of the front cap for use in the syringe assembly of the present invention;  
         [0016]    [0016]FIG. 8 is a cross-sectional view of the front cap taken along line  8 - 8  in FIG. 7;  
         [0017]    [0017]FIG. 9 is a front elevational view of the piston for use in the present invention;  
         [0018]    [0018]FIG. 10 is a top view of the rubber plunger; and  
         [0019]    [0019]FIG. 11 is a cross-sectional view of the plunger taken along line  11 - 11  of FIG. 10. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    Referring to the drawings, FIG. 1 illustrates the syringe assembly of the present invention generally designated by the reference numeral  10 . The main components of the syringe assembly include the syringe barrel  12 , the front cap  14 , the plunger handle  16  (shown disconnected from the syringe), the piston  18  connected to the rubber plunger  20  (shown in FIG. 10). The front cap  14  may have a cover  22 , shown in FIG. 1, as may the piston  18  (see FIG. 2).  
         [0021]    The construction of the barrel  12  can be understood with reference to FIGS. 1, 2, and  3 . The barrel  12  includes a longitudinally extending portion  24 , which defines an inner longitudinally extending cavity  26  for holding and dispensing a bone repair material (not shown). The barrel  12  preferably includes a pair of opposed finger grips  28 , 30  at one end and a bayonet mount  32  at the other end (See FIG. 3). Each figure grip  28 , 30  includes a D-shaped ring  34 , and a curved finger rest  36  extending from the barrel  12  to allow the surgeon to grip the syringe assembly  10  while sliding the handle  16  and plunger  20  through the interior of the barrel  12 . The bayonet mount  32  for the bayonet cap  14  on the front end of the barrel includes an outwardly extending curved lip  38  and a pair of L-shaped ribs  40  on its exterior portion on opposite sides of the barrel  12 .  
         [0022]    The front cap  14  shown in FIGS. 2, 7 and  8  includes an annular ring shaped bearing portion  42  which surrounds an opening  44  through which bone graft material may be expressed. The front cap  14  also includes a pair of channels  46 , 48  to accommodate the ribs  40  at the bottom of each channel  46 , 48  are slots  50 ,  52  to engage the ribs  40  surrounding the opening  44  is preferably a conical portion  54  (see FIG. 8) to help facilitate expression of bone implant material (not shown). The opening  44  leads into a conduit  56 . Surrounding the conduit  56  is an annular wall  58  which extends from the syringe barrel  24  at a distance from the conduit  56 . The annular wall  58  preferably includes threading (not shown) along its inside to engage the cover  22  (see FIG. 2). Additionally, the exterior of the annular wall  58  has a plurality of ridges  43  spaced about the periphery thereof to facilitate gripping of the front cap  14 . Of course, other connection mechanisms can be used, including threaded, press fit, and luer lock.  
         [0023]    [0023]FIGS. 4, 5, and  6  illustrate the construction of the handle  22 . The handle  22  includes a ring  60  at one end, a male, conical fitting  62  at the other end, and an intermediate shaft  64 . The circular grip ring  60  includes a tangential bearing surface  66  which arcs to fit comfortably in the hand of the user and to enable even application of pressure to dispense the bone replacement or repair material contained in the barrel  12 . The intermediate shaft  64  extends between the circular grip ring  60  and the male conical fitting  62 . As shown in FIG. 6, it has a “plus shaped” cross-section and includes a plurality of reinforcements  68 . The conical fitting  62  includes an annular wall  70  (see FIG. 5) and a truncated conical pin  72  centered therein. Annular wall  62  and the conical pin  72  define a bearing surface  74  therebetween.  
         [0024]    The piston  18 , shown in FIG. 9, includes an annular base  76  with a hollow shaft  78  extending upwardly therefrom. The hollow shaft  78  has a collar  80  positioned midway between the upper flange  82  and the annular base  76 . A plurality of fins  84  extend outwardly from the hollow shaft  78  in a longitudinal direction around its periphery. A plastic protective cap  86  slides over the upper flange  82  to protect the opening to the hollow shaft  78  from dust and debris.  
         [0025]    A rubber plunger  20  fits over the annular base  76  of the piston  18 , as FIG. 11 illustrates. The plunger  20  includes an X-shaped opening  88  to allow air and excess fluid to escape from the barrel  12  or to permit fluid to be introduced into the inner cavity  26  defined by the barrel  12 , and can include a permeable membrane to control permeation of various suspended particles while permitting passage of liquids.  
         [0026]    The opening  88  connects to a passageway  90  through the body of the plunger  20 . The interior of the plunger  20  has a C-shaped recess included therein to meet with the upper flange  82  of the piston  18 . While the exterior has a plurality of spaced annular rings  90  to create a fluid tight, leak free seal with the wall of the barrel  12 . With this construction, the syringe  10  allows liquids to pass in or out of the inner cavity  26  without losing any of the solids contained therein. Moreover, when the handle  16  connects to the piston  18 , it seals the passageway  90  preventing leaks and preserving the sterile environment in the inner cavity  26 . The handle  16  can attach to the piston  16  or even the plunger  14  through one of several conventional techniques including bayonet, threading, and press fit.  
         [0027]    To assemble the components of the syringe assembly  10 , the piston  18  is inserted into the opening  88  in the rubber plunger  20  until it seats in the C-shaped recess  92 . The rubber plunger  20  with the piston  18  extending therefrom slides into the front opening of the syringe barrel  12 . The front end of the syringe barrel  12  inserts into the front cap  14  with the ridges  43  aligned with the channels  46 ,  48 , and twisted so that the prongs  40  engage the slots  50 , 52  to hold the cap  22  tightly in place. The cover  22  which protects the front opening  44  in the front cap  14  twist or screws into place. The handle  16  may be inserted into the syringe barrel  12  until it reaches the upper flange  82  of the piston  18 , where it can be twisted gently to engage the piston  18 . Alternatively, if the handle  16  is supplied in a kit, it can be disconnected from the piston  18 , and a cap  86  can be press fit or twisted onto the upper flange  82  of the piston  18 .  
         [0028]    The syringe assembly of the present invention can be fabricated from a wide variety of materials, such as plastic, glass, or metal, or any combination thereof. The syringe barrel  12 , front cap  14 , and the piston  18  should preferably be made from clear, lipid resistant polycarbonate plastic, available as Bayer Part No. DP1-1805-1118. The plunger handle  16  can also be made from the foregoing lipid resistant polycarbonate material, but preferably should be colored white with Reed Omnicolor No. UN0005 in order to allow the position of the handle within the barrel to be readily detectable to the user. The rubber plunger  20  found on the tip of the piston  18  can preferably be made from 60 durometer dimethyl silicone (Precision Silicone PN PS2622), or other suitable natural or synthetic rubber material.  
         [0029]    As mentioned, the syringe assembly  10  can be supplied as part of a kit for use in implanting solid, particulate bone graft material. Such solids can include, for example, autogenous morselized bone graft, autogenous bone graft strips, allograft chips, demineralized bone matrix in putty, gel, strip, or other forms, xenografts and fired bone. The solids can also be bone graft substitutes, such as hydroxyapatite, calcium carbonate, beta tricalcium phosphate, calcium sulfate or mineralized collagen. In addition, natural or synthetic polymers such as collagen particles, meshes, sponges, and gels, hyaluronic acid and derivatives thereof, liposomes or other natural biomaterials known as potential implants, or carriers of therapeutic agents, such as cytokines, growth factors, cells, antibiotics, analgesics, chemotherapeutic drugs, and the like.  
         [0030]    As synthetic polymers, there can be alpha-hydroxy polyesters, including polylactic acid, polyglycolic acid and their copolymers, polydioxanone, as well as poly methyl methacrylate, separately, in mixture or in admixture with any of the foregoing therapeutic agents. Preferably, in kit form the syringe assembly is supplied with bone graft substitutes such as hydroxyapatite, calcium carbonate, or calcium sulfate.  
         [0031]    The syringe also permits addition and mixing of a liquid, gel, or fluid substance to the inner chamber of the barrel either before, after (or instead of) addition of the solid component. Likewise, the syringe can be used to draw a gel or other fluid through a porous hydroxyapatite block, whether or not the syringe is used to help implant that block. The fluid substance may be drawn through the front opening in the syringe itself or the front cap  44  or injected through the opening in the plunger  88 .  
         [0032]    Among the fluids which can be added are sterile water, saline, blood, or blood components including plasma, platelet-rich plasma, buffy coat, autologous growth factors or other concentrated blood components, red blood cells, white blood cells or platelets in any combination, as well as cryoprecipitates. Other suitable and intended fluids include bone marrow, as well as growth factor solutions suspensions or gels, which include any of the well known growth factors such as Platelet-Derived Growth Factor (PDGF), Transforming Growth Factor Beta (TGF-β), Insulin-Like Growth Factor (IGF), Fibroblast Growth Factor (FGF), Epidermal Growth Factor (EGF), Vascular Endothelial Growth Factor (VEGF), Bone Morphogenetic Proteins (BMPs), and vectors for gene therapy. Further, cellular solutions, suspensions, and materials including osteoblasts, osteoprogenitor cells, chondroblasts, stem cells, or fibroblasts may also be used, as may solutions or suspensions containing other therapeutic agents such as antibiotics, analgesics, antithrombinolytics, or chemotherapeutic agents.  
         [0033]    In use, the surgeon removes the syringe barrel  12  from the surrounding packaging (not shown) and inserts and twists the handle  22  into place so that it connects with the piston  18 . The front cap  14  is removed to permit insertion of the desired solid phase material, after which the cap is replaced and locked into place (Although in some applications, the front cap need not be replaced). The desired liquid or fluid may be drawn through the front opening or inserted through the opening in the plunger (after removing the handle). The handle is reattached, and the plunger is moved toward the front opening in order to express excess fluid or air.  
         [0034]    Various modifications will be apparent to those of ordinary skill in the art upon reading this disclosure. For example, the size and shape of the barrel and the front opening may be adjusted to accommodate different types of materials. Additional ports may be added to the sidewall to permit introduction of still other components to a solid liquid mixture or suspension. It is contemplated, however, that all such modifications, additions, and improvements be included within the scope and spirit of the invention and protected by the following claims.