Abstract:
A bone filter trap for harvesting autogenous bone and cell marrow and blood elements collected by an aspirator during medical and dental bone surgical procedures. The bone trap is disposed between the aspirator suction system and the aspirator tip. The bone filter or trap includes housing through which an air flow induced by the suction system is allowed to pass via inlet and outlet openings in the housing. A cylindrically-shaped mesh is longitudinally disposed therein. The cylindrically shaped mesh is open at its top end (facing the inlet opening) and is fitted with a removable solid base at the distal outlet end, such that the induced air flow carrying liquids, solids and gases from the patient surgical site is forced to pass through the mesh. The mesh is sized such that only autogenous bone and cell marrow and blood elements are trapped in the mesh. Upon completion of the medical procedure, the cylindrically-shaped mesh is removed from the inlet and outlet housings. A circularly-shaped plunger device is pushed up and down inside the mesh open end to effectively and efficiently dislodge the elements, (e.g., autogenous bone) trapped inside the cylindrically-shaped mesh and to compress it against the base. The base is removed from the mesh and the compressed autogenous bone mixture is pushed from within the mesh by the action of plunger. The resultant mixture can be utilized alone, or mixed with synthetic or other graft materials (e.g., alloplasts, allografts or xenografts).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an autogenous bone and cell trap or filter and harvesting system and, more particularly, to a filter capable of collecting autogenous bone and precursor bone cells that are suctioned from a surgical bone site during a surgical procedure and can be harvested for future use, or use during the procedure, to help regenerate bone. This bone “slurry” may be used alone, or in combination with allografts, alloplasts or xenografts. 
     2. Description of Related Art 
     Various surgical procedures performed upon a patient result in fluid, solids and other bodily by-products being deposited in the body generally or mouth specifically of the patient. For example, the common ora/maxillofacial procedure for insertion of dental implants often results in the production and deposit of saliva, water, blood, amalgam and other tooth or root fragments and/or autogenous bone in the mouth of the patient. For health and sanitary reasons, it is generally desirous to continually remove these by-products through suction throughout the procedure in order to the improve the observation of the surgical site by the surgeon and to avoid infection which can occur if these objects are permitted to remain in the area adjacent to the surgical site or body of the patient. 
     Accordingly, aspirators are commonly employed to continuously remove by-products produced during oral/maxillofacial and general surgical and non-surgical procedures. An aspirator is typically embodied as a narrow-tipped, hand held tube connected to a flexible hose. The hose is attached to an electric motor driven suction system which draws air through the hose forming a vacuum, such that the tip of the hand-held tube continuously removes the undesirable solid, liquid and gaseous by-products resident at the surgical or other procedure site in the patient&#39;s mouth or body. 
     Though many of the products removed from the patient&#39;s body during these procedures are infectious and generally undesirable, osseous materials, such as autogenous bone, are an exception. Autogenous bone carries gross bone particles, stem cells and other blood elements necessary for regeneration of new bone. Accordingly, the separation and collection of the autogenous bone (also known as “bone harvesting”) resulting from surgical, medical and dental procedures is a desirable goal. 
     The types of bone harvesting devices presently available utilize an existing aspirator system in conjunction with a filtering device to capture autogenous bone traveling in the air flow induced by the suction system. One such filter comprises a solid, non-transparent body which connects directly to the aspirator tip and traps osseus bone in an enclosed mesh basket. The autogenous bone is thereafter collected by scraping the basket to dislodge the autogenous bone. Because of the basket shape of the mesh, it is difficult to remove all of the autogenous bone captured in the mesh. Also, because the body of the filter is non-transparent, it is impossible to know when the mesh basket has reached its capacity in instances where a large amount of autogenous bone is collected. Other bone harvesting devices utilize generally flat, peel-back mesh filter elements. (See U.S. Pat. No. 5,766,134 issued to Arab) Such devices can be used only once and are difficult to sterilize, subject to clogging and contamination with bad elements that would normally pass through the filter and are therefore costly to utilize. 
     SUMMARY OF THE INVENTION 
     Accordingly the present invention is directed to providing a transparent and disposable apparatus, as well as a method for efficiently trapping and collecting autogenous bone removed from a patient by an aspirator system during medical or dental procedures in which autogenous bone along with its marrow elements may be dislodged. 
     In an illustrative embodiment of the present invention, an autogenous bone trap or filter has a substantially cylindrical housing or body portion with narrower hollow cylindrical projections extending longitudinally from each end thereof. These projections allow the standard hollow flexible tubing used in aspirator systems to be connected to each end of the cylindrical housing body. The tubing at a proximal or inlet end of the cylindrical body extends to a conventional aspirator tip and the tubing at the distal or outlet end extends to the aspirator suction motor. As a result, the bone trap may be placed anywhere between the tip and the aspirator suction motor. 
     A cylindrically-shape mesh of lesser diameter than the cylindrical body or housing has a removable solid base mounted at its proximal end and an open circular area at its distal end. The base is in the form of a tray with a peripheral ring and a raised disk-shaped surface mounted on the ring by a connecting circular wall. The cylindrical body of the trap is made as two sections which can be separated so the mesh and base can be placed within the main body portion of the suction trap so that the open end of the mesh faces the inlet of the bone trap. Accordingly, when flow is induced by the suction system, the liquids, solids and gases which are captured by the aspirator tip are forced to pass along the tubing from the tip to the inlet projection of the cylindrical body, into the open end of the cylindrical mesh, laterally through the mesh to the cylindrical body wall, along the wall to the outlet projection and through further tubing to the suction motor. The mesh is appropriately sized such that autogenous bone particles and cells that are too large to pass through the mesh are collected on its inner wall and on the surface of the tray that blocks the end of the mesh. 
     Because the body of the bone trap is transparent, the amount of autogenous bone collected by the mesh may be visually monitored by the user of the present invention. This prevents clogging and contamination on by elements that would normally pass through. 
     When the procedure is completed, the two housing sections of the cylindrical body are manually separated. Before and after the cylindrical mesh and tray are removed, a circularly-shaped plunger device is then utilized to scrape the inner walls of the cylindrical mesh. The plunger is moved into the open end of the mesh and toward the tray, such that substantially all of the autogenous bone and marrow elements are removed from the mesh inner wall and pressed onto the tray. The tray is removed manually and the compressed autogenous bone is left on the surface of the sample tray, where it can be conveniently and effectively removed and used either alone, or in combination with other materials (e.g. alloplasts, allogafts or xenografts). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various features of the present invention will be described hereinafter in detail by way of preferred embodiments with reference to the accompanying drawings, in which: 
     FIG. 1 is a side perspective view of a bone filter or trap of the present invention; 
     FIG.  2 ( a ) is a perspective view of the outlet section of the cylindrical housing of a bone trap of the present invention; 
     FIG.  2 ( b ) is a cross-sectional view of the outlet section of the cylindrical housing of FIG.  2 ( a ); 
     FIG.  2 ( c ) is a left side elevation of the cylindrical housing of FIG.  2 ( a ). 
     FIGS.  3 ( a ) and  3 ( b ) are top plan and side views of the collection tray of a bone trap of the present invention; 
     FIG. 4 is a side view with parts broken away of the cylindrical mesh of the present invention mounted on the sample tray of FIGS.  3 ( a ) and  3 ( b ); 
     FIG.  5 ( a ) is a side view of the inlet section of the cylindrical housing of a bone tap of the present invention; 
     FIG.  5 ( b ) is a cross-sectional view of the inlet section of the housing; 
     FIG. 5 ( c ) is a right side view of the inlet section of the housing; 
     FIG. 6 is a cross-sectional view of an assembled bone trap according to the present invention; 
     FIG. 7 is a representation of the flow path through the bone trap of FIG. 6; 
     FIG.  8 ( a ) is a rear perspective view of a plunger for use in removing autogenous bone fragments from a cylindrical mesh of the present invention; 
     FIG.  8 ( b ) is a front plan view of the plunger of FIG.  8 ( a ); 
     FIGS.  9 ( a )- 9 ( f ) illustrate the method of using the plunger of FIG.  8 ( a ) to remove autogenous bone from the cylindrical mesh. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The filtration and collection of autogenous bone is accomplished by means of a filter device placed between a hand-held aspirator tip and the suction systems of the aspirator. FIG. 1 illustrates such a suction filter trap for filtering autogenous bone fragments from the fluid suctioned by an aspirator during oral/maxillofacial or other surgical or medical procedures. The filter trap may also filter cellular elements, e.g., bone precusor cells, in the fluid and gross specules of autogenous marrow bone elements. The device includes a hollow body or housing  10  of substantially cylindrical shape. The body  10  is separated into an inlet housing section  12  and an outlet housing section  14 . Extending from the inlet section  12  is a narrower cylindrical projection  16 , and a narrow cylindrical projection  18  extends from the outlet housing section  14 . As shown in FIGS. 1 and 7, a fitting  13  on the projection  16  forms an inlet opening  11  for the trap and is adapted to receive a flexible hollow tube  110  connected to a hand-held tip (not sown) of an aspirator device. A fitting  15  of the projection  18  forms an outlet opening  17  for e filter trap and is adapted to receive a flexible hollow tube  120  connected to the vacuum motor (not shown) of an aspirator device. 
     A cylindrically-shaped mesh screen  48  is mounted within the hollow body  10  to intersect the flow path of the suction system such that autogenous bone particles being carried by the flow are caused to be trapped within the cylindrically shaped mesh screen  48  for later collection and use. 
     FIGS.  2 ( a )- 2 ( c ) illustrate various views of the outlet section  14  of the housing of the bone filter device. The outlet section housing  14  comprises a substantially hollow cylindrical main body portion  30  with the narrower cylindrical projection  18  extending longitudinally therefrom. The diameter of the outer surface of the cylindrical main body portion  30  is substantially constant throughout its length. In the preferred embodiment, the outer surface of the main body portion  30  has a diameter of approximately 1.625″. 
     The diameter of the projection  18  is two-tiered, the diameter of that portion connected to the main body part  36  being greater than the second part  15 , and both being significantly smaller than the diameter of the main body portion  30 . The sharp taping of the longitudinally extending portion  18  between portions  36  and  15  forms an edge or lip  34  against which the hollow tubing terminus can be securely attached. In the preferred embodiment, the diameter of the first portion  36  of the longitudinally extending projection  18  is approximately 0.435″, and the width of the second portion  15  measures approximately 0.34″. The overall length of the projection  18  is about 0.965″. 
     Because gases such as air molecules seek to maintain a constant pressure, a reduction in volumetric space (from the main body portion  30  to the longitudinally extending portion  18 ) will cause the speed of the traveling air molecules to increase beyond the mesh so as to maintain a constant flow rate. Therefore, the reduction in volumetric space between the main body portion  30  and the projection  18  increases the suction effect of the air flow through the body portion. In the preferred embodiment, the diameter of the inner surface of the main body portion measures proximately 1.618″ and the diameter of the second part  38  of the projection  18  measures approximately 0.2″. 
     Also, the extension of the flow cross section as the flow enters the inlet housing causes the flow rate to drop, thus permitting better filter action. The enlarged filter also allows for increased surface area for the mesh, which also improves filtration 
     The inner walls of the main body porion  30  support four lateral support projections  40 . The support projections  40  form a slight edge or seats  44 , then angle sharply inward along the longitudinal direction until the support projections  40  again become substantially flat, forming a second set of seats  42  upon which a circular object can be supported laterally with respect to the wall of the inner surface of the main body portion  30 . In the preferred embodiment, the distance between the proximate ends of facing seats  44  measures approximately 1.350″ (See line  45  in FIG.  2 ( b )). The distance between the proximate ends of the facing seats  42  measures approximately 1.0″. (See line  47  in FIG.  2 ( b )). 
     In the preferred embodiment, the outlet housing, as well as all other components of the bone trap (except for the mesh and the gasket described below) are preferably manufactured by injection molding high-impact polypropylene. It is recognized, however, that other sterilizable plastics, e.g., transparent plastics, and/or manufacturing techniques could be used. The preferred embodiment requires only that the bone trap be capable of withstanding the pressure induced by the air and fluid flow through the bone trap device produced by standard medical aspiration systems. 
     Two views of a circular surface of an inverted tray  50 , which is used as a base for the mesh filter in the assembled device, are shown in FIG.  3 ( a ) and  3 ( b ). This tray can be seated upon the second set of seats  42 . The tray  50  has a raised a platform  52  and a ring or lip  54  formed around the outer edge of the tray and connected to the platform  52  by an annular side wall. The side or connecting wall  56 , which forms the transition from platform surface  52  to lip  54 , is slightly tapered and is of a height that allows secure retention of the tubular filter mesh  48  on to the tray. In the preferred embodiment, the platform  52  has a diameter of approximately 0.876″ and the overall height of the sample tray from the bottom portion of the lip  54  to the upper portion of the platform  52  measures approximately 0.250″. 
     The filter mesh  48  and sample tray  50  are illustrated in FIG.  4 . In the preferred embodiment, an 80 micron mesh measuring 160×155 mms is formed into a cylindrical shape with a height measuring approximately 1.25″ and a diameter of approximately 0.950″ (slightly greater than the diameter of the raised platform of the tray) such that the mesh  48  can be securely positioned on the tray  50  as shown in FIG.  4 . Other dimensions and mesh sizes may also be used effectively. 
     The cylindrical mesh remains open at the distal end  58  of the cylinder opposite the tray  50  such that the mesh  48  and tray  50  form a cylinder closed at one end and opened at the other so that fluid flow enters unimpeded at the mesh&#39;s open end  58  and is forced to exit laterally through the openings in the mesh  48  because of the tray  50 . The dimensions of the openings of the mesh  48  preferably, (80 microns) are such that autogenous bone is retained by the mesh  48  while other nonresinous elements and fluids are allowed to pass through the mesh  48  and out of the main body potion  30 . 
     FIGS.  5 ( a )-( c ) illustrates various views of the inlet housing  12  of the bone trap  10 . The inlet housing comprises a substantially hollow cylindrical main body portion  60  with a narrower cylindrical projection  16  extending longitudinally from the main body portion  60 . The outer diameter of the main body portion  60  is dimensioned such that the large opening portion  64  of the inlet housing can be frictionally secured in the large open portion of the outlet housing  30 . To insure further sealing, a groove  66  is present around the circumference of the main body portion  60  into which a annular seal ring or gasket  68 , preferably made from elastomeric material, is deposited. When the large opening  64  of the inlet housing is fitted into the large opening of the outlet housing  30 , the gasket  68  forms a fluid and vacuum-tight seal between the two housings. In the preferred embodiment, the diameter of the main body portion  60  of the inlet housing measures approximately 1.617″ and the width of the groove  64  into which the seal ring is secured measures approximately 0.1100″. 
     The cylindrical width of the outer portion of the projection  16  is two-tiered in a manner similar to the projection  18  of the outlet housing for the similar purpose of providing a seat for flexible hollow tubing to be securely fitted to the inlet of the bone trap. 
     The cylindrical width and height of the inner portion of the inlet housings main body  60  is formed such that the open end  58  of the filter mesh  48  will fit securely in the inlet housing when the inlet housing and outlet housing are brought together and sealed by the frictional force of the gasket  68 . Furthermore, a ring  80  is formed on the distal wall of the inlet housing. The ring  80  is sized such that the open end  58  of the mesh  48  fits against it and is held in place. In the preferred embodiment the ring  80  has a diameter of approximately 0.949″ (i.e., slightly less than the diameter of the mesh) and protrudes longitudinally into the housing by approximately 0.1″. 
     The measurements described herein are merely exemplary and are not intended to limit the scope of the invention. Such measurements may vary to a wide degree depending on manufacturing techniques and fit acceptable for a particular type of aspirator equipment. The bone trap of the of the present invention can thus be constructed to fit a variety of aspirators and tips in many combinations. 
     Of course, the overall shape of the bone trap of the present invention may vary depending on these measurements. Furthermore, junctures between ledges and walls of the bone trap may be rounded to a variety of radii and wall thicknesses, and edge projections may vary in a large range. 
     The method of assembling the various parts to form a bone trap will now be described with reference to FIG.  6 . The mesh  48  and the tray  50  are assembled and are placed into the main body portion  30  of the outlet housing forming a filter element. The filter element is disposed such that the tray  50  of the filter element rests upon the seats  42  formed by the lateral flanges  40 . In this way, the opening of the mesh  58  is in the same plane as the large opening of the outlet housing. 
     The large opening of the inlet housing is then brought into frictional contact with the inner walls of the outlet housing at the large opening end of the outlet housing. Manual pressure is applied to both the inlet and outlet housings until the edge of the inlet housing makes contact with the four seats  44  formed by the lateral flanges  40  of the outlet housing. The seats  44  are positioned with reference to the outlet housings inner wall such that when contact is made with the inlet housing, the gasket  68  will have formed an annular seal between the inner wall of the outlet housing and the outer wall of the inlet housing. Effectively, the two housings will be sealed, such that the only flow path for air, fluid or debris from outside the bone trap will be through the openings in the longitudinal projections  16  and  13  of the outlet and inlet housings, respectively. 
     The seats  44  of the lateral flanges  40  of the outlet housing are positioned with the further purpose of tightly securing the mesh filter in the bone trap. As is shown in FIG. 6, the height of the mesh is appropriately sized such that, when the inlet and outlet housings meet at the seats  44 , the open side of the mesh is engaged and held firmly in place by the ring  80  formed on the distal side wall of the inlet housing. The ring  80  insures the structural integrity of the mesh by supporting the cylindrical structure when high pressure flow is induced through the attached suction system. 
     FIG. 7 illustrates the flow path of air, solids and liquids through the bone tap. The cylindrical projection  16  of the inlet housing is connected to standard flexible hollow tubing  110 , the distal end of which is connected to a handheld hollow aspirator tip placed in the mouth or body of the patient. The cylindrical projection  18  of the outlet housing is likewise connected to standard flexible tubing  120 . The other end of the tubing  120  is connected to the suction system of the aspirator. Upon activation of the suction system, air flow is induced from the tip of the hand-held device through the bone trap and into the suction system. The airflow creates a vacuum in the mouth or body of the patient, such that all unencumbered liquids, solids and gases in the patient&#39;s mouth or body within a certain proximity to the tip are drawn into the tip device, through the flexible tubing and into the bone trap. The flow of liquid, solids, and gases then proceeds into the open end of the mesh  48  (arrow  90 ). The tray  54  of the mesh filter is solid, the air flow must proceed laterally through the lattice of the mesh as shown by arrow  92 . The size of the lattice in the mesh allow all liquid, fine solids and gasses being carried by the air flow to pass, except for significantly sized autogenous bone and other cellular marrow elements Hence, the autogenous bone and stem cells are collected or harvested by the interaction between the mesh and the airflow, and is left deposited on the inside of the mesh. The airflow carrying the remaining liquid, gases and solids removed from the patient&#39;s mouth or body proceeds through the cylindrical projection  18  of the outlet housing and through the flexible tubing  120  to the aspirator suction motor. 
     The autogenous bone and other cellular marrow element are removed from the mesh filter through the use of a plunger illustrated in FIGS. 8 a  and  8   b . The plunger  100  is comprised of a circular base  104  and an elongated stem  102  attached to the center of the circular base  104 . Although in the preferred embodiment the stem  102  has a cross-shaped cross-section, it may, of course, have any suitable shape, e.g., round. The diameter of the circular base  104  is sized to conform to the inner dimensions of the cylindrical mesh  48 , such that when the circular base  100  is inserted into the open end of the mesh  48 , the edges of the circular base  104  come into contact with the inner surface of the mesh  48 , causing the autogenous bone to be disengaged from the mesh  48 . In the preferred embodiment, the circular base  104  is formed to have a diameter of approximately 0.935″. The plunger stem  102  is sized to have a length greater than the height of the mesh netting (approximately 1.25″). 
     FIG. 9 illustrates the method of harvesting the autogenous bone. FIG.  9 ( a ) shows the bone trap immediately following an oral/maxillofacial or some other surgical procedure wherein autogenous bone and cellular elements are deposited inside the mesh  48 . Because in the preferred embodiment, the housing  10  is transparent, the amount captured in the trap can be viewed. The flexible tubing is then removed from the inlet  16  and outlet  18  of the bone trap and, as shown in FIG.  9 ( b ), the inlet housing is manually separated from the outlet housing by applying a minimal amount of pressure to overcome the friction holding the two housings together. Note that the inner housing ring  80  anchors the mesh filter  48  to the inlet housing. As shown in FIG.  9 ( c ) and ( d ), the mesh filter is removed from the inlet housing and the circular base end of the plunger is inserted into the open end of the mesh cup and downward pressure is applied. This action causes the sides of the circular base  104  to dislodge the autogenous bone and cells deposited on the inner walls of the circular mesh  48  and to press it towards the surface  52  of the tray  50 . The downward pressure compacts the autogenous bone toward the tray  50  of the mesh filter. This can be repeated by moving the plunger up and down inside the mesh to ensure that most of the bone and cell elements have been dislodged. 
     Once the user is satisfied that most of the autogenous bone and the other cellular elements have been dislodged from the mesh, the tray  50  is manually removed from the mesh as shown in FIG.  9 ( e ). Finally, the mesh  48  is held over a sterile so dish  112  or some other suitable container. As shown in FIG.  9 ( f ) the plunger is fully inserted through the distal end of the mesh causing the compacted mass  122  to fall onto the specimen dish  112 . 
     The collection of compacted autogenous bone can then be used, for example, alone or in combination with synthetic bone grafts, e.g., Bioplant®, HTR®, (alloplasts) or allografts or xenografts to fill alloplasts an extraction socket, or any bony void around dental or medical implants, in any oral/maxilla facial or medical bony surgical procedure. 
     While the present invention has been particularly shown and described with reference to preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.