Patent Publication Number: US-2021169663-A1

Title: System and method of bone processing

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 16,721,041, filed Dec. 19, 2019, which is a divisional of U.S. patent application Ser. No. 14/287,733, filed May 27, 2014, entitled “System and Method of Bone Processing,” now abandoned, which is a continuation of U.S. patent application Ser. No. 12/683,707, filed Jan. 7, 2010, entitled “System and Method of Bone Processing” now U.S. Pat. No. 8,740,114, the entire teachings of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Morselized bone particles are used in various medical and surgical procedures. For example, finely morselized bone particles can be used for spinal fusion, to repair defects caused by trauma, transplant surgery, or tissue banking. In order to process bone for use in a medical or surgical procedure, several bone processing steps are taken. In one example procedure, a tissue sample including bone is surgically removed (i.e., harvested) from a patient. After removal of the bone from the patient, non-bone tissue (e.g., muscle, periosteum, connective tissue) is removed from the bone in order to prepare the bone for morselizing. Current bone processing approaches to remove the non-bone tissue can be time consuming, labor intensive and hazardous to healthcare personnel (e.g., cutting through gloves). In one example, a technician uses a scalpel to remove non-bone tissue from bone by hand. Hand removal of the non-bone tissue using a scalpel lasts approximately 45 minutes and is prone to operator fatigue and possible injury. Once non-bone tissue is removed from the bone, denuded bone can further be processed by a bone mill to produce morselized bone particles. In any event, it is important for bone processing in a medical environment to be performed in a sterile manner. Additionally, it is important for bone processing steps to be performed efficiently and in a safe, reliable manner. 
     SUMMARY 
     Concepts presented herein relate to aspects of bone processing. In one aspect, a method includes positioning bone at least partially covered in non-bone tissue comprising at least one of muscle, periosteum and connective tissue in a bone denuding device. A power source of the bone denuding device is operated to separate the tissue from the bone to produce denuded bone. A bone milling device is operated to morselize the denuded bone and produce morselized bone particles. 
     In another aspect, a denuder includes a cutting drum having a cutting surface and an impeller positioned within the cutting drum. A shaft is coupled to at least one of the impeller and the drum to rotate therewith and a power source is coupled to the shaft to provide rotational force thereto. 
     In yet another aspect, a tissue separator is coupleable to a power source for use in removing non-bone tissue comprising at least one of muscle, periosteum and connective tissue from a bone. The tissue separator includes an external casing, a cutting drum positioned in the external casing and an impeller positioned within the cutting drum. 
     In yet a further aspect, a method of bone processing includes placing a bone at least partially covered with non-bone tissue comprising at least one of muscle, periosteum and connective tissue inside a sterile casing. The sterile casing includes an impeller and a cutting surface. The impeller is coupled to a power source and the impeller is rotated with the power source to urge the bone against the cutting surface to remove the tissue from the bone. 
     Another aspect includes a tissue separator having a brushed impeller positioned in a drum. The brushed impeller rotates to remove non-bone tissue from bone. 
     Another aspect includes a tissue separator having a pressurized fluid nozzle positioned in a drum. Pressurized fluid is directed at bone covered in non-bone tissue to remove non-bone tissue from bone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow diagram of a method of processing bone. 
         FIG. 2  is a schematic diagram of a bone processing system. 
         FIG. 3  is a schematic, sectional view of a bone denuder. 
         FIG. 4  is a perspective view of a tissue separator of a bone denuder having a first embodiment of an impeller. 
         FIG. 5  is a perspective view of a tissue separator of a bone denuder having a second embodiment of an impeller. 
         FIG. 6  is a perspective view of a tissue separator of a bone denuder having a third embodiment of an impeller. 
         FIG. 7  is a perspective view of a tissue separator of a bone denuder having a drum and a plurality of bristles extending radially inward from the drum. 
         FIG. 8  is a perspective view of the tissue separator of  FIG. 7  with an alternative impeller. 
         FIG. 9  is a perspective view of a tissue separator of a bone denuder having a plurality of brushed impellers, 
         FIG. 10  is a perspective view of a tissue separator of a bone denuder having a plurality of brushed impellers coupled to a carrier. 
         FIG. 11A  is a top view of a tissue separator of a bone denuder having a plurality of brushed impellers positioned about a circumference of a drum. 
         FIG. 11B  is a perspective view of the tissue separator of  FIG. 11A . 
         FIG. 12  is a sectional view of a tissue separator of a bone denuder having a plurality of nozzles delivering pressurized fluid. 
         FIG. 13  is a sectional view of a tissue separator of a bone denuder having a nozzle delivering pressurized fluid and a rotating impeller. 
         FIG. 14  is a sectional view of a tissue separator of a bone denuder having a rotating drum and a nozzle delivering pressurized fluid. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a method  100  and system  200  are illustrated that can be utilized to process material for medical use. The method and systems below are discussed in terms of autograft from a patient, but is also applicable to other materials such as allograft, synthetic materials, combinations including one or more of autograft, allograft and synthetic materials. Other materials can include bone morphogenic protein (BMP), demineralized bone matrix, hydroxyapatite (HA), coral, etc. In method  100  and system  200 , tissue samples  202  are harvested (step  102 ) from a patient using known surgical bone harvesting techniques. The tissue harvested includes bone and non-bone tissue such as muscle, periosteum and connective tissue. The harvested tissue samples  202  are then placed in a bone denuder  204  (alternatively referred to as a bone denuding device) that removes tissue (step  104 ) from the bone. 
     As used herein, denuding relates to removal of non-bone tissue from the bone. In particular, bone denuder  204  includes a tissue separator  206 , a coupling  208  and a power source  210 . The tissue separator  206  is capable of reducing one or more pieces of harvested tissue  202  into denuded bone  212 . As used herein, denuded bone is bone that is substantially free of non-bone tissue such as muscle, periosteum and connective tissue. Power source  210  can take many forms such as an electric motor, pneumatic supply, manual crank, etc. The power source  210  is used for moving the tissue separator  206  in an automatic fashion. The coupling  208  couples the power source  210  to the tissue separator  206 , and in some embodiments, may allow for relatively easy connection and disconnection of the particle reducer to and from the power source  210 . In one embodiment, tissue separator  206  is removed from the coupling  208  and turned over to empty the denuded bone  212 . 
     The denuded bone  212  is then placed in a bone mill  214 , which moreselizes the bone (step  106 ) for use in surgery. The bone mill  214  also includes a particle reducer  216 , a coupling  218  and a power source  220 . The particle reducer  216  is capable of reducing one or more pieces of denuded bone into smaller particles to create moreselized bone  222 . The power source  220  is used for moving the particle reducer  216  in an automatic fashion and can take various forms such as an electric motor, pneumatic supply, manual crank, etc. Coupling  218  is used for connecting the power source  220  to the particle reducer  216 , and in some embodiments, may allow for relatively easy connection and disconnection of the particle reducer  216  to and from the power source  220 . Morselized bone particles  222  can then be utilized in a procedure, such as a medical or surgical procedure (step  108 ). Example procedures include, but are not limited to, spinal fusions (e.g., lumbar, thorasic, cervical), hip implants, orthopedic procedures, autograft procedures, allograft procedures, maxofacial procedures, cranial procedures, tissue banking, research and mastoidectomies. 
     Although bone denuder  204  and bone mill  214  are illustrated as separate components, it is worth noting that the bone denuder  204  and bone mill  214  can be integrated together and/or share one or more components such as a motor, coupling, external casing, etc. For example, tissue separator  206  of bone denuder  204  and particle reducer  216  of bone mill  214  can each form sterile casings that are selectively coupled to a coupling and power source to perform bone processing steps  104  and  106 . In this example, tissue separator  206  and particle reducer  216  can form sterilized casings that are single-use or, alternatively, sterilized after each use. Additionally, although bone denuder  204  and bone mill  214  are illustrated in a generally upright, vertical orientation, the bone denuder  204  and bone mill  214  can be oriented in a generally horizontal orientation or other orientation as desired. 
       FIG. 3  is a schematic, sectional view of bone denuder  204 . In the illustrated embodiment, tissue separator  206  includes a cap  302 , an exterior casing  304 , an impeller  306 , a shaft  308 , and a cutting drum  310 . During use, cap  302  is secured to the casing  304  and impeller  306  is positioned within cutting drum  310 . In other embodiments, cap  302  can be excluded. For example, exterior casing  304  can be formed of a split clam-shell design or simply a tubular design with openings for which harvested tissue samples pass through tissue separator  206  from a first open end to a second open end. Shaft  308  is coupled to power source  210  through coupling  208 . Impeller  306  is coupled to shaft  308  in order to rotate therewith. As discussed above, impeller  306  and shaft  308  can be oriented in a generally vertical orientation (as illustrated) or in a generally horizontal orientation as desired. As impeller  306  rotates, tissue samples are pushed against cutting drum  310  in order to remove non-bone tissue from the bone. In one embodiment, impeller  306  and shaft  308  are offset with respect to cutting drum  310  such that a central axis  312  shared by impeller  306  and shaft  308  is laterally displaced from a central axis  314  of drum  310 . That is to say, impeller  306  and shaft  308  are eccentrically located with regards to cutting drum  310 . As a result, there exists a non-uniform positioning between edges of the impeller  306  and cutting drum  310 , as explained below. 
     Impeller  306  includes a first blade  316  and a second blade  318  extending radially from a hub  320  toward an interior cutting surface  322  of cutting drum  310 . In alternative embodiments, impeller  306  includes only a single blade. First blade  316  includes a blade edge  324  and a second blade  318  includes a blade edge  326 . Illustratively, first blade  316  and second blade  318  are of similar length and blade edges  324  and  326  extend substantially parallel to cutting surface  322 . Due to the eccentric relationship between impeller  306  and drum  310 , a non-uniform positioning between blade edges  324 ,  326  and the cutting surface  322  is established. The non-uniform positioning can be described with respect to a first minimum distance  330  from cutting surface  322  to blade edge  324  that is less than a second minimum distance  332  from cutting surface  322  to blade edge  326 . 
     As impeller  306  rotates about shaft  308 , the distance between blade edges  324 ,  326  and cutting surface  322  changes based on the eccentric relationship between impeller  306  and cutting drum  310 . Other blade edges of the impeller are positioned at distances between distance  330  and distance  332  depending on the respective radial position of the blade edge. Upon a 180° rotation of impeller  306 , blade edge  324  will be positioned at distance  332  from surface  322  whereas blade edge  326  will be positioned at distance  330  from surface  322 . In one embodiment, distance  330  is substantially zero such that blade edge  324  is in close proximity to or contacting surface  322 . Put another way, blade strain and/or interference between blades of impeller  306  and cutting drum  310  vary with angular displacement of impeller  306 . 
     As an alternative to positioning impeller  306  eccentrically within cutting drum  310 , a length of individual blades of impeller  306  can be adjusted so as to create non-uniform positioning between edges of the blades and cutting surface  322 . For example, impeller  306  and cutting drum  310  could be positioned concentrically, wherein some blades could be positioned at varying distances from cutting surface  322 . The distances can be gradually varied so as to provide similar relative distances between blade edges of impeller  306  and cutting surface  322  as the eccentric relationship depicted in  FIG. 3 . In any event, these alternative embodiments can vary blade strain and/or interference between blades of impeller  306  and cutting drum  310  with angular displacement of impeller  306 . 
     With further reference to  FIG. 4 , impeller  306  includes a plurality of blades  336  extending radially outward from central axis  312 . Each of the plurality of blades  336  is of similar length, with respective edges extending substantially parallel to cutting surface  322 . Based on the radial position of each blade, a distance from its respective edge to cutting surface  322  (and thus blade strain and/or interference) will vary due to the eccentric relationship between impeller  306  and drum  310 . In one example, impeller  306  is formed of a plastic or rubber material exhibiting a durometer approximately in the range of 50 Shore A to 97 Rockwell M and, in a specific embodiment, is around 70 Shore A. In any event, impeller  206  can be formed from a flexible material exhibiting a low flexural modulus, such as a polymer, or through a material exhibiting low section modulus geometry, such as a thin cross section. Alternatively, impeller  306  could be formed of hinged blades. 
     Moreover, as illustrated, a number of blades in the plurality of blades  336  is eight, although any number of blades can be used, for example any number of blades in a range at of at least one blade to more than ten blades. For example, the number of blades can include at least one blade, at least two blades, at least five blades and at least eight blades. During operation, the plurality of blades  336  cooperates with the cutting surface  322  to cycle harvested tissue  202  through random paths in which the tissue  202  frictionally engages the cutting surface  322  at different positions given the rotational force of impeller  306 . 
     In one embodiment, the cutting surface  322  is formed of a plurality of perforations formed in the cutting drum  310 . The perforations include round holes that aid in removing the non-bone tissue and the rotational force of impeller  306  forces non-bone tissue out of drum  310  through the perforations and into the external casing  304 . Alternatively, the perforations can be various regular and irregular forms such as rectangles, slits, triangles, etc. In another embodiment, cutting surface  322  need not include perforations and instead can include a plurality of raised or recessed cutting edges that engage bone to remove non-bone tissue therefrom. 
     In yet another alternative embodiment illustrated in  FIG. 5 , an alternative impeller  500  is positioned in cutting drum  310 . Impeller  500  includes a plurality of blades  502  configured to rotate about a shaft  504 . Each of the plurality of blades  502  are of similar length and their respective blade edges extend parallel to cutting surface  322 . In contrast to impeller  306  of  FIG. 3 , the plurality of blades  502  of impeller  500  deflect upon rotation of impeller  500  as the blades come into contact with cutting surface  322 . For example, blade  508  is in a deflected (i.e., bent) position, whereas blade  510  extends substantially straight from shaft  504 . As impeller  500  rotates 180° with respect to the position in  FIG. 5 , blade  510  would be in a deflected position whereas blade  508  would extend substantially straight from shaft  504 . 
     Regardless of the particular configuration of the impeller (e.g.,  306  or  500 ), harvested tissue samples are positioned within cutting drum  310  so as to remove non-bone tissue therefrom and produce denuded bone. As the impeller rotates, individual blades of the impeller force the tissue samples against the cutting surface of the cutting drum. The non-uniform relationship between the tips of blades and the cutting surface allows the tissue samples to contact the cutting surface at random positions so as to denude the bone to a sufficient level for use as is or in a bone milling process. In one embodiment, the impeller rotates at a rate greater than 200 revolutions per minute and, in a specific embodiment, at a rate of around 2,000-5,000 revolutions per minute. 
     Several other configurations for tissue separator  206  can be utilized to denude bone from harvested tissue samples. For example, in one embodiment, a drum (e.g., drum  310 ) is configured to rotate while an impeller (e.g., impellers  306 ,  500 ) remains stationary. In an alternative embodiment, both the drum and impeller rotate, either in the same direction or in opposite directions. If both the impeller and drum rotate, one of the impeller or drum can rotate faster than the other. In other embodiments, the drum and impeller can be coaxial. Further exemplary concepts for tissue separator  206  are illustrated in  FIGS. 6-13 , described below. 
       FIG. 6  illustrates an alternative embodiment in which a brushed impeller  600  is positioned within drum  310 . The brushed impeller  600  includes radially projecting bristles  602  arranged to extend from a central shaft  604  of the impeller  600 . Bristles  602  can be formed of various different materials. For example, the bristles may be metal, such as stainless steel, or polymeric, such as nylon. In one embodiment, the bristles  602  can be coated and/or impregnated with an abrasive ceramic, such as silicon carbide and/or alumina. Impeller  600  can be operated up to 100,000 revolutions per minute, and in a particular embodiment, in a range of 700 to 10,000 revolutions per minute to remove non-bone tissue from harvested tissue samples. 
       FIG. 7  illustrates another alternative embodiment, for tissue separator  206 , in which bristles  700  can be attached to drum  310  and extend inwardly toward a brushed impeller  702 . The radially inwardly extending bristles  700  can act to increase friction between tissue samples as impeller  600  forces tissue samples against the bristles. 
     In another alternative embodiment, illustrated in  FIG. 8 , an impeller  800  can replace brushed impeller  600  such that relative motion occurs between impeller  800  and the radially extending bristles  700 . Impeller  800 , in one embodiment, comprises a polymer material. 
     In yet another alternative embodiment, a plurality of brushes can be provided within drum  310 , as illustrated in  FIG. 9 . The plurality of brushes includes a central brush  900  and a plurality of radial brushes  902  extending around central brush  900 . In one embodiment, radial brushes  902  can be fixed and remain stationary with regard to the central brush  900 . Central brush  900  rotates and tissue samples are subject to friction between brushes  900  and  902 . In an alternative embodiment, central brush  900  can remain stationary while radial brushes  902  rotate. In yet a further embodiment, all of the brushes  900  and  902  rotate. In any event, in embodiments in which multiple brushes rotate, a single input shaft and a sun/planet gear configuration can be used to transmit rotational force to the brushes. 
     In another embodiment, as illustrated in  FIG. 10 , central brush  900  is removed and radial brushes  902  are coupled together on a carrier  1000  that provides translational motion of the brushes  902  relative to the drum  310  while the brushes  902  rotate. 
       FIGS. 11A and 11B  illustrate another embodiment of tissue separator  206 , including a plurality of brushes  1100  positioned around a circumference of cylindrical casing  1102 . Casing  1102  is formed of two hemispherical halves  1104  and  1106  joined together at a hinge  1108 . A gear  1110  is coupled to corresponding gears (not shown) for each of the plurality of brushes  1100  such that rotation of gear  1110  causes rotation of the plurality of brushes. A central shaft  1112  is coupled to a power source in order to provide rotational force to gear  1110 . During operation, harvested tissue of bone and non-bone tissue is positioned in a central area  1114  and the plurality of brushes  1100  are caused to rotate. This rotation separates non-bone tissue from bone and transfers the non-bone tissue toward casing  1102  (i.e. away from central area  1114 ) whereas bone remains in central area  1114 . 
     In still other embodiments, denuding may be accomplished through the use of a pressurized fluid and/or media. Embodiments in  FIGS. 12-14  below discuss tissue separation with the use of fluid. However, in other embodiments, the fluid can further include media such as a sterile, biocompatible material such as titanium. In other embodiments, the media can include dry ice, which is utilized to freeze and separate non-bone tissue from bone. As illustrated in  FIG. 12 , particle reducer  1200  includes a container  1202 , nozzles  1204 ,  1205  and  1206  and a cap  1208 . The nozzles  1204 - 1206  direct and concentrate an energy of fluid and/or media under pressure onto a tissue sample  1210 . The pressurized fluid works to separate muscle and connective tissue from bone in the tissue sample  1210 . In one embodiment, a screen  1212  is utilized to filter the separated muscle and connected tissue from the bone, which can be drained through an opening  1214  in the container. In one embodiment, the pressurized fluid is sterile water or saline and can be directed at a level of 100 to 100,000 pounds per square inch. In a more particular embodiment, the fluid can be directed at a level of 1,000 to 20,000 pounds per square inch. Nozzles  1204 - 1206  can be any type of nozzle in which to spray fluid. In one embodiment, the nozzles can be a “turbo” nozzle wherein a narrow jet creates a radially moving pressure spray. Alternatively, the nozzles can be connected to a power source to move the nozzle laterally or in a rotational direction, as desired. In other embodiments, one or more of the nozzles  1204 - 1206  can be removed. In yet further embodiments, other nozzles can be added, for example adjacent any of the nozzles  1204 - 1206  and/or coupled to cap  1208 . 
       FIG. 13  illustrates yet another alternative embodiment, where an impeller  1300  or other rotational member is utilized in combination with a nozzle  1302  in order to move tissue sample  1304  and expose the tissue sample to pressurized fluid from nozzle  1302 . 
     In the embodiment illustrated in  FIG. 14 , a rotating drum  1400  is provided wherein a nozzle  1402  directs pressurized fluid toward a tissue sample  1404 . If desired, radial projections  1406  can be provided around a circumference of drum  1400  such that sample  1404  tumbles against projections  1406  and into the pressurized fluid stream created by nozzle  1402 . 
     With reference to  FIG. 2 , once the bone has been denuded by bone denuder  204 , the denuded bone can be further processed by bone mill  214  to produce morselized bone particles for use in a procedure. One exemplary bone mill that can be used is described in U.S. Pat. No. 6,824,087, entitled “Automatic Bone Mill”, the contents of which are hereby incorporated by reference in their entirety. By utilizing both bone denuder  204  and bone mill  214  in an automatic fashion, an efficient bone processing system is established that can efficiently process bone for medical or surgical procedures in a safe and sterile manner. 
     Although the concepts presented herein have been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the concepts.