Abstract:
A bone morselization apparatus and method according to which a cutter bit is mounted to a casing containing a motor; and the casing is manually grasped and positioned over a plurality of bone segments. When the motor is activated, the cutter bit reciprocates and the bone segments are impacted by the cutter bit to morselize the segments.

Description:
BACKGROUND 
   This invention relates to an apparatus and method for fracturing bones into smaller bone particles, or morsels, for use in surgical procedures such as surgical grafting for bone augmentation or repair. 
   Surgeons, particularly when dealing with spinal fusion, oral/maxillofacial, orthopedic, periodontal, and implant applications, often perform autologous bone grafts using autogenous bone that is ground into relatively small particles, or morsels. For example, in a spinal fusion application, the surgeon can use bone from the patient&#39;s mandibular symphsis or ramus, then grind the bone and utilize the bone morsels in the fusion procedure. Such procedures reduce the costs of surgery compared with other products, such as hydroxy appetite (HA) granules, processed coral, or freeze-dried bone. 
   Bones are often morselized by bone mills having a cutting blade with a plurality of teeth. However these devices are relatively inefficient since they require a significant amount of mechanical force as well as time to complete the morselization process. Also, there is often a significant loss of bone within the bone grinders themselves, since chunks of bone become wedged between adjacent teeth of the cutting blade and/or between the teeth and the milling apparatus. Other designs of bone mills involve rasp tools and are very complicated and expensive. 
   Therefore, what is needed is an apparatus and method for bone morselization which avoid the above problems. 
   All patents listed in Table 1 are hereby incorporated by reference herein in their respective entities. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the teachings of the present invention. 
   
     
       
             
             
             
           
         
             
               TABLE 1 
             
             
                 
             
             
               Patent/Publication No. 
               Patented/Published Date 
               Inventor 
             
             
                 
             
           
           
             
               6,318,651 
               Nov. 20, 2001 
               Spiering 
             
             
               6,287,312 
               Sep. 11, 2001 
               Clokie et al. 
             
             
               6,162,227 
               Dec. 19, 2000 
               Eckhardt et al. 
             
             
               5,918,821 
               Jul. 6, 1999 
               Grooms et al. 
             
             
               5,769,853 
               Jun. 23, 1998 
               Quetin 
             
             
               5,607,269 
               Mar. 4, 1997 
               Dowd et al. 
             
             
               4,706,897 
               Nov. 17, 1987 
               Moeller 
             
             
               4,252,282 
               Feb. 24, 1981 
               Vermeulen, et al. 
             
             
               6,142,997 
               Nov. 7, 2000 
               Michelson 
             
             
               5,653,713 
               Aug. 5, 1997 
               Fischer 
             
             
                 
             
           
        
       
     
   
   SUMMARY 
   According to an embodiment of the invention, a bone-morselization apparatus is provided that includes a vertically reciprocating cutter bit having a plurality of cutting elements. As a result, when the blade is reciprocated, the cutting elements impact and fracture bone segments into multiple morsels. 
   Various embodiments of the invention discussed below may possess one or more of the above features and advantages, or provide one or more solutions to the above problems existing in the prior art. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partial sectional/partial elevational view of an apparatus according to an embodiment of the invention. 
       FIG. 2  is an enlarged elevational view of the tool in the embodiment of  FIG. 1 . 
       FIG. 3  is a view similar to that of  FIG. 1  but depicting another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1  of the drawings, the reference numeral  10  refers, in general, to an apparatus for morselizing bones into smaller bone particles, or morsels, for use in surgical grafting. The apparatus  10  includes a substantially L-shaped casing  12  having a manually gripable handle  12   a  and containing a motor  14 . In one embodiment, the motor  14  is a conventional variable speed, brushless, dc motor adapted to produce a reciprocal output. 
   A collet  16  is located at one end of the casing  12  and is adapted to be coupled between the output shaft (not shown) of the motor  14  and the shaft of a cutter bit to be described. 
   The motor  14  is adapted to reciprocate its output shaft and is powered by a conventional rechargeable battery pack  18  disposed in the handle  12   a  or, alternately, by house current through an electric cable (not shown) attached to the casing  12 . 
   A trigger  20  is provided that extends outwardly from the handle  12   a  and is adapted to control the speed of the motor  14  and/or turn it on or off. In this context, it is understood that proper electronics (not shown) can be provided in the casing to facilitate control of the motor  14 . In the event the motor  14  is not turned on and off by the trigger  20 , a separate switch (not shown) for this purpose can be provided on the casing  12 . 
   Referring to  FIGS. 1 and 2 , a cutter bit  22  is provided that consists of a shaft  24  having one end portion that extends in, and is lockingly engaged by, the collet  16 . A circular base member  26  extends from the other end of the shaft  24  and a plurality of cutting elements  28  extend from the lower surface of the base member  26 . In the example shown, there are five cutting elements  28 , each having a substantially triangular cross-section that tapers inwardly in a direction from the base member  26 , with the taper being such that a relatively sharp point is formed at the distal end of each cutting element  28 . In one embodiment, the shaft  24 , the base member  26 , and the cutting elements  28  are formed integrally. 
   It is understood that the design of the casing  12  ( FIG. 1 ) and the collet  16  are such that the collet  16  is coupled between the output shaft of the motor  14  and the shaft  24  of the cutter bit  22 , and that reciprocal movement of the motor shaft in response to activation of the motor  14  causes corresponding reciprocation of the cutter bit  22 . 
   A vessel  30 , having an open end, is provided for receiving a plurality of bone segments  32 . After the segments  32  are placed in the vessel  30 , the handle  12   a  is manually grasped and the cutter bit  22  positioned over the vessel  30  with the shaft  24  extending substantially vertically. The motor  14  is turned on causing reciprocal movement of the bit  22 , and the bit is lowered into the vessel  30  until the cutting elements  28  impact and morselize the bone segments  32 . 
   According to the embodiment of  FIG. 3 , the reference numeral  40  refers, in general, to an apparatus for morselizing bone segments according to another embodiment of the invention. The apparatus  40  includes a substantially vertically-extending pedestal  42  mounted on a base member  44 . An arm  46  is pivotally mounted to the pedestal  42  for movement between the substantially horizontal position shown and a position at a slight angle to the horizontal. 
   The reciprocal motor  14  of the previous embodiment is mounted in the arm  46 , and a collet  48  extends from the lower surface of the distal end portion of the arm  46  and is coupled to the output shaft of the motor  14  for reciprocation therewith. An end portion of the cutter bit  22  of the previous embodiment is mounted in the collet  48  with its shaft  24  extending substantially vertically. 
   It is understood that the motor  14  can be connected to a source of house current by a cable (not shown) connected to the pedestal  42 , and that an on-off switch and a speed control can be provided on the arm  46  or the pedestal  42  to control the motor  14 . In the latter context, electronics can also be provided in the arm  46 , the pedestal  42 , or the base member  44  to facilitate this control. It is also understood that the cable for house current, the on-off switch, or the speed control can be supplied, independently of each other, on any combination of the arm  46 , the pedestal  42 , or the base member  44 . 
   As in the previous embodiment, it is understood that the design is such that the collet  48  is coupled between the output shaft of the motor  14  and the shaft  24  of the cutter bit  22  in a manner to allow reciprocation of the cutter bit  22  in response to activation of the motor  14 . 
   The vessel  30  of the previous embodiment, with a plurality of segments  32  contained therein, is positioned on the base member  44  directly under the cutter bit  22 . If necessary, the arm  46  can be pivoted so that its distal end portion moves upwardly to allow the vessel  30  to be placed in position. The arm  46  is then pivoted back to its substantially horizontal position shown in  FIG. 3  and is activated to cause reciprocal movement of the bit  22  so that the cutting elements  28  impact and morselize the bone segments  32 . 
   In both of the above embodiments, the term “morselize” is used in a broad sense and is intended to cover fracturing, cracking, comminuting, milling, pulverizing, hacking, rupturing, cutting, disintegrating, all other forms of morselization, or any combination thereof. 
   Variations 
   It is understood that variations can be made in the above without departing from the scope of the invention. For example, the design of the cutter bit  22 , including the design of the elements  28 , can be varied within the scope of the invention. Also, mechanisms other than the collets  16  and  48  can be used to lockingly engage the cutter bit  22  while permitting reciprocal movement of the bit. Further, the shape of the casing  12 , the arm  46  and the pedestal  42 , as well as the pivotal mounting of the arm  46  to the pedestal  42 , can be varied. Still further, the motor  14  in the embodiment of  FIG. 1  can be disposed in the handle  12   a,  and, in the embodiment of  FIG. 3 , it can be disposed in the pedestal  42 . Moreover, the vessel  30  can be eliminated or replaced by a container of a different design. Also, the particular type of medical procedure utilizing the morselized bone in accordance with the above can be varied. 
   The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, therefore, that other expedients known to those skilled in the art or disclosed herein, may be employed without departing from the invention or the scope of the appended claims. For example, the present invention is not limited to the particular design of the casing  12 , and the support assembly consisting of the pedestal  42 , the base  44 , and the arm  46 , but may find further application with other types of casings and assemblies. 
   The present invention further includes within its scope methods of making and using the apparatus described hereinabove. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts a nail and a screw are equivalent structures.