Patent Document

FIELD OF INVENTION 
       [0001]    This invention is in the field of surgery and surgical instruments, more specifically in the field of instruments for obtaining tissue samples, and more specifically, automated instruments. 
       BACKGROUND OF INVENTION 
       [0002]    In specific instances it is necessary for a physician to obtain a sample of bone marrow. Most commonly, the sample is biopsied to determine the presence of disease, although other purposes may exist, e.g., recovery of cells for transplantation. A biopsy may be prescribed to remove liquid aspirates from the marrow space as well as a core sample of the bone marrow to determine whether cancer or other disease is present. Liquid aspirate must be drawn from the marrow cavity for cytological study and a core sample of marrow material must be obtained if histological study is desired. 
         [0003]    In the conventional prior art procedure, the physician penetrates the hard bone of the patient with a cannula/trocar combined needle from a bone marrow biopsy set (see, e.g., U.S. Pat. No. 3,628,524, inter alia, to Jamshidi, and U.S. Pat. No. 7,278,972 to Lamoureux, et al.). The needle is twisted down through the cortex of the bone into the marrow space. Once the marrow cavity is accessed, the trocar is removed and a syringe is attached to the opening where the trocar resides. A liquid sample can be withdrawn from the marrow space using the syringe attached to the needle. Alternatively, a core sample of marrow can be obtained. The hollow center of the cannula needle is specially shaped with a first proximal diameter, tapering to a distal end of a second diameter. The needle is tapered in the last 2 to 3 centimeters of the distal end to a smaller sharpened opening with a cutting edge. This reduced second diameter of the large bore needle assists in capturing and holding a core sample instead of a liquid sample. 
         [0004]    To obtain a core sample using this Jamshidi (R) method, the bone cortex is penetrated in the same manner as for a liquid sample, but once the trocar is removed, the hollow cannula is driven farther manually, into the marrow space, to obtain a solid core of marrow. A core sample of a certain length is obtained by inserting a rod into the cannula, and driving the cannula into the marrow until the proximal end of the rod rises to the desired length above the proximal end of the cannula. To preserve the integrity of the core sample, the physician rocks the needle from side to side to break the distal end of the sample free from the rest of the matrix of marrow. The cannula is then removed from the patient and the marrow sample is removed by pushing the rod all the way through the cannula, discharging the sample into a sample bottle. 
         [0005]    This apparatus and method are widely used because the apparatus is single-use disposable and reasonably priced. The main drawback of this apparatus and method is that it requires significant manual axial pressure and rotation to drive the needle through the bone cortex, all the while attempting to sense the interface between the cortex and the marrow and avoid either penetrating the marrow completely or mechanically damaging the marrow before a sample can be obtained. Even the most skilled practitioners often find it necessary to reinsert the instrument, causing another wound and taking more time. 
         [0006]    The manual procedure has been improved more or less, cost notwithstanding, by automated devices. A number of prior art devices automate obtaining biopsies, but most of them are suitable for soft tissue use only. (See, e.g., U.S. Pat. No. 7,189,207 to Viola, comprising a trocar driver, a knife driver and firing module.) U.S. Pat. No. 4,919,146 to Rhinehart incorporates an electric drill and a syringe into a hand-held device, but the patent specification does not mention bone or marrow biopsy nor does the device appear to be suitable for those procedures. In any case, it appears that the drill bit of Rhinehart will not produce a core sample with sound architecture. One prior art device intended to solve the problem of manual control and get a good intra osseous sample in one operation is U.S. Pat. No. 6,022,324 to Skinner, comprising a sampling needle driven by a gun which applies axial bone-penetrating force of up to 200 pounds. This force is supplied by an electric motor or gas cylinder. It incorporates a syringe to withdraw a sample after actuation of the firing mechanism. A problem here is that, while it reduces the time required to get a sample, it would seem not to provide sufficient sample quality and reproducibility because of the wide patient-to-patient variation in soft tissue depth and thicknesses of bone cortex and marrow, and the likely trauma caused by the impact of the syringe on the tissues. A later patent, U.S. Pat. No. 6,626,848 to Neuenfeldt, moves the sampling needle in a reciprocal rotating motion about its axis as it is guided into the bone and thence into the marrow. The sampling is performed in a manner similar to the aforementioned Jamshidi method after the bone cortex is penetrated. The unsolved problem here is that no provision is made for withdrawal of both liquid and solid samples in one operation and the use of relatively-inexpensive tissue-contacting parts for disposal. 
         [0007]    What is needed is a power-driven device that not only accomplishes the above-mentioned goals of improved sampling success and reduced time requirement, but also improves, rather than diminishes, the physician&#39;s tactile sense of cannula placement. It is also highly desirable to provide these qualities in a device that has single-use disposable tissue and liquid contact parts, the parts being of simple construction and reasonable price, operable by a mechanism that does not require large capital investment. 
       BRIEF DESCRIPTION OF INVENTION 
       [0008]    This invention comprises an ergonomic handle containing a driver, with a detachable and disposable sterile single use cannula/trocar and disposable vacuum containers. The drill cannula has a crown tip and smooth external and internal surfaces to allow accurate cutting with minimal tissue trauma and maximum sample integrity. The driver has a control switch enabling either variable speed forward, neutral, or variable speed reverse axial rotation of the drill cannula, the driver motor being either electric, compressed air, or vacuum operated. The handle optionally further comprises a vacuum trigger to supplement withdrawal of a suitable liquid sample while the cannula is still inserted into the patient. The device and method for use improve the ability of a physician to locate accurately the target tissue in a patient, increase the probability that one or more suitable samples will be recovered from the patient at a single attempt, and decrease attendant tissue trauma and patient discomfort. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  is a schematic diagram of the invention being prepared for use. 
           [0010]      FIG. 2  is a schematic diagram of the invention being advanced into the tissue of a patient. 
           [0011]      FIG. 3  is a schematic diagram of the invention with trocar removed prior to sampling. 
           [0012]      FIG. 4  is a schematic diagram of the evacuated sample container of the invention. 
           [0013]      FIG. 5  is a schematic diagram of the evacuated container being used to collect a liquid marrow sample. 
           [0014]      FIG. 6  is a schematic diagram of the invention being partially withdrawn for repositioning to collect a solid marrow sample. 
           [0015]      FIG. 7  is a schematic diagram showing the evacuated sample container being removed and the spacing stylet being inserted in preparation for obtaining a solid marrow sample. 
           [0016]      FIG. 8  is a schematic diagram showing the invention with the spacing stylet fully inserted into the cannula. 
           [0017]      FIG. 9  is a schematic diagram showing the spacing stylet partially withdrawn for solid sample collection. 
           [0018]      FIG. 10  is a schematic diagram showing the invention tilted and drilled into undisturbed marrow. 
           [0019]      FIG. 11  is a schematic diagram showing the invention finally withdrawn from the patient. 
           [0020]      FIG. 12  is a schematic diagram showing the spacing stylet used to push the solid sample from the cannula. 
           [0021]      FIG. 13  is a schematic diagram of the invention with all disposable parts discarded. 
           [0022]      FIG. 14  is a side view of the preferred embodiment of the invention. 
           [0023]      FIG. 15  is a top view of the preferred embodiment of the invention. 
           [0024]      FIG. 16  is a front view of the preferred embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0025]    Referring now to the drawings, in which like elements in each drawing are represented by like reference numerals,  FIG. 1  is a schematic diagram of the invention being prepared for use. It consists of a permanent reusable driver portion  1  and principal sterile disposable parts including drill  2 , spacing stylet  18  and bushing  19 . Spacing stylet  18  has a button  60  to allow aseptic handling of the rest of the stylet. Driver portion  1  includes a handle  21 , a control switch assembly  3 , a motor  4 , motor power input  5 , a driven bevel gear  6 , an optional vacuum source  7 , an optional vacuum switch assembly  8 , a drill chamber  9 , a latch  10 , and an optional vacuum needle  11 . The motor  4  may be electric, compressed air, or vacuum operated. If operated by electricity, it can be battery powered or utilize AC power through power input  5 . It is controlled by switch assembly  3 , which may toggle forward, neutral, or rearward to drive motor  4 , and, in turn, rotate bevel gear  6 , clockwise, neutral, or counterclockwise. Vacuum may be applied to a sample container (see below) by pressing the trigger on optional vacuum switch assembly  8  to allow optional vacuum source  7  to pull a vacuum at optional vacuum needle  11 . Note that vacuum source  7  and power input  5  may be combined into a utility cable  12 . Drill  2  consists of cannula  13 , cannula gear  14 , and a trocar  15  (see  FIG. 2  below, only trocar tip  16  and trocar cap  17  are visible in this view). Cannula  13  is hollow along its entire length and trocar  15  is slidably removable within it. The cannula optionally may be tapered as in Jamshidi with conforming trocar shape to help retain a solid marrow sample if desired. 
         [0026]    Trocar cap  17  is removably attached to the top of cannula gear  14  by frangible connector  20 . To prepare the device initially for use, disposable bushing  19  is inserted into a receiving hole  22  in the bottom of drill chamber  9 , and drill  2  is inserted downwardly through bushing  19  until cannula gear  14  meshes with bevel gear  6 , and latch  10  can secure drill  2  in place. The bushing isolates all of the non-disposable portions of the invention from contact with the patient. 
         [0027]      FIG. 2  is a schematic diagram of the invention after having been advanced into the tissue of a patient by pressing thumb switch  23  forward to drive drill  2  clockwise. Drill  2  is cut away lengthwise in this view so that trocar  15  can be seen within cannula  13 . Also visible here is that trocar cap  17  is fixed to the upper end of trocar  15 , and it has an annular recess  27  that covers a syringe tip  28  at the top of cannula  13 . Cannula  13  has, at its other end, a crown tip  23 , and trocar  15  has a matching trocar tip  16  which together enable cutting through soft tissue and bone with minimal tissue damage. Inset  FIG. 2A  shows magnified detail of crown tip  23  and trocar tip  16 . In  FIG. 2 , drill  2  has been advanced through an outer tissue layer  24  and bone cortex  25  of a patient (shown in dashed lines as environmental structure). When bone is reached, the physician senses it by increased resistance to forward motion, just as would be the case with the Jamshidi (R) set, but the cannula keeps moving forward as long as the physician continues to exert pressure on the handle an continues to hold the switch in direction A. Whereas a physician must apply considerable repetitive manual pushing and twisting to advance the Jamshidi (R) set, accompanied by a certain amount of pressure discomfort to the patient, reaching the bone marrow with the instant invention is achieved smoothly with very little impact. Reaching bone with the instant invention is sensed by increased torque on the handle and decreased drill speed. The physician can now carefully control the rate of advancement of the drill until the cortex is penetrated. At that point, the physician can feel the decreased resistance to forward motion and increased drill speed. The physician&#39;s sense of touch is important here in preventing over extensive drilling, and the shape of handle  21  (see  FIGS. 14-16 ) augments that by causing the reactive force of the handle to be applied against the fingers instead of the palm of the hand. The physician is now free to select any drill speed or no speed to advance the drill into the marrow cavity  26 . 
         [0028]      FIG. 3  is a schematic diagram of the invention with trocar  15  removed prior to withdrawal of a liquid sample. Latch  10  is now opened allowing trocar cap  17  to be broken free of cannula gear  14 . Note that cannula syringe tip  28  and optional vacuum needle  11  are now exposed. 
         [0029]      FIG. 4  is a schematic diagram of the evacuated sample container  40 . It consists of an evacuated sterile test tube  41  having a frangible seal, such as a septum  42 , at one end. The septum may further comprise an optional vacuum inlet tube  43  molded in unitary fashion with septum  42 . 
         [0030]      FIG. 5  is a schematic diagram of the evacuated container  40  being used to collect a liquid marrow sample. Sample tube  40  has been pressed down over syringe tip  28  and optional vacuum needle  11  which both penetrate septum  42 . The vacuum in the tube has sucked the liquid  50  from the marrow cavity  26  into tube  40 . If additional vacuum assist is necessary to pull liquid into the tube, vacuum switch assembly  8  may be actuated by the user. 
         [0031]      FIG. 6  is a schematic diagram of the invention being partially withdrawn from the marrow cavity  26  for repositioning to collect a solid marrow core sample. Repositioning the cannula by partial withdrawal and re-insertion into an undisturbed portion of the marrow cavity is desirable because it improves the likelihood that the solid sample will accurately represent the patient&#39;s marrow structure, and it reduces the chance that continued drilling through the marrow will cut into the bone on the other side. Control switch assembly  3  is pulled into reverse to drive cannula  13  counterclockwise if necessary. 
         [0032]      FIG. 7  is a schematic diagram showing the evacuated sample container  40  removed and the sterile spacing stylet  18  being inserted into syringe tip  28  of cannula  13  in preparation for obtaining a solid marrow core sample. 
         [0033]      FIG. 8  is a schematic diagram showing the invention with the spacing stylet  18  fully inserted into the cannula  13 , initially pushing liquid out of the cannula  13  and back into the marrow cavity, thereby making room for a solid marrow sample. The spacing stylet  18  can be made from any material that maintains its approximate length for spacing purposes. It can be made from liquid-wicking material such as a hydrophilic open-cell foam, which would allow it to soak up liquid as it is inserted into cannula  13 , thereby preventing liquid from emerging from the cannula  13  into the surrounding area. 
         [0034]      FIG. 9  is a schematic diagram showing the spacing stylet  18  partially withdrawn from cannula  13  for solid sample collection. This is one method of collection allowing pre-determination of the approximate length of the core. The distance D withdrawn is a matter of physician&#39;s judgment as to how long the sample core should be. If stylet  18  is made from liquid-wicking material, it is less likely to draw contamination down into the cannula  13  when stylet  18  is raised, and it allows liquid to rise up into the cannula  13  when cannula  13  encounters solid matter. Another method of measuring the core is to leave the stylet  18  fully in, and watch it rise to the desired core length when cannula  13  is drilled down into undisturbed solid marrow. Here again, liquid-wicking, but substantially rigid, stylus material will be pushed upward by solid matter but not by liquid. 
         [0035]      FIG. 10  is a schematic diagram showing the invention tilted downwardly (clockwise in this view) and drilled farther into undisturbed marrow by actuating control switch assembly  3  forward. A common syringe (not shown) may be applied to syringe tip  28  if necessary to assist in drawing solid matter into the cannula  13 . 
         [0036]      FIG. 11  is a schematic diagram showing the invention finally withdrawn from the patient by actuating control switch assembly  3  in reverse. 
         [0037]      FIG. 12  is a schematic diagram showing the spacing stylet  18  used to push the solid sample  120  from the cannula  13  into a sample bottle  121  (shown in dashed lines as environmental structure). 
         [0038]      FIG. 13  is a schematic diagram of the invention with all disposable parts discarded. 
         [0039]      FIG. 14  is a side view of a preferred, ergonomically-shaped embodiment of the invention, containing the elements shown in the preceding schematic diagrams. It is operable with one hand, having a smooth case to create maximum contact with the inner surface of the hand, in the manner of a dental drill. Unlike a dental drill, however, the axis of the handle is nearly in line with the axis of the drill, preferably off collinear by no more than about 30 degrees, for optimum tactile responsiveness. This is because all of the thrust of this operation is forward, rather than upwards or downwards. Handle  21  has control switch assembly  3  arranged upon it so that it can be actuated forward, neutral or reverse by a thumb, and it has vacuum switch assembly  8  placed so that it can be actuated upwardly by a forefinger. Note also the embodiment of visible features latch  10 , utility cable  12 , and cannula  13 . Other shapes of driver portion  1 , handle  21  and latch  10  not depicted here, but which are sized and shaped so as to accommodate all of the other elements depicted in the foregoing schematics, are included within the scope of this invention without limitation. 
         [0040]      FIG. 15  is a top view of the preferred embodiment of the invention. 
         [0041]      FIG. 16  is a front view of the preferred embodiment of the invention.

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