Patent Abstract:
The cannula handle housing includes a recessed seat, wings extending outwardly from the recessed seat in the housing for engagement with a physician&#39;s hand and a stem which extends from said housing to hold a portion of a cannula The cannula has a distal sharpened end and a proximal end secured to a Luer lock. The stylet includes a longitudinal member having a sharp tip with the other end of the stylet formed with an anvil structure which is molded into a stylet cap. The stylet cap is a housing which includes a projection portion having a complimentary configuration to the recessed seat formed in said cannula housing for interlocking with the Luer lock of the cannula housing. The stylet inserts into the cannula and with a twist, locks about the Luer lock on the proximal end of the cannula.

Full Description:
RELATED APPLICATIONS 
   There are no related applications. 
   FIELD OF THE INVENTION 
   The present invention generally relates to a bone marrow aspiration instrument for gathering bone marrow for the repair and replacement of the various portions of the human skeletal system. The present invention is specifically directed to provide a bone marrow aspiration instrument having a cannula which extends from a handle and a stylet assembly including a striking anvil which extends through the handle and cannula. This instrument can be conveniently grasped by the physician or surgeon in the palm of the hand to provide secure control during insertion of the instrument into a human bone and subsequent withdrawal of bone marrow. 
   BACKGROUND OF THE INVENTION 
   The repair, as well as the replacement, of diseased and damaged human bone have been the subject of substantial research efforts over the past several decades. This research has yielded advances in the reconstruction of many areas of the human skeletal system As a result of these advances, bone replacements and repair are presently being undertaken in several areas including the restructuring of the craniofacial system, bone repair, spinal repair, the introduction of knee and hip joints and ligament replacement. 
   The biological mechanisms underlying the reconstruction and repair varies according to the type of bone implant selected. New bone can be formed by three basic mechanisms: osteogenesis, osteoconduction and osteoinduction. In osteogenic transplantation, viable osteoblasts and osteoclasts are moved from one body location to another where they establish centers of bone formation. Autograft tissue, cancerous bone and marrow grafts provide such viable cells. As a generalization, spongy cancerous bone permits rapid and usually complete reossification. 
   In the transplantation of large segments of allogenic banked bone, direct osteogenesis does not occur. In these cases, osteoconduction transpires—the dead bone acts as a scaffold for the ingrowth of blood vessels, followed by the resorption of the implant and deposition of new bone. This process is slow, sometimes requiring years to reunite a large segmental defect. As a generalization, cortical bone has high strength and undergoes osteoclastic digestion of the bone and revascularizes through pre-existing anatomical channels, a relatively slow process. 
   Osteoinduction is the phenotypic conversion of connective tissue into bone by an appropriate stimulus. As this concept implies, formation of bone can be induced at even non-skeletal sites. Osteoinduction is the preferred method of providing new bone growth as allografts of this type are typically incorporated into the host bone within several weeks. In contrast, some osteoconductive grafts have been found to be non-incorporated as long as one year after implantation. 
   In order to provide an environment suitable for osteoinduction, a material should be selected which is not only capable of inducing osteogenesis throughout its volume, but is also biocompatible, non-inflammatory, and possesses the ability to be ultimately resorbed by the body and replaced with new, natural bone. Demineralized bone is osteoinductive and when used in surgery by a physician is quite often mixed with marrow retrieved from the patient at the time of surgery. 
   In most bone marrow collecting procedures, multiple aspirations of bone marrow are required to enable enough bone marrow to be collected to perform a bone marrow transplant to the surgical site or be mixed with the osteoinductive material being used at the surgical site. Bone marrow density can and does vary from patient to patient and there is no uniform viscosity to bone marrow. Younger healthy patients often have denser thicker marrow. Usually thicker marrow is the result of more trabecula tissue present in the cavity. All of these bone marrow collecting procedures require that the bone be punctured in order to access the bone marrow within. Generally bone marrow aspiration is accessed via an open wound, most typically by exposing the iliac crest. In many instances, the instrument tip is difficult to fix into the bone as it skates over the curved hard irregular surface of the iliac crest. Thus, it is important to provide an instrument which enhances the ability of the user to easily puncture bone and obtain bone marrow with minimal trauma to the patient. 
   The bone marrow removal procedure is quite painful to the patient and requires much exertion and care by the physician in operating the instrument. Early problems with biopsy needles involved the sharpness of the cannula and trocar and the gripping means used so that the needle could be placed accurately and the bone could be penetrated quickly. U.S. Pat. No. 4,356,828, for example, discloses an improved finger gripping member and U.S. Pat. No. 4,403,617 discloses particular cutting edge configurations for the trocar and cannula. Developments in the gripping means of the trocar and cannula continued with emphasis being placed on the secure engagement of the trocar within the cannula and ease of use for the physician. 
   All bone marrow biopsy, aspiration and transplant needles or cannulas currently on the market have a handle with a cannula extending outwardly from the handle. The handle is used by the surgeon to apply force to the cannula as the cannula penetrates the bone. Such needles typically include a stylet with a sharpened tip which is inserted through the cannula and is used to initially penetrate the bone. The stylet also serves to occlude the cannula while the bone is penetrated, so that the marrow sample subsequently taken is free from bone chips. The stylet is then removed and bone marrow is withdrawn from the patient by manipulating the cannula to cause bone marrow to move into the interior of the cannula. In some cases a slight suction is applied to the cannula to hold the bone marrow specimen within the cannula as the device is removed from the patient or a syringe can be attached to the cannula to remove the bone marrow as is shown in U.S. Pat. No. 4,838,282. 
   Previous prior art biopsy or collection instruments have grips which do not really fit into the physician&#39;s hand to provide for positive gripping by the physician but have grips which are required to be engaged by the physician in a negative way making the process of biopsy or bone marrow collection uncomfortable to the physician/surgeon using the instrument. The handles of the bone marrow collection instrument must securely engage into the physician&#39;s or surgeon&#39;s palm for optimum control of the instrument during a biopsy or surgery and be easily grasped by the fingers of the user. It is also necessary that the stylet and cannula be engaged to each other during the surgical process for providing total control to the physician or surgeon. 
   Prior art needles have secured cannula tubes into the cannula housing in numerous ways providing increased manufacturing processes, resulting in an increased end cost to the patient. 
   The present invention overcomes the disadvantages of the prior art references by providing a bone marrow aspiration instrument having a winged cannula handle and detent locking between the stylet handle and cannula handle. 
   Bone marrow needles have traditionally been designed so that the needle is attached to the center of the handle. While many physicians feel comfortable with a centrally attached needle, it has been discovered that it may be easier to guide a needle with a user&#39;s index finger when the needle is not centrally located on the handle of the needle assembly. It has also recently been discovered that when an off-center device is used, it is important to insure that a physician&#39;s arm, wrist, and index finger are all generally in alignment with the cannula of the needle to provide enhanced control over the needle. Examples of such devices are described in U.S. Pat. No. 4,469,109. 
   Another disadvantage of most bone marrow instruments currently on the market is that when the stylet is removed from the cannula, the shape of the handle typically is materially changed. For example, the bone marrow needle assembly described in U.S. Pat. No. 4,838,282 involves removing approximately half of the handle assembly when the stylet is removed from the cannula. It is desirable to maintain substantially the original shape of the handle after the stylet has been removed to allow a physician to more easily manipulate the cannula within a patient&#39;s bone. 
   SUMMARY OF THE INVENTION 
   In a preferred embodiment of the invention the cannula handle has a body which is mounted to a cannula offset form the cannula axis. The proximal surface of the body defines a recess forming a saddle which receives a mating section of a stylet assembly. A Luer lock connected to the cannula extends outward from the saddle surface to receive a locking assembly carried by the stylet assembly. The off-center radius causes the handle to have a first major wing extension and a second minor wing extension on opposite sides of the cannula which provides a curved lower surface designed to be easily gripped by a user&#39;s fingers. Thus, when a user grips the handle, the user&#39;s index finger can be naturally applied to a stem extending from the handle housing opposite the saddle recess which surrounds the cannula to guide the cannula into a patient. A stylet is mounted in the cannula and a portion of the stylet handle is seated in the cannula handle saddle. The striking end of the stylet slightly extends from the stylet handle to allow direct force to be applied to the stylet tip. 
   It is an object of the invention to provide a bone marrow aspiration instrument having an ergonomically shaped offset handle to assist a physician in inserting a needle into a patient. 
   It is still another object of the invention to provide a bone marrow aspiration instrument having a handle design such that the shape of the handle allows the same to be easily used after the stylet has been removed. 
   It is yet another object of the invention, that the stylet is provided with a handle that is received within a saddle recess formed in the cannula handle with the stylet having a striking surface which extends beyond an upper surface of the stylet handle and provides direct transmission of force to the stylet. 
   It is a further object to provide a bone marrow instrument wherein an improved means is provided to prevent rotation and movement of the stylet relative to the cannula. 
   It is still another object of the invention to provide a bone marrow aspiration instrument having wing-shaped handles facilitating gripping and engagement by the physician or surgeon user. 
   These and other objects, advantages, and novel features of the present invention will become apparent when considered with the teachings contained in the detailed disclosure which along with the accompanying drawings constitute a part of this specification and illustrate embodiments of the invention which together with the description serve to explain the principles of the invention 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded side elevational view of the inventive bone marrow aspiration instrument; 
       FIG. 2  is an assembled elevational view of the bone marrow aspiration instrument of  FIG. 1 ; 
       FIG. 3  is an end view of the bone marrow aspiration instrument of  FIG. 2  taken from directional line  3 ′— 3 ′; 
       FIG. 4  is a top plan view of the bone marrow aspiration instrument of  FIG. 2 ; 
       FIG. 5  is an enlarged broken side view of a cannula used in the bone marrow aspiration instrument; 
       FIG. 6  is an end view of the cannula of  FIG. 5 ; 
       FIG. 7  is an enlarged broken side view of another cannula used in the bone marrow aspiration instrument; 
       FIG. 8  is an end view of the cannula of  FIG. 7 ; 
       FIG. 9  is an enlarged broken side view of a stylet used in the bone marrow aspiration instrument; 
       FIG. 10  is an end view of the stylet tip of  FIG. 9 ; 
       FIG. 11  is an enlarged broken side view of another stylet embodiment which can be used with the bone marrow aspiration instrument; 
       FIG. 12  is an end view of the stylet tip of  FIG. 11 ; 
       FIG. 13  is an enlarged broken view of the stylet of  FIG. 9  with a strike anvil on the proximal end. 
       FIG. 14  is an exploded side elevational view of another embodiment of the inventive bone marrow aspiration instrument; 
       FIG. 15  is an assembled elevational view of the bone marrow aspiration instrument shown in  FIG. 14 ; 
       FIG. 16  is an end view of the bone marrow aspiration instrument of  FIG. 15  taken in the direction of line  16 ′— 16 ′; and 
       FIG. 17  is atop plan view of the bone marrow aspiration instrument shown in  FIG. 15 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the present invention and best mode of the invention is shown in  FIGS. 1 through 3  and will be described in connection with certain preferred embodiments, it is not intended that the present invention be so limited. On the contrary, it is intended to cover all alternatives, modifications, and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims. 
   In the present invention the bone marrow aspiration instrument  10  includes a hollow cannula  12  having a shaft  14  with an open sharpened distal end  16  having a scalloped sharpened edge  17  and a proximal end  18  which is secured to a luer lock  20 . The cannula  12  preferably has a diameter running from 8 gauge to 14 gauge with an OD ranging from about 0.1660′ to about 0.0820′ and an ID ranging from about 0.1540′ to about 0.0610′ and is constructed of 304 alloy stainless steel with a ground straight bevel cut end as shown in  FIGS. 7 and 8  or a radius cut end as shown in  FIGS. 5 and 6 . The cannula lumen  13  and cannula outer shaft surface  15  is preferably completely coated from the proximal to distal end with a surface modified lubricant coating which reduces the coefficient of friction such as silicon, TEFLON or a medical lubricant such as MH (ground sapphire). This improves the lubricity of the lumen and reduces the resistance to draw the aspirate through the lumen thus reducing any trauma imposed on the marrow cells. The lubricity of the outer shaft surface is also improved allowing easier entry and travel through the bone material. The exterior surface  15  of the cannula  12  can also be laser etched with bands  19  as shown in  FIG. 8  to enable the surgeon to gauge the depth of penetration of the instrument. 
   The proximal end portion of cannula shaft  12  and associated Luer lock  20  which is mounted thereto are mounted in the cannula handle section  32  of handle assembly  30 . The handle assembly  30  is composed of two interlocking sections, gripping cannula handle section  32  and stylet handle section  60 . The handle sections as well as any other parts coming into fluid contact, are preferably formed from a polystyrene terpolymer of acrylonitrile, butadiene and styrene (ABS) or, alternatively, a polycarbonate polymer. The cannula handle section  32  has a curved body  34  eccentrically mounted on the cannula  12  with a stem extension  36  extending away from the curved body  34  surrounding the cannula  12  on its proximal surface. This stem extension  36  of the handle stiffens the cannula  12  so that there is less flexing of the cannula  12  when it is penetrating through the cortical bone. Flexing is not desirable because it absorbs some of the force applied to penetrate the cortical bone. A stiff shaft also transmits more tactile feedback into the hands of the surgeon. Another desirable aspect of the stem extension  36  is that it provides a place for the surgeon to position and rest his or her index finger. This pointing posture provides enhanced control and precision placement of the needle or stylet tip. 
   The handle geometry is ergonomically contoured to fit the hand and the shape is specifically tailored for the twisting and controlled removal of the needle from cortical bone. The distal tip of the handle is extended beyond the grip portion of the handle. The contour provides an optimum position for the fingers to hold and stabilize the handle while tapping the stylet striking surface with a hammer. The curved body  34  has a major wing portion  37  and a minor wing portion  38  which serve to allow grasping by the little finger of the hand on the underside of the minor wing portion  38  and the several fingers of the hand on the underside of the major wing portion  37 . The contours of the handle section  32  are designed to provide a stable balanced grip on the handle. The cannula handle section  32  is designed to enhance grasping, turning, manipulation and twisting of the cannula  12  and stylet  50 . The body  34  defines a arcuate recessed saddle or seat  40  which seats and holds a correspondingly shaped portion  62  of the stylet handle  60  in a mating relationship. Luer lock  20  secured to cannula  12  extends upward and away from the outer surface of seat  40 . The upper surface of the wings of body  34  on either side of the recessed seat  40  has a planar surface  41  with a small locking depression  42  cut therein on the major wing portion planar upper surface to receive a locking nipple  66  extending from planar surface  65  of the stylet handle  60 . 
   A stylet  50  with a solid cylindrical shaft  52  is mounted in the cannula  12  so that it&#39;s triangular pointed tip  54  slightly protrudes from the distal end of the cannula  12  past the scalloped edges  17  as can be seen in  FIG. 2 . Alternatively the tip  54  can be positioned flush with the distal end of the cannula  12  adjacent the scalloped edges. A striker or anvil end member  56  is secured with the other end of the stylet  50  and is mounted in the stylet upper handle body  61 , so that it has an exposed striking surface  59  slightly extending above the body surface. The stylet point is very sharp and formed from a harder grade of stainless alloy such as 420 alloy stainless steel which tends to maintain its sharp point and edges so that it will set into the bone with just a very slight force applied to the strike anvil  56 . The stylet point or tip  54  can have a straight cut as seen in  FIGS. 11 and 12  or a straight bevel cut as seen in  FIGS. 9 and 10 . The center of the striking end  59  of the strike anvil  56  is in line with the axis of the stylet  50 . The strike anvil  56  is machined from stainless steel and has a cylindrical body  58  machined at one end 45 degrees as is more clearly shown in  FIG. 13  to form a taper leading to the cylindrical shaft  52  with the other end of the strike anvil  56  forming a flat surface  59  which transmits the force from the hammer in a precise and controlled manner. All of the force is thus transmitted to the stylet tip  54  with none of the force being absorbed into the handle structure. The anvil  56  is mounted in the handle section  60  and is slightly raised or extended beyond the outer surface of the handle body  61  to allow easier striking force to be applied. 
   The stylet handle section  60  has the stylet  50  secured thereto and its body  61  has major and minor wings  67  and  68 , respectfully, which can be respectively positioned adjacent to the lower wings  37  and  38  of the cannula handle. The body  61  has a curved seating projection  62  having a complementary dimension to fit into and mate with seat  40 . Projection  62  defines a central cylindrical chamber  64  which can receive the Luer lock  20  of the lower gripping handle  32 . The portions of the underside surface of the body  61  on opposite sides of projection  62  have a planar surface  65  allowing it to set flush against planar surface  41  of the corresponding structure of the lower cannula handle section  32 . The major wing portion  67  of the body defines locking nipple  66  which fits in locking depression  42  on the upper planar surface of the lower cannula handle  32  to keep the two handle sections in a fixed relationship when the device is being used. Two parallel locking pins or rods  70  are mounted to the curved projection  62  on opposite sides of the cylindrical chamber  64 . The parallel orientation of the rods  70  allows insertion of the same over the Luer lock  20  and rotation of the body  61  90° degrees to lock the handle assembly  30  in place, with the respective major and minor wing portions of the two handle sections  32  and  60  being positioned adjacent each other. The stylet can be removed by twisting the stylet handle section  60  in relation to the lower cannula handle section  32  to disengage the rods  70  from the Luer lock  20  allowing the stylet to be removed from the cannula  12  and a standard syringe (not shown) to be attached to the Luer lock  20  for the purpose of withdrawing bone marrow. 
   An alternate instrument embodiment  10  is shown in  FIGS. 14–17 . In this embodiment a cannula handle  132  has an outwardly curved body  134  mounted on the cannula  112  with a stem extension  136  extending away from the curved body  134  surrounding the proximal end of the cannula  112 . This stem extension  136  of the handle stiffens the cannula  112  so that there is less flexing of the cannula  112  when it is penetrating through the cortical bone for the reasons previously mentioned. The stem  136  is also provided with annular gripping rings  135  cut into the body of the stem to provide a better gripping surface for the surgeon. The curved body  134  has two extending substantially identically formed curved wings  137  and  138  which serve to allow grasping by the fingers of the surgeon&#39;s hand on the underside of the wings. The contours of the section are designed to provide a stable balanced grip on the handle. 
   The body  134 , stem  136  and the upper lateral end wings  137  and  138  are preferably formed from a single molded piece of plastic having a composition the same as that previously disclosed above in the preferred embodiment. A Luer lock  120  or associated cannula hub is molded to the proximal end of cannula  112  and serves to secure the cannula  112  to the stylet  150  in a conventional Luer lock grip. The Luer lock  120  extends upwardly into a recess  139  defined between the wings  137  and  138 . 
   The stylet  150  has a shaft  152  with the distal tip  154  of the stylet extending beyond the distal end  113  of cannula  112  when it is fully inserted in the cannula. The stylet can have the same point structure as shown in  FIGS. 9–12 . A stylet handle or knob  160  is secured to the other end of the stylet to the stylet anvil member  156 . The anvil member  156  is constructed with a cylindrical body which sits in the recess  139  between the wings and a cylindrical locking assembly  164  which extends over the Luer lock  120 . The locking assembly  164  defines a central chamber  166  and locking pins (not shown) which fit over the Luer lock  120  extending between the wings  137  and  138 . The wings shelter between them the Luer lock  120  which is molded onto the cannula. When the stylet knob  160  has been received by the cannula Luer lock the detent ribs or pins overlap the shouldered projection of the Luer lock to enclose the Luer lock. The upper surface of the knob body is provided with a striking surface  170  which can be a tapped with a hammer to drive the stylet into the bone. The stylet should be very stiff and have a very sharp edge with a large diameter cannula to reduce the resistance of the marrow draw. 
   In the operation of the instrument of this invention, the instrument is grasped in the physician&#39;s hand and is introduced through an incision, through the soft tissue toward and into contact with bone structure being tapped, usually the posterior iliac spine. Gentle tapping of the anvil should set the stylet and cannula into the bone so that it does not skid or walk when it is implanted on the iliac crest as some patients have dense bone which makes it difficult to initially pierce. The surgeon slowly advances the stylet and cannula through the cortical bone, millimeter by millimeter by tapping gently on the stylet striking surface. Tapping on the top of a molded plastic handle which attached to the aspiration needle reduces the tactile feedback. It is thus better to have a metal striking surface which would provides a much better striking surface. The striking surface of the present invention allows transmittal of the force to the stylet tip more efficiently and provides precise tactile and audible feedback. Pushing or drilling into the pelvic bone with a tool always presents the possibility of trauma and in older patients that may have a thin cortical bone, it is possible to accidently puncture a structure if the instrument passes through quickly. The surgeon is thus able to feel passage through cortical bone which is an important characteristic of the present invention. The cannula and stylet are advanced into the marrow cavity. Once the marrow cavity has been reached, the stylet is removed. Deep penetration of the cannula into the marrow cavity does not product quality aspirate as deeper penetration generally will produce a thinner aspirate. The surgeon then rotates the tip of the cannula to help draw out aspirate. A syringe plunger is attached to the Luer connector on the cannula handle and bone marrow is withdrawn into the syringe plunger to remove the quantity of bone marrow desired. This procedure can be repeated as many times as is necessary to remove the desired amount of bone marrow which the surgeon believes is necessary for the procedure. When the instrument is to be withdrawn, the handle is grasped by the physician under the wings and pulled out of the incision area. 
   The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification However, the invention should not be construed as limited to the particular embodiments which have been described above. Instead, the embodiments described here should be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the scope of the present inventions defined by the following claims.

Technology Classification (CPC): 0