Abstract:
An automatic skin biopsy device that includes a drive unit and a variety of shapes and sizes of disposable cartridges. The device is capable of automatic extraction of a small and precisely located portion of skin having a shape similar to a wide canoe. A disposable cartridge is mounted onto and driven by the drive unit which incorporates at least one gear motor. In a preferred embodiment the gear motor in the drive unit drives, via gears and cams, two cutter blades in the disposable cartridge through separate curved paths to extract from the skin the generally wide canoe-shaped skin sample. Preferably another gear motor via gear and cam action produces back and forth oscillation of the blades to assure easy slicing of the skin tissue. The canoe-shape incision that is about 1 to 4 mm deep produces a good biopsy sample and the incision is easily closed with a medical staple or sutures. In preferred embodiments a stapler is provided as a part of the sample acquisition device. Materials used to fabricate the driver and the cartridge preferably transparent to permit accurate placement of the incision.

Description:
[0001]     This invention is related medical devices and in particular to automated skin biopsy devices.  
       BACKGROUND OF THE INVENTION  
       [0002]     A typical prior art method of obtaining a skin biopsy sample is to use a scalpel to incise a skin section in the general shape of an ellipse down through the epidermis and dermis Forceps are used to lift up the elliptical skin section and a cut is made under it to complete the excision. The practitioner then inspects the wound for completeness of the excision, cauterizes it for the control of bleeding if necessary and then sutures the incision site closed with one of various types of suture material or he may use a staple gun to close the incision site. Alternatively, the practitioner may employ punch biopsy devices such as Sterile Disposable Biopsy Punches, Model 33-35, that are available from MedicalMailOrder.Com with offices in Bangor, Me. These devices allow the practitioner to use a circular hollow shaped blade that cuts a circular hole in the skin by using a twisting motion of the hand. The biopsy is then lifted out and a scalpel is used to cut underneath the circular-shaped incision to free it from the subcutaneous tissues. Again after cautery the incision is separately closed.  
         [0003]     The cosmetic results from these techniques depend upon the surgical training of the practitioner and the strict adherence to plastic surgery skin handling and suture techniques which are taught during surgical residency training. However, the vast majority of biopsies are in fact done by family practice physicians, dermatologists and internists whose abilities to perform surgery vary considerably.  
         [0004]     The time that a biopsy takes with conventional techniques requires a surgical set-up that includes a sterile drape, a sterile forceps, scissors and scalpel and suture package. Quite often this requires a medical assistant or a nurse to participate in the procedure, package the biopsy, send it to a pathology laboratory and re-sterilize the instruments in order to prepare for another biopsy during the day.  
         [0005]     At present there are approximately 91,000 skin biopsies done in the U.S. on a daily basis, with about 13,000 registered dermatologists each averaging seven per day. Additional biopsies are performed by other medical entities. The need for biopsies will certainly increase as sun-exposure continues to be the main cause for the development of skin cancers of various varieties (squamous cell and basal cell carcinomas and malignant melanomas) and the fact that more people are living longer so that the consequences of sun-damaged skin are being realized.  
         [0006]     What is needed is a device to automatically collect skin biopsy samples in a quick, simple, consistent manner.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention provides an automatic skin biopsy device that includes a drive unit and a variety of available disposable cartridges that have different blade dimensions to suit the application . The device is capable of automatic extraction of a small and precisely located portion of skin having a shape similar to a wide canoe or ellipse. A disposable cartridge is mounted onto and driven by the drive unit which incorporates at least one gear motor. In a preferred embodiment the gear motor in the drive unit drives, via gears and cams, two cutter blades in the disposable cartridge through separate curved paths to extract from the skin the generally ellipse-shaped skin sample. Preferably another gear motor via gear and cam action produces back and forth oscillation of the blades to assure easy slicing of the skin tissue. The ellipse-shape incision that is about 1 to 4 mm deep produces a good biopsy sample and the incision is easily closed with a medical staple or sutures. In preferred embodiments a stapler is provided as a part of the sample acquisition device. Materials used to fabricate the driver and the cartridge preferably transparent to permit accurate placement of the incision.  
         [0008]     Preferred embodiments are hand held and battery powered. With a press of a button the first motor initiates motion of the curved blades contained in the disposable sterile cartridge so that the blades while oscillating back and forth move first downward into the skin then inward toward each other to under cut the biopsy sample so that the sample is freed from the body and is contained within the cartridge. The cartridge, with the biopsy tissue safely enclosed within it, can then be ejected into a pathology specimen container either with formalin or without depending upon the requirements of the pathologist and practitioner. The practitioner may then cauterize the wound as needed and either use the attached staple gun to quickly close the skin edges or employ routine suturing techniques depending upon his/her preference. Preferred embodiments include large numbers of single use cartridges with several differing blade lengths, cut widths and depths, and curve shapes to accommodate larger lesions or requirements to extract samples of various sizes and shapes. There are instances when complete excision of a lesion is required and alternatively there are times when an incisional biopsy is preferred; thus having the option of different blade dimensions and configurations meets both of these requirements. Important advantages of the present invention is that it saves time, provides a biopsy result superior to punch biopsies and cosmetic results generally equivalent to those obtained by a well-trained and experienced surgeon. This entire procedure takes less than three seconds to complete the entire excision. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a overall illustration of a preferred embodiment of the present invention.  
         [0010]      FIGS. 2A through 4  show drive mechanism details.  
         [0011]      FIGS. 5 through 9 F show sample cartridge details.  
         [0012]      FIGS. 10A, 10B  and  10 C show a cut pattern in skin produced by a preferred embodiment.  
         [0013]      FIG. 11  shows a stapling configuration.  
         [0014]      FIGS. 12A and 12B  show the sample cartridge and its package  
         [0015]      FIG. 13A through 16  and  FIGS. 18, 19A  and B show details of stapler and its operation.  
         [0016]      FIG. 17A through 17E  represent a moving picture of a blade actuation.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     First Preferred Embodiment  
       [0017]     A preferred biopsy assembly of the present invention is shown in  FIGS. 1A, 1B ,  1 C and  FIG. 2A, 2B , and  2 C. It includes: (1) a drive unit  2  shown in  FIG. 2A , (2) a large number of disposable biopsy cartridge assemblies  1 , one of which is shown in detail in  FIGS. 6 through 9 F and (3) a stapler unit shown at  11  shown in  FIG. 2D  and shown in detail in  FIGS. 13A through 16 .  
         [0000]     Drive Unit  
         [0018]     The preferred drive unit  2  includes electronic controls  9 , battery unit  8 , blade drive gear motor  3 , drive gear  5 , stapler drive gear motor  10 , oscillator drive motor  4 , oscillator drive pulley  27 , oscillator drive belt  12  and drive oscillator cam  6  with cam finger  6 A.  
         [0000]     Disposable Biopsy Cartridge Assembly  
         [0019]     Preferred disposable biopsy cartridge assembly  1  shown in  FIG. 5  includes cam drive gear  21  driven by drive gear  5  in drive unit  2 . The cartridge also includes oscillator block  19  with finger slot  19 A into which cam finger  6 A fits and produces a back and forth oscillation of block  19  and blades  18 A and  18 B as well as all of the other components shown in  FIG. 8E . The direction of the back and forth oscillation is indicated by double arrow  19 B in  FIG. 8E . In a preferred embodiment the extent of the back and forth oscillation is about 0.2 mm. The turning of cam drive gear  21  in cartridge  1  by blade drive unit  2  causes blades  18 A and  18 B as shown in  FIG. 9B  to first move in a downward direction slicing into the skin with the back and forth oscillation produced by oscillator cam  6 . After the blades have cut into the skin to a predetermined depth within the range of about 2 to 4 mm, the continued rotation of gear  21  and cam action of cam  17 A and  17 B causes blade  18 A and  18 B to cut inward toward each other to cut under the skin section and to trap the biopsy sample within the blades as they move to their closed position. Five sequential positions of one of the blade and other cartridge components are shown in  FIGS. 17A through 17E .  
         [0000]     Stapler Unit  
         [0020]     The first preferred embodiment of the present invention also includes stapler unit  10  as shown in  FIG. 2B and 2C  and in detail in  FIG. 13, 14 ,  15 ,  16  and  18 . The stapler cartridge  11  snaps into the drive unit  2 , and a tab in the end of stapler coupling  26  as shown in  FIG. 2A  engages stapler shaft engagement slot  46 A as shown in  FIG. 13A . Stapler coupling  26  couples the stapler shaft to stapler drive motor  10  in drive assembly  2 . The stapler is used to close the wound after the sample has been extracted.  
       Mechanical Operation of the Device  
       [0021]     A sterile cartridge assembly  1  is removed from its package  24  as shown in  FIG. 12 , under sterile conditions and inserted into the driver assembly  2  as shown in  FIGS. 1A, 1B  and  10 . The insertion engages gear  5  in drive unit  2  as shown in  FIG. 3  with the cam drive gear  21  in cartridge  1  as shown in  FIG. 5 . Drive unit  2  comprises electromagnetic coils  7  as shown in  FIG. 3 . Control electronics  9  are configured such that the pressing the cartridge release  15  once will activate the cartridge retaining electromagnetic coils  7  which will hold the cartridge in its place in the drive  2  by attracting the ferrous metal discs  26  on the sample cartridge  1  as seen in  FIG. 5 . Cartridge assembly  1  is located, by a medical operator who is intending to obtain a skin sample, over a previously prepared skin location (such as one containing a lesion) from which a sample is required. When the operator presses the control switch  14  shown in  FIG. 1  on the driver assembly  2  the control electronics  9  as shown in  FIG. 2  receives a start signal, causing the gear motor  3  and oscillation gear motor  4  to begin to rotate their rotors. The output shaft of gear motor  3  is attached drive gear  5  and all begin to rotate with the rotor of gear motor  3 . Drive gear  5  is engaged with the cam drive gear  21  in cartridge  1  as shown in  FIG. 5  when cartridge  1  is attached to the driver assembly as explained above. As cam drive gear  21  begins to turn, it rotates its attached cam drive shaft  20  as shown in  FIG. 8B  and blade actuation cam  17 A and also partial gear  17 A( 1 ) which is an integral part of cam  17 A as shown in  FIG. 8B . Gear teeth on partial gear  17 A( 1 ) are meshed with teeth on a second partial gear  17 B( 1 ) on cam  17 B to rotate the two cams at the same speed in the opposite direction. As the cams rotate, they begin to force the two identical blades  18 A and  18 B down toward the skin surface, guided by slots  30  in the cartridge  1 . At this time the blades are approximately perpendicular to the skin surface as shown in  FIG. 9B  and  FIG. 17A . At the time the blade drive gear motor  3  begins to turn, oscillation drive gearmotor  4  as shown in  FIG. 3 , with its attached oscillation drive pulley  27  starts to rotate. Pulley  27  rotates the oscillation drive belt  12  which rotates the oscillation cam  6 . Finger  6 A shown in  FIG. 4  on oscillation drive cam  6  is engaged in slot  19 A in the oscillation block  19  in the cartridge assembly  1  at the time the cartridge is attached to the driver assembly. The oscillation cam rotates, at a speed of 200 to 600 rpm in the preferred embodiment, causing the entire interior component set of the cartridge assembly  1  shown in  FIGS. 8A through 8F  to oscillate back and forth a distance of about 0.1 to 0.5 mm (preferably about 0.2 mm). The back and forth oscillation is preferably in a direction indicated at  19 B in  FIGS. 8E  along the long axis of the proposed canoe shape cut to impart a rapid short slicing action to the blades. As the blades come in contact with the skin surface, they will begin to slice into the skin normal to the surface as shown in  FIG. 17A, 17B  and  17 C. When the blades reach to bottom of their guide slots  30 , as shown in  FIG. 17C , a second surface on each cam will come into contact with mounting arms  34 A and  34 B on the blades as shown in  FIG. 9D , forcing the blades to start to rotate toward each other as shown at  36  in  FIG. 17D . The cut is completed when the blades come together and slightly overlap, as shown in  FIG. 9D  and as indicated in  FIG. 17E  cutting the sample free. The sample is thus trapped inside the cartridge, requiring no operator contact. A detent (not shown) on each blade control cam will act to hold the blades in the closed position so as to positively retain the tissue sample. The cut will have produced a skin sample with a cross section similar to the shape of a canoe section and the cut shape and approximate dimensions as shown in  FIGS. 10A, 10B  and  10 C with dimensions of width, depth, and length being defined by the specific cartridge selected. In the preferred embodiments a variety of cartridges are provided with cut depth preferably ranging from about 2 mm to about 4 mm.  
       Electronic Control  
       [0022]     All the power and timing come via the control electronics module  9  shown in  FIG. 2 , which is connected to battery  8  and a wire harness not shown. Sensors are provided to mark the rotational position of the drive gear  5  and the presence of the cartridge  1 . Cartridge case  15  is provided with internal walls to protect the drive assembly from possible blood contamination. The interior of the drive unit is further protected by flexible seals (not shown) at the motor shafts. The drive assembly is designed for easy cleaning as it is not a disposable item. Should blood contamination occur, the cavity in the driver assembly  2  wherein the cartridge is installed may be rinsed out by any appropriate means using denatured alcohol, betadine, distilled water or the unit may be gas-sterilized.  
       Detailed Description of Stapler Unit  
       [0023]     Stapler unit  11  is shown in  FIG. 2B and 2C  and in detail in  FIG. 13, 14   15  and  16 . Drive shaft  46  is integral with the fold cam  43 , position cam  46 , and foot actuation cam  47 . The points of the first-in-line staple in preformed stapler stack  49  are positioned typically about 2 mm from each edge of the gap in the skin left by the removal of the biopsy sample. Pressing the stapler control switch  16  in  FIG. 1B  will start stapler drive gear-motor  10  turning, which turns the cams and initiates stapler operation. As seen in  FIG. 13A, 13B , and  13 C, when the cams rotate the fold cam  43  contacts pusher  41  which slides in a slot in base rear  40 . Tabs on pusher  41  contact the two pinch arms, pusher arms  42 A and  42 B. At the same time position cam  46  pushes pin holder  44  and its integral pin  50  down toward the bottom of the stapler, carrying the pinch arms  42 A and  42 B along with it. Pusher arms  42 A and  42 B pivot around pin  50 . The pinch arms  42 A and  42 B contact the first-in-line preformed staple  49  and push the staple  49  out of stapler case  54  as shown in  FIG. 16  and into the patient&#39;s skin. Staple  49  is spread in its initial form to allow skin entry outside of the open skin incision. As the staple is folded to the shape shown in  FIG. 14A  and further skin penetration occurs, the staple pulls of the edges of the incision together to close the wound left by the removal of the biopsy sample.  
         [0024]     The staple  49  is pushed into the skin until it contacts foot  48 , which stops the progress of the staple  49 . The pinch arms  42 A and  42 B continue to rotate, bending the staple  49  to the folded staple configuration  51 . The staples  49  may be pre-scored to ease the folding operation. When the folding action is completed continued turning of the foot actuation cam  47  pulls the foot actuator  45  up forcing a tapered tang at the bottom of the foot actuator  45  to work on a similar tapered surface on the foot  48  to pull the foot  48  out from the folded staple  51 , allowing the stapler to be removed from the patient with the staple in place as shown in  FIG. 11 . As the cams continue to turn the foot  48  is pushed back into the start position through action of the foot actuation cam  47  and the foot actuator  45 . The other components return to their start positions under the influence of return springs (not shown). A spring in the cartridge (not shown) acts upon the stack of staples  49  to push the next staple into the ready position.  
         [0025]     The stapler cartridge  11  is conceived as a single-patient disposable unit, with inexpensive, mostly molded plastic component and a small number of staples to minimize opportunities for contamination of other patients and medical personnel. After use on its patient the stapler cartridge  11  may be snapped out of the drive assembly  2  and discarded in a suitable sanitary receptacle.  
         [0026]     Staples may be removed from the patient as shown via use of a tool having a three-pronged configuration as shown in  FIG. 19A and 19B . The shape of the staples and their removal tool will minimize tearing of the patient&#39;s tissue at removal.  
       General Description of Excision Operation  
       [0027]     The forward portion of the body of cartridge  1  is preferably molded of clear plastic and is transparent so the operator can see clearly through it to achieve a precise location for the incision. The sample shape as shown in  FIGS. 10, 10A  and  10 B is similar to the plan view of a canoe, with dimensions similar to those shown in the figures. Other patterns can be obtained depending on the cartridge selected. The operator presses the cartridge lightly and evenly against the skin and presses the sample trigger control switch  14 . The sample is taken in 1 to 3 seconds. It is trapped inside the cartridge at the end of the cycle. The operator then lifts the sampler away from the skin with the sample trapped in the cartridge. The wound shape is ideal for best closure, most effective healing, and minimal scarring. Using a stapler  10  that in the preferred embodiment is incorporated in the driver  2  as shown in  FIG. 1 , the operator closes the wound.  FIG. 11  shows the preferred position of two staples to close the wound. The operator places the cartridge back into its package  24 , which has been maintained in a sterile condition, and presses the cartridge release switch  15 . The cartridge drops back into its sterile seat in the package and the package is closed and sealed with closure  28 . The package may then be stored or transferred to a laboratory for analysis. Alternatively, the cartridge may be ejected directly into a pathology specimen container filled with a tissue fixative, such as formalin.  
       Removal of Sample and Wound Closure  
       [0028]     When the incision has been completed and the sample is trapped inside the cartridge the sampling system is lifted from the skin. The cartridge may be placed back inside its sterile package or in some other suitable container at the discretion of the operator by pressing the cartridge release switch  15  to shut off power to the cassette retention electromagnets  7  to allow the cartridge to release from the driver assembly. The operator may then close the wound using the stapler  11  built into the driver assembly, a separate stapler, stitches, or other methods as determined by the operator.  
       Clean-Up  
       [0029]     The cartridges and their packaging are expected to be single-use, disposable items. The cartridge package  24  is preferably equipped with cartridge locating and seating package base and a snap-on package closure  25  to maintain an internal sterile condition prior to use and after re-insertion of the cartridge with the skin sample inside. Removal of the cover allows the cartridge to be installed on the driver assembly with no operator contact being required. Re-installation of the cartridge into the package also will not require any operator contact except for replacement of the package cover.  
       Removal of Sample from Cartridge  
       [0030]     At the analysis laboratory, the sample may be removed from the cartridge as follows: The cartridge package  24  is opened either under sterile conditions when microbiological analysis is needed or under non-sterile conditions. Cartridge  1  is removed from the package by lifting it from its seat holding only the cartridge body  22 . The skin sample is removed from the cartridge by holding the cartridge&#39;s central section over an appropriate receptacle and simultaneously rotating cam drive gear  21 , which rotates the two cutters  18  to allow the skin sample to drop out of the cartridge into the laboratory receptacle. The cartridge and its package may then be discarded in an appropriate waste container.  
       Performance Features  
       [0031]     Performance features of this preferred embodiment include the following:  
         [0000]     General:  
         [0000]    
       
         
           
              Curved cut pattern for best closure and healing scenario.  
              Cut shape and size variable by using different cassettes.  
              Disposable cassette; clean, single use.  
              Single cut produces sample: 2 blades make tailored motion to achieve the desired cut shape.  
              Blades are retracted in cassette, extend automatically to start cut, stop at a central location at the end of the cut to trap sample.  
              Battery powered, no wires.  
              Integrated with stapler for efficient motion.  
              Rapid action: about 1 to 3 seconds to generate a sample  
              Staples and actuation system located in a disposable cartridge.  
              Option of adding a light source at the point of excision for improved illumination 
 
 Sample Cartridge: 
 
              Cut shape best for staple closure, best healing configuration.  
              Sterile, single use.  
              Sealed in package, eject into sterile package container after sample is taken.  
              Multiple cut size and depth ranges for cassettes.  
              Snap in place on driver.  
              Metal or molded plastic cut blades.  
              Traps sample inside at end of cut  
              2 Blades cut simultaneously, guided in slots and by cams to rotate into skin to make the cut and capture the sample.  
              Lightweight, almost all components made from molded plastic.  
              Designed to protect driver unit and operator from blood contamination. 
 
 Driver Unit: 
 
              Convenient size and shape for hand hold.  
              Battery inside.  
              Lightweight, mostly plastic construction.  
              Small dc gear motor drives cutters.  
              Small dc motor or gearmotor drives blades oscillation  
              Small dc gearmotor drives stapler  
              Small solenoids to retain and release the cartridge electromagnetically.  
              No contact with patient.  
              Clean, no lubrication required.  
              Light emitting diode optional 
 
 Stapler Cartridge 
 
              Sterile, disposable, single patient use.  
              Sealed in package with sample cartridge.  
              Integral staple forming components.  
              Initially spread staples to pull wound edges together.  
              Lightweight, almost all components made from molded plastic.  
           
         
       
     
       Staple Removal  
       [0067]     Staples can be removed after the wound has healed using a prior art three prong staple removal tool. A two edge prongs slide under the top portion of the staple and the center prong is positioned over the top of the top portion of the staple. Downward pressure of the center prong causes the staple points to spread apart from each other and the legs of the staple to pull out of the skin.  
         [0068]     While the present invention has been described above in terms of a preferred embodiment, persons skilled in the medical arts will recognize that many changes, alterations and additions can be made to the described device. For example, a simpler design could eliminate the back and forth oscillation of the blades and the medical stapler does not have to be incorporated in or attached to the driver, in fact as indicated the wound can be closed with stitches. While transparency of the cartridge is desirable, it is not absolutely necessary. Other obvious techniques are available for accurate placement of the cartridge on the skin. While battery power is desirable, wall power with an electrical connection is an obvious alternative and carries with it some obvious advantages, such as the unit could be lighter without the battery. Batteries used may be standard disposables or rechargeable types. The cartridge retention and release can be effected by a simple latch mechanism rather than through use of electromagnetic coils. The oscillation drive may be direct rather than via belt, but clear vision for proper placement of the sample cartridge on the patient may be compromised. There may be situations where users would prefer that the cartridge be reusable, such as to obtain several samples from the same person. Further, it should be stressed that the outer package of the driver device may be configured to fit ergonomically to the hand of the practitioner and these electronics and gears described herein would be placed into such a plastic form. Therefore, the reader should determine the scope of the invention from the appended claims and not the examples that have been given.