US2590299A

US2590299A - Apparatus for removing human skin for grafting purposes

Info

Publication number: US2590299A
Application number: US50096A
Authority: US
Inventors: Douglas Beverly
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-09-20
Filing date: 1948-09-20
Publication date: 1952-03-25
Anticipated expiration: 1969-03-25

Description

March 25, 1952 v B. DOUGLAS 2,590,299

APPARATUS 'FOR' REMOVING HUMAN SKIN FOR GRAF'IIING PURPOSES Filed Sept. 20, 1948 3 SheetsSheet 1 March 25, 1952 I a. DOUGLAS 2,590,299

APPARATUS FOR REMOVING HUMAN SKIN FOR GRAFTING PURPOSES Filed Sept. 20, 1948 3 Sheets-Sheet 2 49:51 66 7 2/ 5. i I C 1/5 -4 95 March 25, 1952 B. DOUGLAS 2,590,299

APPARATUS FOR REMOVING HUMAN SKIN FOR GRAFTING PURPOSES Filed Sept. 20, 1948 3 Sheets-Sheet 3 Patented Mar. 25, 1952 UNITED STATES PATENT OFFICE APPARATUS FOR REMOVING HUMAN SKIN FOR GRAFTING PURPOSES 16 Claims.

This invention relates to an apparatus for removing human skin for grafting purposes.

As is well known, it has been the common practice for many years to remove patches or areas of skin from a patient to replace skin areas which are not healed over, for example in the case of severe burns. Devices employed for removing such areas of skin have been in numerous forms, none of which have been wholly satisfactory. For example, in the most practicable type of such device of which I am aware, a cutting blade has been arranged adjacent and parallel to a cylinder and has been reciprocated by hand to out to a predetermined depth to remove the skin areas which are caused to adhere to the cylinder by an adhesive. It is impossible in device of such character to. hand-reciprocate the blade with such steadiness of movement that the blade isreciprocated in accurate lines lying in a common plane so as to remove the skin patches uniformly. Moreover, difilculty is encountered in such devices in removing the separated skin from the cylinder due to the use of the adhesive employed for causing the skin to adhere to and be picked up by the cylinder as the latter progresses over the skin area being detached as the blade advances.

Animportant object of the present invention is to provide a device of the character referred to wherein the cutting blade is automatically reciprocated by power, thus providing accurate and uniform blade reciprocation without the inaccuracies necessarily attendant upon manual operation of the blade.

A further object is to provide a device of this character wherein the separated skin lap is picked up and effectively held against a cylinder through the medium of automatically controlled vacuum thus causing the skin lap to be effectively held on the cylinder without the use of an adhesive.

A further object is to provide such a device wherein the cylinder is perforated over all or at least a portion of its circumference to permit the I vacuum to be utilized for causing a skin lap of substantial area to be picked up and held by the cylinder, and to so control the application of the vacuum to the perforations as to prevent the loss of vacuum through the opening to the source of vacuum of perforations to which no skin is adhering by applying vacuum progressively to the perforations around the cylinder as such perforations are called upon to cause the skin to adhere to the cylinder.

A further object is to provide a device of this character wherein an automatically reciprocating vacuum-operated motor is connected to the cut- 2 ting blade to cause the latter to be automatically reciprocated, and to utilize the cylinder as a housing for the vacuum motor.

A further object is to provide novel vacuum manifold control means, connected to the same source of vacuum which operates the motor, for progressively connecting lines of vacuum apertures in the cylinder with the source of vacuum as the device advances in its operation to thus provide the necessary vacuum means for holding the detached skin areas against the cylinder.

A further object is to provide spring means operative for tending to rotate the cylinder to advance it over the skin, thus eliminating the necessity for manually pulling the device to rotate the cylinder in contact with the skin as the cutting operation progresses.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the drawings, I have shown one embodiment of the invention. In this showing,

Figure 1 is a perspective view of the device,

Figure 2 is an elevation of one end of the device,

Figure 3 is an elevation of the opposite end of the device. a

Figure 4 is a longitudinal sectional view through the device taken substantially axially thereof, parts being broken away and parts being shown in elevation,

Figure 5 is a transverse vertical sectional View on line 5-5 of Figure 4,

Figure 6 is a sectional view on line 6-6 of Figure 4,

Figure? is a detailed perspective view of the vacuum motor manifold ring and the adjacent cylinder head and associated elements,

Figure 8 is a fragmentary detailed perspective view of a portion of one of the blade supporting arms and associated elements, and

Figure 9 is a detailed perspective view of the motor cylinder and blade reciprocating shaft, the valve snap-over arm for the motor being shown separated therefrom.

Referring to Figures 4 and 5, the numeral l0 designates a preferably cast cylinder having a head I I at one end thereof which may be formed integral therewith and a separate head I2 is provided for the opposite end of the cylinder and these heads project radially outwardly beyond the cylinder as shown in Figure 4. A relatively thin cylinder l4 surrounds and is concentric with the cylinder l0 and is provided substantially throughout its area with relatively small perforations [5. The cylinder l4 surrounds and is supported by radially outstanding ribs I6 preferably formed integral with the cylinder H) as shown in Figure The cylinder head II is provided in its outei face with an annular groove and ports 2i communicate between the groove 29 and the spaces or chambers 22 provided between adjacent walls or ribs [6 and defined by such ribs and between cylinders Ill and I4. Each opening 2| communicates with one of the chambers 22 as will be apparent in Figure 6. The head II is provided with an outwardly extending hub 24, and a stationary plate 25, preferably substantially equal in diameter to the head ll, surrounds the head 24 and closes the manifold groove 20. Apipe 26 (Figure 4) extendsthrough the plate 25 to communicate at all times with the groove 26 and the pipe 26 is connected to a suitable source of Vacuum. A boss 21 (Figure 6) is carried by the plate 25 and is normally initially arranged in the position shown in Figure 6 adjacent the pipe 26. The plate 25 being stationary, it necessarily follows that the boss 21 also is stationary and as the cylinders l0 and I4 rotate in a counter-clockwise direction as indicated by the arrow shown in Figure 6 and as further described below, the boss 21 moves relatively away from the pipe 26 and progressively uncovers the openings 2| to successively connect the chambers 22 to the pipe 26 through the groove 29.

A cap 36 (Figures 1, 2, 4 and 7) is arranged at the other end of the cylinder and is provided with an annular flange 3| fitting within the head I2. At circumferentially spaced points, the cap '30 is secured to the head I! by screws 32 which extend through the cylinder I0 from end to end thereof, thus anchoring the cylinder l9 and the heads H and I2 together as a unit.

The cap 36 is provided with an outwardly extending hub 35 (Figure 4), and

hubs

24 and 35 serve as bearings for a shaft 36 the ends of which extend substantially beyond the bearings. Within the cylinder I0 is. arranged a vacuum motor indicated as a whole by the numeral 38. This motor comprises a cylinder 39 parallel to and offset from the axis of the cylinder l0 and shaft 36 as shown in Figure 5. Spaced pistons 40 are arranged in the cylinder 39 and are connected by piston rod 4| to the center of which is connected a transverse pin 42 extending laterally through a slot 43 in the cylinder 39. This pin is connected to the? shaft 36 as shown in Figure 5, and reciprocation of the pistons 40 in a manner to be described effects reciprocation of the shaft 36. The motor cylinder 39 may be supported in any suitable manner in the cylinder 10, for example by screws 45.

A valve mechanism indicated as a whole by the numeral 48 controls reciprocation of the motor pistons 46. Inasmuch as the motor 38 and its valve mechanism 48 form no part per se of the present invention, they need not be completely illustrated in detail. This motor and valve mechanism may be of the type conventionally employed to operate motor vehicle windshield wipers. Generally speaking, the valve mechanism comprises a body 49 supported in any suitable manner in the cylinder ID, for example by a bracket 50. The body 49 supports a shaft 5| parallel to and arranged beneath the pin 42. The shaft 5| has fixed thereto an upwardly extending fork 52 engaging the pin 42 to be rocked thereby through the reciprocation of the piston 'rod 4|.

The outer end of the shaft 5| carries a depending finger 55 having an inwardly extending finger 56 (Figure 5) successively engageable with lugs 51 carried by a valve plate 58. The finger 56 engages a ring 59 connected to one end of an off-center spring 66. The upper end of this spring is connected to a frame 6! fixed to the valve body 49. The valve body 49 is provided with ports 62 connected to the end of the cylinder 39 by pipes 63. The mechanism for operating the valve plate 58 successively uncovers the ports 62 to the interior of the cylinder [0 while the other port is connected by a groove 64 in the valve plate 58 to a port 65 to which a vacuum pipe 66 (Figure 4) is connected.

The vacuum pipe extends through the cap 36 as shown in Figure 4 and communicates with a manifold groove 10 formed in a ring 1| adapted to remain stationary during rotation of the cap 30 and cylinder [0, the annular groove 16 serving to connect the pipe 66 to the source of vacuum, as will be described, in any relatively rotated positions of the cap 30 and ring I l. The groove 10 (Figures 2 and '7) communicates with a pipe 12 fixed at one end to the ring H and having its other end tapped into the vacuum pipe 26. The latter pipe may be connected by a suitable flexible hose 13 to any desired source of vacuum.

A nut 15 (Figure 4) is threaded on the hub 24 and a similar nut 76 is threaded on the hub 35 in spaced relationship to the ring ll. Suitable expansion washers 11 are arranged between the nut 76 and ring H to exert endwise pressure against the latter to fit it in leakproof engagement with the cap 30 and to maintain the plate 25 in similar leakproof engagement with the cylinder head ll. It will be noted that a collar 18 is interposed between the nut 15 and plate 25, thus preventing endwise movement of the plate 25 and rendering the expansion washers 17 effective for maintaining the leakproof engagement between the plate 25 and cylinder head II.

The collar 78 sets loosely on the hub 24 and remains stationary with the plate 25 as the hub 24 rotates therewithin. Obviously the nut 15 rotates with the hub 24. For the purpose of adjusting the relatively rotated position of the collar 18 with respect to the plate 25, the collar 18 is provided with an arcuate concentric slot 19 (Figures 3 and 8) and a screw 80 extends through this slot and is threaded into the plate 25.

The shaft 36 is provided at its ends with arms and 86, the latter of which is provided with a slit portion 81 surrounding the shaft 36 and fixed in position relative thereto by a clamping screw 88. The arm '85 is fixed to the adjacent end of the shaft .36 in any suitable manner (not shown). The purpose of the slit collar 8'! is to permit accurate adjustment of the arm 86 relative to the arm 85 for a purpose which will become apparent.

A blade guard 99 is fixed to the lower ends of the

arms

85 and 36 in any suitable manner, for example by screws 9| (Figure 4). Above this guard is arranged a cutting blade 92 having aforwardly extending cutting edge 93. This blade is maintained in position by screws 94 threaded through bosses 95 preferably formed integral with the

arms

85 and 86. It will be apparent that the blade 92 is reciprocated by the shaft 36 through operation of the motor 38 to advance beneath the skin to be severed in a sliding or shearing action thus making a clean out.

Spring means are provided for tending to rotate the cylinders l0 and i4 during the operation of the apparatus. end anchored as at IOI to the arm 86 and its other end fixed to the nut I6 as at I02. This spring, when wound, tends to rotate the cylinder I4 in contact with the skin. Similar torsional forces are delivered to certain parts of theapparatus by e, torsion spring I04 arranged at the opposite end of the mechanism. This spring has one end fixed as at I05 to the nut I5 which rotates with the hub 24. The collar 18 is provided with parallel longitudinally extending fingers I06, and the other'end of the spring I04 is fixed to the end of one of these fingers as at I01 (Figure 4). The arm 85 is provided with inwardly extending parallel fingers I08, and as will be clear from Figure 8 of the drawings, each finger I08 engages and slides longitudinally of one of the fingers I06 during reciprocation of the shaft 36. This tends to maintain certain parts of the mechanism in proper relationship as will become apparent below. This relationship is adjustable by changing the position of the'fingers I06 (Figure 3) by loosening the screw 80, turning the collar 18 to the desired position, and then tightening the screw.

A handle III) is provided for the device. This handle has parallel end portions III and H2 which are preferably slit as shown in Figures 2 and 3 and respectively surround the collar 18 and cap 30. The handle ends are rotatable relative to the elements which they surround so as to assume a vertical position as in Figure 1 or an angular position, as may be desired during the operation of the apparatus.

As previously stated, the severed skin is adapted to be held in contact with the cylinder I4 by vacuum in the chambers 22. It is preferred that the end of the skin flap be initially severed and connected to the cylinder l4. To this end, the cylinder I4 and the adjacent portions of the head I2 are longitudinally grooved as at II5 (Figure 6) at the point in the cylinder I4 which will be adjacent to blade 92 at the point where initial operation of the apparatus is started. Within this groove are arranged a plurality of skinpiercing points H6 adapted to project through A torsion spring I00 has one and thus positively engage the initially severed Preparatory to the removal of an area of skin,

the area desired will be measured and marked. While the cylinder I4 is of substantial length and accordingly adapted to pick up a patch of skin of equal width, an area of this size is not always desired. Cellulose tape or the like will be wrapped around the cylinder I4 at the ends thereof with a space therebetween equal to the desired width of the skin, which has been marked as stated. Therefore, the perforations I5 lying outwardly of the desired width of skin to be picked up will be covered and accordingly will exert no vacuum effect on the skin outwardly of the marked area.

A cut will be made through the skin at the end which is to be first picked up and the skin will be manually cut therebeneath to provide a short flap. A suitable long slender implement will then be inserted under such flap and the present device will be placed in position with the groove II5 lying over the severed end of the skin area to be picked up. The implement inserted beneath the skin flap will then be moved upwardly to force the flap into the groove H5 and toward the left end thereof as viewed in Figure 6 to cause the pick-up points II6 to penetrate the skin and thus tightly engage it ready for the operation of the device. Thus the skin flap will be positively engaged at the beginning of the operation of the present device.

A suitable valve (not shown) in the line I will be opened to supply vacuum to the device. The line 13 communicates through th pipe 26 with the groove 20 at the point indicated in Figure 6. The pipe 26 will communicate through the adjacent opening 2I with the corresponding chamber 22. The remaining openings will be blocked to communicate with the pipe 26 by the valve lug 21, which will initially occupy the position shown in Figure 6.

The pipe 12 is tapped into the pipe 26 and thus ,connects the valve mechanism of the motor 38 with the vacuum source through pipe 66 (Figure 4) and groove '10. In accordance with the conventional operation of a vacuum motor of the type illustrated, the snap-over valve mechanism 43 will so function that one port 62 will always be in communication with the interior of the cylinder I0 while the other port 62 will communicate with the vacuum port 65 (Figure 5) at the end of the pipe 66. One end of the cylinder 39 thus will always be connected to the source of vacuum while the other end is connected to the atmosphere. The interior of the cylinder 50 will be maintained at atmospheric pressure through any suitable means (not shown) such as a bleed port through the cap 30, etc. In the position of the parts shown in Figure 4, the valve plate 58 will have just snapped to the position shown to connect the left hand end of the cylinder 39 to the source of vacuum with the opposite end of the cylinder opened to the atmosphere. Thus the pistons 40 will be moving to the left as viewed in Figure 4 and the pin 42 (Figure 5) will transmit such movement to the shaft 36 to move the

arms

35 and 86 in the same direction and correspondingly move the blade 92. The cutting edge 93 accordingly is caused to partake of a shearing cutting action.

When the pistons 40 reach their left hand limit of movement, the spring 60 will cause the valve plate 58 to snap over to its other position, thus connecting the right hand end of the motor cylinder 39 to the source of vacuum and venting the left hand end to the atmosphere. It will be obvious that the blade 92 accordingly is caused to reciprocate during the operation of the device, and as described below, the cylinders) and I4 will roll over the surface of the skin, rotating on the axis of the shaft 36.

The rolling action of the cylinders may be effected manually by the operators holding the handle H0 at an angle from the vertical toward the left as viewed in Figures 3 and 5. The device is fully operative in this manner but it is preferred that the tension of the spring I00 be depended upon to effect rotation of the cylinders I0 and I4. To this end, the operator, prior to placing the device in position to begin its operation, will turn the cylinder I4 manually in a clockwise direction as viewed in Figure 3 to tension the springs I00 and I04, the function of the latter of which is referred to below. Under such conditions, the principal resistance to rolling movement of the cylinder I4 over the skin will result from the engagement of the cutting edge 93 with the tissue beneath the skin. This resistance is constantly being minimized or progressively eliminated, however, through the reciprocation of the blade in its sliding or shearing action. As the cutting progresses, resistance to turning movement of the cylinder I4 will b progressively reduced, thus permitting the torsion spring It!) to roll the cylinder [4 over the skin. The use of the spring I is much preferred over manual rolling of the cylinder since it is automatic in operation, the rolling takin place only as resistance to the rolling movement is progressively decreased as the cutting act progresses. If the cylinder 14 is rolled by hand, the operation is somewhat more awkward and there is a tendency for the operator to roll the cylinder too rapidly for the skin with the result that the skin will not be as smoothly and uniformly cut.

The spring 100 is connected at one end at It! to the arm 86, which is relatively stationary, and

the other end of the spring is connected at N52 to the nut is to transmit a torsional force through the bearing 35 to the rotatable parts of the apparatus. Such parts rotate, during operation, in a counter-clockwise direction as indicated by the arrow in Figure 6, the reaction forces of the spring on the pin iti being opposite, of course, and tendin to advance the blade toward the left. Thus the spring maintains two forces tending to operate the device in the manner stated. The screw 86 (Figure 3) is loosened and the collar 1% turned to bring the fingers I05 into contact with the fingers 58, and during the reciprocation of the blade and the parts connected thereto, the fingers E08 slide back and forth'longitudinally in contact with the fingers Hi6 thus causing the plate 25 (Figure 4) to maintain a constant position relative to the cutting blade. The relative advancing of the plate 25 with respect to the cylinder I9 is assisted by the torsion spring Hi, the reaction force of such spring overcoming friction between plate 25 and cylinder ii] and thus reducing the necessity for the performance of all of the work by the spring I00.

As the cylinder 54 rolls over the skin and the cutting action progresses, the vacuum in the initial chamber 22, that is the chamber with which the pipe 26 directly communicates in the initial stage of operation as indicated in Figure 6, will hold the severed skin in firm contact with the cylinder Ht. As the cutting progresses, the valve block 21 will move beyond the next port 2 I, thus opening the second chamber 22 to the source of vacuum. The skin out by the blade opposite such second chamber 22 accordingly will be firmly held in contact with the cylinder hi. This operation progresses for the full length of the area of skin to be cut, the chambers 22 being progressively opened to the source of vacuum as needed for the picking up and holding of the skin.

If the valve block 2'1 were not employed, the groove would act as a manifold connecting all of the chambers 22 to the source of vacuum. Under such conditions, all of the perforations l5 would be uncovered and the volume or" air fiowing into the chambers 22 and through the pipe 26 would be so great as to substantially destroy the necessary vacuum effect for holding the skin. The proper and necessary vacuum accordingly is maintained by connecting the chambers 22 to the source of vacuum only as they are needed, and the skin lying against the perforations l5 communicating with the chambers which are connected to the source of vacuum prevents the flow of air into such chambers and accordingly prevents any appreciable drop in vacuum. In this connection, it will be noted that the adjustment provided by the screw 80 is for the purpose of so positioning the plate and valve block 2? by operation of the fingers a ure 6) at the proper times.

Hi5 and IE8 as to open successive ports 2i (Fig- Accordingly the device will automatically progress over and sever the desired marked area of the skin and the skin readily may be severed when the end of the area is reached by manually rolling back the cylinder I4 to expose the line at the end of the skin area for the severance thereof from the body. The device then may be removed from the patient and the vacuum in the operative chambers 22 will hold the skin firmly against the cylinder I4. There will be no adhesion of the skin to the cylinder I l except through the medium of the vacuum, and when the vacuum is out 01f, the skin may be easily raised from the cylinder [4 ready for the grafting operation.

From the foregoing, it will be apparent that the operation of the present device is fully automatic, the vacuum motor causing the blade automatically to slide back and forth to smoothly and uniformly shear the desired skin area from the patient. While the device may be moved by hand over the desired skin area, the use of the spring means is highly desirable since the reaction forces provided thereby tend to advance the blade in its cutting operation while advancing the cylinder 14 over the skin. It has been found that an extremely smooth and uniform cutting operation thus may be performed.

The device is readily adapted for cutting either rectangular or irregular skin areas, as may be desired. Where an irregular skin area is to be removed, a desired pattern will be marked on the skin and on a broad piece of adhesive equal in length and width to the cylinder I l. The patterned area then may be cut from the adhesive and the latter wrapped around the cylinder 14. The area of the cylinder thus exposed will correspond exactly to the area of the skin to be out. One end of such area as represented by the adhesive will be arranged at the groove I I5 and the device will be placed at the corresponding point where the skin is to be cut, it being understood, of course, that an initial flap will have been cut and attached to the points HG.

Attention also is invited to the fact that the cutting blade will sever only those portions of the skin held in direct contact with the cylinder M. The cellulose tape surrounding the cylinder [4 to define the area or pattern to be cut will be of appreciable thickness and the skin over which it rolls not only will be spaced from the cylinder l4 by the thickness of the adhesive but the covering of the perforations l6 by the adhesive will eliminate any tendency to hold toward the cylinder Hi any areas outwardly of the pattern which are not to be cut. Accordingly the device will operate so that the blade will sever all skin within the pattern area but will slide over the skin outside such area.

I claim:

1. A device for removing skin for grafting purposes, comprising a cutting blade for cutting the skin area to be grafted, a plurality of vacuum chambers having a common wall of cylindrical form over and adjacent said blade and perforated for communication with said chambers, means rotatably supporting said wall whereby successive perforations thereof approach said blade, and means for connecting said chambers successively to a source of vacuum as the perforations of said wall associated with successive chambers approach said blade whereby skin severed by said blade will be held by vacuum in contact with said wall.

2. A device for cutting skin areas for grafting purposes, comprising a cutting blade mounted for endwise movement, means for effecting endwise reciprocation of said blade to out progressively beneath the skin area to be removed, a cylindrical perforated wall adapted to roll over the skin area adjacent said blade as the latter is severed by said blade, means forming a series of chambers within said wall whereby a plurality of the perforations in said wall will communicate with each chamber, said wall being mounted in proximity to and rotatable on an axis parallel to said blade whereby said wall and said chambers progressively advance past said blade as said wall rolls over the skin area, and means for successively connecting said chambers to a source of vacuum as they approach said blade whereby the severed skin will be held by vacuum against said wall.

3. A device for severing skin for grafting purposes, comprising a blade mounted for endwise movement, a reciprocating motor connected to said blade to reciprocate it endwise to advance it in cutting relation beneath a skin area to be removed, and vacuum means adjacent said blade for picking up and holding the skin as it is progressively severed by said blade, said vacuum means comprising a housing in which said motor is arranged.

4. A device for severing skin for grafting purposes, comprising a blade mounted for endwise movement, a reciprocating motor connected to said blade to reciprocate it endwise to advance it in cutting relation beneath a skin area to be removed, a cylindrical wall adjacent said blade mounted for rotation on its axis with such axis parallel to the cutting edge of said blade, means within said wall forming a plurality of chambers adapted to be moved successively into proximity to said blade as said wall rotates, said wall having a plurality of perforations communicating with each chamber, and means successively connecting said chambers to a source of vacuum as they approach said blade whereby said perforations are adapted to pick up the skin by vacuum and hold it against said wall as the skin is progressively severed by said blade.

5. A device constructed in accordance with claim 4 provided with torsion spring means acting oppositely against said blade and said wall to tend to advance the cutting edge of said blade beneath the skin area to be cut and to rotate said wall on said axis to cause said wall to roll over the skin area being cut.

6. A device for severin skin areas for grafting purposes, comprising a cylinder having radial walls projecting outwardly therefrom, a cylindrical wall surrounding said radial walls and forming with said radial walls and with said cylinder a plurality of substantially segmental chambers, a blade having a cutting edge parallel to the axis of said cylindrical wall and arranged in proximity thereto, means for reciprocating said blade endwise thereof, said cylindrical wall being adapted to turn on its axis'to roll over the skin area being cut by said blade, said cylindrical wall having perforations communicating with each of said chambers, and means for connecting said chambers to a source of vacuum as they successively approach said blade whereby vacuum actin through said perforations will pick up and hold the skin against said cylindrical wall as the skin is progressively severed by said blade.

'7. A device constructed in accordance with claim 6 wherein the means for reciprocating said blade comprises a vacuum motor connected to said source and housed within said cylinder.

8. A device constructed in accordance with claim 6 wherein the means for reciprocating said blade comprises a vacuum motor connected to said source, a shaft on which said cylinder is mounted and arranged axially thereof, said shaft being connected to said vacuum motor and said blade being connected to said shaft.

9. A device for severing skin areas for grafting purposes, comprising a cylinder having radial walls projecting outwardly therefrom, a cylindrical wall surrounding said radial walls and forming with said radial walls and with said cylinder a plurality of substantially segmental chambers, a blade having a cutting edge parallel to the axis of said cylindrical walland arranged in proximity thereto, means for reciprocating said blade endwise thereof, said cylindrical wall being adapted to turn on its axis to roll over the skin area being cut by said blade said cylindrical wall having perforations communicating with each of said chambers, said cylinder having a head rotatable therewith and provided with a manifold groove in its outer face and with an opening communicating between said groove and each of said chambers, said groove having a point therein adjacent said blade connected to a source of vacuum, and means for connecting successive of said openings with said groove as the associated chambers approach said blade whereby vacuum acting through said perforations will pick up and hold the skin area as, it is severed by said blade.

10. A device for severing skin areas for grafting purposes, comprising a cylinder having radial walls projecting outwardly therefrom, a cylindrical wall surrounding said radial walls and forming with said radial walls and with said cylinder a plurality of substantially segmental chambers, a blade having a cutting edge parallel to the axis of said cylindrical wall and arranged in proximity thereto, means for reciprocating said blade endwise thereof, said cylindrical wall being adapted to turn on its axis to roll over the skin area being cut by said blade, said cylindrical wall having perforations communicating with each of said chambers, means for connecting said chambers to a source of vacuum as they successively approach said blade whereby vacuum acting through said perforations will pick up and hold the skin against said cylindrical wall as the skin is progressively severed by said blade, and

' spring means acting oppositely with respect to said cylindrical wall and said blade to tend to advance the cutting edge of said blade beneath the skin area and to turn said cylindrical wall to cause it to roll progressively over the skin area as it is severed.

11. A device for severing skin areas for grafting purposes, comprising a cylinder having radial walls projecting outwardly therefrom, a cylindrical wall surrounding said radial walls and forming with said radial walls and with said cylinder a plurality of substantially segmental chambers, a blade having a cutting edge parallel to the axis of said cylindrical wall and arranged in proximity thereto, means for reciprocating said blade endwise thereof, said cylindrical wall being adapted to turn on its axis to roll over the skin area being cut by said blade, said cylindrical wall having perforations communicating with each of said chambers, spring means acting oppositely with respect to said cylindrical Wall and said blade to tend to advance the cutting edge of said blade beneath the skin area and to turn said cylindrical wall to cause it to roll progressively over the skin area as it is severed, and valve means for connecting said chambers successively to a source of vacuum as they approach said cutting edge.

12. A device for severing skin areas for grafting purposes, comprising a cylinder having radial walls projecting outwardly therefrom, a cylindrical wall surrounding said radial walls and forming with said radial walls and with said cylinder a plurality of substantially segmental chambers, a blade having a cutting edge parallel to the axis of said cylindrical wall and arranged in proximity thereto, means for reciprocating said blade endwise thereof, said cylindrical wall being adapted to turn on its axis to roll over the skin area being cut by said blade, said cylindrical wall having perforations communicating with each of said chambers, spring means acting oppositely with respect to said cylindrical wall and said blade to tend to advance the cutting edge of said blade beneath the skin area and to turn said cylindrical wall to cause it to roll progressively over the skin area as it is severed, said cylinder having a head at one end provided with an annular concentric groove in its outer face and being provided with a port communicating between said groove and each of said chambers, a plate arranged over said head and covering said groove, a vacuum connection extending through said plate and communicating with said groove at a point therein adjacent the cutting edge of said blade, and a valve block carried by said plate and fitting said groove whereby rotation of said cylinder causes said block to travel relatively around said groove to connect the successive ports of said chambers to said vacuum connection as successive chambers approach said blade.

13. A device for severing skin for grafting purposes comprising vacuum means including inner and outer walls defining a chamber, said outer wall having at least a portion thereof formed as a section of a cylinder and being perforated to pick up and hold the skin, a blade mounted for endwise reciprocation and supported for movement transverse to its cutting edge concentric with the axis of said portion of said outer wall, and a motor in said inner wall having mechanical connection with said blade to reciprocate it.

14. A device for severing skin for grafting purposes comprising vacuum means including inner and outer walls defining a chamber, said outer wall having at least a portion thereof formed as a section of a cylinder and being perforated to pick up and hold the skin, a shaft coaxial with said portion of said outer wall and supporting said vacuum means for turning movement on the axis of said shaft, said shaft being endwise reciprocable relative to said vacuum means, a blade supported by said shaft and having a cutting edge parallel to the axis of said shaft, and a motor in said inner wall connected to said shaft to transmit reciprocating movement to said blade through said shaft.

15. A device for severing skin for grafting purposes comprising vacuum means including inner and outer walls defining a chamber, said outer wall having at least a portion thereof formed as a section of a cylinder and being perforated to pick up and hold the skin, a blade mounted for endwise reciprocation and supported for movement transverse to its cutting edge concentric with the axis of said portion of said outer wall, a motor in said inner wall having mechanical connection with said blade to reciprocate it, and means exerting a force tending to turn said blade about said axis in a skin severing direction.

16. A device for severing skin for grafting purposes comprising vacuum means including inner and outer walls defining a chamber, said outer wall having at least a portion thereof formed as a section of a cylinder and being perforated to pick up and hold the skin, a shaft coaxial with said portion of said outer wall and supporting said vacuum means for turning movement on the axis of said shaft, said shaft being endwise reciprocable relative to said vacuum means, a blade supported by said shaft and having a cutting edge parallel to the axis of said shaft, a motor in said inner wall connected to said shaft to transmit reciprocating movement to said blade through said shaft, and torsion spring means between said vacuum means and said shaft tending reversely to rotate them relative to said axis whereby said portion of said outer wall tends to roll over the skin and a force is transmitted to said blade to tend to move it in a skin severing direction.

BEVERLY DOUGLAS.

REFERENCES CITED The following references are of record in the :file of this patent:

UNITED STATES PATENTS Eidam Sept. 30, 1947