US 3428045 A
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Description (OCR text may contain errors)
Feb. 18, 1969 H. KRATZSCH ETAL 3,428,045
SURGICAL INSTRUMENT FOR SKIN GRAFTING Sheet Filed Nov. 1, 1966 INVENTOR. fikzvlaTL/fiaizx 59/26/ 13? Feb. 18, 1969 H, KRATZSCH ETAL 3,428,045
SURGICAL INSTRUMENT FOR SKIN GRAFTING Filed Nov. 1, 1966 Sheet 2 of 2 IN VEN TOR5 xikzvzd 1.134523? 3 @626 #1572232;
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United States Patent Ofice 3,428,045 Patented Feb. 18, 1969 7 Claims This invention relates to instruments for removing sections of skin for use in performing skin grafts, and more particularly to an instrument of the type disclosed in United States Patent No. 2,457,772 .upon which it is an improvement. The instrument disclosed in the aforesaid patent comprises generally a pair of opposite side members connected by a fixed foot plate adapted to ride upon the surface of the subjects skin, a pressure plate or guide bar mounted between the side members forwardly of the forward edge of the foot plate, and cutting means comprising an oscillatory cutting element whose cutting edge is presented forwardly of the forward edge of the foot plate, and cutting means comprising an oscillatory cutting element whose cutting edge is presented forwardly of the forward edge of the foot plate and rearwardly of the pressure plate, the pressure plate being adjustable toward and away from the plane of the lower surface of the foot plate and in parallelism with the edge of the latter, for the purpose of varying the depth of cut or, in other words, the thickness of the layer of skin to be removed. In such an instrument it is essential that the guide bar or pressure plate be maintained in exact parallelism with the forward edge of the foot plate, and in the construction disclosed in the aforesaid patent this is accomplished by the same means employed for adjusting the pressure plate relative to the plane of the foot plate. That is, there is an adjusting screw operative upon either end of the pressure plate and in adjusting the level of the pressure plate to vary the thickness of cut, it is also necessary that both ends be carefully adjusted to preserve the afore said parallelism.
A principal object of the present invention is to provide improved means both for calibrating the pressure plate, i.e., fixing its parallelism with the pressure plate as well as its zero position in the plane thereof, and for adjusting the pressure plate relative to the foot plate to vary the thickness of cut. More specifically, it is an object of the present invention to provide, in a dermatome of the type defined above, pressure plate supporting and adjusting means comprising a rigid framework pivotally supported between the slide members rearwardly of the forward edge of the foot plate, separate calibrating means adjustably supporting each end of the pressure plate on the said framework, and separate and single means for causing pivotal movement of the framework to vary the position of the pressure plate relative to the forward edge of the foot plate.
An additional object is the provision of separate means for locking each of the said calibrating means to the end that, once the required calibration is achieved, it will be maintained regardless of the elevation of the pressure plate relative to the foot plate, which may be varied as desired through separate and single adjusting means.
A further object is the provision of adjusting means including a casing pivotally supported on one of said side members, a threaded member extending into said casing and into engagement with a second threaded member within said casing, which second threaded member operatively engages the pivoted framework supporting the pressure plate, whereby rotation of the first threaded member c auses pivoting of said framework, said casing being allowed a slight pivotal movement to accommodate the arcuate movement of the second threaded member about the pivotal axis of said framework, and the corresponding angular movement of said first threaded member.
Another object is the provision, in an instrument having adjusting mechanism as described in the preceding paragraph, of means supporting the first threaded member on said casing for rotation without axial movement, and supporting said second threaded member within said casing for axial movement without rotation.
A still further object is the provision, in adjusting means as described in the preceding paragraph, of means limiting the axial movement of said second threaded member, for the purpose of confining the area of adjustability of said pressure plate relative to said foot plate.
A still further object is the provision, in an instrument of the character described, of a manually operable turning means fixed to the upper end of the first threaded member and inscribed with-graduations, and a cooperating index carried by the side member to which said casing is pivotally attached.
Other and further objects, features and advantages will be apparent from the description which follows, read in connection with the accompanying drawings, in which:
FIGURE 1 is a plan view of the cutting head of an instrument made according to the invention, the handle portion being shown in abbreviated fashion;
FIGURE 2 is a side elevation of the instrument seen in FIGURE 1;
FIGURE 3 is a front elevation of the forward portion of the instrument, with a part broken away for clarity;
FIGURE 4 is a section, on an enlarged scale, taken on line 44 of FIGURE 1;
FIGURE 5 is an elevation of the adjusting mechanism separated from the side member to which it is norm-ally attached;
FIGURE 6 is a section on line 66 of FIGURE 1;
FIGURE 7 is a section on line 7--7 of FIGURE 1;
FIGURE 8 is a section on line 88 of FIGURE 2, on an enlarged scale; and
FIGURE 9 is a fragmentary perspective view of one corner of the pressure plate supporting framework.
In order to facilitate an understanding of the invention, reference is made to the embodiment thereof shown in the accompanying drawings and detailed descriptive language is employed. It will nevertheless be understood that no limitation of the invention is thereby intended and that various changes and alterations are contemplated such as would ordinarily occur to one skilled in the art to which the invention relates.
Referring now to the drawings, the main frame 10 of the instrument comprises side members 11 and 12 which may be integral with a transverse member 13, the side members 11 and 12 being connected by a fixed foot plate 14 having a thin forward edge 15, the foot plate 14 being silver soldered or otherwise permanently secured between the side members 11 and 12 and being tapered downwardly in its forward portion to provide the thin forward edge 15. The side members 11 and 12 are further connected by rods 1.6 and 17 which support in a sliding fashion the oscillatory blade support 18 which may be driven in oscillating movement by any suitable means which form no part of the present invention. The blade support 18 carries a blade 19 secured thereto by bolts 20 in proper registry with the support 18 as determined by pins 21 which extend through and closely fit within corresponding apertures in the blade 19. As seen in FIG- URE 6, the forward edge 19' of blade 19 lies forwardly of the forward edge 15 of the foot plate 14.
A framework 22 pivotally supported on the rod 16 comprises opposite side members 23 and 24 connected by a rearward transverse member 25 and a forward transverse member 26, the side members 23 and 24 having thickened portions of bosses 23', 24' at and near their junction with the rearward transverse member 25 to provide additional bearing surface for engagement upon the rod 16. The entire framework comprising the members 23-26 is adapted to move angularly about the rod 16 to a limited degree.
As best seen in FIGURES 4, 6 and 7, a guide bar or pressure plate 27 is supported from the forward transverse member 26 of the framework 22 by means of calibrating screws 28 which extend through suitable apertures in the reduced portions 27' at the respective ends of the pressure plate 27 and through threaded apertures in the transverse member 26. The pressure plate 27 is restrained from axial movement relative to the screws 28 by means of flanges 28' integral with the screws 28 and engaging the upper surface of the pressure plate 27 at each end, and washers, including a spring lock washer 29 interposed between the lower surf-ace of pressure plate 27 and the head 30 of screw 28. Adjustment of the pressure plate 27 relative to the member 26 is achieved by rotation of the screw 28 by means of a suitable tool-engaging recess 31 in the upper end of screw 28. After the position of the pressure plate 27 is accurately adjusted the adjusting mechanism is locked by tightening the screws 32 to flex the split end portions 26 (FIG. 9) of the member 26 downwardly so that the threads of the respective screws 28, which extend through both the main body 26 and the split portions 26', are tightly gripped to prevent turning of the screws 28. The locking screws 32, of course, extend through unthreaded apertures in the split portions 26' and into threaded apertures in the body portion of the transverse member 26.
The pressure plate 27, after being locked in calibrated position relative to the member 26 and thus becoming a fixed part of the framework 22, may be raised and lowered through pivotal movement of the framework 22 by means now to be described. A hollow casing 33 (FIGS. and 8) is mounted to the side member 12 by means of a pivot pin 34, the recess 33' within the casing 33 opening toward the side member 12. Within the recess 33' there is provided a hub 35 having a threaded aperture in which is engaged the adjusting screw 36. The hub 35 is provided with a flange 35' having sliding engagement against the adjacent surface of the side member 12, and with a cylindrical trunnion 38 which extends through a slot 37 in side member 12 and into a corresponding cylindrical aperture in the side member 24 of the framework 22, where it is secured by means of a screw 39. The adjusting screw 36 is restrained against upward movement relative to the casing 33 by means of integral flange 40 and is provided at its upper end with a knurled head 41 which is locked to the screw 36 by means of lock nut 42 the latter also serves to prevent downward movement of the screw 36 relative to the casing 33 so that the latter is restrained against axial movement in either direction relative to the casing 33, while being permitted to rotate therein, the bearing portion 36 of screw 36 having sliding engagement with the wall of a corresponding aperture in the upper end of casing 33.
As the screw 36 is rotated by turning the knurled head 41, the hub 35 will of course move upwardly or downwardly within the recess 33', carrying with it the trunnion 38 and the framework 22. Upward movement of the hub 35 is limited by the upper end of the slot 37 in the side member 12 while downward movement of the hub 35 is adjustably limited by means of a threaded stop member 43 extending through a threaded aperture in the lower end of casing 33. The range of movement of the hub 35 is so limited as to permit of a desired range of movement of the pressure plate 27, relative to the foot plate 14. The upper surface of knurled head 41 is inscribed with graduations (FIG. 1) for cooperation with an index 12 carried by side member 12, for use in adjusting the instrument to perform as desired by the surgeon.
It will be understood that as the framework 22 pivots 4 about the rod 16, the hub 35 will necessarily describe a small arc of relatively long radius, which movement is permitted by the pivotal mounting of the casing 33 upon the side member '12 by means of the pivot pin 34.
While forming no part of the present invention, it should be mentioned that the width of the skin section to be taken by means of the instrument of the present invention is controlled by means of adjustable guide plates 44 one on either side of the instrument which underlie the blade 19 and the foot plate '14, and are slidably mounted on rods 45 and 46 (FIG. 3) which extend between side plates 11 and 12 at the forward ends thereof. The guide plates 44 are adjustable toward and away from each other by means of right-hand and left-hand screw threads, respectively, formed on a rod 47 rotatably mounted between the rods 45 and 46 and having a knurled head 48 at one side of the instrument, all as described in US. Patent No. 2,457,772.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. In a dermatome of the type comprising opposite side members connected by a fixed foot plate having a forward edge, a pressure plate mounted between said side members forwardly of said edge of said foot plate for vertical adjustment relative to and in parallelism with said edge, and means presenting an oscillatory cutting element forwardly of said edge and rearwardly of said pressure plate, supporting and adjusting means comprising (a) a rigid framework pivotally supported on and between said side members rearwardly of said edge of said foot plate,
(b) separate calibrating means adjustably supporting each end of said pressure plate on said framework, and
(c) means for causing pivotal movement of said framework to vary the position of said pressure plate relative to said foot plate edge.
2. A device according to claim 1, including separate means for locking each said calibrating means.
3. A device according to claim 1, said means for causing pivotal movement comprising a first threaded member rotatably supported on one of said side members and engaging a second threaded member operatively connected to said framework.
4. A device according to claim 3, including a casing pivotally secured to said one side member, said first threaded member extending within said casing and into engagement with said second threaded member, said latter member being movable within said casing, and means restraining said first threaded member against longitudinal movement relative to said casing.
5. A device according to claim 4, said last means comprising a stop member integral with said :first threaded member and abutting a downwardly facing interior surface of said casing and a second stop member secured on said first threaded member outside said casing and abutting an upwardly facing exterior surface thereof.
6. A device according to claim 3, including means for limiting the movements of said second threaded member in either direction relative to said first threaded member.
7. A device according to claim 3, including a manually operable turning means fixed to the upper end of said first threaded member and inscribed with graduations, and a cooperating index carried by said one side member.
References Cited UNITED STATES PATENTS 2,457,772 12/1948 Brownet al 128 -305 FOREIGN PATENTS 774,689 5/1957 Great Britain.
L. W. TRAPP, Primary Examiner.