US2636495A - Dermatome - Google Patents

Description

T. R.' ARDEN nmmom aA-pril 2s, 19153 Filed April 2e. 195o I: @WMM 1'. la ARD'EN DERMATOLE April 2s, 1,9353

Patented Apr. 28, 1953 UNITED STATES PATENT OFFICE DERMATOME Thomas R. Arden, New Fairfield, Conn., assignor to Bard-Parker Company, Inc., Danbury, Conn., a corporation of New York Application April 26, 1950, Serial No. 158,168

8 Claims. (Cl. 12S-305) 1 This invention relates in general to surgical instruments and more especially to a device of the type used for cutting skin grafts.

In particular, the present invention relates to an improvement in the type of skin-graft cutting instrument disclosed in the patents to Reese Nos. 2,479,185 and 2,479,260 of August 16, 1949, and identified as dermatomes. These instruments embody a body member having a convex working surface to which a skin-graft transfer element is adapted to be temporarily but tautly secured; and a graft-cutting blade which is carr'ied Aby a yoke supported, in turn, by the body member for rotation relative thereto in substantially spaced parallel relationship for eXcising a skin graft from a donor surface. In the performance of this operation, considerable care and attention must be exercised by the surgeon as the blade approaches the end of the working surface of the body member, lest the blade override the latter and gouge deeply in to the donor surface. Moreover, there is always present the very real danger that in overriding the working surface of the body member, the surgeon may cut his own wrist with the blade. Also, it has been found that a similar danger exists when applying a skin-graft transfer element such asi for eX- ample, a sheet of Dermatapa to the body mem-,- ber preparatory to excising a skin graft; and when removing the excised skin graft and Dermatape from the body member, since in both instances it is necessary for the surgeon to reach over or across the blade-carrying yoke of the dermatome.

An object of the present invention is to provide a superior dermatome by which skin-grafting operations may be performed rapidly, skillfully and without danger of injury to the donor surface or to the operating surgeon.

A further object of the invention is to provide a dermatome with superior stop means for provide a dermatome with stop means to stop the rotation of the blade relative to the body member of the dermatome after swinging through an arc in excess of 360.

A still further object of the invention is to provide a dermatome with coupling means in the bearing structure of the body member for stopping the rotation of the blade in either direction Y relative to the body member, after swingin through an arc in excess of 360. f

In general the present invention involves providing a vdermatome of the type disclosed in the aforementioned Reese patents with coupling means to limit the relative rotation between the cylindrical body member or drum and the blade I carrier at a position adjacent the end of the skingraft operation and to permit the blade carrier to be swung through an arc in excess of 360 in the opposite direction past this limit. This overcomes any danger of the blade overriding the cy lindrical surface of the dermatome during the cutting operation and, in so doing, accidentally cutting the wrist of the surgeon. Furthermore,-

ter to swing through an arc in excess of 360 in` either direction. Moreover, 'it has been found most desirable to locate the coupling means in the hinge or pivotal connection between the drum and blade carrier. i

Other objectscand advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, vin which cer-'- tain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a perspective view of a dermatome em-V bodying theimproved stop means of this invention for limiting the angle of rotation of the blade-carrying yoke relative to the body member of the dermatome, the latter being shown supported on a stand, the base of which is partly broken away;

Fig. 2 is a front elevation partly in section of l the bearing structure of the body member of the dermatome, showing' details of the improved stop means of this invention;

Fig 3 is anend elevation in section of the bearing structure on line 3 3 of Fig. 2;

Fig. iis Van enlarged perspective view of a;l

second stop sleeve of the improved stop` means of this invention, the second stop sleeve having a stop lug projecting from one end thereof;

Fig. 7 is a schematic end elevation of the body member of the dermatome, showing by broken lines the position of the blade-carrying yoke when engaged against the rest of the supporting stand, and by full lines theposition of the:

yoke when resting against the back of the surgeons wrist preparatory to excising a shin graft;y

Fig. 8 is a broken front elevation of the imf proved stop sleeves together with a portion of-V the shaft, showing the relative positions of the stop lugs when the yoke is in its full-line posi-V tion of Fig. 7;

Fig. 9 is an enlarged fragmentary perspective view of the stop sleeves of Fig. 8, but with the shaft omitted;

Fig. 10 is a schematic view similar' to Fig. 7, but showing the blade-carrying yoke by full lines at the end of its cutting or skin-graft eX- -cising swing, the broken-line position of the yoke corresponding to its full-line position of Fig. '7;

Fig. l1 is a view similar to Fig. 8, but showing. the lugs of the stop sleeves in their respective positions when the yoke is in its full-line position of Fig. 10;

Fig. 12 is an enlarged fragmentary perspective view of the stop sleeves of Fig. 1l, with the shaft omitted, but viewing the same from a different angle from the showing of Fig. 9;

Fig. 13 is a schematic view similar to Figs. 7 and 10, but showing the yoke by full lines at the terminus of its movement in a clockwise direction as seen in Fig. 1 3, from its normal position against the rest of the supporting stand;

Fig. 14 is a view similar to Figs. 8 and 11, but showing the lugs of the stop sleeves in their relative positions when theblade-ca-rrying yoke is its full-line position of Fig. 13; and

Fig. 15 is an enlarged fragmentary perspective view of the stop means of Fig. 14 similar to Figs. 9 and 12, but viewing'the same at a different angle.V A

Referring now to Vthe drawings Vfor greater detail, and in particularvto Fig. l, the reference character Ztl indicates in its entirety a dermatome embodying the improvedestop means of thisinvention. The reference character 2'! indicates the stand on which the dermatome i's mounted, either when it is not in'use, or when a skin-graft transfer element is being applied to or removed from the dermatome, in the man'- ner hereinafter described. The aforesaid stand 2l comprises a substantially rectangular Ybase plate 22 having at one side an upstanding post 23 whichcarries a dermatome-mounting'rod 2-4 arranged to project outwardly laterally therefrom in vertically spaced substantially parallel relationship to the base plate 22. Projecting laterally from the 'post 23 in vertically spaced relationship above the mountingrod 24 and toward the yback of the stand, is al relatively short finger or stud 25, which vis vadapted tc project into anaperture in the corresponding'side plate of the dermatome when the latter lis-mountedon the aforesaid mounting rod, ito prevent `the dermatome from rotating thereon. A suitable latch 26 is provided above the stud 25 for releasably engaging the adjacent side plate of the dermatome, to prevent the latter from accidentally sliding laterally on of the counting rod 24 of the stand. In addition to these principal elements of the stand, the upstanding post 23 includes al backstop or rest 2'1- for lsupporting the `blade'-carrier or bladeecarrying yoke 'of the dermatome. Inasmuch as other details of the stand are ancillary to the invention, further description thereof is deemed unnecessary.

The body member of the derni-atome is indicated.' generally at 23 and comprises a pair of spaced parallel side plates 29 and 39 respectively substantially semicircular in shape and joined along their curved edges by a concavoconvex bottom plate 3l. In a preferred construction; the sides of the bottom plate 3| are joined integrally with the corresponding edges of the sid-e plates l29 and B'respectively as, for example, by forming the body member -by a casting. It will be appreciated however, thatv the side plates and 4the bottom plate of the body .-member may be formed as separate elements.

and joined togetherrby suitable fastening means.

The side plates include upwardly extending ears 32 and 33 respectively having openings '34 and 35 respectively therethrough, whose centers .coincide with the center of revolution of the which. also serves to support the blade-carrying yoke 35 which, as hereinafter described, is rnou'ntn ed so asvto have reciprocatory movement as well as rotational movement relative to the body member. Referring especially to Fig. 2, the bearing structure of the body member includes a substantially cylindrical supporting sleeve 3l', the opposite ends of which are reduced in diameter to form shouldered ends adapted to engage in the apertured ears V32 and 33 respectively of the correspondingside plates of the body member, andl to be iixedly secured therein against rotation by" brazed joints or requivalent fastening means. Formed in the leftnhand end of the supporting sleeve 31, as seen in Fig. 2, are internal threads which are adapted to be engaged by the external threads of a flangedV bushing 33 which projects into the corresponding end of the supporting' sleeve 3l from the outer face of' the'corresponding ear 32. The flanged bushing 39 at the opposite end'of the supporting sleeve S''constitut'es one of a plurality of elements 'having coordinated stop surfaces for limiting the rotary movement "of the clade-carrying yoke 35 relative to the body member and, in this capacity, is provided with an unstop-lug ill which constitutes van l'embossnfient 'on' the Aend of the sleeve portion tl) of the'lang'ed bushing 39, is iixedly located in the supporting sleeve 37 of the body member in `predetermined relationship vtoet-he -rear edge 42 thereof (Fig. fl)

so that, as used in conjunction 'with 'the-other;

'stop""sleeves'= hereinafter described of the Vstop means, the stop lug 4l will serve to stop the bladecarrying yoke 36 during its cutting swing, substantially at the rear edge 42l of the body. member. Referring again to the threaded bushing 3,8- in the left-hand end of the supporting sleeve 31, as viewed in Fig-2, the inner end of the bushing .38 is kerfed, as indicated at.43, so that by inserting a suitable tool in the supporting sleeve from the right hand thereof into engagement with the kerfed end of the left-hand bushing 38, the'latter may be tightened up. The cylindricalsupporting sleeve 31 also serves as a handle forsupporting the dermatome when excising a skin graft and,..to this end, may be knurled to provide. a good gripping surface. .z

Journaled in the flanged bushings v38 and;39 respectively of the supporting sleeve or handley31 for both rotary and reciprocatory movement'relative tothe body member 28, is a shaft-.44., the right-hand end of which is provided with an P- eratinghandle 45 by means of which the shaft 44 may be simultaneously rotated and reciprocated in the flanged bushings of the sleeve 31. In order to prevent improper assembly of the shaft in the supporting sleeve and the resultant malfunctioning of the stop means, the shaft 44 is constructed so that it may be assembled in the supporting sleeve 31 from its right-hand end only, and to this endthe left-hand end of the shaft 44 is reduced in diameter, as at 46, to provide an annular shoulder 4l. Since the internal diameter of the left-handbushing 38 is substantially equal to the reduced portion 46 of the shaft, and hence less than the diameter of the annular shoulder 41 of the shaft, the latter can be assembled in the supporting sleeve only by introducing its reduced end 46 into the right-hand bushing 39, the internal diameter of which corresponds substantially to the diameter of the unreduced portion of the shaft, the latter thus being free to extend into the supporting sleeve until the annular shoulder 41 of the shaft abuts the inner kerfed end of the flanged bushing 38. Extending longitudinally of the shaft 44 from its annular shoulder 41 toward its right-hand end, is a keywayA 48 which serves tolock a stop sleeve of the improved stopmeans of this invention to the shaft, as and fori the purpose hereinafter described. Y The shaft 44 mounts the yoke 36 which carries the cutting blade of. the dermatome, the yoke comprising a pair of spaced parallel'arms 494-49, having at their free ends apertured` hubs '5U-50 adapted to be mounted-on Vand suitably secured to corresponding ends of the shaft 44, the lateral spacing of the hubs 50-50 being greater than the distance between the outer faces 'of the flanged bushings 38 and 39 respectively, as shown especially well in Fig.v 2, so as to permit longitudinal reciprocable movement of the shaft in the flanged bushings. To facilitate assembly and disassembly of the yoke and shaft, the hub 50 at the left-hand end of the shaft is secured thereto by a screw indicated generally at 5I, while 'the hub at the right-hand end of the shaft is secured thereto preferably by means of a pin 45a carried by the hub portion of the handle 45 and extending into an aperture of the adjacent hub portion 50 of the yoke, for coupling engagement therewith. I

The opposite or outer ends of the arms 49-49 of the yoke are joined by an integral crossbar 52 having a flat outer surface against which a graft-cutting blade or knife 53 is .adapted to be clamped by means .of ,a clamping bar- 54,.. v The details of the construction andzmountingof the clamping bar 54are omitted,.in'asmuch as these features of: the dermatome are fully disclosed and described in the Reese patents hereinabove identified, it 'being sufficient ,to say that the cutting edge of the knife 53 is positioned and held in close proximityto the outer convex working face of the body member 28 bymeans of the clamping bar 54, the spacing of the knife with respect to thev outer working surface of the bottom plate 3| of the body member being varied by introducing suitable shims between the knife blade and the outerfsurface of the crossbar 52.

o The mechanism for retaining a skin-graft transfer element taut against the outer convex working surface of the bottom plate includes a clamp, indicated generally at 55, mounted between the respective side plates 29 and 30 of the body member 'and in proximity to the front edge thereof; and a'spool, indicated generally at 56, rotatably mounted between the side plates 29 and 36 respectively and in proximity to the rear edge 42 ofthe body member. Details of the clamp 55 and spool 56 are ancillary to the present invention and hence are omitted for brevity, these features being described in detail in the aforementioned Reese patents.. It will suffice to say that thekclamp 55 is adapted to be used to secure one end of the` skin-grafttransfer element 51 to the corresponding end of the body member, the opposite end of the skin-graft transfer element being engaged with the rotatable spool 56, rotation of which serves todraw the skin-graft transfer element tautly about the outer convex Working surface of the body member. As stated at the outset, the body memberr of the dermatome is adapted to be supported on the stand 2| whenever the dermatome is not in use and when aflixing the skin-graft transfer element 51 to the working surface of the bottom plate 3l. To these ends, the side plates 29 and 39' respectively of the body member are provided with axially alignedapertures 58 and 59 respectively at the lowest points of the respective side plates, that is to say, directly below the apertured ears thereof, the diameter of each aperture corresponding substantially to the diameter of the aforesaid-mounting rod 24 of the stand 2l, whereby the body member of the dermatome may be mounted thereon by engaging the mounting rod 24 in the apertured side plates uof the body member. When mounted in this manner on the rod 24 of the stand, the stud 25 of the post 23 is adapted to project through an aperture 66 formed in the right-hand side plate 30 adjacent the rear edge thereof, so as rto hold the body member 28 of the dermatome from rotating about the mounting rod 24, the body member being releasably held from` axial movement off of the mounting rod 24 by engagement of the aforesaid latch 26 with the upper edge of the side plate 29.

- The stop or coupling means for limiting the rotary movement of the blade-carrying yoke 36 relative to the body member of the dermatome is included inits entirety within the supporting sleeve 31 of the dermatome, and includes, in conjunction with the keyway'48 of the shaft 44, a plurality of coacting stop sleeves mounted thereon within the cylindrical sleeve 31. Referring particularly to Figs.' 2 and 3, the plurality of stop sleeves is seen to comprise an intermediate sleeve or coupling 6I having atv opposite ends thereof respectively laterallyr projecting-'stop-lugs 62 and sag-esenta- GS whieh are; in. substantially alignment and'- ofI substantially equal dimensions. As. as@ sembled. on; the shaftA MQ. the Adouble lugged. in, termediate. sleeve'. 6l; is. located'. adjacent the; right-bandi end; of. the: shaft, with: the.V .stopr lug 63 abutting: the..adjacenty endr. ofthe flanged bushing. 3S, which constitutes one termhial :stop sleeve.. As: pointed: out". above. they .inner end. of thea bushing: .39 is; provided with. an. inwardly proiectingstop l lug 4l which forms an abutment for 'thetstop.y lug'A 83. otisleeve. al: and: which corresponds in size. '.thereto.. The otherV terminal stop sleeve. mcuntedLon-theshait Arto the left ofthe-.double lugged intermediatesleeve: 6l, .is a .single logged sleeve: 6'4', the. rightahand' fend of which is. prm/idedl with a laterally projecting stop lug sthe sizeofwhioh corresponds to the size of the stop lugs 625 and.' t3: of: the double llrgged:U intermediate .sleeveA 6l.. F'oimcedy inte.- grally with: for.y otherwise secured tothe inner .surface of that terminal .stop sleeve 64, is a protuberance or keytf adapted: toy engage in 'the keyway 48: ofthe'rs'liaft 44. In the present .emubodiment ci theainvention, the-key. Se is located slightly. nearer therightehand end ofthe single logged stop: sleeve G4' than: its. left-handY end thereowhich left end is adapted to engage the keried end otth'ebushing 33.011 assembly of the plurality of stop sleevesy within. the supporting sleevest.

Whenf. assembled, in: the latter, in a manner indicated in" the. drawingsthesingle lugged stop sl-eevewill beke'yed or. splined to the rotatable snafu, anrlhencewili be positively rotated-by rotationy of the shaft. M in. either direction 'within the sleeve 31. Due to the relatively long keyway 48, the `shaft 1li, will alsohave. capacity for longitudinal. sliding movement. within the stop sleevef 6.4,. as Well; as rotary movement therewith. Moreover, as assembled onthe shaft fill, the stop lug t5 on. the' single logged; stopv sleeve Sil is adapted-to engage. against the. stop lug 82 oi the double luggedt intermediate'.sleeve` 8i, while the stop lug 53 ofV the latter is adapted to engage the stop lugi of thebushing or terminalstop sleeve 39; which is secured in the supporting sleeve 31.

While the: ter-m coupling means, as used' hereinabove with speciric reference'to the drawings;l includes the. three sleeve elements 39, El and vl1l itus to befunderstoodthat, as used in the appended claims.'r this term'consldered in. its. broaderaspect, .refers to` any coupling arrange.- ment.. between thev bodyy member andthe. blade.- carri-er member which will limit rotation between said members ineither direction through an angulai` range. in excess of 360. Thus, broadly speaking, the Vcoupling means. may be. considered tofbe.- the means intermediate and'rotatablerela-- tive-toboth said members which; inl turn, .have provisionffor interengagement with Said coupling means. Accordingly, in the speci'c embodiment of. the invention disclosedI in the drawings, the coupling means can also be considered to rbe only the intermediate sleeve Si, while-the body membcr has provision,.by means fof sleeveSS, for inter-Y engagement with. sleeve'eiv and the blade-carrier likewise `has: provision, by means of sleeve $4, forv similar engagement with the sleeve .6i

In' order tol-imit rotation. of th'e blade carrier or yoke relative. to the bodymember so as to prevent overtravel 'of the: knife :bla-de during; a` skin-graft. excising operation and to make. safe? the severaimanualoperations required-,to mount the skin-graft transfer"element` k51 on 'the outer convex working; surface' 'of ther.bottom plate. 31,'

the: plurality of. stopsleeves. is assembled. 'on the shaft' 441 in al predetermined. relationship which is. bestv illustratedv in Figs. 7 throughl inclusive, whereinFigs. 8, 9,.1l,.l2, 14 and l5 are arranged substantiallyopposite Figs. 7 l0 and. l3,.ancl serve to illustrate the relative positions of the stop sleevesLfor corresponding positionsof the bladef carrying yoke: of the; dermatome.

To.V illustrate. the 'operation of the stop means for preventing the bladeecarrying yoke from swinging beyond the end :l2 of the body member during a skin-graft excising operatiomreference may be had to Figs. 7 through l2. In Fig. 7the loladefcarrying'ycke 33 is shown by broken lines initsxnormal position against the rest 21 of the stand. It will be assumed also that the skin graft transfer elementf. has been. stretched tautly overthe outer yconvex .working surfacezof the bottomplate of. theV bodyzmeinber 2B vpreparatory to. excisingrtheskin. graft. With the yokeV .it seated on the rest 2li, the .stop sleeves within the supportingasleeve 3?, ofv thedermatome aredsposed as shown in 8 .and,9, wherein the' edge 63a of thelug. e3 of the. intermediate sieeve 6l is in engagement. with the edge Ma of the lug al of the flanged bushing 39, while the edge Ec of the lug 35 of the keyed stop sleeve 64 is spaced. away from. the edge 62a. of the lug 62v of the sleeve el, the edge 52a of the lug 62 being in an angular position which corresponds tothe aforesaid edge 63a of the lug 63, as Ashown in Fig. 9. At this point, it' may-be mentioned that inasmuch as both the yoke 35 and the keyed sleeve S4 are coupled totheshaft lll for rotation therewith, angular rotation of the yoke is indicative of identical angular rotation of the sleeve G4. Moreover, for clarity of description and identification, thekey t6 used to couple the sleeve Erl. to the shaft is shown in Fig. 2 substantially diametrically opposite the arms 49-49 o the yoke.

In carrying out a skin-graft exci'sing operation., the surgeon grasps the supporting sleeve 3'1, which serves as a handle, in his left hand and swings the blade-carrying yoke 36 clockwise, as seen in Fig. '7, to a position against theback of his left-hand Wrist, as indicated bythe full lines in the said ligure. He then releasesthelatch 2G and slides the dermatome: on of its'support-ing A rod 213, whereupon heproceedsftosexcisezth-easkiilgraf-t by grasping theyoke handle de in hisright hand4 and reciprocatingy the blade-carrying; yoke while simultaneously rotating the yoke in accunterclockwise direction, as seen in Fig. 7, relative l to-theouter convex bottom. plate of the dermatome until the cutting bladeon the yoke reaches a point substantially adjacent. the rear edge 42' of the body member 23, as seen in. Fig. 10, at which point further rotation of the yoke ispositively stopped by the relative positions. of the stop sleeves; Thus, as the yoke moves through its graft-excising swing, the stop sleeve 'w'ill'b'e rotated in a counterclockwise direction, as seen in. Fig, 9, until the edge 55a of. its lug 65 engages the edge 62a of the lug 62 of the sleeve 6 l.where upon the latter is picked 'up and rotated. in a. counterclockwise direction until the edge '63h of its lug E3 is brought into engagement with the edge Mb ofthe lug 5i of the flanged bushing. 39, whereupon the several parts of the sleeve are held. positively against further rotation in the positions shown inFig. 12whichv correspond toI thepositionsot theyo-keat the end of the graft:- excising swing. Since rotatioitoisthe blade-carry1ngg yokeand.

knife is positively stopped adjacent the rear edge 42 rof the body member, any possibility of gouging deeply into the donor surface due to inadvertently swinging the blade beyond the rear edge 42 of the body member is precluded. Likewise, the surgeon is protected from inadvertently cutting the wrist of his left hand, by which he is holding the dermatome.

f After excising the skin graft, the surgeon swings the blade-carrying yoke 3S back in a clockwise direction from its full-line position, as shown in Fig. 10. to a position on the back of the wrist of his left hand, which position is indicated by the broken lines of the same figure. Thereupon, he mounts the dermatome on the stand by sliding the body member 28 onto the mounting rod 24 in' the manner hereinabove described. The stop sleeves within the supporting sleeve 31 will have been simultaneously rotated ina clockwise. direction from the positions they have'in Fig. 12 to their original positions, as shown in Fig. 9.

- In anticipation of removing the skin-graft bearing-transfer element 51 from the body member of the dermatome, the surgeon swings the blade-carrying yoke back against the rest 21 of the stand and releases his left-hand hold onthe bearing sleeve 31 of the body member. Since the blade in the yoke 36 is facing away from the rear edge 42 of the body member, the surgeon may unloosen' the spool 56 and release this'end of the transfer element 51 from the body member without danger to his hands. On the other hand, were he to try to disengage the opposite end of the transfer element from the front edge of the body member with the yoke seated on the rest 21,`the proximity of the blade and the direction in. which its exposed edge is facing'would endanger the surgeons hands and wrists. Consequently, before unfastening the forward edge of the transfer element 51, the surgeon swings the blade-carrying yoke 3S from its rest 21, as indicated by the broken lines in Fig. 13, in a clockwise direction, so as to bring the blade-carrying yoke and blade to a position beneath the body member of the dermatome, in which position the surgeons hands and wrists are protected from accidentally engaging the blade while unfastening the forward end of the transfer element from the corresponding edge of the dermatome. It will be apparent that in order to swing the bladecarrying yoke 3S in a clockwise direction to a position beneath the body member 28, the yoke 36 must be able to swing through an angle of more than 360 measured from the end of its skin-graft excising stroke, which position is shown in Fig. 10. The relative positions of the stop sleeves for achieving this result are illustrated in Figs. 12, 14 and l5. In Fig. 12, the sleeves B4 and El are shown locked against further rotation in a counterclockwise direction in the manner hereinabove described, which positions of the sleeves correspond to the position of the yoke at the end of the skin-graft excising cutting stroke. As the yoke is rotated back in a clockwise direction, the edge 65a is moved away from the edge 62a of the lug 62 of the sleeve 6l until the edge 55h of the lug 65 engages the edge 52h of the lug 52 -of the Sleeve El, which occurs after the sleeve 64 has been rotated through substantially 240. Thereupon, the edge 65h of the lug picks up the lug 62 of the sleeve 6l and rotates the latterthrough an angle of substantially 240, whereupon the edge 63apf its'lug 63 engages.. against the edge 4ta of the lug 4! of the flanged bushing, as shown in Fig. 15, to effectively prevent further rotation vof the bladecarrying yoke in a clockwise direction, the limit of rotational movement of the yoke being indicated by full lines in Fig. 13.

Having unfastened the front edge of the transfer element 51, the latter may be removed from the body member of the dermatome and used in the well known manner, to cover the injured surface.

Although the schematic illustration of Figs. '1 through 15 serves to illustrate the principal need for providing a yoke member with stop means adapted to permit the yoke member and blade to swing through an angle of more than 360o4 in either direction before being stopped, it will -be appreciated that the stop means has other and equally important applications, particularly when applying a transfer element 51'to the body memberypreparatory to excising a second skin graft.

In this instance, a blade will be mounted in the yoke and hence will present a hazard to the surgeon when Iattaching a new skin-graft transfer element to the body member of the dermatome. Thus, to attach the forward end of the skin-graft transfer element to the front edge of the body member, the surgeon would normally be compelled to reach across the exposed blade' of the yoke. However, by providing the improved stop means of this invention, the yoke may be swung around in a clockwise direction to a position of safety beneath the underside of the body member, in which position the surgeon may apply the skin-graft transfer element to the forward edge of the body member with safety; When applying the opposite'end of the skin-graft trans fer element to the rear edge 42 of the dermatome,-

the yoke may be swung up to its normal position against the rest 21 of the stand, in which position the blade is directed away and is remote from the rear edge of the dermatome. AV further illustration of the safety factor of the stop means is seen in the final step of preparing the dermatome for excising a skin graft, wherein the printed plastic facing of the skin-graft transfer element is peeled oif. lTo perform this step, the plastic facing of the skin-graft transfer element must be cut through at both the front and back edges thereof, and to perform this cutting operation with safety at the front edge of the dermatome; the yoke member may be swung clockwise to a position beneath the body member.

The invention may be carried out in otherv specific ways than those herein set forth with-A out departing from the spirit and essential characteristics ofthe invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and

all changes coming within the meaning and equivalency range of the appended claims are.

, of coupling means between said body member and said blade-carrier member for limiting the relative rotational movement thereof, said coupling means -being supported by at least one of said members, said members having provision for interengagement with said coupling means to limit said lrelative rotational movement between said affissi-sos members in either direction within fan angular range in excess of' 3609.

21 In a dermatomehavingfa body member with a cylindrical' Working surface Yadapted to roll in contact with the skin of 'a donor 'and a. bladecarrier member mounted "toi rota e relative to said body member about the axis 10i 4said* Working surface, the combination Wtli'said :members of coupling `means between 'said body member and said blade-carrier member for limiting the relative rotational `movement thereof,l sai-d' coupling .means being 'supported by at least one ci said members and comprising an elementfmounted for rotation 'relative to -botli said -members about said axis, .said members :havingprovision for interengagement with said coupling means lto limit :said relative rotational movement iinl .one direction 'adjacent the .end `oisaid Working sun face 'and to permit l-relativeyrotation between members inthe opposite. direction through an angle in excess of'lr* measured irornfsaid-'end of said Working surface f3'. .In 'a -dermatome "havingia hody-'member-with a cylindrical working `surface :adapted :to-roll in contact with "the skin -of fa donor and "a bladecarrier member mounted "to rotate. relative itc said body member about the axis'ofsaiiisuriace, the combination wi-tn said members ci coupling means 'between saidxbodyvrnember and "saidfbladecarrier member fior :limiting 1therelativedotation between "said" members -4Which"-compiises a plural ity v'of nforethan two-coacti-ngelements arranged in series, 'the terminal 'elements of said. series being *rotatable with said members, respectively, and all the 'elements `of said series being sep ported by-at vleast one of said-members for rote.- tion `relative Vto each other` about said 'axis, 'saidccacting elements-having inteiengagingfstopsurfaces coordinated -to limit 'relative rotation flee-- tween saidmembers inuoneidirection adjacent the end of said vWorking; surface and yto lpermit rotation between said 'members in 'fthe Yopposite direction through an angular vrangefin excess-of 360 measured from -fsaid yend of -said Working surface.

4. In a dermateme-having a -body-memberwith a cylindrical Working surf-ace adapted to roll Ain contact with Athe-skin of f-a donor and .a bladecarrier member -mounted lto rotate Arelative to said -body'inember about Athe Laxis .of said suiface and also to moveaxially relative to .sa-.id working surface tov facilitate cutting, the combination with said members of counling-means for limiting the-.relativerotation between said members which comprises .apluralty of .more than ltWo coasting elements arrangedin-series, the terminal elements of said series being rotatable with said members,` respectively, and all'the elements of saidseries being! supported 4by'at least one of'said members fonrotation"relative to each other aboutA said axis, theterminal element rotatable Wth'said blade-carrier 'member having provision permitting axial movement of said blade-carrier relative thereto, s'aid 'coacting elements 'having interengaging stop surfaces coordinated to limit Hrelative rotation ybetween said members in one direction adjacent the end 0f said Working surface and to permit rotation between said members in the opposite direction through an ang-ular-rangeinexcess of--360 measured from saidend of saidworkingsurface.

5. In a dermatome havinga bodyVl member :with a cylindrical Workingfsurfaee-and--a blade-carrier member mounted 1 to rotaterelative f to :said Vbo dy member about theaxisof- :said Workimssurface.`

the *combination wim .said members 'or :a plumb ity of more than two velongated elements carried end-to-end by at least one of said' membersor rotation Yrelative to eachother about/said 'ax-i8.. the endmost elements turning. unison with said members, respectively, and' the: adjacent. ends of successive elements having cooperating stop surfaces, respectively, so coordinated that the stop-'surfaces of all elements limit the relative rotational movement between said body 'member and said blade-carrier in one Adirection Vadjacent the end of said Working surface and permit relative yrotation `between said members'in the oppositedirection .through an angle in excess of 36A)n measured fromfsaid'end of said working surface. 5

.6, vInfa dermatome havinga body member-With a 1 cylindrical Working surface, supporting .means onsaidbody member for-holding` said dermatome when excising :a skin grafts-shaft journaledn sai-d supporting meansv for rotary movement therein relative to said body memberanda blade carrierse'cure'd to said :shaft for rotntiontherewith-abonnee' axis caf/said working surface; ithe ccmbinationof a plurality ofcoacting stop sleeves arranged in longitudinal alignmentwith :each other on'said-shaft, a :tiret stop sleeve being rotatable in unison with-said bodymemberpa :second stop sleeve `bein-g 'rotatable in Aunison with said blade carrier and-a Vthird stop zsleeve fleeing intermediate said first 'and second --sleeves rotatable relative to both said sleeves, v:said rcoacting stop sleeves'havingcooperatlng stopflugs located on their adjacentends, respectively, rand arranged to .be -rotated'to'and `from -mutualengagement by relative-rotation betweenfsaidishaft and said -body 'member to Jlimit -relative 'rotation between said body .member and v'said 'sblade icaririer :adjacent the-,end of said workingsurface during a skin-graft operation and *to permit .frelative rotation therebetween fin 'the opposite direction through an 'angle in vexcess rif-'366 fmeasured froinsaid end' of saidworking surface.

y7. In a dermatome havinga bodymemberwith a "cylindrical VWorking 'surface adapted tozrolln contact with 'the fskin of 1a donor, supporting means on said body 'member for `holding I`said dermatome Whenexcising a 'skin graftfa shaft journaled in said 'supporting means for rotary and axial movement therein relativeto said-body memberanda blade carrier. securedLtor saidfshaft for .rotation therewith about the .'axis of said working" surface the :combination 'of :aplnrality of enacting stopV sleeves arranged in 'longitudinal alignmentwith each yotherun'saidshaft, .ia first stop sleeve being rotatable in unison with saidbod'y' member, a's'econd Vstop sleeve being 'splined to said Vshaft for rotation 'therewith' and permitting axial-movement of lsaid shaft relative thereto, and a thirdl stop sleeve Ybeing intermediate said first and second sleevesand rotatable relative to both said sleeves, `said `coacting stop sleeves having cooperating `stop lugs located on their adjacent ends, respectively, and arrangedto be rotated to and 'from mutual engagementby relative rotation between said shaft and said body member to limit the relative rotation'betweensaid body member and-said blade carrier adjacentthe end of said working surface'duringl askin-graft operation and to 'permit relativeretation therebetween `in the oppositedirectionl measured'fromthrough an angle in excess of 360 said end'of said'w'orking surface.

8. In 'a .derrnatome, including sa tbody-member? havingl aWor-.ldng surface; means `01 impartiti?" said dermatome when excising a skin graft, said supporting-means comprising a bearing-structure carried by said body-member; a shaft journaled in said bearing-structure for rotary and reciprocatory movement therein relative to said body-member; a blade-carrier secured to said shaft, said blade-carrier being spaced from said body-member and arranged to be rotated relative thereto by rotation of said shaft; the combination of stop-means for said blade-carrying means, said stop-means being characterized by elements carried by said bearing-structure and by said shaft respectively, said elements being arranged to be rotated to and from mutual engagement so as to permit rotation of said bladecarrier through an angle in excess of 360 by rotation of said shaft relative to said bearingstructure both to automatically stop the rota- References Cited in the le 0f this patent UNITED STATES PATENTS Number Name Date 2,400,336 Bishop May 14, 1946 2,479,185 Reese Aug. 16, 1949 2,479,260 Reese Aug. 16, 1949

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