Dermatome having finger-tip control

Jan. 10, 1956 g. j. hood 2,730,102

DERMATOME HAVING FINGER-TIP CONTROL Filed May 28, 1954 2 Sheets-Sheet 1

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Jan. 10, 1956

G. J. HOOD

2,730,102

DERMATOME HAVING FINGER-TIP CONTROL

Filed May 28, 1954

Sheets-Sheet 2

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United States Patent Office

2,730,102

Patented Jan. 10, 1956

2,730,102

DERMATOME HAVING FINGER-TIP CONTROL

George 3. Hood, Lawrence, Kans.

Application May 28, 1954, Serial No. 433,070

Claims. (Cl. 128—305)

This invention relates to improvements in dermatomes and reference may be had to my United States Letters Patent to No. 2,288,709, of July 2, 1942, for a full and complete understanding of all of the broad principles of instruments of the character to which the improvements of the present invention relate.

This is a continuation-in-part of my copending application, Serial No. 411,733, filed February 23, 1954, and has for its primary object the provision of control structure in the nature of that disclosed in said application but having certain additional advantages, not only from the standpoint of accuracy, but also for ease of operation and simplicity of manufacture.

In my said copending application there is set forth a dermatome differing essentially from the precision instrument forming the subject matter of my patent aforementioned in that the same includes a hand control which consists of a handle and yoke member swingable on bearings extending from the skin holder and having an operable connection with the skin holder to permit rolling the holder on the donor area of the patient’s body as the handle and yoke are swung in one direction.

It is an important object of the present invention to likewise provide an operable interconnection between the swingable yoke of the dermatome and the skin holder but embodying the use of a finger-tip control that may be moved into frictional or positive engagement with the skin holder when desired or cause drum-yoke interengagement so that the user of the dermatome has complete and accurate control of the rolling movement of the skin holder.

Another important object of the instant invention is to provide structure in a dermatome of the aforementioned character for rigidly locking the skin holder to the yoke which differs from that of my said copending application in that it cooperates with the said finger-tip control.

A still further object of the instant invention is the provision of control means for dermatomes having advantage over other types of controls such as disclosed in my copending application in that no manipulative steps are necessary to permit free rotation of the skin-holding drum freely within the yoke member when desired.

In the drawings:

Figure 1 is an end elevational view of a dermatome having finger-tip control made pursuant to one form of the instant invention.

Fig. 2 is an enlarged, fragmentary, cross-sectional view taken on irregular line II—II of Fig. 1.

Fig. 3 is a fragmentary, detailed, cross-sectional view still further enlarged and taken on irregular line III—III of Fig. 2.

Fig. 4 is a fragmentary, cross-sectional view taken on line IV—IV of Fig. 2.

Fig. 5 is a fragmentary, cross-sectional view similar to Fig. 2 showing a modification of the instant invention.

Fig. 6 is a fragmentary, cross-sectional view taken on line VI—VI of Fig. 5.

Fig. 7 is a sectional view similar to Figs. 2 and 5 showing another form of the present invention.

Fig. 8 is a fragmentary, cross-sectional view taken on line VIII—VIII of Fig. 7.

Fig. 9 is a cross-sectional view similar to Figs. 2, 5 and 7 showing still another form of the instant invention; and

Fig. 10 is a fragmentary, detailed, cross-sectional view taken on line X—X of Fig. 9.

The dermatome chosen for illustration of the form of the instant invention embodied in Figs. 1-4, includes a skin holder broadly designated by the numeral 10, preferably taking the form of a cylindrical drum having therefore, an arcuate outermost surface and a pair of opposed, annular edges 12 and 14 concentric with the axis of rotation of the drum 10, such axis being coincident with the axis of an elongated shaft 16.

Drum 10 is provided with hubs 18 having bushings 20, the latter of which also swingably mount hubs 21 of a yoke 22 on the drum 10: bushings 20 are both slidable and rotatable on shaft 16.

Yoke 22 is preferably U-shaped and, therefore, has a bight 24 and a pair of legs 26 and 28 that embrace the drum 10, legs 26 and 28 being interconnected by a tie rod 30 and having hubs 21 attached thereto.

Shaft 16 may be reciprocated and rotated within the bushings 28 by grasping one of the handles 32 on the arms of a U-shaped frame 34 that has its arms adjustably secured to the shaft 16 at the ends of the latter for movement of knife or cutter blade bed 36 toward and away from the outermost cylindrical periphery of drum 10 and for movement therewith as shaft 16 is reciprocated or roated.

My Patent No. 2,288,709, is incorporated herein by reference for an understanding of the manner of operating the dermatome by reciprocating the shaft 16 and, therefore, the knife bed 36 so that the knife (not shown) mounted on bed 36 by clip 38, severs the skin while the skin is lifted by an adhesive on holder 10 as the holder is rolled over the donor area of the patient.

The present invention relates to the manner of rolling the drum 10 rather than to the method of excising skin and the way in which the knife is reciprocated with respect to the drum 10. To this end there is provided a finger-tip control embodying an L-shaped lever 40 having a pair of arms 42 and 44 and disposed within the confines of the swingable yoke 22. Arm 44 extends to a position between leg 26 and proximal edge 12 of drum 10 and is provided with an opening 46 that receives the tie rod 30. A washer 48 on the tie rod 30 is interposed between the leg 26 and the arm 44.

Arm 42 is embraced by a U-shaped bracket 50 secured to the innermost face of bight 24 by fasteners 52 and serving to limit the extent of rotation of the lever 40 with respect to the tie rod 30.

A spacer 54 secured rigidly to the leg 28 is interposed between the latter and the proximal annular edge 14 of drum 10. Leg 26 of yoke 22 also carries a small screw 56 aligned with the arm 44 and provided with a shoe 58 on its innermost end engageable with the arm 44 when screw 56 is moved to the innermost end of its path of travel. A peripherally knurled disc 68 on the outermost end of the screw 56 facilitates manipulation of the latter. A suitable handle 62 extending outwardly from bight 24 is held in place by a fastening rod 64.

When the instrument is placed in use to roll the drum 10 along an area of contact 66, as shown in Fig. 1, the physician grasps the handle 62 with one hand as he manipulates the frame 34 through one of the handles 32 with the other hand. Normally, the handle 62 and yoke member 22 may be swung freely with respect to the drum 10, but when it is desired to clamp the drum 10 to the yoke

2,730,102 member 22, the physician merely presses the arm 42 of lever 40 toward the inner face of bight 24 with one finger of the hand that is grasping the handle 62. This causes the lever 40 to swing on the washer 48 as a fulcrum, moving the arm 44 of lever 40 tightly against and in frictional engagement with the annular edge 12 of drum 10. Assuming the handle 62 to be in the position shown in Fig. 1 of the drawing when the yoke member 22 is thus connected with the drum 10, downward movement of the handle 62 toward the area of contact 66 will cause the drum 10 to roll on the surface 66 anti-clockwise viewing Fig. 1. Pressure on the arm 42 may be released and the handle 62 swung upwardly at any time to obtain a new “bite” and in this respect it is to be particularly noted that such upward swinging movement of the handle 62 may be varied to suit the desires of the physician since arm 44 may be moved into frictional engagement with the annular edge 12 at any point thereon.

The pressure that is thus applied to the drum 10 is received by the spacer 54 and the drum 10 is, therefore, in effect clamped tightly between the arm 44 and the spacer 54 when the arm 42 is pressed toward the bight 24. The tie rod 30 serves not only as a means to operably mount the lever 40 for swinging movement, but joins the legs 26 and 28 so that they do not spring apart when pressure is applied to the annular edge 12.

To avoid the necessity of applying continuous pressure on lever 40 while cutting a graft, a releasable clutch latch may be provided, one form of which is best shown in Fig. 4. As the arm 42 of lever 40 is sprung toward the bight 24 of yoke 22, lever 40 may be slightly rocked about the tie rod 30 as an axis, thus permitting the notched end 79 of lever 40 to be slipped under the head of a detent 80 which then holds lever 40 in its locked position and from which it may readily be released by pressing on arm 42 and moving it slightly to one side. Detent 80 and screw 56 serve similar desirable purposes.

The friction clutch operated by lever 40 normally gives sufficient clamping action. For some sizes of dermatomes it may be desirable to use some type of jaw clutch in which case the clutch surface of lever 40 and the contacting end of the skin holder may be notched, knurled or roughened to provide a stronger grip between the surfaces.

Since the drum 10 normally rotates freely on the yoke bearings 20, adhesive used in the excising operation, may be easily applied to the outer surface of the drum 10 by inverting the entire instrument so that it rests upon the end of handle 62 and upon a pair of rods 68 secured to the yoke member 22. As the adhesive is applied, and during free rotation of the drum 10 for such purpose, the frame 34 may be swung to a position resting upon a pin 70 on the yoke member 22.

If, at any time during use of the dermatome, during knife-changing operations or otherwise, it is desired to hold the drum 10 against rotation with respect to the yoke member 22, it is but necessary to move the screw member 56 inwardly to a position where it clamps the arm 44 tightly against the edge 12. Or, for the same purpose, arm 40 may be depressed until detent 80 locks the clutch against the end of the holder.

It can now be appreciated that this additional positive screw control 56 for locking the clutch or lever 40 against the drum or holder 10 may also be used when pulling the graft from the drum 10. Or, detent 80 may be brought into action to serve the same purpose.

The finger-tip controlled lever 40 permits turning the cylinder 10 in either direction at the will of the surgeon. When the handle 62 is thus in effect locked to the cylinder 10, there is provided a single unit and when the adhesively coated cylinder 10 is placed upon the adhesively coated donor area 66 of the patient, interengaging surfaces are cemented together. When the dermatome is rolled slightly as a unit on the contact area 66 as a fulcrum, the surgeon is able to lift a line of skin to a level where the knife edge can be moved into severing rela tionship therewith. The surgeon is provided with a convenient and exact control over the rate of rolling of the cylinder 10 and of lifting the skin since the handle 62 is at a considerable distance from the fulcrum while the knife edge is much closer to the fulcrum on the contact area 66. A downward motion of the handle 62 lifts the skin but a fraction of the distance that handle 62 is moved. The rate of lifting of the skin, therefore, and of cutting the graft is thus readily controlled by the surgeon.

In the embodiment shown in Figs. 5 and 6 of the drawings, U-shaped yoke member 122 has its legs 126 and 128 mounted for swinging movement on rotatable, skin holding, cylindrical drum 110 in the same manner as shown in Fig. 2. The material from which yoke member 122 is made is sufficiently resilient to permit springing the legs 126 and 128 together into engagement with annular edges 112 and 114 of drum 110, which edges 112 and 114 are, of course, concentric with the axis of rotation of the drum 110 and the axis of swinging movement of the yoke member 122.

Accordingly, the controls of Figs. 5 to 10 inclusive, contemplate such clamping of the skin holder between the legs of the yoke, and when it is desired to interconnect the yoke and the drum during use of the dermatome. In Figs. 5 and 6 there is provided take-up means in the nature of a tie rod or bolt 130 interconnecting the legs 126 and 128 and preferably in parallelism with bight 124 of yoke 122. Nuts 131 and 133 held against rotation within legs 126 and 128 respectively by setscrews 135, receive the threaded ends of rod 130 and the latter is rotated by a fingerpiece 137 secured rigidly thereto and intermediate the ends of rod 130.

Right and left hand external screw threads provided on the bolt 130 for receiving nuts 131 and 133, cause inward and outward movement of the legs 126 and 128 as the fingerpiece 137 is manipulated to rotate the bolt 130.

In Figs. 7 and 8 of the drawings, the take-up means is in the nature of a tie rod interconnecting the legs 226 and 228 of yoke member 222 and consisting of a pair of bolts 239 and 241. Bolts 239 and 241 are held against rotation with respect to legs 226 and 228 respectively, by setscrews, pins or the like 235. A fingerpiece 237 is in screw-threaded engagement with both of the bolts 239 and 241, and since one of the bolts is provided with a right-hand thread and the other bolt has a left-hand thread, swinging of the fingerpiece 237 with respect to the bolts 239 and 241 causes inward and outward movement of the legs 226 and 228.

In Figs. 9 and 10 of the drawings, a tie rod 330 spans the distance between legs 326 and 328 of yoke member 322 in interconnecting relationship thereto and a Ushaped fingerpiece 337 couples with the tie member 330 intermediate the ends thereof. The resilient legs 326 and 328 are caused to move toward annular edges 312 and 314 of drum 310 by pressure exerted upon the fingerpiece 337 to move the latter toward bight 324 of yoke member 322.

Latching means is provided for the finger control 337 taking the form of a hook 343 extending from the bight of the U-shaped fingerpiece 337 through an opening 345 in the bight 324. The fingerpiece 337 is freely swingable to and from the latching position shown in Fig. 10 and in such position the tie member 330 is held sprung toward the bight 324 and the legs 326 and 328 are held in frictional engagement with the annuli or annular edges 312 and 314 of drum 310.

It is to be understood at this point that while hubs 21 in Fig. 2 of the drawings, are not integral with legs 26 and 28, and that while similar construction is contemplated in Figs. 5 to 10 inclusive, either the legs of the U-shaped yokes or a part thereof, are moved into engagement with the drum whenever it is desired to operably connect the yoke and its handle with the skin holder.

It can also be appreciated that in Figs. 1 to 3 inclusive, the operative connection is effected by a pressure

2,730,102 tending to spring the legs 26 and 28 apart and which is restrained by the action of tie element 30. In Figs. 5 to 10 inclusive however, the action in each case is to spring the legs of the yoke member toward each other, thereby clamping the rotatable skin-holding drum tightly between the legs of the yoke member which embrace the drum whenever it is desired to operably join the drum and the yoke as a unit during use of the surgical instrument.

In Figs. 5 and 6 the single bolt 130 operates in the same manner as the two bolts 239 and 241 of Figs. 7 and 8, the difference being of course, that in Fig. 7, fingerpiece 237 is in screw-threaded engagement with the bolts 239 and 241, whereas in Fig. 5 the bolt 230 is in screw-threaded engagement with the two nuts 131 and 133. In Figs. 9 and 10 however, the resilient tie element 330 is sprung toward the bight 324 whenever it is desired to spring the legs 326 and 328 into engagement with the drum 310. Still further, there is provided in Figs. 9 and 10 latching means in the nature of hook 343 to maintain the operative connection until the surgeon releases the hook 343 and permits the rod 330 and the legs 326 and 328 to spring back to the normal position shown in Fig. 9.

While it would be possible to lift the skin and to cut a graft by rolling the skin holder over the donor area of the patient’s body merely by pulling on the handle, such a procedure probably is not advisable since it would be difficult to roll the holder at a slow and uniform rate.

Still further, the simplified clutch mechanism herein provided, avoids the danger inherent in more complicated mechanisms that could easily become inoperative at a critical time because of the possibility that dried blood between closely-fitted working parts might make the working parts difficult to operate or completely unsatisfactory in their operation.