Mucous membrane cutter for mucogingival membrane surgery

A mucotome or mucous membrane cutter for mucogingival membrane surgery is disclosed. The mucotome comprises a handle having a small, compactly designed cutting head arranged on its forward end, the cutting head including a circular cylindrical blade-holding roller which is reciprocable parallel to the blade edge in a guide by means of a drive shaft having an eccentric crank pin engaging in cross grooves of the blade-holding roller. A cutting shoe is mounted to the ends of the blade-holding roller and is rotatable relative to the cutting head through a limited angle. The cutting head is also selectively positionable in at least two angular positions relative to its support. The cutting blade is secured in a longitudinal radial slot in the roller and projects therefrom through a guide slit formed in a crosspiece of the cutting shoe. The construction and arrangement of the cutting head and cutting shoe assure a compact, versatile structure having a number of adjustment possibilities.

BACKGROUND OF THE INVENTION 
The present invention relates to a mucotome, that is, a dermatome for 
mucous membranes, having a handle and a cutting head arranged on its 
forward end, with a blade holder for carrying a cutting blade. The blade 
holder is reciprocable parallel to the cutting surface along an axial 
guide formed in the cutting head and a cutting shoe, formed as part of the 
cutting head, contributes to the determination of the cutting depth of the 
cutting blade. A drive shaft is arranged in a radial sliding support 
formed by the cutting head and has a front crank with an eccentric crank 
pin engagable in a cross groove in the blade holder, which cross groove 
extends in a radial plane and has a cross section that is adapted to 
receive the crank pin. 
In a mucotome of the type known from German Utility Model Publication No. 
7,526,361, which is moved by pulling, the cutting shoe is also formed as a 
blade holder comprising an element which is bent twice in the same 
direction with two generally rectangular bends. The blade holder is 
provided with transverse bores and is guided along two parallel rods in 
the cutting head. The primary disadvantage of this known mucotome is that 
the cutting head cannot be formed as compactly as necessary because of the 
guiding of the cutting shoe and blade holder along the rods when 
introducing and handling the mucotome in the oral cavity. 
SUMMARY AND OBJECTS OF THE INVENTION 
It is, therefore, a primary objective of the invention to provide a 
mucotome of the general type mentioned above with a cutting head which can 
be made very small and compact. 
This object is accomplished according to the invention, in that a straight 
prismatic bar or a circular cylindrical roller with a longitudinally 
extending radial slit is provided as a blade holder to hold the razor 
blade-like cutting blade, and that the portion of the cutting blade that 
projects radially out of the receiving slit, in the case of a cylindrical 
roller, is guided in a slit of the cutting head. 
This guiding is only necessary when the blade holder provided is the 
preferred circular cylindrical roller, because the non-cylindrical cross 
section of a prismatic bar together with the corresponding cross section 
of its axial guide form a means of assuring that there is no rotation of 
the bar. The alternative solution with roller and cutting head slit is 
basically known from U.S. Pat. No. 1,736,246, which discloses a dermatome 
of a dissimilar type. The use of a straight prismatic bar or a circular 
cylindrical roller as the blade holder allows a compact construction of 
the cutting head, without losing the percise guiding and the inexpensive 
drive of the blade holder. This will be clear from the exemplary 
embodiment described hereinafter. 
In the known similar mucotome, the cutting blade has an unchangeable 
relative position with respect to the handle, an arrangement which has 
been found to be disadvangeous in practice. It is, therefore, advantageous 
to design and construct the mucotome according to the invention in such a 
manner, that this disadvantage is overcome and the cutting blade can be 
brought into various relative positions with respect to the handle as in 
the dermatome disclosed in U.S. Pat. No. 3,934,591. A partial solution 
exists according to one preferred embodiment of the mucotome according to 
the invention in that the guide slit for the cutting blade is formed in 
the cutting shoe, that the cutting head has a rotating joint upon which 
the cutting shoe is rotatably mounted, that the roller holding the blade 
forms the shaft of the rotating joint, that the mount of the rotating 
joint has a longitudinal slit through which the cutting blade projects, 
the azimuthal width of such slit corresponding to the maximum angle of 
rotation of the cutting shoe. The concentricity of this arrangement 
assures, in a simple manner, a first degree of freedom permitting rotation 
of the cutting shoe without limiting the compactness of the cutting head. 
In the preferred embodiment, the cross groove in the blade holder, which 
receives the crank pin, consists of two straight sections that merge with 
each other at a rigid knee having a knee angle of at least 90.degree.. 
This angle allows a maximum rotation of the cutting head of 90.degree., 
during which rotation the crank pin moves through the cross groove, which 
can easily be formed in the preferred embodiment to allow the crank pin 
sufficient play. 
The preferred embodiment is distinguished by the fact that the cutting shoe 
has two clamping plates, which bear against the at least partially 
ring-shaped end surfaces of the rotational joint mount and which are 
provided with coaxial bores for the engagement of the ends of the 
blade-supporting roller which extend from each end of the mount, and a 
crosspiece that connects the two plates and is provided with a guide slit 
for the cutting blade. The two clamping plates with their bores and the 
connecting crosspiece with its guide slit assure an inexpensive mounting 
of the roller with the cutting blade in the cutting shoe. The same holds 
true, of course, for the mounting of the cutting shoe on the 
blade-supporting roller. The crank pin of the drive shaft allows only a 
certain, limited axial movement of the blade-supporting roller as 
determined by the stroke of the crankpin. 
In the preferred embodiment, the two clamping plates and the connecting 
crosspiece are integrally formed in one piece and the guide slit extends 
along the entire length of the connecting crosspiece and through the two 
clamping plates. This embodiment is especially advantageous, because by 
means thereof only a minimal expense is necessary for mounting the cutting 
head. More specifically, all that need be done during mounting is to 
insert the one-piece chassis of the cutting shoe, which chassis consists 
of the two clamping plates and the connecting crosspiece, onto the 
eye-shaped rotational mount of the cutting head, until the bores in the 
clamping plates align with the hollow bore of the mount, whereupon the 
roller with the cutting blade and the mount can be inserted in an axial 
direction into the clamping plate bores and the guide slit respectively. 
Finally, the drive shaft can be inserted into the cutting head in such a 
manner that its crank pin engages in the cross groove of the roller. 
Thereafter, the crank pin holds the roller and the roller holds the 
cutting shoe, which, in turn, prevents relative rotational movement of the 
cutting blade. 
In order to simplify the mounting and securing of the cutting shoe onto the 
rotational joint mount, the preferred embodiment is also distinguished by 
a clamping screw extending freely rotatably through one of the clamping 
plates and screwed into a suitably threaded bore of the other clamping 
plate. The clamping screw is arranged generally diametrically opposite the 
connecting crosspiece with respect to the bores in the clamping plates. By 
loosening the clamping screw, the cutting head can easily be pulled from 
the rotational joint mount after the retraction of the crank pin and the 
sideways removal of the roller containing the blade, if this is desired. 
During the mounting of the cutting head, a tightening of the clamping 
screw causes the clamping plates of the cutting shoe to be pressed tightly 
against the partial ring-shaped end surfaces of the rotational joint 
mount. 
In the preferred embodiment, the clamping plates are formed as mirror 
images of each other and are approximately elliptical in shape. A grooved 
roller is freely rotatably mounted between the clamping plates and the 
cylindrical roller, the connecting crosspiece, the grooved roller and the 
clamping screw are arranged successively along the major axis of the 
elliptical clamping plates. The cutting shoe, which tightens the mucous 
membrane by means of the cylinder, thereby is given the desired flat 
shape, which simplifies the handling of the cutting head in the oral 
cavity. This effect is enhanced in the preferred embodiment in that the 
clamping plates on the end of the cutting shoe that carries the cylinder 
each have a skid, which operate together with the cutting edge and the 
cylinder and which support the cutting shoe outside the cutting area on 
the mucous membrane and on its rigid foundation, whereby the mucous 
membrane is tightened across the cutting area. 
The fact that the cutting head in the preferred embodiment is detachably 
mounted to a support of the handle on the end opposite the cutting shoe by 
means of a screw cap, results not only in a simplified mounting of the 
mucotome, but also results in the further advantage, that the present 
cutting head can easily and rapidly be replaced by another cutting head 
with a different cutting width and/or cutting depth. It is of course, also 
possible to retain all of the other elements of the cutting head and 
replace only the cutting shoe. 
Starting with the embodiment of the cutting head on the handle, a further 
partial solution of the problem of improving the mucotome according to the 
invention in such manner that the cutting blade can be adjusted to 
different relative angular positions with respect to the handle, exists in 
the possibility of an angled support such as that in the preferred 
embodiment, in that the rear end surface of the cutting head has at least 
two and preferably four depressions or slots and that a locking bolt or 
pin projects from the front end of the support, which locking pin engages 
selectively in one of the slots. Depending on the number of slots, the 
cutting head can be connected with the support in various rotational 
positions about the common axis of the drive shaft and the support, the 
axis of which support, as mentioned earlier, together with the main axis 
of the handle can form an obtuse angle when necessary or desired. 
Consequently, the cutting shoe which guides the cutting blade has a second 
degree of freedom, which can be used for its stepwise adjustment. Even 
when no flexible drive shaft is used, a straight, rigid drive shaft can be 
used, which extends from the roller holding the blade and ends at the base 
of the support, i.e., it penetrates the separating plane between the 
cutting head and the handle, which plane is bridged by the screw cap. In 
order to also control the drive shaft from outside the cutting head, that 
is, at its end opposite the cutting shoe, it is provided in the preferred 
embodiment, that a mounting sleeve with an outer collar which holds the 
drive shaft is arranged in the cutting head and in the support, and 
engages between the confronting end surfaces of the cutting head and the 
support, and has a number of openings for the passage of the locking pin 
that corresponds to the number and position of the slots in the rear end 
of the cutting head. The locking pin projects from the front end of the 
support, and its cross-sectional shape determines the shape of the 
openings. The perforated collar holds the mounting sleeve against 
rotation. 
In view of the smallness and compactness of the mucotome according to the 
invention, the lubrication of the drive shaft, which rotates when placed 
in operation, and the pivoting roller create difficulties. These 
difficulties are avoided in the preferred embodiment in that the mounting 
sleeve is provided with longitudinal grooves on its outer side, which 
grooves extend through the collar, and after removal of the cutting head 
from the handle support are accessible from the front side. The mounting 
sleeve is also provided with a radial bore, which is connected with a 
lubricant reservoir formed by a wide annular groove in the drive shaft. 
From this supply reservoir, the lubricant reaches the annular chamber 
surrounding the mounting sleeve after passing between the drive shaft, the 
mounting sleeve and through the bore, from which annular chamber the 
lubricant reaches the rotational joint of the cutting shoe. 
In the following, the invention is described in greater detail with the aid 
of drawings of the exemplary, preferred embodiment of the mucotome 
according to the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
The exemplary embodiment has a basically straight, not completely 
illustrated handle 10 having a cylindrical hollow chamber 12 within which 
a main drive shaft 14 extends forwardly. On the forward end of the handle 
10 a circular cylindrical support 16 is formed in one piece, the axis of 
which forms an obtuse angle of approximately 135.degree. with the axis of 
the hollow chamber 12. 
A cutting head 20 is detachably secured to the support 16 by means of a 
screw cap 18. Cutting head 20 has a hollow, somewhat blunt cone-shaped 
element 22, the rear annular surface 24 of which confronts the similarly 
annular shaped end surface 26 of the support 16 at a certain spacing. 
Interposed in the space between surfaces 24, 26 is an outer collar 28 of a 
mounting sleeve 30. On one side of the collar 28, the mounting sleeve 30 
extends into the support 16 and, on the other side of the collar, extends 
into a cylindrical hollow chamber 32 of the cone-shaped cutting head 
element 22. The outer collar 28 and the rear surface 24 of the cutting 
head element 22 have, at the same positions, four equi-angularly spaced 
radial slots 34, 36, respectively, about their peripheries, the latter 
slots 36 interrupting the surface 24. A locking bolt or pin 38 is engaged 
in one pair of coincident slots 34 and 36 which has a diameter adapted to 
the width of the slot and is anchored in the support 16. The mounting 
sleeve 30 has a radial bore 42 and, on its outer surface, longitudinal 
grooves 40 extending through the collar 28. 
On the forward end of the main drive shaft 14 there is rigidly supported a 
forwardly toothed bevel gear 46, which meshes with a similar bevel gear 48 
rigidly mounted on the rear end of a drive shaft 50, which, in turn, is 
mounted in the sleeve 30. Drive shaft 50 has a wide annular groove 52 
communicating with and adjacent the radial bore 42 in the sleeve 30. 
An eye-like, circular cylindrical rotational joint mount 54 is formed on 
the lower end of the cutting head element 22, the hollow space of which 
rotational joint mount 54 intersects the hollow space 32 of the cutting 
head element 22, which space 32 has a somewhat smaller cross-sectional 
area at the lower end of the mounting sleeve 30. The shaft of the 
rotational joint, by means of which a cutting shoe 56 is joined as a 
further portion of the cutting head 20 at its stationary element 22, 
comprises a circular cylindrical roller 58, which carries a cutting blade 
60. The roller 58 has a milled-out cross groove 62 which is formed outside 
the roller axis and comprises two straight sections that form a rigid knee 
having an angle of about 120.degree.. The groove 62 is also provided with 
two chamfers 66, one on either side thereof. The crank pin 68 of a crank 
on the forward end of the drive shaft 50 engages in the cross groove 62 
and extends almost to the bottom of the groove. The diameter of the crank 
pin 68 is the same as the width of the cross groove 62 and is only 
slightly smaller than the length of each of the straight sections of the 
cross groove. 
The roller 58, which, when moving, pivots about its axis 64, has a 
longitudinally extending radial receiving slit 70 in which the cutting 
blade 60 is mounted. The cutting blade 60 is secured to the roller 58 at 
the location of its radial slit 70 by solder 72 on both sides of the slit. 
The portion of the cutting blade 60 that projects out of the receiving 
slit 70 passes through a continuous, longitudinal slit 74 in the 
rotational joint mount 54. The dimensions of slit 74 correspond to the 
desired maximum angle of rotation of the cutting shoe 56. The cutting 
blade 60 is mounted in a guide slit 76 of the cutting shoe 56. The guide 
plane that coincides with the plane of the flat cutting blade 60 contains 
the roller axis 64 which intersects the axis 44 of the drive shaft 50 at 
right angles. 
As may be best seen in FIGS. 2 and 3, the cutting shoe 56, which has 
limited rotation about the roller axis 64, has two clamping plates 78 and 
80 which bear against the oppositely disposed, partially ring-shaped end 
surfaces of the rotational joint mount 54. The clamping plates 78 and 80 
are mirror images of each other, are formed approximately elliptically, 
and are provided with coaxial bores 82 and 84, respectively, for the 
engagement of the ends of the roller 58 that project outwardly from each 
end of the mount 54. The two plates 78 and 80 are connected by means of a 
crosspiece 86, which is integrally formed in one piece with the plates 78, 
80. The guide slit 76 for the cutting blade 60 is disposed in this 
crosspiece 86, and the cutting blade 60 extends through the connecting 
crosspiece 86 over the entire length thereof between the two clamping 
plates 78, 80 and projects, with its cutting edge 96 into the space beyond 
the crosspiece 86. A clamping screw 88 extends freely rotatably through 
one of the clamping plates, namely, the plate 80 and this screw 88 is 
screwed into a suitably threaded bore 89 in the other clamping plate 78. 
The crosspiece 86 is arranged generally diametrically with respect to the 
bores 82 and 84 in the clamping plates. A grooved cylinder 90 is also 
mounted between the two clamping plates 78 and 80 in such manner as to be 
freely rotatable, and in such position that the cylinder 90, the 
crosspiece 86, the roller 58 and the clamping screw 88 are arranged 
successively generally along the major axis of the elliptically-shaped 
clamping plates. Finally, each of the clamping plates 78, 80 have, on the 
end of the cutting shoe 56 that carries the cylinder 90, a guide skid 92, 
94, respectively, between which the cutting edge 96 of the cutting blade 
60 extends. 
From the FIGS. 4 and 5 it is apparent that the muctome according to the 
invention, in the embodiment described above, can be moved either by 
pushing or pulling without changing the relative angular position of the 
cutting head 20 with regard to the handle 10, depending on the angular 
position of the cutting shoe 56. The surgeon can also change the mentioned 
relative angular position, exchange the cutting head 20 and replace the 
handle 10 with a different one having a support that carries the cutting 
head angled to a greater or lesser degree, such as 30.degree. instead of 
45.degree.. It is also possible to provide a support which orients the 
handle 10 and cutting head 20 coaxially. 
Although only a preferred embodiment is specifically illustrated and 
described herein, it will be appreciated that many modifications and 
variations of the present invention are possible in light of the above 
teachings and within the purview of the appended claims without departing 
from the spirit and intended scope of the invention.