A surgical scalpel for use in ophthalmic and other forms of
surgery having a blade that can be adjustably extended beyond
a foot. The scalpel also includes an indicator for showing the
length of the blade that is exposed beyond the foot. The indicator
can be calibrated to compensate for variations in blade length
and other manufacturing tolerances.
Inventors: Gerhard, Gregory J.; Graham, William M.;
Claims:
The embodiments of the invention in which an exclusive property
or privilege is claimed are defined as follows:
1. A surgical scalpel comprising:
a barrel having a longitudinal channel therethrough, the channel
having first and second ends corresponding to first and second
ends of the barrel;
a blade holder having a blade affixed to one end thereof, the
blade holder being mounted for reciprocation in the channel between
an extended position wherein the blade extends beyond the first
end of the barrel and a retracted position;
adjustment means reciprocably mounted in the channel and coacting
with the blade holder to adjustably reciprocate the blade holder
between the extended and retracted positions, the adjustment means
comprising a rod having intersecting axial and transverse bores
extending therethrough, an expandable plug positioned in the transverse
bore and having a bore therethrough that is oriented substantially
coaxially with the axial bore in the rod, and means for moving
the plug outwardly to engage the walls of the channel, the means
for moving the plug comprising a tapered pin reciprocably mounted
in the axial bore in the rod and the bore in the plug.
2. The scalpel of claim 1, wherein the tapered pin has a head
with external threads thereon, the axial bore having internal
threads therein, the head threadably engaging the axial bore for
reciprocating adjustment of the pin in the axial bore and the
bore in the plug.
3. A surgical scalpel comprising:
a barrel having a longitudinal channel therethrough, the channel
having first and second ends corresponding to first and second
ends of the barrel;
a blade holder having a blade affixed to one end thereof, the
blade holder being mounted for reciprocation in the channel between
an extended position wherein the blade extends beyond the first
end of the barrel and a retracted position;
means for preventing rotational movement of the blade holder
in the channel;
adjustment means comprising a rod, a portion of the rod being
threadably mounted in the channel such that rotation of the rod
is operative to adjustably reciprocate the blade holder between
the extended and retracted positions;
means for selectively affixing the rod to the barrel; and,
means for resiliently biasing the blade holder into contact with
the rod.
4. The scalpel of claim 3, further comprising a friction-reducing
cap interposed between the blade holder and the rod.
5. A surgical scalpel, comprising:
a barrel having a longitudinal channel therethrough, the channel
having first and second ends corresponding to first and second
ends of the barrel;
a blade holder having a blade affixed to one end thereof, the
blade holder being mounted for reciprocation in the channel between
an extended position wherein the blade extends beyond the first
end of the barrel and a retracted position;
adjustment means comprising a rod having a transverse bore, a
portion of the rod being threadably mounted in the channel such
that rotation of the rod is operative to adjustably reciprocate
the blade holder between the extended and retracted positions,
the adjustment means including a plug of expandable material positioned
in the transverse bore; and,
means for causing the plug to move outward into contact with
the barrel to prevent the adjustment means from being inadvertently
moved.
6. The scalpel of claim 5, wherein the rod includes external
threads and wherein the outer surface of the plug includes threads
that are continuous with the external threads of the rod.
Description:
BACKGROUND OF THE INVENTION
The present invention relates to medical instruments and more
particularly to a surgical scalpel having an adjustable depth
of cut.
Many surgical procedures including those in the ophthalmic surgery,
plastic surgery, and neurosurgery fields require scalpels that
have an adjustable depth of cut. Although scalpels are available
that provide the surgeon with an adjustable depth of cut, it is
desirable in most such scalpels to have ready means for determining
the depth of cut provided by the scalpel at any given adjustable
setting so that a measurement of the blade protrusion from the
instrument is not required upon each readjustment. Moreover, it
is desirable that such scalpels be easily calibrated not only
upon initial manufacture but upon replacement of a blade or blade
holding structure. Moreover, it is desirable for such scalpels
to employ a feature that gives infinitely variable adjustment
of the blade extension while providing the capability to hold
the blade in a desired position without inadvertent or accidental
readjustment.
SUMMARY OF THE INVENTION
The foregoing desirable features are provided in a surgical scalpel
comprising a barrel or body, a blade holder and blade, an adjustment
means for reciprocating the blade holder relative to the barrel,
and indicator means to indicate the length of blade exposed. The
barrel has a longitudinal channel therethrough. The first end
of the barrel terminates in a foot. The corresponding end of the
channel opens into the foot. The other end of the channel opens
onto the other end of the barrel. The blade holder is mounted
for reciprocation in the channel between an extended position
wherein the blade is extended beyond the foot and a retracted
position wherein the blade is retracted into the channel to provide
a protected environment for the blade. The adjustment means is
associated with the blade holder and the barrel and includes a
means for biasing the blade holder toward the retracted position.
The adjustment means also includes a rod that is reciprocably
mounted in the channel and coacts with the blade holder to adjustably
reciprocate the blade holder between its extended and retracted
positions. A means is also provided for releasably affixing the
adjustment means to the barrel to prevent the adjustment means
from being inadvertently moved.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the present invention can be derived
by reading the ensuing specification in conjunction with the accompanying
drawings wherein:
FIG. 1 is an isometric view of the surgical scalpel of the present
invention;
FIG. 2 is an exploded isometric view of the surgical scalpel
of the present invention;
FIG. 3 is a greatly enlarged longitudinal sectional view of the
surgical scalpel of the present invention;
FIG. 4 is a cross-sectional view of the surgical scalpel taken
along a section line similar to 4--4 of FIG. 3;
FIG. 5 is a further enlarged longitudinal sectional view of the
adjustment member and means for affixing the adjustment member
to the barrel in any of a plurality of desirable positions; and
FIG. 6 is an enlarged plan view of a segment of the scalpel illustrating
the adjustable indicia bearing structure that indicates the amount
of blade extension.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGS. 1 and 2, the surgical scalpel 10 of the
present invention is configured in the shape of a pencil or other
small hand tool and is similarly sized. The scalpel 10 includes
a body or barrel 12, an adjustment screw 14 and a lockscrew 16.
The barrel 12 has a central longitudinal channel (shown best in
FIG. 3) that extends the entire length of the barrel 12. The bottom
end of the barrel 12 terminates in a tapered nose 18. The nose
18 tapers radially inwardly from the central portion of the barrel
and terminates in foot 20. In this embodiment, the barrel 12 and
nose 18 are separately formed; however, the barrel and nose can
be formed as a unitary structure if desired. The foot 20 is integrally
formed as part of the bottom end of the nose 18. The foot 20 comprises
a pair of spaced abutment members 22 and 24 that are spaced on
opposite sides of the axis of the barrel. The bottoms or edges
of the spaced members 22 and 24 are parallel with each other and
lie in a plane that is preferably oriented orthongonally to the
axis of the barrel. The foot 20 thus resembles the member given
the corresponding name in a sewing machine. The longitudinal channel
opens onto the bottom of the barrel between the two abutment members.
The foot functions to bear against tissue adjacent an incision,
thus limiting the depth of the incision to the length of blade
exposed beyond the bottom of the foot.
A blade holder, generally designated 26, comprises a blade shaft
28 and guide 30. The lower end of the blade shaft carries a longitudinally
oriented recess into which is inserted a blade 32 of any suitable
material, but preferably diamond. The blade holder 26 is reciprocably
mounted in the barrel channel along with the spring 34. The adjustment
screw 14 threadably engages the interior of the barrel channel
and when rotated reciprocates the blade holder 26 against the
bias of spring 34. As will be seen in more detail later the lockscrew
16 threads into an axial channel or bore in the adjustment screw
and provides a means for locking the adjustment screw to the barrel
12 to secure the blade holder and thus the blade 32 in any desired
position.
Referring now to FIGS. 2 and 3 conjunctively, the longitudinal
channel 44 extends through the entire length of the barrel 12,
opening onto the foot 20 at the bottom of the barrel and also
opening onto the upper end of the barrel. The portion 46 of the
channel extending through the nose 18 has a slightly smaller diameter
than the remainder of channel 44. The blade shaft 28 has a diameter
slightly smaller than the diameter of the channel 46 and is reciprocally
mounted therein. The bottom end of the blade shaft 28 carries
a longitudinally extending recess 48 into which the blade 32 is
adhesively or otherwise suitably secured. The upper end of the
shaft 28 is inserted into a bore 50 running axially down a guide
30, which has a cylindrical configuration that is slightly smaller
in diameter than the diameter of the channel 44 in the barrel
12. The shaft 28 and bore 50 are sized such that the shaft fits
in an interference relationship with the bore 50 and thus is secured
to the guide 30.
Referring to FIGS. 2, 3 and 4, the guide 30 carries a longitudinally
extending groove 52 along the entire length of its outer surface.
A radially extending pin 54 is mounted in the barrel and extends
into the channel 44 and into the slot 52. The slot 52 and the
pin 54 thus coact to prevent the guide 30 from rotating in the
channel 44. In this manner, the blade 32, which is rotationally
oriented in a predetermined manner relative to the slot 52, is
always oriented in the same direction relative to the foot 20
regardless of its longitudinal position within the foot 20. Preferably
the blade is oriented such that the cutting edge of the blade
when viewed from the bottom of the foot 20 is oriented to run
in the same general direction as the bottom edges of the abutment
members forming the foot 20.
Referring back to FIGS. 2 and 3, the spring 34 is positioned
in the channel 44 between the shoulder 56 formed at the intersection
of the barrel channel 44 and the nose channel 46 and the shoulder
58 formed between the lower end of the guide 30 and the blade
shaft 28. The spring is under a compression load so that the blade
holder and thus the blade 32 is always biased toward a retracted
position, that is, a position wherein the blade tip is positioned
upwardly from the bottom edges of the foot 20.
The adjustment screw 14 is a generally cylindrical shaped rod
having three portions: a lower threaded portion carrying external
threads 60 that engage internal threads in the channel 44 in the
barrel 12; a central cylindrical portion 62; and an upper end
portion 64. The central cylindrical portion 62 has a slightly
smaller diameter than the threaded portion 60 and carries a cylindrical
sleeve 66 that is mounted snugly on the cylindrical portion 62.
The sleeve 66 can be moved both in the circumferential direction
and in the axial direction relative to the adjustment screw 14.
The fit is sufficiently snug so that the sleeve cannot be moved
with the application of only a minor force, but so that upon being
manipulated with a predetermined amount of force the sleeve can
be repositioned on the central cylindrical portion 62. The upper
end of the adjustment screw 64 carries a knurled knob 68 that
is fitted over the upper end 64 of the adjustment screw in an
interference relationship so that the knob can be grasped and
the entire adjustment screw rotated as desired. The bottom end
of the knurled knob 68 carries an annular recess 70 having a thickness
slightly greater than the sleeve 66. The upper end of the sleeve
66 extends into the recess 70 while the lower end of the sleeve
extends under the upper edge or top of the barrel 12 and into
the upper end of channel 44. The purpose of the sleeve will be
discussed in more detail below in conjunction with FIGS. 3 and
6. The primary function of the adjustment screw 14 is to selectively
position the blade holder 26 in the barrel channel 44. The threaded
portion of the screw 14 engages matching internal threads in the
upper end of the channel 44. The lower end of the adjustment screw
includes friction reducing cap 72 positioned such that it is interposed
between the lower end of the screw and guide 30.
Referring conjunctively to FIGS. 2, 3 and 5, the adjustment screw
14 carries an axial bore 74 at its lower end having a first diameter.
This bore transitions into a second bore 76 of larger diameter
that carriers internal threads. A diametrically oriented bore
78 extends through the threaded portion 60 of the adjustment screw
and intersects the smaller diameter bore 74. This diametrically
oriented bore 78 carries a resilient and expandable plug 80, composed
of any suitable polymeric material such as an acetal resin. The
plug 80 is inserted into the bore 78 before the external threads
on the bottom threaded portion 60 of the plug are formed. Thus
the resilient, expandable plug 80 also carries threads in its
outer ends that provide continuity to the external threads on
the lower portion 60 of the adjustment screw. Another axial bore
82 oriented coaxially with the smaller diameter bore 74 is formed
through the central portion of the plug 80. The axial bore 82
in the plug has a diameter that is slightly less than the smaller
diameter bore 74 in the adjustment screw. Another threaded member
84 has external threads that engage the internal threads in the
larger diameter bore 76. The bottom end of the threaded member
84 carries a tapered pin 86. The larger end of the tapered pin
86 lies adjacent the threaded member 86 while the smaller end
extends through and beyond the bore 82 and the plug 80. As the
threaded member 84 is threaded down into the adjustment screw
14, the sides of the tapered pin 86 bear radially outwardly with
increasing force against the surfaces of the bore 82. As force
is exerted on the expandable plug 80, the pin is expanded outwardly
against the threaded sidewalls of the upper portion of the channel
44 in the barrel 12. When sufficient force is exerted on the plug
80, resistance to rotation of the adjustment screw 14 is created
by the friction of the outer ends of the plug 80 on the threaded
surface of the channel wall. In this manner, the coaction of the
threaded member 84, tapered pin 86 and resilient plug 80 on the
inner walls of the barrel serve to selectively fix the adjustment
screw in any desired position, thereby preventing its inadvertent
or accidental movement once the blade extension beyond the foot
20 has been set to a desired degree.
Referring now to FIGS. 3 and 6, the surgical scalpel has a plurality
of indicia associated with the barrel and adjustment screw for
providing a readout on the amount of blade extension. The exterior
surface of the upper end of the barrel 12 carries a plurality
of circumferentially spaced gradation lines 90. These gradations
extend longitudinally along the outer surface of the barrel 12
and divide the outer surface into a predetermined number of circumferential
increments. The basic division is 5 segments with subdivisions
of the segments being multiples thereof. One of the basic subdivision
demarking lines 90 is labeled zero and the other lines are labeled
100, 200, 300 and 400 respectively. A complementary, longitudinally
extending line 92 is placed on the sleeve 66, which is mounted
on the central cylindrical portion 62 of the adjustment screw
14. Additionally, circumferentially extending, longitudinally
spaced gradation lines 94a, 94b, 94c . . . divide the longitudinally
extending line 92 into a plurality of equal increments. The bottom
circumferentially extending line 94a intersects and extends on
both sides of the line 92 while other lines 94 extend alternately
from opposite sides of the line 92. The line 94a is a zero line.
The threads on the adjustment screw 14 are thus sized so that
one revolution of the adjustment screw will preferably advance
the adjustment screw and thus the blade holder and blade, for
example 0.5 mm. The distance between the gradation lines 94a to
94b is therefore preferably set at 0.5 mm. Similarly, the distance
between the gradations 94b to 94c and so on is set at 0.5 mm.
To calibrate the reading of blade extension, the adjustment screw
14 is rotated so that the very tip of the knife blade coincides
with the plane formed by the bottom edges of the foot 20. When
the blade is so positioned, the sleeve 66 is moved axially relative
to the adjustment screw such that the bottom zero line 94a coincides
with the location of the upper lip or edge of the barrel 12. Similarly,
the zero line 92 on the sleeve is positioned so it corresponds
to and aligns with the zero line 90 formed on the outer surface
of the barrel 12. When so calibrated, the amount of extension
of the blade beyond the plane of the foot 20 can be determined
by merely reading first the indicia on the cylindrical sleeve
66 to determine the major increment that whether the blade has
been extended some fraction of 0.5, 1.0 or 1.5 millimeters and
thereafter reading the fraction of the extension by reading the
particular increment on the outer portion of the barrel 12 with
respect to the location of the zero line 92 on the sleeve 66.
For example, if the line 92 is positioned adjacent the line marked
400 and the upper lip of the barrel 12 lies between the lines
94b and 94c on the sleeve 66, the blade is extended 0.9 mm, provided
the device has been properly calibrated.
The present invention has been described in relation to a preferred
embodiment. One of ordinary skill after reviewing the foregoing
specification will be able to make various changes, substitutions
of equivalents and other alterations to the invention as described
without departing from the broad concepts disclosed herein. For
example, a variety of incision depth limiting structures or alternatives
therefore can be substituted for the foot 20 without changing
the basic nature of the disclosed invention. Further, the scalpel
has been disclosed in relation to a preferred embodiment for use
in ophthalmic surgery. It is to be understood, however, that the
scalpel can be utilized in many forms of surgery in which incisions
to precise depths must be performed. Examples of such surgery
include plastic surgery as well as neurosurgery. It is therefore
intended that the Letters Patent granted hereon be limited only
by the definition contained in the appended claims and equivalents
thereof. |
