Surgical knife with retractable and angularly adjustable blade

A surgical knife intended for use in ophthalmic surgery has a blade which is angularly adjustable with respect to the knife handle without requiring removal of the blade or adjustment of mechanical elements such as clamps, screws, levers, locks or the like. The blade can be retracted into the knife handle to protect the blade from damage between uses, and to protect against accidental cuts.

This invention relates generally to surgical knives and, more particularly, 
to knives for ophthalmic surgery with blades that are angularly adjustable 
during surgery and that retract into the knife handle between uses. 
BACKGROUND OF THE INVENTION 
Ophthalmic surgeons work within a very small operating field upon organs 
whose tissues are complex and delicate. Cuts made during surgery must be 
precise as to length, direction and depth, requiring surgical knives of 
unsurpassed sharpness and maneuverability. 
Heretofore, most surgical knives available had blades held in fixed, 
non-adjustable relationship to the knife handle. Some blades were offset 
at a selected angle, while most blades extended straight out from the 
handle. Blades could be made with different configurations for particular 
cuts, but once these cuts were made, a new blade (or a new knife) had to 
be substituted for the remainder of the surgery. 
Others have developed surgical knives with blades or blade holders that are 
angularly adjustable. 
U.S. Pat. No. 4,672,964 (Dee) describes and claims a knife having a blade 
holder with a ball formed on one end which fits rotatably into a socket 
formed on a housing which then, in turn, is threadably attached to a knife 
handle. Mounted on the handle is a crank lever which moves a push rod 
toward the socket to contact the ball (and fix it in a selected position), 
or moves the push rod away from the ball to enable the ball (and, thereby, 
the blade holder) to rotate with respect to the handle. Changing the angle 
of the blade is an involved procedure: the surgeon must hold the handle 
with one hand and release the ball with the other by lifting the lever, 
reorient the blade, and re-clamp the ball by lowering the lever. 
U.S. Pat. No. 4,788,976 (Dee, et al.) is a continuation-in-part of the '964 
Dee patent, and adds to the '964 Dee patent a modified version of the 
crank lever mechanism used to clamp the ball and lock the blade in a 
selected position. Changing the blade angle still calls for significant 
manipulation of the knife adjusting mechanism. 
U.S. Pat. No. 3,609,864 (Bassett) teaches and describes a surgical blade 
handle with a blade holder mounted to a ball. A knurled knob is threaded 
into the end of the handle, and a push rod extends within the handle from 
the knob to the ball. When the knob is threaded into the handle, the push 
rod contacts and clamps the ball at a selected angle, a two-handed 
procedure. 
An arrangement very similar to that of Bassett is shown in Swiss patent 
490,072 (Muller). A blade-and-ball assembly fits into a socket in a blade 
holder, and a handle is threaded into the blade holder until a handle 
projection contacts the ball. 
U.S. Pat. No. 4,275,735 (Chutter) teaches and describes a blade holder 
within which a surgical blade may be selectively oriented and clamped. 
There is no capability for changing the angle of the blade during an 
operation without disassembling the holder and reinserting the blade. It 
appears that Chutter contemplates the prior setup of the knife rather than 
"on-the-fly" changes that may be required during surgery. 
U.S. Pat. No. 3,922,784 (Prince, et al.) teaches and describes a swivel 
knife consisting of a handle and a blade holder clamped to the end of the 
handle. The blade holder allows the blade to be rotated about the axis of 
the blade holder, and the angle at which the blade holder is "skewed" with 
respect to the handle may be changed by loosening and retightening a thumb 
screw. 
None of the prior art adjusting mechanisms described above allow the knife 
blade to be withdrawn into the handle to protect the blade when the knife 
is not being used, and to protect against accidental cuts to one who picks 
up the knife. It is particularly important to prevent accidental cuts 
during surgery, or accidental perforation of surgical gloves, where the 
danger of contamination in a bloody operating field is present. 
The need exists, then, for a knife particularly suited to ophthalmic 
surgery with a blade that is angularly adjustable without the operation of 
mechanical locks or levers, or the removal and reinstallation of the 
cutting blade. 
The need also exists for a blade angularly adjustable to selected, discrete 
angular positions. 
The need also exists for a blade adjustment mechanism which holds the blade 
with a force firm enough to allow use in surgery, yet allows simple, 
one-handed adjustment of the blade angle during surgery. 
The need also exists for a blade adjusting mechanism that will allow the 
blade to be moved simply to a straight position and then to be withdrawn 
into the knife handle when not in use to protect the blade and to prevent 
accidental cuts to one picking up the knife.

DETAILED DESCRIPTION OF THE DRAWINGS 
While the present invention is described herein within the context of 
ophthalmic surgery, it is to be understood that other uses for the 
invention are contemplated as well. 
Referring now to FIG. 1, the numeral 10 indicates generally a surgical 
knife, typically of the type used during ophthalmic surgery. Knife 10 has 
a generally hollow, tubular case 11 with a tapered case tip 12 which 
terminates in a generally circular case mouth 13. Ridges are formed along 
a portion of case 11 and tip 12 to form a handgrip 14. 
A preferred cutting element is a diamond blade 15, shown mounted in a 
bladeholder 16. In a preferred embodiment of the invention, bladeholder 16 
is rotatably mounted to mounting block 17 in a manner to be more fully set 
forth herein. Blade 15 is formed with a series of cutting edges 18 which, 
in a preferred embodiment, is particularly useful for ophthalmic surgery. 
Because the tissues to be cut during ophthalmic surgery are delicate and 
somewhat flexible, it is critical that edges 18 be extremely sharp and 
free from nicks. Keeping the edges so sharp also increases the risk of 
accidental cuts, particularly to the user's hands and to surgical gloves 
worn by users. It is a decided advantage to incorporate into such a 
surgical knife a means to protect the blade when the knife is not being 
used or is being retrieved prior to actual cutting. Accordingly, blade 
holder 16 is attached to mounting block 17 which, in turn, is selectably 
retractable into case 11, in a manner to be set forth more fully below. 
The user may then choose between the retracted blade position shown in 
FIG. 3 or the extended position shown in FIGS. 1 and 2. 
Referring to FIG. 2, it can be seen that knife 10 has a cylindrical handle 
19 sized and shaped to be concentric and coaxial with case 11 and to fit 
closely within and slide into and out of case 11. At its outermost end, 
handle 19 has a knob 20 attached thereto, and at its innermost end, a 
cylindrical collar assembly 21. Collar assembly 21 consists of a solid 
plug 22 from which a cylindrical skirt 23 extends in a direction toward 
tip 12. 
A cylindrical plunger 24 is attached at one end to plug 22 and extends 
therefrom toward tip 12, and mounting block 17 is attached to the 
remaining end thereof. Plunger 24 is sized and shaped to create and define 
an annular cavity 25 between the outer surface of plunger 24 and the inner 
surface of skirt 23. A cylindrical coil plunger spring 26, sized to have a 
diameter larger than that of plunger 24 and smaller than that of skirt 23, 
has one end nested within cavity 25 and extends along the length of 
plunger 24 to abut shoulder 27 formed within case 11. 
Spring 26 is compressed as handle 19 is moved into case 11; when handle 17 
is released, spring 26 returns to its unstressed position forcing handle 
19 out of case 11. Thus, spring 26 is compressed as plunger 24 and, 
thereby, mounting block 17 and blade 15, are extended from tip 12. 
Similarly, as handle 19 is released, spring 26 acts to withdraw mounting 
block 17 and blade 15 into case 11. 
FIG. 1 demonstrates a preferred manner in which to lock blade 15 in an 
extended position. A locking slot 28 is formed as a generally J-shaped 
channel in case 11, with an axially-extending slot segment 29 and a 
circumferentially-extending foot segment or retaining bend 30. In FIG. 2, 
there is shown a locking peg 31 attached to and extending outward from 
handle 19. Peg 31 is positioned to register with slot 28 when knife 10 is 
assembled. Pushing knob 20 inward causes peg 31 to travel along axial slot 
segment 29 while spring 26 is being compressed and blade 15 is being 
extended from tip 12. As peg 31 reaches the end of axial segment 29, knob 
20 is rotated to move peg 31 into foot segment 30, and as knob 21 is 
released, spring 26 causes peg 31 to push against and frictionally engage 
case 11 within foot segment 30, thus preventing blade 15 from being 
withdrawn into case 11. Twisting peg 20 to move knob 31 back into 
alignment with axial segment 29 allows blade 15 to be drawn back into case 
11. 
Referring now to FIG. 4, a blade angle adjusting assembly is shown. A 
sector plate 38 is pivotally attached to mounting block 17 by pivot pin 
33. Mounting block 17 is split at one end to form legs 34 and 35. Each leg 
has a mounting hole (36 and 37, respectively) positioned to allow pivot 
pin 33 to pass therethrough. As seen in FIG. 4, bladeholder 16 is mounted 
to mounting block 17 by aligning mounting hole 39 on sector plate 38 with 
holes 36 and 37, and passing pivot pin 33 therethrough. 
As seen in FIGS. 3 and 5, a retaining post 44 extends between and is 
attached to mounting block legs 34 and 35, and is positioned to engage 
said detents as sector plate 38 is rotated. 
To adjust the angle of blade 15, bladeholder 16 is pivoted by rotating 
sector plate 38 about pivot pin 33. Throughout the arc of rotation, sector 
plate 38 contacts retaining post 44, bringing detents 40, 41, 42 and 43 
into engagement, seriatim, with retaining post 44. Bladeholder 16 and, 
thereby, blade 15, are held at preselected, discrete angles of rotation by 
the interengagement of detents 40, 41, 42 and 43 with retaining post 44. 
The detents, as shown, are formed as arcuate grooves or cutouts to give 
the interengagement with cylindrical retaining post 44 a smoother and more 
cam-like action, allowing the angle of blade 15 to be changed with a 
minimum of manual effort. Other shapes for said detents and said retaining 
post, or selected surface finishes can be used to affect the degree of 
ease or difficulty with which the angle of blade 15 may be adjusted. The 
preferred embodiment presented herein contemplates the use of relatively 
smooth finishes on both sector plate and retaining pin, and the use of a 
cylindrical retaining pin. 
Use of the present invention can be described as follows. Knife 10 is held 
with one hand at grip 14, while knob 20 is gripped with the other hand and 
pushed toward tip 12, moving plunger 24 with respect to case 11, causing 
locking peg 31 to travel along locking slot 28 while, at the same time, 
compressing return spring 26. When peg 31 reaches the end of its travel, 
peg 20 is then twisted to seat knob 31 in foot segment 30, holding plunger 
24 in its extended position to expose blade 15, blade holder 16 and a 
portion of mounting block 17. 
Blade 15 may then be set at a desired angle by pressing on bladeholder 16 
with sufficient force to overcome the frictional engagement of retaining 
post 44 with one of detents 40, 41, 42 and 43, an operation that can be 
carried out as many times as found to be necessary or desirable during 
surgery. 
Engagement with detent 40 holds bladeholder 16 and, thereby, blade 15 in a 
"straight" position, that is, with blade 15 aligned with the axis of case 
11. Engagement with detent 43 orients blade 15 at approximately right 
angles to the axis of case 11. The machining and positioning of said 
detents is done to allow blade 15 to be held at preselected angles found 
to be advantageous for surgery. 
To protect the blade 15, it must first be adjusted to the "straight" 
position before being retracted. Thereafter, knob 20 is twisted to move 
peg 31 from foot segment 30 back into alignment with axial slot 29, thus 
allowing spring 26 to push plunger 24 rearward, retracting blade 15 into 
case 11 via mouth 13. 
While the foregoing has described certain preferred embodiments of the 
present invention, it is to be understood that these descriptions are by 
way of example only and are not intended to limit the allowable scope of 
the invention. It is expected that others will perceive variations which, 
while differing from the foregoing, do not depart from the spirit and 
scope of the invention herein described and claimed.