U.S. patent application number 11/963749 was filed with the patent office on 2008-08-28 for disposable vitrectomy handpiece.
Invention is credited to Aaron Barnes, Charles De Boer, Matthew McCormick.
Application Number | 20080208233 11/963749 |
Document ID | / |
Family ID | 39563257 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080208233 |
Kind Code |
A1 |
Barnes; Aaron ; et
al. |
August 28, 2008 |
DISPOSABLE VITRECTOMY HANDPIECE
Abstract
Electric vitrectomy handpieces are provided. The handpiece
includes a motor, a clutch mechanism, an oscillating drive
mechanism, a cutting tip and a handle. The motor is attached to the
clutch, and the clutch is attached to the oscillating drive
mechanism. When the motor is operational, the clutch expands to
engage the oscillating drive mechanism and the oscillating drive
mechanism converts the rotational motion of the clutch to the
reciprocating motion of the cutting tip. When the motor is at rest,
the clutch retracts to allow aspiration.
Inventors: |
Barnes; Aaron; (Los Angeles,
CA) ; De Boer; Charles; (Pasadena, CA) ;
McCormick; Matthew; (Forest Falls, CA) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
PO BOX 7068
PASADENA
CA
91109-7068
US
|
Family ID: |
39563257 |
Appl. No.: |
11/963749 |
Filed: |
December 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60876796 |
Dec 21, 2006 |
|
|
|
Current U.S.
Class: |
606/171 ;
606/180 |
Current CPC
Class: |
A61F 9/00763 20130101;
A61B 2017/0023 20130101; A61B 17/320016 20130101; A61B 2017/00477
20130101 |
Class at
Publication: |
606/171 ;
606/180 |
International
Class: |
A61B 17/32 20060101
A61B017/32 |
Claims
1. A vitreous cutter comprising: a motor configured to provide
rotary motion; a handle; a cutter tip; an aspiration line; and a
clutch mechanism coupled to the motor and the cutter tip, the
clutch mechanism configured to expand for engaging the cutter tip
when the motor is activated, and retract for aspiration through the
aspiration line when the motor is at rest.
2. The vitreous cutter according to claim 1, wherein the clutch
mechanism comprises a component including a groove.
3. The vitreous cutter according to claim 2, wherein the groove is
a sinusoidal groove.
4. The vitreous cutter according to claim 1, wherein the motor is a
disposable motor.
5. The vitreous cutter according to claim 1, wherein the cutter tip
is integrated into the handle.
6. The vitreous cutter according to claim 1, wherein the aspiration
line is routed through the handle.
7. The vitreous cutter according to claim 6, wherein the aspiration
line is routed around the motor.
8. The vitreous cutter according to claim 1, further comprising a
means for sensing a speed of the cutter tip.
9. The vitreous cutter according to claim 8, wherein the means for
sensing the speed of the cutter tip comprises a sensor and a
magnet.
10. The vitreous cutter according to claim 1, further comprising a
means for detecting motor failure by monitoring high current
draw.
11. The vitreous cutter according to claim 1, further comprising an
oscillating drive mechanism configured to convert the rotary motion
of the motor to oscillatory linear motion.
12. The vitreous cutter according to claim 1, further comprising a
means for reducing vibration in the handle.
13. The vitreous cutter according to claim 12, wherein the means
for reducing vibration in the handle comprises a rubber or foam
tube surrounding the motor, wherein the tube is compressed against
the motor by the handle.
14. The vitreous cutter according to claim 12, wherein the means
for reducing vibration in the handle comprises a compressed
silicone tubing surrounding the motor.
15. The vitreous cutter according to claim 1, further comprising a
means for preventing heat transfer from the motor to the
handle.
16. The vitreous cutter according to claim 15, wherein the means
for preventing heat transfer from the motor to the handle comprises
an insulating material surrounding the motor.
17. A vitreous cutter comprising: a motor configured to provide
rotary motion; a handle; a cutter tip; an aspiration line; and a
clutch mechanism coupled to the motor and the cutter tip, the
clutch mechanism configured to expand for engaging the cutter tip
when the motor is activated, and retract for aspiration through the
aspiration line when the motor is at rest, the clutch mechanism
comprising first and second components rotatable relative to each
other.
18. The vitreous cutter according to claim 17, wherein the clutch
further comprises a ball riding in a groove in the first component,
the second component maintaining the ball in the groove of the
first component.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority to and the benefit of U.S.
Provisional Patent Application Ser. No. 60/876,796, filed on Dec.
21, 2006, entitled DISPOSABLE VITRECTOMY HANDPIECE, the entire
content of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention is directed to electric vitrectomy handpieces,
and more particularly, the invention is directed to disposable
electric vitrectomy handpieces that are small in size and light in
weight.
BACKGROUND OF THE INVENTION
[0003] Vitreous is a normally clear, gel-like substance that fills
the center of the eye. Certain problems affecting the eye may
require a vitrectomy, or surgical removal of all or a part of the
vitreous. To perform a vitrectomy, various instruments are used
including a vitrectomy handpiece, a light pipe and an infusion line
or port. The vitrectomy handpiece includes a cutter for removing
all or a portion of the eye's vitreous. The light pipe is used as a
light source, and the infusion line or port is used to replace
fluid and maintain proper pressure in the eye.
[0004] Current vitrectomy handpieces have several parts, many of
which can be rather expensive. For example, current vitrectomy
handpieces include positional sensors that detect the position of
the motor to determine when to begin aspiration. This increases the
cost of manufacture, thereby increasing the cost of the device to
the ultimate consumer. Moreover, while these devices are designed
to be reused, the cutting tip must be replaced. Replacement cutting
tips can be expensive, with a common model costing over $100.
[0005] In addition to expense, current vitrectomy handpieces
include several electrical and pneumatic lines attached to the
device, making the device cumbersome to operate and maneuver. Also,
in order to accommodate the number of parts included in the device
and the electric and pneumatic lines, the handpieces tend to be
larger, contributing to the cumbersome nature of the device.
Accordingly, a need exists for a less cumbersome, less expensive
device that is easy to maneuver and comfortable to handle during
surgery.
SUMMARY OF THE INVENTION
[0006] The invention is directed to vitrectomy handpieces that are
light in weight and small in size. The light weight and small size
of the device makes it easy to maneuver and comfortable to handle
during surgery. In one embodiment, a vitrectomy handpiece includes
an electric motor, a clutch mechanism, an oscillating drive
mechanism and a cutting tip. The motor is attached to the clutch
which is attached to the oscillating drive mechanism. The motor may
be any electric motor suitable for use in vitrectomy handpieces.
The oscillating drive mechanism may be any mechanism capable of
converting rotational motion of the motor to reciprocating motion
of the cutting tip.
[0007] The clutch mechanism engages the oscillating drive mechanism
when the motor is running and is stationary when the motor is at
rest. When the motor is at rest, the clutch mechanism allows
aspiration, and when the motor is running, the clutch mechanism
engages the oscillating drive mechanism, which converts the
rotational motion of the clutch to reciprocating motion of the
cutting tip.
[0008] In one embodiment, the vitrectomy handpiece is disposable.
The disposable vitrectomy handpiece according to this embodiment is
manufactured using low cost parts for assembly and manufacture. For
example, an inexpensive, disposable motor may be used to
manufacture a disposable vitrectomy handpiece according to an
embodiment of the present invention.
[0009] The inventive vitrectomy handpieces are small in size and
light in weight, enabling greater maneuverability of the device by
the surgeon. In addition, the inventive vitrectomy handpieces are
ergonomically designed, making the handpiece comfortable to handle
during surgery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] These and other features and advantages of the present
invention will be better understood by reference to the following
detailed description when considered in conjunction with the
attached drawings in which:
[0011] FIG. 1 is a photograph comparing a vitrectomy handpiece
according to an embodiment of the present invention with a
vitrectomy handpiece according to the prior art;
[0012] FIG. 2A is a partial cross-sectional view of a vitrectomy
handpiece according to one embodiment of the present invention;
[0013] FIG. 2B is an exploded view of area B in FIG. 2A;
[0014] FIG. 2C is an exploded view of area C in FIG. 2A;
[0015] FIG. 3 is a partially cut-away side view of a vitrectomy
handpiece according to one embodiment of the present invention;
[0016] FIG. 4 is an exploded schematic view of a motor, clutch
mechanism, drive mechanism and cutting tip of a vitrectomy
handpiece according to one embodiment of the present invention;
[0017] FIGS. 5A through 5E are schematic diagrams depicting the
motion of a clutch mechanism and drive mechanism during a cutting
process of a vitrectomy handpiece according to one embodiment of
the present invention; and
[0018] FIG. 6 is an exploded view of a vitrectomy handpiece
according to one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Embodiments of the present invention are directed to
disposable electric vitrectomy handpieces. The handpieces are
useful with, for example, 20-gauge or smaller instrumentation (e.g.
23, 25-gauge). The handpieces are small in size and cost-efficient.
According to one embodiment of the invention, the small size is
achieved by a disposable tool including a cutter tip integrated
into the tool handle. In another embodiment, cost efficiency is
achieved by a tool using plastic components and an inexpensive,
disposable motor. Although described as disposable and made of
plastic, it is understood that the device need not be disposable
and may be made of any suitable material other than plastic, for
example, metal. The drive mechanism and vitreous cutting tip have
performance characteristics that are equivalent to or better than
existing handpieces. Moreover, the vitrectomy handpiece maintains a
substantially constant aspiration duty cycle over a range of
operating speeds, such as, for example, about 3,000 to about 10,000
cpm or about 600 to about 6000 cpm.
[0020] According to one embodiment of the invention, the vitrectomy
handpiece is well balanced, light in weight and has low rotational
and line torque. Accordingly, the handpiece is easily maneuverable
by the surgeon. In one embodiment, the vitrectomy handpiece is
smaller than conventional electric handpieces, thereby facilitating
mobility. According to one embodiment of the present invention, the
pneumatic lines are incorporated into the handle or fully enclosed
within the handle, reducing clutter and improving ease of
manipulation by the surgeon. The electrical lines are much lighter
than those in conventional cutters, reducing the amount of external
torsion experienced by the surgeon. According to one embodiment,
the electrical lines may be disposable lines that are integral with
the handpiece. In another embodiment, a reusable line connecting a
machine (external or otherwise) to the handpiece may be used. In
yet another embodiment, an internal power supply may be used
instead of electrical lines.
[0021] The vitrectomy handpiece according to embodiments of the
present invention is an inexpensive surgical tool providing an
electric alternative to pneumatic cutters. In some embodiments, the
vitrectomy handpiece is inexpensive and disposable, eliminating the
need for replacement parts. The vitrectomy handpiece may be
provided as a sterile package with the cutting tip incorporated
directly into the handpiece. As the handpiece may be provided fully
assembled, the time needed to prepare for surgery may be
significantly reduced. Also, with disposable designs, the surgeon
may bill directly for the tools used in the procedure, which option
is not available when using a reusable vitrectomy tool with
replacement parts.
[0022] Many considerations are taken into account when designing a
vitrectomy handpiece. Some such considerations include cost, size,
low noise and vibration, aspiration duty cycle and traction. In the
disposable embodiments of the present invention, cost is a concern.
To reduce cost, the components of the vitrectomy handpiece may be
manufactured in high volume, using low cost techniques such as
injection molding, CNC machining, overmolding, deep drawing, EDM,
and the like. Additionally, reducing part count and handpiece size
significantly reduces the total cost of the handpiece. To that end,
integrating the tip into the handpiece not only lowers part count,
but also reduces the overall size of the unit, yielding a size
comparable to or smaller than existing vitrectomy handpieces (e.g.
the Alcon Innovit). As shown in FIG. 1, a vitrectomy handpiece 100
according to one embodiment of the present invention is smaller
than the Alcon Innovit handpiece 102.
[0023] Another consideration in designing vitrectomy handpieces is
minimizing noise and vibration. High levels of noise and vibration
adversely affect maneuverability of the tool during surgery, and
makes it difficult for the surgeon to make precise cuts. To
minimize noise and vibration, the drive mechanism according to one
embodiment has balanced components, smooth transitions as the
cutter is extended and retracted, and good alignment of the drive
components. These characteristics increase the precision of the
internal components and therefore impact the method of manufacture.
In one embodiment of the invention, to reduce noise and vibration,
the vitrectomy handpiece has an invariable cutting duty cycle at a
wide range of operating speeds. In addition, to reduce traction in
comparison to existing electric cutters, a vitrectomy handpiece
according to one embodiment of the present invention has a maximum
cut speed targeted between about 6000 cpm and about 10,000 cpm.
Another way to dampen vibration includes providing a rubber, foam,
silicon, or other like tube around the motor.
[0024] FIGS. 2 through 4 are detailed diagrams of various
vitrectomy cutters 20 according to certain embodiments of the
present invention. According to the illustrated embodiment, the
cutter 20 includes a motor 1, a clutch mechanism 2, an oscillating
drive mechanism 7, and a cutter tip 10 mounted inside a handle 14.
The handle 14 is used to mount and align the various components,
provide ergonomic design for the surgeon, and route aspiration
lines. In one embodiment, the cutter tip 10 is directly integrated
into the handle 14. This integration helps reduce complexity and
part count by eliminating the interface components between the tip
and the handle.
[0025] According to one embodiment, the motor 1 is attached to the
clutch 2. The clutch expands to engage the oscillating drive 7 and
cutter tip 10 when the motor 1 is operational and retracts to allow
aspiration via the aspiration line 15 when the motor 1 is at rest.
The oscillating drive 7 converts the motor 1 rotation into a smooth
reciprocating motion of the cutter tip 10. The oscillating drive
may be any device capable of converting rotary to oscillating
linear motion, such as, for example, a crankshaft.
[0026] Although the clutch is described as allowing aspiration when
the motor is off, it is understood that the vitrectomy handpiece
aspirates during the cutting process as well. During a cutting
process, the aspiration port 201 opens and closes repeatedly as the
cutter is extended and retracted. Aspiration occurs through the
open aspiration port 201 throughout the cutting process. However,
in conventional vitrectomy handpieces, when the motor is turned
off, the cutter may either be extended to close the aspiration port
or retracted to open the aspiration port, and the position of the
cutter is random depending on when during the cutting process the
motor is turned off. In contrast, according to one embodiment of
the present invention, the clutch mechanism 2 5 retracts the cutter
when the motor is turned off, ensuring that the aspiration port is
open when the motor is turned off.
[0027] The actuation of the clutch 2 may be achieved in different
ways. For example, the clutch 2 may retract by reversing the motor
1. In this embodiment, the motor automatically runs in reverse for
a short period when the motor turns off. The reverse motion of the
motor causes the clutch to retract, thereby allowing aspiration via
the aspiration line 15.
[0028] In an alternative embodiment, a spring return may be
employed so that when the motor 1 is off, the clutch 2 retracts.
This alternative clutch mechanism may be used in conjunction with a
spring to retract the clutch and open the aspiration port when the
cutter is turned off. The design of the previous embodiment uses
slow reversed motion of the motor to open the aspiration port. A
design with light springs allows the clutch to retract without any
reverse motion of the motor. This helps simplify the control
required for the tool, but may increase the complexity and thus the
overall cost of the unit.
[0029] The clutch mechanism 2 is used to engage the cutter tip 10
when the handpiece is operated, and allow aspiration when the
cutter is stationary. Existing electric vitrectomy handpieces use a
positional sensor to monitor the position of the motor to determine
when to initiate aspiration. In such conventional handpieces, the
motor is rotated to a position where the aspiration port is open
when the cutter is at rest. This allows full aspiration through the
tip of the instrument when it is not being used to cut. However,
the vitrectomy handpieces according to embodiments of the present
invention use clutching mechanisms to reduce cost and part count,
as well as to improve maneuverability of the instrument. The clutch
eliminates the need for a positional sensor, which not only reduces
overall unit cost, but also reduces the number of electrical lines
attached to the cutter. The smaller cord attached to the cutter
makes it easier to maneuver by the surgeon. This also results in
less line torque.
[0030] According to one embodiment, the clutch mechanism 2 includes
two components that rotate relative to each other when torque is
transmitted across them. With reference to FIGS. 2B and 4, a groove
200 is cut in the first component 3. The groove may have any
suitable profile, and in one embodiment, is half of a sinusoidal
groove. The second component 5 captivates a ball 4 which rides in
the groove 200. When the motor is turned on, torque is transmitted
across the two components of the clutch mechanism, causing them to
rotate relative to one another. As the two components rotate with
respect to one another, the ball rolls or slides along the groove,
causing the two components to expand or contract. When the ball
reaches the end of the groove, it comes to a hard stop.
Subsequently, both components of the clutch rotate together,
transmitting rotary motion to the oscillating drive mechanism 7.
The oscillating drive mechanism 7 converts the rotational motion
into smooth reciprocating linear motion of the cutter.
[0031] As an alternative to the groove 200, the clutch may include
a pin riding on a cam (not shown), or the like. Regardless of the
embodiment, however, the clutch/cam may be implemented as a single
component to reduce cost, or be separated into two elements.
[0032] FIGS. 5A to 5E illustrate portions of the oscillating drive
mechanism 7 and clutch mechanism 2 during a cutting process. The
cutter tip 10 at each step is shown in a box 104a-104e below the
drive and clutch mechanisms. The motor provides rotary motion which
is depicted by curved arrows 106a-106e. At the position illustrated
in FIG. 5A, the cutter is starting from rest and beginning to cut.
In this position, both the clutch 2 and cutter tip 10 are retracted
and the aspiration port 201 is open. As the motor begins to rotate,
the clutch expands until it reaches the engaged position (the
position illustrated in FIG. 5B). The clutch remains engaged as
long as the cutter is cutting (the positions illustrated in FIGS.
5B through 5E). When the clutch is engaged, the oscillating drive
mechanism 7 travels enough to move the cutter across the aspiration
port 201. At the positions illustrated in FIGS. 5C through 5E, the
clutch 2 is engaged, and the oscillating drive 7 is opening and
closing the cutter. At the position illustrated in FIG. 5C, the
oscillating drive mechanism 7 closes the cutter for the first cut.
The cutter is then open at the position illustrated in FIG. 5D and
closed again at the position illustrated in FIG. 5E.
[0033] The motor may be any suitable motor known in the art, and in
one embodiment, may be a disposable motor. Using disposable motors,
which are generally less expensive than their reusable
counterparts, reduces not only the cost of the motor but also the
cost of the vitrectomy handpiece. A disposable design also allows
use of plastic components and gearing. When purchased in high
volumes, high quality, miniature DC motors with gearing may cost
about $30 or more. Although such disposable motors typically have
shorter lifespans than their non-disposable counterparts, because
the motor is disposable, the lifespan requirement is reduced
compared to non-disposable motors. For a disposable instrument, the
longevity of the motor is not as stringent, and more cost effective
motors can be considered.
[0034] Small DC motors generally require gearing due to the output
speed range (which may be about 600 cpm to about 6000 cpm), and the
high torque needed (stall torque of about 7 mNm). Typical small DC
motors run at speeds above about 5000 rpm, with many of them having
free running speeds above about 15000 rpm. Pre-geared motors meet
the shaft speed and torque requirements, but they increase both
price and footprint.
[0035] Gearing small DC motors is another option to optimize
overall cost. One method of achieving this includes using a motor
with relatively high torque (stall torque of about 2 to about 3
mNm) and relatively low free running speed (about 10,000 rpm), and
incorporating minimal gearing to obtain the desired speed. Gearing
may include a frictional drive, a single set of spur gears, a
plastic planetary gear, or a harmonic drive. Typically, a motor
with high torque and low free running speed will be larger than the
faster running lower torque models. The cost of the different
motors will be similar. To reduce the footprint of the vitrectomy
handpiece, a smaller motor may be used with gearing similar to a
harmonic drive. This type of gearing has a relatively low part
count and allows for high reduction ratios in a small space.
Ultimately, the gearing decision will be a cost trade-off analysis
of the various designs and projected cost of manufacture.
[0036] According to one embodiment, the handle 14 of the vitrectomy
handpiece not only holds the motor 1 and drive mechanisms 2 and 7,
but also the aspiration line 15. Routing the aspiration line
through the handle reduces clutter and improves maneuverability of
the tool. According to one embodiment, the aspiration line begins
inside the handle and is routed to a port in the back of the
handle. A small electrical line is bundled with the aspiration line
at the back of the handle in a single cord. The cord (including the
aspiration line and electrical line) may be integrated with the
handpiece to form a single component.
[0037] According to other embodiments of the invention, the
vitrectomy handpiece interfaces with existing cutter tips 10a as is
illustrated in FIG. 6. As shown in FIG. 6, a vitrectomy handpiece
according to one embodiment of the present invention including a
motor 1a, clutch mechanism 2a and oscillating drive mechanism 7a
interfaces with a commercially available cutter tip 10a.
[0038] According to another embodiment of the invention, as shown
in FIGS. 2-3, the vitrectomy handpiece incorporates the cutter tip
10 into the handle 14 and the aspiration line 15 is routed through
the handle 14. This configuration eliminates the need for an
externally connected aspiration line, and thus improves
maneuverability of the handpiece. In one embodiment, the aspiration
line 15 may be routed around the motor, as shown in FIGS. 2A and 3.
In addition to yielding all the benefits of routing the aspiration
line inside the handle, this configuration cools the motor, keeping
it from overheating, as the aspiration fluid runs across the motor
1 through the aspiration line 15. Such a configuration also helps
dampen vibration.
[0039] In another embodiment of the invention, a speed sensor may
be incorporated into the handpiece for sensing speed, proper
operation of the handpiece, and the like. The speed sensor may
include a sensor and a magnet. In another embodiment, instead of
using a sensor, speed may be measured by measuring a current ripple
as the motor rotates, measuring current/voltage curves and
extrapolating speed based on the measured data, and the like.
[0040] According to another embodiment of the invention, stall of
the handpiece may be detected by looking at the current draw to
find failure.
[0041] In one embodiment, tabs may be integrated into the handle to
prevent rotation of the tip by the drive mechanism.
[0042] According to another embodiment, a seal is provided. As
shown in FIGS. 2 and 3, the seal may include a seal housing 11, an
o-ring or diaphragm seal 12 and a seal retainer 13.
[0043] To be viable alternatives to pneumatic cutters, the cost of
the inventive vitrectomy handpieces should be comparable to or less
than existing cutter tips. To reduce cost, according to one
embodiment, all components in the design are made of plastic.
However, it is understood that the present invention is not limited
to plastic, and that any other material that lends itself to high
volume and low cost manufacturing techniques may be employed in
lieu of or in addition to plastic.
[0044] The components of the vitrectomy handpiece may be
manufactured by molding or CNC techniques conventional in the art.
Molding may have a higher upfront tooling cost, but provides low
unit cost unit when purchased in large volumes. CNC parts provide
improved component tolerances, but unit cost is increased when
purchased in large volumes. If high tolerance is required for the
clutch mechanism, molding may be used in conjunction with a CNC
finishing pass (bored hole or a sinusoidal cam cut). A study on
performance versus part tolerance may be evaluated to understand
the exact specifications for the mold and/or CNC parts.
[0045] Optimal gearing of the handpiece may be achieved by testing
traction and cutting efficiency as a function of cutter rate. This
testing will allow optimization of top speed. With this
information, the gearing of the handpiece may be modified for
operation at an optimal cut rate.
[0046] Although this invention has been described with respect to
certain specific embodiments, those skilled in the art will have no
difficulty devising variations to the described embodiments which
in no way depart from the scope and spirit of the present
invention. For example, although the present invention has been
described with respect to electric vitrectomy handpieces, those of
ordinary skill in the art will appreciate that the described
designs may also apply to pneumatic vitrectomy handpieces.
Furthermore, to those skilled in the various arts, the invention
itself herein will suggest solutions to other tasks and adaptations
for other applications. It is Applicants' intention to cover all
such uses of the invention and those changes and modifications
which could be made to the embodiments of the invention herein
chosen for the purpose of disclosure without departing from the
spirit and scope of the invention. Thus, the present embodiments of
the invention should be considered in all respects as illustrative
and not restrictive.
* * * * *