U.S. patent application number 14/947465 was filed with the patent office on 2016-07-21 for surgical handpiece with a drive spindle having a distal bore to which locking elements are mounted and an adjacent proximal bore defined by faces shaped to transfer torque to the attached cutting accessory.
The applicant listed for this patent is Stryker Corporation. Invention is credited to James B. Wiebe, III.
Application Number | 20160206327 14/947465 |
Document ID | / |
Family ID | 37025042 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160206327 |
Kind Code |
A1 |
Wiebe, III; James B. |
July 21, 2016 |
SURGICAL HANDPIECE WITH A DRIVE SPINDLE HAVING A DISTAL BORE TO
WHICH LOCKING ELEMENTS ARE MOUNTED AND AN ADJACENT PROXIMAL BORE
DEFINED BY FACES SHAPED TO TRANSFER TORQUE TO THE ATTACHED CUTTING
ACCESSORY
Abstract
A surgical handpiece with a rotating spindle for receiving the
coupling head of a cutting accessory. The spindle has a proximal
bore with faces shaped to transfer torque to the cutting accessory.
A distal bore extends forward from and the proximal bore to the
distal end of the spindle. The distal bore is shaped so the outer
perimeter of the bore is located radially outwardly from the
proximal bore. One or more openings are formed in the spindle open
into the distal bore. The openings are forward of the proximal end
of the distal bore. A locking member is able to move in and out of
each opening so as to move in and out of the distal bore. The
locking members, when seated in the distal bore releasable hold the
cutting accessory seated in the distal and proximal bores to the
spindle.
Inventors: |
Wiebe, III; James B.;
(Riner, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stryker Corporation |
Kalamazoo |
MI |
US |
|
|
Family ID: |
37025042 |
Appl. No.: |
14/947465 |
Filed: |
November 20, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13795064 |
Mar 12, 2013 |
9192394 |
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14947465 |
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11471266 |
Jun 20, 2006 |
8419760 |
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13795064 |
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60693638 |
Jun 25, 2005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2017/00477
20130101; Y10T 279/3418 20150115; A61B 17/1624 20130101; A61B
2017/00734 20130101; A61B 17/1628 20130101; B23B 45/008 20130101;
A61B 17/162 20130101; A61B 17/1631 20130101; A61B 17/1622 20130101;
A61B 17/32002 20130101; A61B 2017/00464 20130101; B25F 5/001
20130101; A61B 17/1615 20130101; B23B 31/1074 20130101; A61B
2017/320032 20130101 |
International
Class: |
A61B 17/16 20060101
A61B017/16 |
Claims
1. A surgical tool comprising: a housing; a motor disposed in said
housing, said motor having a rotating shaft; a spindle rotatably
mounted to said housing, said spindle being connected to said motor
shaft to be rotated by said motor shaft, said spindle having a
distal end and being shaped to define: a distal bore that extends
proximally from the distal end the spindle, the distal bore having
an outer perimeter and proximal end; a proximal bore that is
contiguous with the distal bore and extends proximally from the
distal end of the distal bore, the proximal bore being defined by
plural spindle inner faces that are located inwardly of the outer
perimeter of the distal bore and that are shaped to transmit torque
to the proximal end of the cutting accessory seated in the distal
and proximal bores; and at least one opening into the distal bore
that is located forward of the proximal end of the distal bore; and
a coupling assembly attached to said housing or said spindle for
removably holding the cutting accessory in the spindle bore, said
coupling assembling including at least one locking member that is
positioned to move in and out of the at least one opening of into
the distal bore so as move in and out of the distal bore, so that
when said at least one locking member is disposed in the distal
bore, said at least one locking member holds the proximal end of
the cutting accessory in the distal and proximal bores of said
spindle.
2. The surgical tool of claim 1, further including a pin is
statically mounted to said spindle so as to project into the distal
bore of said spindle.
3. The surgical tool of claim 1, wherein a pin is statically
mounted to said spindle so as to project into the distal bore and
said pin is mounted to said spindle so as to be located distal to
the proximal end of the distal bore and proximal to the at least
one opening formed in the distal bore.
4. The surgical tool of claim 1, wherein said spindle is shaped so
that the plurality of faces that define the proximal bore of said
spindle are shaped so that the proximal bore, in cross section, is
in the shape of polygon.
5. The surgical tool of claim 1, further including a gear train
that connects said rotating shaft of said motor to said
spindle.
6. The surgical tool of claim 1, further including a gear train
that connects said rotating shaft of said motor to said motor and
said gear train is configured to reduce the rotational speed of
spindle relative to the rotation speed of said motor shaft.
7. The surgical tool of claim 1, further including: a gear train
assembly mounted in said housing, said gear train assembly having a
plurality of drive heads that are connected to said motor shaft to
rotate at different speeds upon actuation of said motor shaft; and
a clutch assembly that selectively connects a single one of said
gear train drive heads to said spindle so that said spindle is
rotated by the said drive head to which said spindle is
connected.
8. The surgical tool of claim 1, wherein said: said spindle is
formed with a plurality of openings into the distal bore; and said
coupling assembly includes a plurality of locking members, each
said locking member being positioned to move out of a separate one
of the openings into the distal bore.
9. The surgical tool of claim 1, wherein said coupling assembly at
least one locking member is a pin.
10. The surgical tool of claim 1, wherein: a longitudinal axis
extends proximally to distally through the spindle; and said
spindle is formed so that the at least one opening into the distal
bore is in the form of a slot that is centered on a plane that is
angled relative to the longitudinal axis of the spindle, the angle
being selected so that the at least one locking member that moves
in and out of the slot moves diagonally relative to the
longitudinal axis of said spindle.
11. The surgical tool of claim 1, wherein said spindle is further
formed so that the distal bore has a circular cross sectional
profile.
12. A surgical tool comprising: a housing; a motor disposed in said
housing, said motor having a rotating shaft; a spindle rotatably
mounted to said housing, said spindle being connected to said motor
shaft to be rotated by said motor shaft, said spindle shaped to
have: a plurality of inner faces that define a proximal bore
internal to the spindle, the inner faces shaped to transfer torque
to a define a cutting accessory seated in the proximal bore; a
distal bore that extends forward from the proximal bore to a distal
end of the spindle so as to define a distal opening in the spindle
for receiving the cutting accessory and, wherein, the distal bore
has an outer perimeter that is located radially outwardly of the
proximal bore; and at least one opening into the distal bore, the
at least one opening being spaced distally away from the proximal
bore; a pin that is statically mounted to said spindle so as to
extend in the distal bore, said pin being located distal to the
proximal bore and proximal to the at least one opening into the
distal bore; and a coupling assembly attached to said housing or
said spindle for removably holding the cutting accessory in the
spindle bore, said coupling assembling including at least one
locking member that is positioned to move in and out of the at
least one opening of into the distal bore so as move in and out of
the distal bore, so that when said at least one locking member is
disposed in the distal bore, said at least one locking member holds
the proximal end of the cutting accessory in the distal and
proximal bores of said spindle.
13. The surgical tool of claim 12, wherein said spindle is shaped
so that the plurality of inner faces that define the proximal bore
of said spindle are shaped so that the proximal section of the
spindle bore, in cross section, is in the shape of a polygon.
14. The surgical tool of claim 12, wherein said spindle is shaped
so that the plurality of inner faces that define the proximal bore
of said spindle are shaped so that the proximal section of the
spindle bore, in cross section, is in the shape of a hexagon.
15. The surgical tool of claim 12, further including a gear train
that connects said rotating shaft of said motor to said
spindle.
16. The surgical tool of claim 12, further including a gear train
that connects said rotating shaft of said motor to said motor and
said gear train is configured to reduce the rotational speed of
spindle relative to the rotation speed of said motor shaft.
17. The surgical tool of claim 12, further including: a gear train
assembly mounted in said housing, said gear train assembly having a
plurality of drive heads that are connected to said motor shaft to
rotate at different speeds upon actuation of said motor shaft; and
a clutch assembly that selectively connects a single one of said
gear train drive heads to said spindle so that said spindle is
rotated by the said drive head to which said spindle is
connected.
18. The surgical tool of claim 12, wherein said: said spindle is
formed with a plurality of openings into the distal bore; and said
coupling assembly includes a plurality of locking members, each
said locking member being positioned to move out of a separate one
of the openings into the distal bore.
19. The surgical tool of claim 12, wherein said coupling assembly
at least one locking member is a pin.
20. The surgical tool of claim 12, wherein: a longitudinal axis
extends proximally to distally through the spindle; and said
spindle is formed so that the at least one opening into the distal
bore is in the form of a slot that is centered on a plane that is
angled relative to the longitudinal axis of the spindle, the angle
being selected so that the at least one locking member that moves
in and out of the slot moves diagonally relative to the
longitudinal axis of said spindle.
21. The surgical tool of claim 12, wherein said spindle is further
formed so that the distal bore has a circular cross sectional
profile.
Description
RELATIONSHIP TO EARLIER FILED APPLICATION
[0001] This application claims priority from U.S. patent
application Ser. No. 13/795,064 filed 12 Mar. 2013, now U.S. Pat.
No. 9,192,394. U.S. patent application Ser. No. 13/795,064 claims
priority from U.S. patent application Ser. No. 11/471,266 filed 20
Jun. 2006, now U.S. Pat. No. 8,419,760. U.S. patent application
Ser. No. 11/471,266 claims priority under 35 U.S.C. Sec. 119 from
U.S. Provisional Pat. App. No. 60/693,638 filed 25 Jun. 2005. The
above-identified priority applications are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to a surgical handpiece able to
accept different rotating attachments and cutting accessories. More
particularly, this invention is related to a surgical handpiece
with a clutch for transferring rotational moment from a drive
assembly that is compact in size. This invention is further related
to a surgical handpiece with a coupling head for receiving
different attachments or accessories that minimizes
attachment/accessory rotational wobble.
BACKGROUND OF THE INVENTION
[0003] In modern surgery, an important instrument available to
medical personnel is the powered surgical tool. Often, this tool is
a handpiece in which a motor is housed. Secured to the handpiece is
a cutting accessory designed for application to a surgical site on
a patient in order to accomplish a specific medical task. Some
powered surgical handpieces are provided with drills or reamers for
cutting bores or other void spaces in tissue. The ability to use
powered surgical tools on a patient lessens the physical strain of
surgeons and other medical personnel when performing procedures on
a patient. Moreover, most surgical procedures can be performed more
quickly, and more accurately, with powered surgical tools than with
the manual equivalents that preceded them.
[0004] One such type of tool is the surgical rotary handpiece. A
rotary handpiece has spindle that rotates in response to actuation
of the handpiece motor. Attached to the front end of the spindle is
a coupling assembly. The coupling assembly releasably holds a
device to the spindle so that the device rotates in unison with the
spindle. Generally, two types of devices are releasably coupled to
a handpiece spindle. One type of device is the actual cutting
accessory, for example, the drill or the reamer. The cutting
accessory has a shaft. The proximal end, the rear end, of the shaft
is releasably held to the spindle by the coupling head.
[0005] The second type of device coupled to a rotary handpiece is a
front end attachment. The attachment has a housing with opposed
front and rear ends. An input shaft extends from the attachment
rear end. The attachment front end has its own output spindle and
complementary coupling assembly. Sometimes a gear assembly is
located between the input shaft and the output spindle of an
attachment. The gear assembly contains gears that typically
increase the torque/decrease the speed of the rotational motion
applied to the attached cutting accessory through the attachment
output spindle. When the attachment is attached to the handpiece,
the attachment housing is often statically coupled to the handpiece
housing. The handpiece coupling assembly holds the attachment input
shaft to the handpiece spindle. The actual cutting accessory is
locked to the attachment spindle. The attachment speed reduces or
speed increases the rotational moment output by the handpiece that
is applied to the cutting accessory. Typically an attachment is
used to speed reduce/torque increase the rotational moment of the
attached cutting accessory.
[0006] Other attachments provide a means to attaching a cutting
accessory to the handpiece spindle so the two components rotate at
the same speed. An attachment of this variety typically does not
have a gear assembly.
[0007] It is known to provide surgical handpieces with internal
torque increasing/speed reducing gear assemblies. Some of these
assemblies have plural output heads. This gear assembly receives
the rotational moment from the motor output shaft and
simultaneously rotates the plural output heads at different speeds.
A clutch selectively connects the drill output spindle for rotation
to one of the gear assembly output heads. The output speed/torque
producing capability of the handpiece spindle is set by setting the
clutch to selectively set the gear assembly-to-drill spindle
connection. In some circumstances, these assemblies eliminate the
need to employ a front head torque increasing/speed reducing
attachment.
[0008] Known handpiece gear and clutch assemblies are relatively
long in length. A disadvantage of this type of structure is that it
increases the overall length of the handpiece. This runs contrary
to a goal of efficient handpiece design, namely, the handpiece
should be made as short as possible. This is because it easier for
a surgeon to accurately position the working end of the cutting
accessory that is relatively close to his/her hand than one further
away. To provide this feature it is, therefore, desirable to
construct a handpiece that has an overall length, especially from
the motor forward, that is as compact as possible.
[0009] Moreover, a surgical handpiece is typically designed to be
held at or near its center of gravity. This design reduces the
physical stress to which the surgeon is exposed when he/she holds
and needs to precisely position the tool in order to accomplish a
given surgical procedure. The positioning of any mass away from a
surgical handpiece's center of gravity/hand hold makes it more
difficult for the surgeon to hold and precisely position the
handpiece. Known gear and clutch assemblies, because of their
lengths and masses, are typically off center from the center of
gravity of the handpieces with which they are integral. During a
surgical procedure, it may be necessary for the surgeon to
precisely control a tool's position for an extended period. The
off-center mass of a gear and clutch assembly can add to the
physical stress to which the surgeon is exposed when so holding the
tool.
[0010] Other disadvantages are associated with known coupling
assemblies used to releasably hold cutting accessories and
attachments to the handpiece spindles. Known coupling assemblies
are effective for transmitting torque, rotational moment, from a
handpiece spindle to the attached accessory/attachment and hold the
accessory/attachment firmly to the spindle. Nevertheless, many
coupling assemblies allow that shaft of the attached
accessory/attachment to radially shift position, relative to the
axis of the associated handpiece spindle.
[0011] The looseness of this fit allows the accessory/attachment to
wobble when coupled to the handpiece. Wobble present in the shaft
adjacent the surgical handpiece is amplified at the distal free end
of the attachment, the end applied to the surgical site. Some
attachments, for example reamers and drills used to perform certain
procedures have lengths of 10 cm or more. The wobble, the radial
shifting, at the distal end of these attachments can therefore be
quite significant. The presence of this movement can appreciably
add to the overall control the surgeon must exert in order to
ensure that the working end of the attachment remains accurately
position at the surgical site to which the attachment is
applied.
SUMMARY OF THE INVENTION
[0012] This invention is related to a new and useful surgical
rotary handpiece. The handpiece of this invention has both a clutch
assembly that is compact in length and a coupling assembly that
limits the wobble of the shaft of the complementary
accessory/attachment fitted to the handpiece.
[0013] The clutch of the surgical rotary handpiece of this
invention has moveable pins that selectively connect one of a
plurality of the gear assembly drive heads to the handpiece output
spindle for simultaneous rotation. A shifter positions the movable
pins. A shift ring displaces the shifter. The moveable pins and
members that transfer the motion from the shift ring to the shifter
overlap. Collectively, these features combine to form a clutch of
short axial length.
[0014] The coupling assembly of the handpiece of this invention is
partially integral with the handpiece spindle. Internal to the
spindle is a bore in which a coupling head of the
attachment/accessory shaft is seated. The most proximal end of the
surfaces of the spindle that define the bore and the most distal
end of the coupling head are formed with complementary geometric
features that force the transfer of torque, rotation movement, from
the spindle to the shaft.
[0015] Extending forward, the coupling head is formed with a
stabilizing body. This spindle bore is shaped so that the body is
tightly fitted in the adjacent section of the bore. In some
preferred versions of the invention, the stabilizing body and
complementary bore-defining shaft inner wall have circular cross
sectional profiles. Owing to the tight fit of the shaft in the
bore, wobble of the shaft is minimized.
[0016] The accessory/attachment stabilizing body is formed with an
indentation. In one version of the invention, this indentation is
an annular groove that extends around the stabilizing body. The
coupling assembly has retractable pins that extend into the spindle
bore. The pins seat in the complementary stabilizing body
indentation to releasably lock the accessory/attachment to the
housing spindle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The invention is pointed out with particularity in the
claims. The above and further features of this invention may be
better understood by reference to the following detailed
description taken in conjunction with the accompanying drawings in
which:
[0018] FIG. 1 is a side view of a surgical rotary handpiece of this
invention to which a surgical accessory of this invention is
attached;
[0019] FIG. 2 is a cross sectional view of the front end of the
handpiece along the longitudinal axis;
[0020] FIG. 2A is an enlarged cross sectional view of the distal
end of the handpiece of FIG. 2;
[0021] FIG. 3 is an exploded view of the distal front end of the
handpiece;
[0022] FIG. 4 is an exploded view of the gear train of the surgical
handpiece of this invention;
[0023] FIG. 5 is a cross sectional view of the gear train;
[0024] FIG. 6 is a plan view of the spindle of the surgical
handpiece of this invention;
[0025] FIG. 7 is a cross sectional view of the spindle taken along
line 7-7 of FIG. 6;
[0026] FIG. 8 is a perspective view of the output coupler;
[0027] FIG. 9 is a cross sectional view of the output coupler;
[0028] FIG. 10 is an end view of a rotary housing of the surgical
handpiece of this invention;
[0029] FIG. 11 is a plan view of the rotary housing;
[0030] FIG. 12 is a cross section view of the rotary housing taken
along line 12-12 of FIG. 11;
[0031] FIG. 13 is an exploded view of the components forming the
clutch;
[0032] FIG. 14 is a perspective view of the inner shifter of the
clutch of this invention;
[0033] FIG. 15 is a cross sectional view of the inner shifter;
[0034] FIG. 16 is a perspective view of the shifter housing;
[0035] FIG. 17 is a cross sectional view of the shifter
housing;
[0036] FIG. 18 is a perspective view of the shift ring;
[0037] FIG. 19 is a cross sectional view of the shift ring;
[0038] FIG. 20 is a perspective view of the shift ring nut;
[0039] FIG. 21 is a cross sectional view of the shift ring nut;
[0040] FIG. 22 is an exploded view of the coupling assembly;
[0041] FIG. 23 is a side view of the coupling assembly actuating
ring;
[0042] FIG. 24 is a cross sectional view of the actuating ring;
[0043] FIG. 25 is a perspective view of the actuating sleeve;
[0044] FIG. 26 is a cross sectional view of the actuating
sleeve;
[0045] FIG. 27 is a plan view of a cutting accessory with the
coupling head of this invention;
[0046] FIG. 27A is a perspective view of the coupling head of the
cutting accessory;
[0047] FIG. 28 depicts how a coupling assembly pin seats in a
groove of the coupling head according to this invention;
[0048] FIG. 29 is a lateral cross section view illustrating how the
coupling assembly pins seat in the coupling head indentation;
[0049] FIG. 30 is a cross sectional view illustrating the position
of the coupling assembly when in the load state;
[0050] FIG. 31 is a lateral cross section view illustrating the
position of the coupling assembly pins when in the load state;
[0051] FIG. 32 is a plan view of an attachment with the coupling
head of this invention;
[0052] FIG. 33 is an exploded view of a section of an alternative
clutch assembly of this invention; and
[0053] FIG. 34 is a cross sectional view of a portion of the
assembly of FIG. 33.
DETAILED DESCRIPTION
[0054] FIGS. 1 and 2 illustrate a rotary surgical handpiece 20
constructed in accordance with the invention. Handpiece 20 has a
housing 22 in which in a motor 24 is seated. In one version of the
handpiece 20, motor 24 is a DC motor. In other versions of the
invention, motor 24 may be an AC motor, or a pneumatic or
hydraulically driven motor. Integral with the motor 24 is rotating
output shaft 26. Handpiece housing 22 is shaped to have a generally
cylindrical head 28 in which motor 24 is fitted. Extending
downwardly from head 28, handpiece housing 22 is shaped to have a
handle 30 generally in the form of a pistol grip.
[0055] At least one trigger switch 32 extends distally forward from
the front face of handle 30. ("Distal", it shall be understood
means toward the surgical site to which the handpiece 20 is
directed. "Proximal", means away from the surgical site.) A control
circuit internal to the housing 22, (not illustrated and not part
of this invention) monitors the actuation of the trigger switch 32.
Based on the extent to which the trigger switch 32 is actuated, the
control circuit selectively energizes the motor 24 to cause the
output shaft to rotate at the desired speed.
[0056] A gear train 36 is connected to the exposed distally located
front end of the motor shaft 26. Gear train 36 includes gears that
reduce the speed and increase the torque of the rotational moment
output by shaft 26. The gear train 36 has two rotating drive heads
86 and 92 (FIG. 4). Owing to the arrangement of the gears forming
gear train 36, the rotation of motor shaft 26 causes drive heads 86
and 92 to simultaneously rotate at different speeds. Gear train 36
thus functions as a speed reduction assembly that outputs
rotational force at two separate speeds.
[0057] With reference to FIGS. 2, 2A and 3 it can be seen that a
spindle 42 is rotatably mounted to the housing head 28 forward of
gear train 36. A clutch 44 selectively connects one of the two gear
train drive heads 86 or 92 to spindle 42 so that the spindle and
connected drive head rotate in unison.
[0058] A coupling assembly 46 releasably holds a surgical
attachment or a surgical cutting accessory 48, seen in FIG. 27 to
the spindle 42. The particular cutting accessory 48 is an
acetabular reamer. Again, it should be appreciated that this is
exemplary, not limiting. Cutting accessory 48 has a distal end
tissue working head 50, in the example, an acetabular reamer head.
Extending proximally from tissue working head 50, cutting accessory
48 has an elongated shaft 52. A coupling head 54 is attached to the
proximal end of shaft 52. Coupling head 54 is formed with geometric
features that facilitate the rotational coupling of cutting
accessory 48 to spindle 42 and minimize wobble of the accessory
relative to the handpiece 30.
[0059] Surgical handpiece 20 of this invention is constructed so
that the distal end of spindle 42 is formed with a bore 120 (FIG.
7) for receiving the attachment/accessory coupling head 54.
Coupling assembly 46 locks the accessory coupling head 54 in
spindle bore 120. As a consequence of this engagement, the coupling
head 54, and therefore the whole of cutting accessory 48, rotates
in unison with the spindle 42.
[0060] Gear train 36, now described by reference to FIGS. 3-5,
includes a first set of three (3) planet gears 62 (two shown).
Planet gears 62 are each rotatably mounted to a generally disc
shaped planet carrier 64. Planet gears 62 and planet carrier 64, as
with the remaining planet gears and planet carriers of gear train
36 are housed in a generally tubularly shaped ring gear 66. Ring
gear 66 has a smoothed shaped outer wall and a toothed inner wall,
(teeth not illustrated). The teeth of planet gears 62, as well as
the teeth of the remaining planet gears 74 and 82, engage the teeth
of ring gear 66.
[0061] Ring gear 66 is statically mounted in the handpiece housing
head 28 forward of motor 24. To facilitate the static mounting of
ring gear 66, the ring gear is formed with two proximally extending
feet 68. The feet seat in openings formed in an internal structural
web 70 of the housing to block rotation of the ring gear (openings
not identified).
[0062] Planet gears 62 seat over and engage a gear pinion 71
disposed over motor shaft 26 (identified in FIG. 2). Thus, the
rotation of motor shaft 26 results in the rotation of planet gears
62 and planet carrier 64.
[0063] A first sun gear 72 is integrally mounted to, concentric
with and extends distally forward from planet carrier 64. Sun gear
72 engages a second set of three (3) planet gears 74 (two shown).
Planet gears 74 are rotatably disposed around a second planet
carrier 76. A tubular post 78 is integrally attached, concentric
with and extends distally forward from second planet carrier 76. A
set of teeth disposed around the proximal end base of post 78 form
a second sun gear 80.
[0064] Second sun gear 80 engages a third set of planet gears, four
(4) planet gears 82 (one shown). Planet gears 82 are rotatably
attached to and disposed around a third planet carrier 84. A first
drive head 86 is formed integrally with and extends axially forward
from the third planet carrier. The first drive head 86 has a
generally circular outer profile. The outer surface of drive head
86 is further shaped to have a plurality of longitudinally
extending inwardly concaved, notches 88. The notches 88, which are
circumferentially spaced apart, are located around the whole of the
circumference of drive head 86. Planet carrier 84 is further formed
to have an axially extending through bore 90. Bore 90 extends
completely through both the planet carrier 84 and drive head
86.
[0065] A second drive head, drive head 92, is positioned distally
forward of and is concentric with drive head 86. Drive head 92 has
the same outer diameter as drive head 86. Drive head 92 is further
shaped to notches 94 that have the same profile of notches 88 of
the first drive head 86. A tubularly shaped stem 96 extends
proximally rearward from drive head 92. In many versions of the
invention, second drive head 92 and stem 96 are integrally formed.
When gear train 36 is assembled, post 78 of the second planet
carrier 76 is disposed in bore 90 of third planet carrier 84 and
drive head 86. Stem 96 similarly is disposed in bore 90. More
particularly, stem 96 is dimensioned to be tightly press fit over
post 78. Thus, drive head 92 rotates in unison with the second
planet carrier 76. Collectively, post 78 and stem 96 are shaped so
that there is a longitudinal separation between drive heads 86 and
92.
[0066] Drive head 86 and stem 96 are further collectively shaped so
that the outer surface of the stem is spaced inwardly of the
adjacent bore 90 defining inner wall of the drive head. This
arrangement allows stem 96 to rotate freely relative to the drive
head 88. Adjacent the proximal end of stem 96, a bearing assembly
97 extends between post 78 and an adjacent inner circular wall
internal to planet carrier 84. More particularly, the planet
carrier internal wall against which the outer race of bearing
assembly 97 seats defines an elongated groove 99 that is concentric
with and has a large outer diameter than planet carrier bore 90. A
retaining ring 100 disposed proximal to the bearing assembly 97
holds the bearing assembly in position. Retaining ring 100 is snap
fitted in a groove 101 also formed in the interior of planet
carrier 84. The planet carrier 84 is formed so that groove 101 is
between the proximal end opening of bore 90 and groove 99 and is of
greater diameter than groove 99.
[0067] Drive head 92 has a nose 91. Nose 91 extends forward of the
portion of the drive head formed with notches 94. An O-ring 89 is
disposed over nose 91. O-ring 89 is fitted over the drive head nose
91 portion immediately distal to the portion of the nose that
defines notches 94.
[0068] A bearing assembly 95 rotatably holds planet carrier 84 to
the static ring gear 66. Bearing assembly 95 has an outer race (not
illustrated) seated in the perimeter of a counterbore 67 that forms
the open end of ring gear 66. The inner race of bearing assembly 95
(not illustrated) seats against an annular step 98 formed in the
outer perimeter of the third planet carrier 84. A retaining ring 87
holds bearing assembly 95 and, by extension, the moving components
of gear train 36, in ring gear 66. Retaining ring 87 is snap fitted
in a groove 93 formed in the inner wall of the ring gear 66 that
defines counterbore 67.
[0069] The structure of the spindle 42 is now described by
reference to FIGS. 6 and 7. Generally, spindle 42 is formed from a
single piece of metal that has circular sections of different
diameters. At the most proximal end, spindle 42 has a head 102.
Spindle 42 is further formed so that, internal to head 102 is a
bore 104 with a hexagonal cross-sectional profile. The specific
cross-section profile of bore 104 is not relevant to the basic
structure of this invention. What is relevant is that bore 104 is
shaped to closely slip fit receive the proximal end of the cutting
accessory coupling head 54 fitted to the cutting accessory 48. The
close fitting is required because the inner surfaces of the spindle
42, face surfaces 105, that define bore 104 are the surfaces that
transmit the torque to the cutting accessory 48.
[0070] Extending distally from head 102, spindle 42 has a collar
106. Collar 106 is shaped to have an outer diameter greater than
that of head 102. Immediately forward, proximal, of the distal end
of the collar 106, the collar is shaped to have a groove 108 that
extends circumferentially around the outer surface of the collar.
Collar 106 is further formed to define an opening 110 that extends
laterally through the collar. Opening 110 is located to extend
through an arcuate section of the collar 106 that defines the base
of groove 108. Opening 110 extends from a base of a recess 111 cut
into the outer surface of collar 106.
[0071] Spindle 42 is further formed to have a stem 112 that
projects distally forward from collar 106. Stem 112 has a number of
sections with different outer diameters. A proximal section 113
adjacent collar 106 has a diameter approximately equal to that of
sleeve head 102. Stem section 113 is formed to have two
diametrically opposed receiving slots 114. Each receiving slot 114
is in a plane that, relative to the longitudinal axis of spindle
42, extends diagonally forward. In some versions of the invention,
each slot 114 is in a plane that, relative to the longitudinal axis
of the spindle 42, is at an angle of approximately 45.degree..
Thus, as seen in FIG. 6, when viewing a slot 114 from the front, a
slot 114 appears to have a curved profile.
[0072] Forward of section 113, the stem 112 is further formed to
have a circumferential groove 116. Forward of groove 116 stem 112
has an intermediate section 115. Section 115 has a diameter
slightly less than that of proximal section 113. The reduced
diameter of stem section 115 allows below discussed wave spring 177
(FIG. 22) to freely flex.
[0073] Forward of section 115, spindle stem 112 is formed with a
distal end section 117. Stem section 117 has an outer diameter
between the diameters of sections 113 and 115. The inner race of a
bearing assembly 173 (FIG. 2A) tightly fits over stem section 117.
A groove 118 extends circumferentially around the outer surface of
stem 112. Groove 118 is located immediately proximal to the distal
end of stem section 117, which is also the distal end of spindle
42.
[0074] Spindle 42 is further formed to have a bore 120 that extends
from the distal end, through stem 112 and collar 106 to bore 104.
Bore 120 is concentric and contiguous with bore 104. In preferred
versions of the invention, bore 120 has a circular cross sectional
profile, though that need not always be the case. Bore 120 is
dimensioned to facilitate the close slip fitting of a coupling head
54 of the cutting accessory 48 as discussed below.
[0075] A pin 121, seen in FIG. 13, is fitted in spindle opening 110
so as to be directed to the longitudinal center axis of the spindle
42. Pin 121 extends into bore 120
[0076] A generally tubular shaped outer coupler 124 is tightly
fitted to the spindle 42, now described by reference to FIGS. 8 and
9. Outer coupler 124 has a constant outer diameter. The outer
coupler 124 is further formed to have a proximal end bore 126 that
extends distally forward from the proximal end of the coupler. In
one version of the invention, proximal end bore 126 extends
approximately half way through the length of the coupler. Output
coupler 124 also has a distal end bore 128 that extends rearward
from the distal end of the coupler. Distal end bore 128 has a
diameter that facilitates the compression fitting of sleeve head
102 in the bore 128.
[0077] Between the proximal end and distal end bores 126 and 128,
respectively, output coupler 124 is formed to have a circular void
space 127. The outer perimeter of void space 127 is defined by a
circular flange 129 that extends inwardly from the inner walls of
coupler 124 that define bores 126 and 128 and space 127. The
distally-directed laterally extend annular face of flange 129 is
the surface against which the proximally directed face of sleeve
head 102 abuts. Outer coupler 124 is further formed to have four
longitudinally extending slots 134. Each slot 134 extends from the
outer surface of the coupler 124 into the proximal end bore 126.
Slots 134 are equangularly spaced apart from each other around the
perimeter of the outer coupler 124.
[0078] Outer coupler 124 itself is shaped to have an outer diameter
that is slightly greater than the outer diameter of spindle collar
106. When the spindle head 102 is fit in the outer coupler 124, the
distal end face of the outer coupler forms an annular step around
the proximal end of the spindle collar 106.
[0079] Returning to FIG. 2, it can be seen that, when surgical
handpiece 20 of this invention is assembled, the spindle 42 and
outer coupler 124 sub-assembly are fitted in the housing 32 so that
gear train drive heads 86 and 92 are disposed in the proximal end
bore 126 of the outer coupler. Outer coupler 124 is shaped so that
the inner wall that defines the proximal end bore 126 is spaced
away from the drive heads 86 and 92. Drive head nose 91 seats in
outer coupler void space 127. O-ring 93 abuts the adjacent inner
face of coupler flange 129.
[0080] Gear train 36, outer coupler 124 and spindle 42 are
substantially disposed in a rotary housing 130 that extends
distally forward from the front of handpiece housing 22. The rotary
housing 130, now described by reference to FIGS. 10-12, is formed
from a single piece of metal that has a number of circular
cross-sectional sections. The most proximal section of the rotary
housing 130 is a base 132. The outer surface of rotary section base
132 adjacent the proximal end of the rotary section is formed with
threading 137 (seen in FIG. 11 only). Base 132 is formed with an
open ended bore 136. Bore 136 is dimensioned to facilitate the
loose slip fitting of the base over gear train ring gear 66. When
handpiece 20 is assembled, base threading 137 engages complementary
threading 138 formed around an inner wall of housing 28 (FIG. 2).
This threaded engagement holds rotary housing 130 to the handpiece
housing 22.
[0081] Extending distally of the threaded section, rotary housing
base 132 is formed with a section 140 with a smooth outer wall.
Forward of base section 140, the rotary housing 130 has a flange
142 that extends radially outward of base 132. Flange 142 is the
structural component of the rotary housing 130 that stops proximal
movement of the rotary housing when the housing is screw fitted to
the handpiece housing 22. Rotary housing 130 is further formed to
define four slots 144 that extend through base section 140 and
flange 142. Slots 144 are equangularly spaced apart. The slots 144
function as spaces for receiving a fastening tool (not illustrated)
used to screw secure the rotary housing 130 to the handpiece
housing 22 during manufacture.
[0082] Forward of flange 142, rotary housing 130 forms a clutch
sleeve 146. Clutch sleeve 146 has a diameter slightly less than
that of base 132. The clutch sleeve 146 is formed to have four
equangularly spaced apart slots 148. Slots 148 extend diagonally
downwardly around the outer circumference of the clutch sleeve 146.
Four equangularly spaced apart holes 150 are also formed in the
clutch sleeve 146. Holes 150 are in a common circumferential
section of the clutch sleeve located proximal to the proximal ends
of slots 148. Holes 150 are provided to facilitate manufacture and
disassembly of the handpiece 20.
[0083] A groove 152 is formed in the clutch sleeve 146 to extend
circumferentially around the outer surface of the sleeve. Groove
152 is located proximally rearward of the forward distal end of the
clutch sleeve 146. The outer surface of the clutch sleeve 146
located distal to groove 152 and extending to the distal end of the
clutch sleeve is provided with threading 154 (seen in FIG. 11
only).
[0084] Projecting distally forward of clutch sleeve 146, rotary
housing 130 has a coupling neck 156. Coupling neck 156 has a
diameter less than that of clutch sleeve 146. The coupling neck 156
is formed to define four equangularly spaced apart slots 158. Slots
158 extend longitudinally along the coupling neck 156 and are
generally located in the most distal portion of the coupling neck
158.
[0085] A head 160 forms the most distal section of rotary housing
130. Head 160 extends forward from and has a diameter less than
that of coupling neck 156. Head 160 is formed with an inwardly
directed circumferential lip 162. Lip 162 defines the open distal
end of the rotary housing, (distal end opening not identified).
[0086] Rotary housing 130 is further formed so that extending
axially, distally forward from bore 136 there is a bore 166 that
extends to the distal end of the housing. Bore 166 has sections of
different diameters. The diameters of the different bore sections
(not identified) are generally sized relative to each other in the
same manner the outer diameters of the clutch sleeve 146 and
coupling neck 156, and head 160 correspond to each other. The
rotary housing 130 is further formed to have a groove 168 that
extends inwardly from a housing inner wall that defines one of the
sections of bore 166. Specifically, groove 168 is formed in the
housing clutch sleeve 146 so as to be immediately distal to the
circular slice of the sleeve 146 in which outer circumference
groove 152 is formed.
[0087] Bearing assemblies 172 and 173, seen best in FIGS. 2A and
13, rotatably hold the spindle and outer coupler sub-assembly to
the rotary housing 130. The outer race of bearing assembly 172
(outer race not illustrated) seats against the bore 166-defining
inner wall of the housing clutch sleeve 146. The proximal end of
the bearing race seats against the stepped inner annular surface of
the rotary housing between the clutch sleeve 146 and the coupling
neck 156. The proximally-directed face of the outer race of bearing
assembly 172 abuts a retaining ring 174 disposed in bore 166.
Retaining ring 174 is snap fitted in rotary housing groove 168.
[0088] The inner race of bearing assembly 172 (not illustrated) is
press fit over spindle collar 106. When the handpiece 20 of this
invention is assembled, the proximal end of the inner race of
bearing assembly is disposed against the annular portion of the
distally directed face of the adjacent outer coupler 124. As
discussed above, the outer race of bearing assembly 172 is blocked
from distal movement by the adjacent inner walls of the rotary
housing 130. Thus, the abutment of the outer coupler 124 against
the inner race of bearing assembly 172 by extension blocks distal
movement of the spindle and outer coupler sub-assembly.
[0089] Bearing assembly 173 extends between the distal front end of
spindle stem 112 and the adjacent inner wall of the rotary housing
head 160. The outer race of bearing assembly 173 (race not
illustrated) seats against the inner wall of the rotary housing 130
within the housing head 160. The bearing assembly outer race also
abuts the proximally directed surface of rotary housing lip 162.
The distally directed face of the inner race of bearing assembly
173 seats against a retaining ring 175. Retaining ring 175 is snap
fitted into groove 118 of spindle stem 112. Thus, collectively,
rotary housing lip 162 and retaining ring 175 block forward
movement of bearing assembly 173.
[0090] Washers 176 and 177 and retaining ring 178 cooperate to
prevent proximal movement of bearing assembly 173. Two washers 176
are provided. The more distal of the two washers 176 is disposed
against the proximally-directed face of the bearing assembly 173.
Washer 177, which is flexible wave washer, is sandwiched between
the distal and proximal washers 176. The retaining ring 178 seats
in spindle groove 116. The retaining ring 178 extends above the
outer surface of the surrounding spindle sleeve 112. When handpiece
20 is assembled, the exposed portion of the retaining ring 178
blocks proximal movement of washers 176 and 177 and, therefore,
similar movement of bearing assembly 173. Wave washer 177 is
provided to ensure that, in the event of manufacturing variations,
the distal washer 176 is disposed against the bearing assembly
173.
[0091] Washers 176 are L-shaped. The short vertical sections of the
washers 176, (not identified) are disposed around the outer surface
of the spindle stem 112. The washer 176 closest to bearing assembly
173 is positioned so its vertical section is against the inner race
of the bearing assembly. This arrangement holds the washer 176 off
the inner race of the bearing assembly 173. The washer 176 adjacent
retaining ring 178 is positioned so that its vertical section abuts
the retaining ring.
[0092] When the spindle and outer coupler sub-assembly is so
positioned, gear train drive heads 86 and 92 are both seated in the
outer coupler proximal end bore 126. Slots 134 are formed in the
outer coupler 124 so as to extend over the drive heads 86 and 92.
Also, the components of this invention are dimensioned so that when
the spindle 42 is seated in the rotary housing 130, the most distal
end of the spindle projects a slight distance forward of the
surrounding distal end of the rotary housing.
[0093] The construction of the clutch 44 is now described by
reference to FIGS. 2A and 13. The clutch includes a circular inner
shifter 180 disposed inside the rotary housing clutch sleeve 146
over the outer coupler 124. As best seen in FIGS. 14 and 15, inner
shifter has a proximal end base 181. Extending distally forward
from base 181, the inner shifter 180 is shaped to have a head 182.
Head 182 has an outer diameter less than that of base 181. A
constant diameter bore 183 extends axially through the inner
shifter 180 from the proximal end of base 181 to the distal end of
head 182.
[0094] Inner shifter 180 is shaped so that when the outer coupler
124 is seated in bore 183, the shifter is able to move
longitudinally along the length of the outer coupler. Clutch 44
includes four equangularly spaced apart torque pins 184 that extend
radially inwardly from the inner shifter base 181. Each torque pin
184 is seated in a laterally extending opening 185 formed in the
inner shifter base 181. Each torque pin 184 extends through an
associated one of the outer coupler slots 134. Torque pins 184 are
of sufficient length so end tips of the pins can seat in notches 88
and 94 of, gear train drive heads 86 and 92, respectively.
[0095] A shifter housing 186 disposed over the inner shifter 180
longitudinally moves the inner shifter 180 over the outer coupler
124. The shifter housing 186, now described by reference to FIGS.
16 and 17, is generally in the form of a constant outer diameter,
ring shaped structure. Shifter housing 186 is further formed to, at
the proximal end, have an inwardly extending lip 188. A groove 190
extends inwardly from the annular inner wall of the shifter housing
186 that defines the center opening 192 through the housing. Groove
190 is located proximal to the distal end face of the shifter
housing 186. The shifter housing 186 is further formed to define,
on the outer surface, two diametrically opposed spherical
indentations 194.
[0096] Shifter housing 186 is disposed in the rotary housing clutch
sleeve 146. Inner shifter head 182 is positioned inside the shifter
housing 186. A bearing assembly 196 is disposed between the outer
circumferential wall of the inner shifter head 182 and the adjacent
inner wall of the shifter housing 186. The proximal end of bearing
assembly 196 abuts the adjacent distally-directed annular surface
of the inner shifter base 181 that projects radially beyond head
182. The outer perimeter of the distally directed face of bearing
assembly 196 abuts a retaining ring 198 fitted to the shifter
housing 186. Specifically, retaining ring 198 is snap fitted in
shifter housing groove 190. Thus, the capture of the opposed ends
of bearing assembly 196 by the inner shifter base 181 and retaining
ring 198 lock the inner shifter 180 and shifter housing 186
together for longitudinal movement. Bearing assembly 196 allows the
inner shifter 180 and shifter housing 186 to axially rotate
relative to each other.
[0097] A shift ring 202 rotatably mounted over the rotary housing
clutch sleeve 146 is manually actuated to set the longitudinal
position of the shifter housing 186 and, by extension, the inner
shifter 180. Seen best in FIGS. 18 and 19, the shifter ring 202 is
generally in the form of a tubular member. Indentations 204 formed
in the outer surface of the shifter ring 202 facilitate the finger
grasping of the ring. The shifter ring 202 is further shaped to
define an axially extending through bore 206. Bore 206 is
dimensioned to allow the shift ring 202 to rotate over the
underlying rotary housing clutch sleeve 146. At the proximal end,
shifter ring defines a first counterbore 208 that defines the
proximal end opening into bore 206. A second counterbore 210 is
located between the first counter bore 208 and bore 206. The second
counterbore 210 has a diameter between that of bore 206 and
counterbore 208.
[0098] At the distal end, shift ring 202 is formed to have a third
counterbore 212. The third counterbore 212 forms the distal end
opening into bore 206. The second and third counterbores 210 and
212, respectively, are of identical diameter. The inner wall of
shift ring 202 that defines bore 206 is further formed to define
two longitudinally extending, diametrically opposed concave grooves
214. Each groove 214 extends from the second counterbore 210 to the
third counterbore 212.
[0099] When handpiece 20 of this invention is assembled, ball
bearings 216 transfer the rotational motion of shift ring 202 into
axial motion that displaces the shifter housing 186. Each ball
bearing 216 is seated in opposed ones of the rotary housing clutch
sleeve slots 148. Two ball bearings 216 are provided; there are
four slots 148. The additional slots 148 aid component orientation
during assembly of the handpiece 20. Inside the rotary sleeve 130,
each ball bearing 216 seats in a separate one of the indentations
194 formed in the shifter housing 186. Outside of rotary housing
130, each ball bearing 216 seats in a separate one of the grooves
214 formed in shift ring 202.
[0100] When handpiece 20 of this invention is assembled, rotary
housing flange 142 seats in the shift ring first counterbore 208.
O-rings 218 extend between the outer circumferential face of rotary
housing 130 and the inner walls of shift ring 202. A first O-ring
218 is seated in the annular space of shift ring second counterbore
210. The second O-ring 218 is seated is seated in the shift ring
third counterbore 212. Both O-rings 218 extend over the smooth
outer surface of the rotary housing clutch sleeve 146.
[0101] A shift ring nut 220 holds the shift ring 202 to the rest of
the handpiece 20. Shift ring nut 220, best seen in FIGS. 20 and 21,
is generally tubularly shaped. The shift ring 220 is formed to have
a base 222 with a generally constant outer diameter. Forward of
base 222 shift ring nut 220 has a head 224. Extending distally
forward, the outer diameter of the shift ring head 224 tapers
inwardly. The shift ring 220 is further formed to define two
opposed flats 226 in the proximal end of the outer surface of base
222. Flats 226 receive a fastening tool used to screw secure the
shift nut 220 to the rotary housing 130 during assembly.
[0102] Bore 228 extends axially through the shift ring nut 220 from
the proximal end to the distal end. The shift ring is further
formed to have an inwardly stepped annular lip 230 that extends
inwardly from the inner circular wall that defines bore 228. The
inner round face of lip 230 is formed with threading 231 (seen in
FIG. 20). The shift ring nut 220 is screw secured to the rotary
housing by engaging shift ring nut threading 231 with threading 154
on the rotary housing clutch sleeve 146.
[0103] An understanding of the coupling assembly 46 of the surgical
handpiece of this invention is now obtained by initial reference to
FIGS. 2A, 3 and 22. Specifically, coupling assembly 46 includes two
cylindrical retaining pins 240 each of which is seated in one of
the spindle slots 114. When pins 240 are in the most forward
position in slots 114, the pins seat in a groove (indentation) 306
formed in the coupling head 54 of the attachment/accessory attached
to the handpiece 20. Pins 240 thus hold the attachment/accessory to
the tool spindle 42.
[0104] An inner washer 242 and outer washer 248 are the components
of coupling assembly 46 that releasably hold retaining pins in
slots 114 and attachment/accessory indentation 306. Inner washer
242 is shaped to have along any one slice thereof an L-shaped cross
sectional profile. More specifically, the inner washer has
cylindrical base 244 that extends over the spindle stem 112. The
spindle 42 and inner washer 242 are dimensioned relative to each
other such that the inner washer can freely move longitudinally
over the spindle. Inner washer 242 is further shaped to have a lip
246 that extends perpendicularly outwardly from the distal front
end of base 244.
[0105] Inner washer 242 nests in the outer washer 248, also
disposed over the spindle stem 112. The outer washer is shaped to
have flat, circularly shaped head 250. Extending proximally
rearwardly from the outer perimeter of the head 250 and formed
integrally with the head is a cylindrically shaped skirt 252. The
outer washer 248 is positioned over the spindle stem 112 so that
the washer head 250 is generally aligned with the distal ends of
the spindle slots 114. The distal end of the inner washer 242 is
disposed in the annular space defined by the outer wall of the
spindle stem 112 and the inner wall of skirt 252 of the outer
washer 248.
[0106] A coil spring 254 disposed around the spindle stem 112
normally urges the inner washer 242 towards the outer washer 248.
The proximal end of spring 254 seats against a washer 256 seated
over the most distal portion of the spindle collar 106. The
proximally-directed face of washer 256 abuts a retaining ring 258.
Retaining ring 258 is snap fitted in spindle groove 108 and
projects beyond the outer surface of the spindle collar 106. The
retaining ring 259 thus stops proximal movement of washer 256 and,
by extension, spring 254. A washer 257 is disposed between the
proximally directed face of retaining ring 258 and the adjacent
distally directed face of the inner race of bearing assembly
172.
[0107] Spring 254 thus urges the inner washer 254 forward. This
movement of the inner washer 254 first compression traps the
retaining pins 240 trapped between the inner and outer washers 242
and 248, respectively. The continued force imposed by the spring
254 continues to urge washers 242 and 248 and pins 240 forward. As
a result of this forward movement of this sub assembly, pins 240
are held in a forward distal section of spindle slots 114. The
distal forward movement of this sub-assembly is stopped by the
abutment of retaining pins 240 against the inner surfaces of the
stem sleeve 112 that define the distal perimeters of slots 114.
When pins 240 are so positioned, each pin extends into spindle bore
120.
[0108] An actuating ring 262 selectively moves washers 242 and 248
and, by extension, pins 240 away from the attachment/accessory
indentation 306 in which they are seated. The actuating ring 262
extends circumferentially around the outer perimeter of the distal
end of the rotary housing coupling neck 156. Now described in
detail by reference to FIGS. 23 and 24, the actuating ring 262,
which is generally ring shaped, is formed to have a proximal end
base 264. The outer circumferential surface of the actuating ring
base 264 is provided with threading, (not illustrated). Actuating
ring 262 is further formed so that extending distally forward of
base 264 there is a neck 266. Neck 266 has an outer diameter less
than that of the base 264. The inner wall that defines the through
bore through the actuating ring 262 (bore and inner wall not
identified) is of a constant diameter along the length of the
sleeve.
[0109] Four equangularly spaced apart pins 268 are mounted in
radial openings 270 formed in the actuating ring neck 266. Pins 268
are directed inwardly towards the axial center of the actuating
ring 262. When handpiece 20 of this invention is assembled, pins
268 extend through slots 158 formed in the rotary housing coupling
neck 156. The seating of pins 268 in the rotary housing slots 158
limits the range of proximal and distal movement of the actuating
ring 262. Pins 268 are of sufficient length that, when the
actuating ring 262 is moved proximally rearward, the free ends of
the pins press against the distally directed face of head 250 of
the outer washer 248.
[0110] An actuator sleeve 272 functions as a handhold that allows
the surgical personnel to move the actuating ring 262. As seen in
FIGS. 25 and 26, the actuator sleeve 272 is formed so as to have
along the outer surface thereof four spaced apart tabs 274. Tabs
274 function as finger holds that allow personnel to hold and
rearwardly depress the actuator sleeve 272. In the sleeve of FIG.
1, a single circumferential lip 274a performs the same function as
tabs 274.
[0111] The actuator sleeve 272 has an axially extending bore that
extends completely through the sleeve. The bore has a first
proximal end section 276. Forward of section 278 the bore has a
second section 280. Section 280 has a diameter less than that of
bore section 278. The inner wall of the actuator sleeve 272 that
defines bore section 280 has threading, (not illustrated). Forward
of bore section 280, actuating sleeve 272 is formed to have a bore
section 282. (Between bore sections 280 and 282 there is a groove,
not identified, present for manufacturing reasons.) Bore section
282 has an outer diameter less than that of bore section 280. Bore
section 284, is the most distal section of the actuating sleeve
through bore. Bore section 284 has a diameter less than that of
bore section 282.
[0112] When the handpiece 20 is assembled, the actuator sleeve 272
is secured to and over the actuating ring 262. Specifically, the
threaded surface that defines bore section 280 of the actuator
sleeve 272 is screw secured to the threading on outer surface of
the actuating ring base or ring base 264.
[0113] A coil spring 286 normally holds the actuating ring 262
distally forward, away from the outer washer 248. Spring 286 is
disposed between the rotary housing coupling neck 156 and the shift
ring nut 220. The proximal end of coil spring 282 seats against the
outer annular step surface between the rotary housing coupling
clutch sleeve 146 and the coupling neck 156. The distal end of
spring 286 seats against the proximally directed face of the
actuating ring base 264. Spring 286 urges actuating ring forward so
as that pins 268 are normally spaced away from outer washer
248.
[0114] A torque ring 288 is press fit over the rotary housing head
160. Torque ring 288 is formed with two opposed laterally extending
tabs 290. When the handpiece 20 is assembled the whole of the
torque ring 290 is normally disposed in bore section 284 of the
actuating sleeve 272. Torque ring 288 is shaped so that tabs 290 do
not abut, and therefore do not restrict the movement of the
actuating sleeve 272. When an attachment is fitted to handpiece 20,
at least one torque ring tab may seat in a complementary notch
formed in an exposed static component of the attachment. This
engagement prevents the static elements of the attachment from
rotating relative to the handpiece 20. In alternative versions of
the invention, torque ring 288 has a single tab 290 or three or
more tabs 290.
[0115] The cutting accessory 48 constructed in accordance with this
invention is now described by reference to FIGS. 27 and 27A. The
cutting accessory 48 has an elongated shaft 52. The coupling head
54 is integrally attached to the proximal end of the shaft 52.
Coupling head 54 has the features that both receive the torque
generated by the handpiece 20, facilitate the lock the cutting
accessory 300 to the handpiece and inhibit the generation of
accessory wobble.
[0116] The tissue working head 50 is attached to the distal end of
the shaft 52. In the illustrated version of the invention, the
tissue working head 50 is an acetabular reamer. It is understood
that this is exemplary not limiting. In other versions of the
invention, the tissue working head may be other members such as a
drill head or a bur. Also, it should be understood that in some
versions of the invention, the tissue working head may be
releasably attached to the shaft 52. For example, a reamer head is
often removably attached to the shaft 52 employed to rotate the
reamer.
[0117] The coupling head 54, the most proximal end of the accessory
48, is formed to have three longitudinally spaced apart sections.
The first, most proximal section of the coupling head 54 is a boss
302. Boss 302 is dimensioned to closely slip fit in spindle bore
104 and receive the torque output by the spindle 42. In the
illustrated versions of the invention, bore 104 has a hexagonal
cross sectional profile. Therefore, in this version of the
invention, coupling head boss 302 has a hexagonal shape and is
dimensioned to be of marginally smaller size than bore 104. The
individual outer facial surfaces 303 of boss receive the torque
that is transmitted by the complementary adjacent inner faces 105
of spindle 42.
[0118] The second, intermediate section of coupling head 54 is the
body 304. Coupling head body 304 is shaped to closely slip fit in
spindle bore 120. In the illustrated version of the invention,
spindle bore 120 has a circular cross sectional shape. Coupling
head body 304 has an identical circular cross section shape with a
diameter marginally less than that of spindle bore 120. The
coupling head body 304, it is further understood, occupies a cross
sectional area greater than that occupied by the coupling head boss
302. The coupling head body 304 is further formed to have a groove
306 that extends circumferentially around the outer surface of the
body. Groove 306 is positioned at approximately midway between the
proximal and distal ends of the body. More particularly, groove 306
is positioned so that, when the coupling head 54 is seated in the
handpiece spindle 42, the proximal surface of the head body 304
that defines the groove is approximately aligned with the proximal
interior surfaces of spindle 42 that define spindle slots 114.
[0119] The proximal end of the coupling head body 304 is further
formed to define a number of circumferentially spaced apart, slots
308. The base of each slot 308 is defined by a flat face 310 that
is recessed relative to the surrounding curved outer surface of the
rest of the coupling head body 304. Each face surface 310 is
coplanar with and extends distally forward from a separate one of
the faces forming the hexagonal coupling head boss 302. The
proximal end sections of the portions of the coupling head 304
between slots 308 are formed with beveled faces 312. Each pair of
beveled faces 312 meets at a point 314.
[0120] Shoulder 305 is the most distal section of the coupling head
54. The shoulder 305, which is contiguous with coupling head body
304, has a diameter greater than that of the body. In some versions
of the invention, especially in coupling heads integral with an
attachment 320 (FIG. 32) as described below, shoulder 305 is
physically separate from the rest of the coupling head 54. In these
versions of the invention, shoulder 305 is press fit over the
associated shaft to rotate in unison with the shaft.
[0121] Surgical handpiece 20 of this invention is prepared for
operation by inserting cutting accessory 48 into the handpiece
spindle 42. This process begins by the insertion of the cutting
accessory coupling head 54 in spindle bore 120. Eventually points
314 of the coupling head body 304 press against pins 240. The
manual force of this action is enough to overcome the opposite
force imposed by spring 254. Thus, the continued application of
this force results in the pushing of pins 240 diagonally outwardly
and rearwardly. Pins 240 thus ride up over the outer surface of the
coupling head body 304.
[0122] As coupling head 54 is continued to be inserted into the
spindle 42, one of the beveled faces 312 of the coupling head body
304 abuts spindle pin 121. The continued insertion of the coupling
head 54 results in the rotation of the coupling head until pin 121
seats in the body slot 308 with which the beveled face 312 is
adjacent. This rotational movement of the coupling head 54 ensures
that, as the coupling head is continued to be inserted into the
spindle 42, the coupling head boss 302 is aligned with and seats in
the spindle bore 104.
[0123] Once the accessory coupling head 52 is so seated, spring 254
pushes the sub-assembly of pins 240 and washers 242 and 248
forward. This movement results in the pins 240 moving diagonally
forward in spindle slots 114, toward the coaxial longitudinal
center axes of the accessory coupling head 54 and the spindle bore
120. This results in the seating of pins in coupling head groove
306, as seen in FIGS. 28 and 29. This seating of pins 240 in groove
306 latches coupling head 54 and, therefore, cutting accessory 48,
to the handpiece spindle 42.
[0124] Clutch 44 is then set to couple the spindle 42 to one of the
gear train drive heads 86 or 92 so that the spindle rotates with
the selected drive head. Specifically, the clutch 44 is set so that
torque pins 184 seat in the notches 88 or 94 of the drive head 86
or 92, respectively, with which the spindle is to be connected. The
setting, the longitudinal positioning of, the torque pins 184 is
performed by rotating shift ring 202. The rotation of shift ring
202 results in the helical movement of ball bearings 216 in rotary
housing slots 148. The longitudinal displacement of ball bearings
216 results in an identical longitudinal displacement of the
shifter housing 186. The longitudinal movement of the shifter
housing 186 causes a like movement of the inner shifter 180.
[0125] Since torque pins 184 are integral with inner shifter 180,
longitudinal displacement of the inner shifter results in the
selective seating of the pins in either the notches 88 of the
proximally located drive head 86 or notches 94 of the distally
located drive head 92.
[0126] Handpiece 20 of this invention is now ready for operating.
The depression of trigger switch 32 results in the actuation of
motor 24. Motor shaft 26 rotates. Gear train 36 reduces the
rotation moment output by shaft to two different speeds.
Specifically, the gears internal to the gear train cause drive head
86 to rotate at a first reduced speed. Drive head 92 is caused to
rotate at a second reduced speed less than the first reduced
speed.
[0127] Depending on the setting of the clutch 44, the torque pins
184 are seated in the notches 88 or 94 of one of the drive heads 86
or 92, respectively. The torque pins 184 thus rotate at the speed
of the drive head 86 or 92 with which the pins are engaged. The
torque pins 184 extend through the outer coupler slots 134.
Consequently, the rotation of the torque pins results in a like
movement of the outer coupler 124 and, therefore spindle 42. Since
the coupling head boss 302 is relatively closely fitted in the
spindle bore 104, and these components have non-circular cross
sectional profiles, rotary motion of the spindle 42 is transferred
by boss 302 to the coupling head 54 and the rest of the cutting
accessory 48.
[0128] When it is time to remove the cutting accessory 48, actuator
sleeve 272 is pushed rearwardly. This movement of the actuator
sleeve 272 results in a diagonal rearward and outward movement of
pins 240. Pins 240 thus retract out of the coupling head groove 306
and spindle bore 120, as seen in FIGS. 30 and 31. This allows the
cutting accessory 48 to be removed and a new accessory to be
removably coupled to the handpiece 20.
[0129] Clutch 44 of surgical handpiece 20 of this invention is
constructed so that torque pins 184 directly transfer the
rotational motion output by a drive head 86 or 92 directly to the
spindle-outer coupler sub-assembly. Each clutch pin 184 extends
laterally through the output coupler 124, which is an extension of
spindle 42. Thus, the clutch pins 184 do not occupy a significant
amount of longitudinal space. Also, the shifter housing
indentations 194 in which ball bearings 216 are spaced relatively
close to the clutch pins 184. In some versions of this invention,
the distance from the center of the indentions 194 to the center of
the clutch pins is 2.0 cm or less. In more preferred versions of
this invention this distance is 1.0 cm or less. Collectively, these
features of the invention make it possible to provide an inner
shifter and shifter housing assembly that has an overall length of
3.0 cm and, more preferably, 2.0 cm or less. In most preferred
versions of this invention, the overall length of this sub-assembly
is 1.0 cm or less.
[0130] Thus, the clutch 44 of this invention is relatively compact
in length. This makes it possible to provide a handpiece with gear
train and clutch assembly that likewise has a reduced axial length.
Moreover, employing the clutch 44 of this invention reduces the
extent to which the mass of components forming the handpiece 20 are
distributed away from the center of gravity. By centering the
component mass near the center line of the center of gravity, the
stress to which a surgeon is exposed when precisely positioning the
handpiece 20 is reduced.
[0131] When an attachment/cutting accessory coupling head is fitted
to the spindle 42 of the handpiece of this invention, there is a
relatively long and close interface between the inner wall of the
spindle 42 that defines bore 120 and the outer surface of the
coupling head body 304. In some versions of this invention, this
interface has a length of 0.6 inches or more. In more preferred
versions of the invention, this interface has a length of 1.0
inches or more. This interface is located distal to where the
spindle transfer torque to the coupling head boss 302. This
construction minimizes the wobble of the coupling head in the
spindle when both components are rotated. The minimization of the
coupling head wobble results in a like reduction of the wobble
present at the cutting accessory tissue working head 50.
[0132] Moreover, when coupling head 54 is fitted in spindle bore
120, the coupling head shoulder 305 abuts the distal end opening of
the spindle that defines the bore. Thus collectively, pins 240 and
shoulder 305 prevent longitudinal wobble of the coupling head 54 in
the spindle. Since the distal end of the rotating spindle 120 is
spaced slightly forward of the static components of the handpiece
20, the presence of shoulder 305 does not inhibit rotation of the
cutting accessory 48. To further ensure that there is no contact
between the shoulder 305 and the static components of the handpiece
20, the shoulder is dimensioned so it does not subtend area
subtended by the static components. Thus, the outer diameter of
shoulder 305 is less than the distal end opening into the rotary
housing defined by lip 162.
[0133] FIG. 32 illustrates an attachment 320 constructed in
accordance with this invention. Attachment 320 includes a housing
322. An input shaft 324 is extends rearwardly from the housing 322.
Input shaft is shaped to have a proximal end coupling head 326 with
the same features as cutting accessory coupling head 54. Internal
to the housing is a coupling assembly 328 represented by a phantom
rectangle. Coupling assembly 328 is designed to releasably hold the
proximal end of a cutting accessory (not illustrated) for rotation.
The exact structure of the coupling assembly 328 is not relevant to
this invention. Coupling assembly 328 may include the features of
coupling assembly 46. Alternatively, coupling assembly 328 may be
provided with features to hold coupling heads other than the
described coupling head 54 for rotation. These include coupling
heads with trinkle fittings, Hudson.RTM. fittings and modified
trinkle fittings that are known in the surgical art.
[0134] Input shaft 324 rotates coupling assembly 328. In some
versions of the invention, input shaft 324 and the spindle of
coupling assembly 328 are the same component. In these versions of
the invention, attachment 320 thus serves as a means for connecting
an accessory with a head different from coupling head 54 to the
handpiece. In these versions of the invention, the attachment
rotates at the speed at which the handpiece spindle 42 rotates. In
other versions of the invention, there is a speed reducer or speed
increases gear assembly internal to the attachment housing 322 for
transferring the rotational moment received by the input shaft 326
to the coupling head. The Applicants' Assignee's U.S. Pat. No.
5,993,454, DRILL ATTACHMENT FOR A SURGICAL DRILL, issued 30 Nov.
1999 and incorporated herein by reference, shows one such assembly.
This type of attachment may be provided with a spindle and coupling
assembly substantially identical to the spindle 42 and coupling
assembly 46 of this invention.
[0135] The foregoing is directed to one specific version of the
invention. It should be appreciated that alternative versions of
the handpiece, cutting accessory and attachment of this invention
may have features different from what have been described.
[0136] For example, there is no requirement that all handpieces of
this invention include both the described clutch and coupling
assembly. Some versions of the invention may have only the clutch
or only the coupling assembly.
[0137] The gear train and drive heads of this invention may be of
different design. For example, in some versions of the invention,
the gear train may have three or more drive heads, each or which,
in response to the single input rotational moment, operates at a
different rotational speed. In some versions of the invention, the
gear train has gears that cause one or more drive heads to rotate
at speeds faster than those at which the motor shaft 26
rotates.
[0138] The means by which the motor 22 rotates shaft 26 may
likewise vary from what has been described.
[0139] Similarly, the structure of the clutch 44 may differ from
what has been described. For instance, some versions of the
invention may have few or more laterally extending members, clutch
pins or other torque transmitting components, for simultaneously
engaging a gear train drive head 86 or 92 and the spindle 42. In
some versions of the invention, clutch 44 may even include a single
one of these members.
[0140] In some versions of the invention, the inner shifter and/or
outer shifter may be arranged so that the points at which
longitudinal motion are transferred to this sub assembly
(indentions 194 in the described embodiment) are within the
longitudinal slice in which the lateral member that transfers
torque from one of the drive heads to the spindle is located. Such
construction can further reduce the overall longitudinal length of
the clutch.
[0141] Also in some versions of the invention, the clutch pins may
be integrally attached to the spindle. In these versions of the
invention, the spindle itself is displaced in order to cause the
clutch pins to engage the appropriate gear train drive head.
[0142] Similarly, in other versions of the invention, means other
than a rotating shift ring may be employed to set the position of
the clutch pins. In some versions of the invention, a switch member
moveable mounted to the handpiece housing to move longitudinally is
the surgeon-actuated component that is displaced to set the
position of the clutch pins.
[0143] As seen in FIGS. 33 and 34, it is possible to provide the
clutch assembly of this with a tactile and audible feedback
assembly for indicating the switching of the clutch between the
clutch states. In the illustrated feedback assembly, the feedback
is provided by a detent ball 340. Detent ball 340 is seated in a
bore 342 formed in the base 181a of inner shifter 180a. The detent
ball is positioned to extend inwardly, towards the outer coupler
124a. A spring 344 is also seated on inner shifter bore 342 so as
to urge ball 340 inwardly, toward the outer coupler 124. Shifter
housing 186, it is understood, is disposed over the inner shifter
180a. Thus, the inner annular wall of the shifter housing 186
functions as the static surface against which the outer end of
spring 344 abuts.
[0144] The outer coupler 124a has the same basic geometry of the
first described outer coupler 124 (FIGS. 8 and 9). Outer coupler
124a is also formed to have two parallel arcuately extend grooves
348. Grooves 348 are formed in the outer surface of the outer
coupler 124a between two adjacent slots 134 formed in the coupler.
A first one of the grooves 348 is located adjacent the distal ends
of the slots 134. The second groove is located adjacent the
proximal end of the slots 134.
[0145] As the clutch is actuated, inner shifter base 181a moves
between the opposed ends of the outer coupler slots 134. This
movement of the inner shifter causes detent ball 340 to move out of
a first one of the grooves 348 into the second groove 348. The
spring resistance overcomes moving the ball 340 out of the first
groove 348 provides an initial tactile feedback that the clutch is
being moved from a first state. When the inner shifter base 181a is
moved to the position wherein the clutch pins 184 engage the second
one of the drive heads 86 or 92, the detent ball 340 seats in the
groove 348 aligned with the drive head. This results in an audible
mechanical. Also, the individual actuating the shift ring 202 (FIG.
1) is exposed to an additional resistance when try urge the ball
out of the groove.
[0146] Thus, the feedback assembly of the clutch of this version of
the invention provides feedback both when the clutch is moved from
the first setting and when the clutch sets in the second
setting.
[0147] Also, the structure of the coupling assembly 46 and
complementary attachment/cutting accessory coupling head may vary
from what has been described. There is no requirement that in all
versions of the invention the surfaces of the spindle that output
torque and complementary coupling head boss 302 have a hexagonal or
even a polygonal cross sectional profile. It is believed that a
polygonal cross sectional geometry is the most efficient for
ensuring torque transfer to the coupling head.
[0148] Similarly, the coupling head body 304 may have a geometry
different from what has been described and illustrated. There is no
requirement that in all versions of the invention this component
and the complementary spindle bore have circular cross-sectional
profiles. In some versions of the invention, these components may
even have one or more planar faces. It is believed though such
geometry is an optimal geometry for reducing coupling head wobble.
Similarly, there is no requirement that in all versions of the
invention, the indentation defined by the coupling head body for
receiving the locking member associated with the handpiece coupling
assembly be an annular groove. In some versions of the invention,
one or more indentations are provided in the coupling head body for
receiving the complementary locking member integral with the
complementary handpiece coupling assembly.
[0149] In some versions of the invention, the coupling body may not
have any geometric features for receiving a complementary coupling
assembly locking members. Also, there may be versions of the
invention wherein the geometric features for facilitating the
engagement of the handpiece coupling assembly with the coupling
head project beyond the surface of the coupling head body.
[0150] Similarly, there may be versions of the invention in which
the coupling head body has a diameter that is identical with that
of the distally adjacent attachment/accessory shaft. In still other
versions of the invention, the attachment/accessory shaft may have
a diameter greater than that of the coupling head.
[0151] Likewise, an accessory/attachment coupling head of this
invention may be constructed with geometric features different from
slots 308 and beveled faces 312 to facilitate the alignment of the
coupling head in the spindle bore. Some versions of the invention
may not even be provided with any of these features.
[0152] Other coupling assemblies may, instead of holding an
attachment/accessory coupling head to the spindle serve only to
cause the coupling head to be driven by the spindle.
[0153] Therefore, it is an object of the appended claims to cover
all such variations and modifications that come within the true
spirit and scope of the invention.
* * * * *