1
`
`NUVASIVE 1035
`NuVasive, Inc. v. Warsaw Orthopedic, Inc.
`IPR2013-00206
`IPR2013-00208
`
`

`

`5,792,044
`Page 2
`
`US. PATENT DOCUMENTS
`,
`8/1988 HHSSCID ....................................... 128/6
`4.762.120
`604/283
`4,875,379 10/1989 Lee ......
`.
`
`2/1990 G111 et a].
`4,899,729
`123/3
`.
`.
`.
`2/1990 HJShlgakl et 81.
`. 358/98
`4,905,082
`
`,
`.
`4,972,327
`11/1990 Klshl et al.
`.....
`128/3
`5 004 457
`4/1991 Wyatt el al
`604/158
`...... ,
`1.... 604/164
`.5'071‘410
`12/1991 Pazell
`
`6/1992 Ray .......... 128/20
`5:125:396
`604/164
`$153543 10/1992 Lazarus
`
`5,171279 12/1992 Mathews
`“ 623/17
`3/1993 Obenchain .....
`123/898
`5.195.541
`
`4/1993 Hertzmann et a].
`5,201,729
`606/2
`5,242,444
`9/1993 MachJJan .....
`.. 606/61
`5,334,150
`8/1994 K3311 .......
`604/164
`5,354,302 10/1994 K0 ........................................... 606/104
`
`
`
`5.357.983 10/1994 Mathews ................................. 128/898
`5.376.076 12/1994 Kaali
`....................................... 604/164
`5.380.291
`1/1995 K3811 ...................................... 604/164
`5.392.766
`2/1995 Mastemon et al.
`..... 128/4
`
`~
`3/1995 Kambm ..................................... 604/51
`5.395.317
`5.396.880
`3/1995 Kagan el 81.
`128/6
`1
`8/1995 L1eber el 31.
`5,437,637
`604/96
`
`51439349
`3/1995 Mapese‘all
`° 604““
`... 606/83
`5.439.464
`8/1995 Shapiro .....
`
`5,441,041
`3/1995 Sauer e! a].
`. 600/106
`5,445,142
`8/1995 Hassler. Jr,
`600/105
`5.4721426 12/1995 3011311 61314 -
`604/164
`
`5,534,009
`7/1996 LaDdel’ ......
`. 606/135
`5,551,947
`9/1996 Kaali
`.........
`. 606/264
`5,562,696 10/1996 Nobles at a].
`606/185
`
`5,569,290 10/1996 McAfee .................................. 606/135
`
`.
`-
`
` 2
`
`

`

`US. Patent
`
`Aug. 11, 1993
`
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`US. Patent
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`Aug. 11, 1998
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`US. Patent
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`Aug. 11, 1998
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`Sheet 3 of 7
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`5,792,044
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`US. Patent
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`Aug. 11, 1993
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`Aug. 11, 1998
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`US. Patent
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`Aug. 11, 1998
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`US. Patent
`
`Aug. 11, 1998
`
`Sheet 7 of 7
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`5,792,044
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`

`

`5.792.044
`
`1
`DEVICES AND METHODS FOR
`PERCUTANEOUS SURGERY
`
`FIELD OF THE INVENTION
`
`The present invention relates to devices. instruments and
`methods for performing percutaneous surgeries. particularly
`at locations deep within the body. One specific application
`of the invention concern devices.
`instruments and tech-
`
`niques for percutaneous. minimally invasive spinal surgery.
`In another aspect of the invention. the percutaneous surgery
`is performed under direct vision at any location in the body.
`
`BACKGROUND OF THE INVENTION
`
`Traditional surgical procedures for pathologies located
`deep within the body can cause significant trauma to the
`intervening tissues. These open procedures often require a
`long incision. extensive muscle shipping. prolonged retrac-
`tion of tissues. denervation and devascularization of tissue.
`Most of these surgeries require a recovery room time of
`several hours and several weeks of post—operative recovery
`time due to the use of general anesthesia and the destruction
`of tissue during the surgical procedure. In some cases. these
`invasive procedures lead to permanent scarring and pain that
`can be more severe than the pain leading to the surgical
`intervention.
`
`Minimally invasive alternatives such as arthroscopic tech—
`niques reduce pain. post~operative recovery time and the
`destruction of healthy tissue. Orthopedic surgical patients
`have particularly benefitted from minimally invasive surgi—
`cal techniques. The site of pathology is accessed through
`portals rather than through a significant incision thus pre-
`serving the integrity of the intervening tissues. These mini-
`mally invasive techniques also often require only local
`anesthesia. The avoidance of general anesthesia reduces
`post—operative recovery time and the risk of complications.
`Minimally invasive surgical techniques are particularly
`desirable for spinal and neurosurgical applications because
`of the need for access to locations deep within the body and
`the danger of damage to vital
`intervening tissues. For
`example. a common open procedure for disc herniation.
`larninectomy followed by discectomy requires stripping or
`dissection of the major muscles of the back to expose the
`spine. In a posterior approach. tissue including spinal nerves
`and blood vessels around the dural sac.
`ligaments and
`muscle must be retracted to clear a channel from the skin to
`
`the disc. These procedures normally take at least one-two
`hours to perform under general anesthesia and require
`post-operative recovery periods of at least several weeks. In
`addition to the long recovery time. the destruction of tissue
`is a major disadvantage of open spinal procedures. This
`aspect of open procedures is even more invasive when the
`discectomy is accompanied by fusion of the adjacent ver-
`tebrae. Many patients are reluctant to seek surgery as a
`solution to pain caused by herniated discs and other spinal
`conditions because of the severe pain sometimes associated
`with the muscle dissection.
`
`In order to reduce the post-operative recovery time and
`pain associated with spinal and other procedures. micro-
`surgical techniques have been developed. For example. in
`micro—surgical discectomies. the disc is accessed by cutting
`a channel from the surface of the patient’s back to the disc
`through a small incision. An operating microscope or loupes
`is used to visualize the surgical field. Small diameter rnicro—
`surgical instruments are passed through the small incision
`and between two laminae and into the disc. The intervening
`tissues are disrupted less because the incision is smaller.
`
`2
`Although these micro—surgical procedures are less invasive.
`they still involve some of the same complications associated
`with open procedures. such as injury to the nerve root and
`dural sac. perineural scar formation. reherniation at
`the
`surgical site and instability due to excess bone removal.
`Other attempts have been made for minimally invasive
`procedures to correct symptomatic spinal conditions. One
`example is chemonucleolysis which involved the injection
`of an enzyme into the disc to partially dissolve the nucleus
`to alleviate disc herniation. Unfortunately.
`the enzyme.
`chymopapain. has been plagued by concerns about both its
`effectiveness and complications such as severe spasms.
`post-operative pain and sensitivity reactions including ana-
`phylactic shock.
`The development of percutaneous spinal procedures has
`yielded a major improvement in reducing recovery time and
`post-operative pain because they require minimal. if any.
`muscle dissection and they can be performed under local
`anesthesia. For example. U.8. Pat. No. 4.545.374 to Jacob—
`son discloses a percutaneous lumbar discectomy using a
`lateral approach. preferably under fluoroscopic X—ray. This
`procedure is limited because it does not provide direct
`visualization of the discectomy site.
`Other procedures have been developed which include
`arthroscopic visualization of me spine and intervening struc-
`tures. US. Pat. Nos. 4.573.448 and 5.395.317 to Kambin
`
`disclose percutaneous decompression of herniated discs
`with a posterolateral approach. Fragments of the herniated
`disc are evacuated through a cannula positioned against the
`annulus. The ’3 17 Kambin patent discloses a biportal pro-
`cedure which involves percutaneously placing both a work-
`ing cannula and a visualization cannula for an endoscope.
`This procedure allows simultaneous visualization and
`suction. irrigation and resection in disc procedures.
`Unfortunately. disadvantages remain with these proce-
`dures and the accompanying tools because they are limited
`to a specific application or approach. For example.
`Jacobson. Kambin and other references require a lateral or
`a posterolateral approach for percutaneous discectomy.
`These approaches seek to avoid damage to soft
`tissue
`structures and the need for bone removal because it was
`thought to be impractical to cut and remove bone through a
`channel. However. these approaches do not address other
`spinal conditions which may require a mid—line approach.
`removal of bone or implants.
`US. Pat. No. 5.439.464 to Shapiro discloses a method and
`instruments for performing arthroscopic spinal surgeries
`such as laminectomies and fusions with a mid—line or medial
`
`posterior approach using three cannulas. Each of the can-
`nulas requires a separate incision. While Shapiro discloses
`an improvement over prior procedures which were limited to
`a posterolateral or lateral approach for disc work. Shapiro's
`procedure still suffers from many of the disadvantages of
`known prior percutaneous spinal surgery techniques and
`tools. One disadvantage of the Shapiro procedure is its
`requirement of a fluid working space. Another significant
`detriment is that the procedure requires multiple portals into
`the patient.
`Fluid is required in these prior procedures to maintain the
`working space for proper function of optics fixed within a
`prior art cannula and inserted percutaneously. Irrigation. or
`the introduction of fluid into the working space. can often be
`logistically disadvantageous and even dangerous to the
`patient for several reasons. The introduction of fluid into the
`working space makes hemostasis more difficult and may
`damage surrounding tissue. Excess fluid may dangerously
`
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`5.792.044
`
`3
`dilute the sodium concentration of the patient’s blood supply
`which can cause seizures or worse. The fluid environment
`can also make drilling difficult due to cavitation. The
`requirement for a fluid environment generally increases
`expenses associated with the surgery and adds to the com-
`plexity of the surgery. due in part to the relatively high
`volume of fluid required.
`A need has remained for devices and methods that provide
`for percutaneous minimally invasive surgery for all appli-
`cations and approaches. A need has also remained for
`percutaneous methods and devices which do not require a
`fluid-filled working space. but that can be adapted to a fluid
`environment is necessary.
`A significant need is present in this field for techniques
`and instruments that permit surgical procedures in the work-
`ing space under direct vision. Procedures that reduce the
`number of entries into the patient are also highly desirable.
`The fields of spinal and neuro surgery have particularly
`sought devices and techniques that minimize the invasion
`into the patient and that are streamlined and concise in their
`application.
`
`SUMMARY OF THE INVENTION
`
`Briefly describing one aspect of the invention. there is
`provided devices and method for performing percutaneous
`procedures under direct visualization. even at locations deep
`within a patient. In one embodiment. a device for use in
`percutaneous surgery includes an elongated cannula having
`a first
`inner diameter and an outer diameter sized for
`percutaneous introduction into a patient. The cannula further
`includes a distal working end and an opposite proximal end
`and defines a working channel between the ends having a
`second diameter which is equal to the first inner diameter.
`The working channel is sized to receive a tool therethrough.
`The device also includes an elongated viewing element
`mounted inside the cannula adjacent the working channel.
`The viewing element has a first end connectable to a viewing
`apparatus and an opposite second end disposed adjacent the
`distal working end of the cannula.
`In another aspect. a fixture is provided for mounting the
`elongated viewing element
`to the cannula. The fixture
`includes a housing attachable to the proximal end of the
`cannula. The housing defines a worldng channel opening
`therethrough in communication with the working channel.
`The working channel opening is sized to substantially cor-
`respond to the second diameter of the working channel. The
`housing also defines an optics bore adjacent the working
`channel opening. The optics bore is sized to receive the
`elongated viewing element therethrough.
`In some embodiments. the fixture supports the viewing
`device for movement within the optics bore along the
`longitudinal axis of the bore to extend or retract the lens
`relative to the distal working end of the cannula. In other
`embodiments. the fixture supports the viewing device for
`rotation within the optics bore about the longitudinal axis of
`the bore. In some embodiments. the housing is rotatable
`relative to the cannula so that the longitudinal axis of the
`optics bore is rotatable about the longitudinal axis of the
`working channel.
`Novel tools are also provided which are insertable into the
`working channel of the cannula. A tissue retractor in one
`embodiment includes a body and an integral working tip
`configured to atraumatically displace tissue as the retractor
`is manipulated through tissue. The body has a convex
`surface configured to conform to the inner cylindrical sur-
`face of the cannula and an opposite concave surface which
`
`4
`
`does not obstruct the working channel or visualization of the
`working space. Cannulated tissue dilators are also provided
`which are insertable over a guidewire or another dilator as
`well as insertable into the working channel.
`In some
`embodiments. the tissue dilators include a tapered working
`end to displace tissue and a gripping portion having a
`number of circumferential grooves to enhance gripping and
`manipulation of the dilator.
`According to the methods of this invention. spinal and
`other surgeries can be performed percutaneously with direct
`visualization without the requirement for a fluid-maintained
`working space. In another aspect of the inventive surgical
`techniques. all steps of a surgical procedure are conducted
`under direct vision through a single working channel can-
`nula. An optical scope or viewing device is moved within the
`working channel and throughout the working space from a
`variety of angles and orientations to provide a clear View of
`the operative steps.
`The techniques of the present invention also encompass
`passing multiple tools and instruments through the single
`working channel cannula and manipulating the instruments
`and tools within the working space.
`In one specific
`embodiment. a tissue retractor is provided that extends
`through the working channel without significantly reducing
`the dimensions of the channel.
`
`It is an object of the invention to provide devices and
`methods for percutaneous spinal surgery for all applications
`and approaches. One advantage of this invention is that
`percutaneous procedures can be accomplished in a dry
`environment because a fluid working space is not required
`for the proper function of the optics. One benefit of this
`invention is that it provides instruments and methods which
`reduce the cost. risk. pain and recovery time associated with
`surgery. These and other objects. advantages and features are
`accomplished according to the devices and methods of the
`present invention.
`DESCRIPTION OF THE FIGURES
`
`FIG. 1 is a side elevational view of a device according to
`this invention.
`
`FIG. 2 is a top elevational view of a fixture for supporting
`a viewing device within a cannula according to this inven-
`tion.
`FIG. 3 is a side cross-sectional view of the fixture shown
`in FIG. 2.
`
`FIG. 4 is a side elevational view of a retractor according
`to one embodiment of this invention.
`FIG. 4A is an end cross-sectional view of the retractor of
`FIG. 4 taken along lines A—A.
`FIG. 5 is a top elevational view of the retractor shown in
`FIG. 4.
`FIG. 6 is an end elevational View of the retractor shown
`in FIGS. 4 and 5.
`FIG. 7 is a side elevational View of a retractor according
`to another embodiment of this invention.
`FIG. 7A is an end cross-sectional view of the retractor of
`FIG. 7 taken along lines A—A.
`FIG. 7B is an end cross-sectional view of the retractor of
`FIG. 7 taken along lines B—B.
`FIG. 8 is a top elevational view of the retractor shown in
`FIG. 7.
`FIG. 9 is a side elevational View of a dilator according to
`this invention.
`
`FIG. 10(a)—(i) depicts the steps of a method according to
`this invention.
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`5.792.044
`
`5
`FIG. 11 is a side cross—sectional view of a device accord-
`ing to one embodiment of this invention.
`FIG. 12 is a side cross—sectional view of an aspiration cap
`as shown in FIG. 11.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`For the purposes of promoting an understanding of the
`principles of the invention. reference will now be made to
`the embodiments illustrated in the drawings and specific
`language will be used to describe the same. It will never—
`theless be understood that no limitation of the scope of the
`invention is thereby intended. such alterations and further
`modifications in the illustrated devices and described
`methods. and such further applications of the principles of
`the invention as illustrated therein being contemplated as
`would normally occur to one skilled in the art to which the
`invention relates.
`
`The present invention provides instruments and methods
`for performing percutaneous surgery. including spinal appli-
`cations such as larninotomy. laminectomy. foramenotomy.
`facetectomy or discectomy. with a single working channel
`endoscope. The present inventors have discovered that many
`percutaneous surgeries may be performed without a fluid
`workspace through the use of optics which move indepen-
`dently of the cannula. The present invention contemplates
`techniques and instruments that can be implemented with or
`without a fluid environment.
`
`This invention also brings the advantages of percutaneous
`procedures to applications that previously required open
`surgery. One advantage is based upon the further discovery
`that bone work can be performed percutaneously through a
`large working channel. Another advantage is realized in the
`use of a single portal within the patient to perform a wide
`range of simultaneous procedures.
`According to one embodiment of the present invention. as
`depicted in FIG. 1. a device 10 is provided for use in
`percutaneous surgery which includes an elongated cannula
`20 having a first inner diameter D, and an outer diameter D0
`sized for percutaneous introduction into a patient. The
`cannula 20 also includes a distal working end 21 and an
`opposite proximal end 22. The cannula defines a working
`channel 25 between the ends 21. 22 having a second
`diameter d2 equal to the first inner diameter D, sized for
`receiving a tool therethrough. The cannula has a length
`along its longitudinal axis L that is sized to pass through the
`patient from the skin to an operative site or working space.
`In some cases. the working space may be adjacent a vertebra
`or disc. or in the spinal canal.
`An elongated viewing element 50 is mountable inside
`cannula 20 adjacent the working channel 25. The viewing
`element 50 has a first end 51 connectable to a viewing
`apparatus. such as an eyepiece or camera. and an opposite
`second end 52 disposed or positionable adjacent the distal
`working end 21 of the cannula 20. The particular elongated
`viewing element 50 is not critical to the invention. Any
`suitable viewing element is contemplated that creates an
`optical or image transmission channel. In one embodiment.
`the elongated viewing element 50 includes a fiber optic
`scope 54 and a lens 55 at the second end 52. Preferably. the
`fiber optic scope includes illumination fibers and image
`transmission fibers (not shown). Alternatively. the viewing
`element may be a rigid endoscope or an endoscope having
`a steerable or bendable tip.
`One advantage of this invention is that it provides optics
`which are movable relative to the cannula 20. Because the
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`optics are movable. it is not necessary to provide a fluid-
`maintained work space. The optics can be removed. cleaned
`and replaced while the cannula is percutaneously positioned
`within the patient over the working space. Any configuration
`which allows the optics to be movably supported adjacent
`the working channel 25 is contemplated.
`In one
`embodiment. shown in FIGS. 1—3. a fixture 30 is provided
`for mounting the elongated viewing element 50 to the
`cannula 20. Preferably. the fixture 30 includes a housing 31
`attachable to the proximal end 22 of the cannula 20. The
`working channel opening 35 is sized to substantially corre-
`spond to the second diameter (:12 of the working channel 25
`to receive tools. The fixture 30 includes a housing 31 which
`defines a working channel opening 35 arranged to commu-
`nicate with the worldng channel 25 when the fixture 30 is
`mounted to the cannula 20. The working channel opening 35
`is sized to receive tools therethrough for passage through the
`working channel 25. In the embodiments shown in FIGS.
`1—3.
`the fixture 30 is configured to mount the viewing
`element 50 within the working channel 25.
`The housing 31 also defines an optics bore 60 adjacent the
`working channel opening 35. The optics bore 60 has a
`longitudinal axis 1 that is preferably substantially parallel to
`the axis L of the cannula and working channel. The optics
`bore 60 is preferably sized to removably receive the elon-
`gated viewing element 50 therethrough. The fixture 30
`preferably supports the viewing element 50 for movement
`within the optics bore 60 along the longitudinal axis 1 of the
`bore 60 to extend or retract the lens 55 relative to the distal
`working end 21 of the cannula 20. The retractable/
`extendable feature of the optics of this invention provides an
`advantage over prior endoscopes because it eliminates the
`requirement for a fluid workspace. While the device 10 and
`its viewing element 50 can be easily used in a fluid
`environment. the fluid is not essential for the system to
`operate. contrary to prior systems. Furthermore. many of the
`prior endoscopes were not suited to access certain areas
`because of their large diameters. For example. prior endo-
`scopes could not access the spinal canal. However. with this
`invention. access to the spinal canal is not limited by the
`diameter of the channel or cannula. The cannula 20 can be
`left behind in the soft tissue or supported by the lamina while
`the second end 52 of the elongated viewing element 50 can
`be advanced into the spinal canal along with any spinal
`instruments which have been inserted into the working
`channel 25.
`
`Preferably the fixture 30 also supports the viewing ele—
`ment 50 for rotation within the optics bore 60 about the
`longitudinal axis 1 of the bore 60. The lens 55 of the viewing
`element 50 defines an optical axis A0. As in many
`endoscopes. the optical axis A0 can be offset at an angle
`relative to the longitudinal axis 1 of the optics bore 60. This
`feature allows the optical axis A0 of the lens to be swept
`through a conical field of view F for greater visibility of the
`working space. The fixture 30 can further be configured so
`that the viewing element 50 is rotatable relative to the
`cannula 20. In this embodiment. the housing 31 is rotatable
`relative to the cannula 20 so that the second longitudinal axis
`1 of the optics bore 60 rotates about the longitudinal axis L
`of the working channel 25. The rotatable features of this
`invention allows visualization of the entire working space.
`This feature also aids in simplifying the surgical procedure
`because the optics 50 and accompanying fittings can be
`moved out of the way of the surgeon’s hands and tools
`passing through the working channel.
`In one embodiment depicted in FIG. 3. the housing 31
`defines a receiver bore 40 having an inner diameter d,
`
`12
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`

`

`5.792.044
`
`7
`
`slightly larger than the outer diameter D0 of the cannula 20.
`In this configuration. the proximal end 22 of the cannula 20
`can be received within the receiver bore 40 so that the
`housing 31 can rotate about the proximal end 22 of the
`cannula 20. As shown in FIG. 3. the housing 31 also includes
`an upper bore 41 which is contiguous with the working
`channel opening 35 and the receiver bore 40. In one
`embodiment. the optics bore 60 is disposed within the upper
`bore 41 of the housing 31.
`In a preferred embodiment depicted in FIG. 2. the optics
`bore 60 is defined by a C-shaped clip 61 disposed within the
`upper bore 41. Preferably. the C-shaped clip 61 is formed of
`a resilient material and the optics bore 60 defined by the clip
`61 has an inner diameter Di that is slightly less than the outer
`diameter of the elongated viewing element 50. When the
`viewing element 50 is pushed into the optics bore 60 it
`resiliently deflects the C-shaped clip 61. The resilience of
`the clip 61 provides a gripping force on the element 50 to
`hold it in the desired position. while still allowing the
`element 50 to be repositioned.
`Alternatively. the optics bore 60 can have an inner diam-
`eter larger than the outer diameter of the viewing element. In
`this instance.
`the viewing element 50 can be supported
`outside the device 20. either manually or by a separate
`support fixture.
`Preferably the device 10 provides engagement means for
`securely yet rotatably engaging the fixture 30 to the cannula
`20. Most preferably. the fixture 30 is configured to engage a
`standard cannula 20. Engagement means can be disposed
`between the housing 31 and the cannula 20 when the fixture
`30 is mounted to the proximal end 22 of the cannula 20 for
`providing gripping engagement between the housing 31 and
`the cannula 20. In one embodiment depicted in FIG. 3 the
`engagement means includes a number of grooves 32 within
`the receiver bore 40 and a resilient sealing member. such as
`an O—ring (see FIG. 11) disposed in each groove 32. The
`sealing members. or O-rings. disposed between the housing
`31 and the outer diameter D0 of the cannula 20 rotatably
`secure the fixture 30 to the cannula 20. The O-rings provide
`sufficient resistance to movement to hold the fixture 30 in a
`selectable position on the cannula. In another embodiment.
`the housing 31 defines a receiver bore 40 which has an inner
`diameter d, which is only slightly larger than the outer
`diameter Doof the cannula 20 so that the housing 31 can
`rotate freely about the cannula 20.
`The working channel 25 and the working channel opening
`35 are both sized to receive a tool or instrument there-
`through. Preferably. the working channel opening 35 of the
`housing 31 has a diameter Dw which is substantially equal
`to the inner diameter d2 of the working channel 25 so that the
`effective diameter of the working channel is not reduced by
`the fixture 30. This configuration provides a maximum
`amount of space for the insertion of tools into the working
`channel 25. The present invention is advantageous because
`standard micro-surgical spinal tools can be inserted into the
`working channel and manipulated to perform a surgical
`procedure. The present invention is particularly advanta-
`geous because the working channel 25 will simultaneously
`accept a plurality of movable instruments. No other known
`prior art device has a working channel that accepts more
`than one movable instrument at a time through a single port.
`Therefore. according to this invention. an entire percutane-
`ous surgical procedure can be performed through the work-
`ing channel 25 of the device 10 under direct visualization
`using the viewing element 50 disposed within the optics
`bore 60.
`
`Although standard micro-surgical instruments may be
`used with the present invention. this invention also contem-
`
`8
`plates certain novel tools which capitalize on and enhance
`the advantages of this invention.
`According to one preferred embodiment of the invention.
`a tissue retractor 70 is provided as depicted in FIGS. 4-6.
`The retractor 70 is removably and rotatably insertable
`through the working channel 25 and the working channel
`opening 35 of the device 10. The tissue retractor 70 includes
`a working tip 75 configured to atraumatically displace tissue
`as the retractor 70 is manipulated through the tissue and a
`body 76 having a proximal first end 77 and a distal second
`end 78. The second end 78 can be integral with the working
`tip 75 which preferably has a blunt curved end 82. In
`addition. the working tip 75 is also preferably bent or curved
`away from the body 76. as shown in FIG. 7. The body 76 is
`sized to be rotatably received within the cannula 20 and has
`a length B from the first end 77 to the second end 78
`sufficient so that the first end 77 and the working tip 75 can
`both extend outside the cannula 20 when the body 76 is
`within the cannula 2A).
`
`This invention contemplates any suitable retractor for use
`through the working channel 25. However. retractors such as
`the retractor 70 depicted in FIGS. 4—6 are preferred in which
`the body 76 includes a curved plate 84 that is configured to
`conform to the inner cylindrical surface 26 of the cannula
`without substantially blocking the working channel 25. The
`curved plate 84 has a convex surface 80 and an opposite
`concave surface 81. In one embodiment. the curved plate 84
`includes a first plate portion 85 defining a first convex
`surface 80 and an opposite first concave surface 81. A
`second plate portion 86 is integral with the first plate portion
`85 and is disposed between the first plate portion 85 and the
`working tip 75. The second plate portion 86 defines a second
`convex surface (not shown) and an opposite second concave
`surface 81'. Both the first plate portion 85 and the second
`plate portion 86 include opposite edges 90 extending sub—
`stantially parallel to the length B of the body 76.
`Preferably.
`the curved plate 84 subtends an arc A1
`between the opposite edges 90 of at least 200 degrees. and
`most preferably 270 degrees. In a specific embodiment. the
`second plate portion 86 and specifically the second concave
`surface 81' subtends an angle that decreases along the length
`of the retractor. Thus. in an embodiment. the second concave
`surface 81' subtends an angle of about 200 degrees adjacent
`the first plate portion 85. decreasing to an angle of less than
`about 10 degrees at end 78.
`An alternate embodiment of a tissue retractor according to
`this invention is depicted in FIGS. 8—11. This retractor 100
`has a body 106 which includes a first plate portion 115
`defining a first convex surface 110 and an opposite first
`concave surface 111 and includes first opposite edges 120
`extending substantially parallel to the length B of the body
`106. The first plate portion 115 subtends a first are A2
`between the first opposite edges 120. The retractor body 106
`also includes a second plate portion 116 which is integral
`with the first plate portion 115 and is disposed between the
`first plate portion 115 and a working tip 105. The second
`plate portion 116 defines a second convex surface 110' and
`an opposite second concave surface 111' and includes second
`opposite edges 120' extending substantially parallel to the
`length B. The second plate portion 116 subtends a second arc
`A3 between the second opposite edges 120' that is difierent
`from the first are A2 in this embodiment. Preferably. the first
`arc A2 subtends an angle of less than 180 degrees and the
`second arc A3 subtends an angle of more than 180 degrees.
`Most preferably. the first are A2 subtends an angle of about
`90 degrees and the second arc A3 subtends an angle of about
`270 degrees.
`
`10
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`15
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`20
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`25
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`30
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`35
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`45
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`50
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`SS
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`65
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`13
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`13
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`5.792.044
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`9
`
`The retractors of this invention may be provided with
`means for engaging the retractors 70. 100 within the work-
`ing channel 25 of the cannula 20. For example. the convex
`surfaces 80. 110 can be configured to have a diameter that
`is greater than the diameter D, of the inner cylindrical
`surface 26 of the cannula 20. In that case. the body 76. 106
`may be formed of a resilient material that is deformable to
`be insertable into the cannula 20 so that the convex surface
`80. 110 is in contact with the inner cylindrical surface 26 of
`the cannula 20. When the body 76. 106 is deformed. it exerts
`an outward force against the surface 26 to frictionally hold
`the retractor in its selected position.
`The preferred components provided by this invention are
`configured so that multiple tools and instruments can be
`accepted and manipulated within the working channel 25 of
`the cannula 20. The components are also configured so that
`more than one surgeon may manipulate instruments through
`the working channel 25 of the cannula 20 at one time. For
`example. one surgeon may be manipulating the retractor
`whi