Devices and methods for percutaneous surgery

Abstract
A device (10) is provided which includes an elongated cannula (20) having a first inner diameter (DI) and an outer diameter (DO) sized for percutaneous introduction into a patient. The cannula (20) defines a working channel (25) between its ends (21, 22) which has a second diameter (D2) equal to the diameter (DI) of the cannula sized for receiving a tool therethrough. An elongated viewing element (50) is engageable to the cannula (20) adjacent the working channel (25), preferably by a fixture (30, 170). The fixture (30, 170) includes a housing/body (31, 171) attachable to the proximal end (22) of the cannula (20). The housing (31) defines an optics bore (60, 180) to support a viewing element (50) for translation and rotation relative to the cannula (20) so that the longitudinal axis of the optics bore (60, 180) will translate parallel to and rotate about the longitudinal axis of the working channel (25). Methods are also provided for performing surgeries percutaneously with direct visualization and without the requirement for a fluid-maintained workspace.
Description




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 techniques 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.




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 stripping, prolonged retraction 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 techniques reduce pain, post-operative recovery time and the destruction of healthy tissue. Orthopedic surgical patients have particularly benefited from minimally invasive surgical techniques. The site of pathology is accessed through portals rather than through a significant incision thus preserving the integrity of the intervening tissues. These minimally 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, laminectomy 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 vertebrae. 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 loupe is used to visualize the surgical field. Small diameter micro-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. 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 anaphylactic 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.S. Pat. No. 4,545,374 to Jacobson 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 the spine and intervening structures. U.S. 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 '317 Kambin patent discloses a biportal procedure which involves percutaneously placing both a working 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 procedures 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.




U.S. 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 cannulae. Each of the cannulae 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 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 complexity 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 applications 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 if necessary.




A significant need is present in this field for techniques and instruments that permit surgical procedures in the working 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 dimension and an outer dimension 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 dimension which is equal to the first inner dimension. The working channel is sized to receive a tool therethrough. The device also includes a 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 some embodiments, the viewing element can be a fiber optic cable, a GRIN rod, a rod-lens device or a remote optics (“chip on a stick”) device.




In another aspect, a fixture is provided for mounting the viewing element to the cannula. The fixture includes a housing attachable to the proximal end of the cannula. The housing defines a working channel opening therethrough in communication with the working channel. The working channel opening is sized to substantially correspond to the second dimension 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.




In one aspect of the invention, the working channel can be created by components other than a tubular cannula. For example, an expanding tissue dilator or tissue retractor is also contemplated. With this modification, the fixture would engage the dilator or retractor in its expanded condition.




In a further aspect of the invention, the optical viewing device is connected to a tissue retractor, such as a speculum. An apparatus of this type can be particularly useful in various applications such as transnasal transphenoidal surgery and pituitary procedures.




In a further aspect of the invention, the working channel maintained by the cannula or similar components can have a length calibrated so that the surgeon can maintain a tactile feel for instruments manipulated through the working channel. In spinal applications, certain beneficial aspects of the invention are attained by providing a cannula having a length slightly greater than the distance from the lamina of a vertebra to the surface of the patient's skin for posterior procedures. The viewing device is dimensioned relative to the cannula so that the viewing end of the device can project beyond the distal working end of the cannula or working channel to allow the surgeon to selectively survey the surgical site.




In accordance with one embodiment, the fixture includes at least one irrigation/aspiration port. Preferably, the port(s) can communicate with at least one itrigation/aspiration channel in the optical viewing device. In this manner, irrigation and/or aspiration can also be applied at the surgical site. When aspiration alone is applied, the port is connected to a vacuum or suction source. The aspiration will draw ambient air through the working channel, across the distal working space, and into the irrigation/aspiration channel of the viewing device. One benefit is that this ambient air aspiration eliminates smoke generated by various working tools and clears the optics lens of fog and debris.




In one embodiment, the fixture is mounted over and supported by the proximal end of the cannula.




In another embodiment, the fixture can be supported adjacent the proximal end of the cannula by a clamp engaging the outer surface of the cannula. In one specific embodiment, the clamp is a barrel clamp mechanism that is selectively operated by a lever arm and barrel cam. With this embodiment, the fixture itself can be translated along the length of the cannula to extend or retract the lens of the viewing device relative to the end 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 surface of the cannula and an opposite concave surface which 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 cannula. 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 invention.





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.




FIGS.


10


(


a


)-(


i


) depicts the steps of a method according to this invention.





FIG. 11

is a side cross-sectional view of a device according to one embodiment of this invention.





FIG. 12

is a side cross-sectional view of an aspiration cap as shown in FIG.


11


.





FIG. 13

is a top perspective view of a device according to another embodiment of the present invention.





FIG. 14

is a side perspective view of a fixture for supporting a viewing device forming part of the device shown in FIG.


13


.





FIG. 15

is a side elevational view of the device depicted in

FIG. 13

with the device shown connected to optical equipment depicted in phantom lines.





FIG. 16

is a side elevational view of a scope body forming part of the fixture depicted in

FIGS. 13 and 14

.





FIG. 17

is a bottom elevational view of the scope body shown in FIG.


16


.





FIG. 18

is a top elevation view of a lever arm forming part of a barrel clamp mechanism used with the fixture depicted in FIG.


14


.





FIG. 19

is an end cross-sectional view of the lever arm shown in

FIG. 18

taken along line


19





19


as viewed in the direction of the arrows.





FIG. 20

is a top elevational view of a barrel cam forming part of a barrel clamp mechanism incorporated into the fixture depicted in FIG.


14


.





FIG. 21

is a side elevational view of the barrel cam shown in FIG.


20


.





FIG. 22

is a bottom assembly view showing the assembly of the lever arm of

FIGS. 18-19

, the barrel cam of

FIGS. 20-21

with the scope body shown in FIG.


14


.





FIG. 23

is a side elevational view of a scope body as depicted in

FIG. 14

connected to an aspiration circuit.





FIG. 24

is a cross-sectional view of a human patient at a lumbar vertebral level with a device according to one embodiment of the invention situated within the patient to define a working channel above the laminae of the vertebra.





FIG. 25

is a side elevational view of a tissue retractor incorporating an optical viewing device.





FIG. 26

is a top elevational view of the tissue retractor incorporating an optical viewing device as shown in FIG.


25


.











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 nevertheless 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 applications such as laminotomy, 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 independently 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


I


and an outer diameter D


O


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 d


2


equal to the first inner diameter D


I


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 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 correspond to the second diameter d


2


of the working channel


25


to receive tools. The fixture


30


includes a housing


31


which defines a working channel opening


35


arranged to communicate with the working 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 f 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 elongated viewing element


50


therethrough. The fixture


30


preferably supports the viewing element


50


for movement within the optics bore


60


along the longitudinal axis l 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 endoscopes 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 element


50


for rotation within the optics bore


60


about the longitudinal axis l of the bore


60


. The lens


55


of the viewing element


50


defines an optical axis A


O


. As in many endoscopes, the optical axis A


O


can be offset at an angle relative to the longitudinal axis l of the optics bore


60


. This feature allows the optical axis A


O


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 l 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 receive r bore


40


having an inner diameter d


I


slightly larger than the outer diameter D


O


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 D


i


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 diameter 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 D


O


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


I


which is only slightly larger than the outer diameter D


O


of 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 therethrough. Preferably, the working channel opening


35


of the housing


31


has a diameter Dw which is substantially equal to the inner diameter d


2


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 advantageous 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 percutaneous surgical procedure can be performed through the working channel


25


of the device


10


under direct visualization using the viewing element


50


disposed within the optics bore


60


.




In accordance with the present embodiment, the components of the device


10


are cylindrical in configuration. In other words, the cannula


20


, working channel


25


and fixture


30


have corresponding cylindrical configurations which yield the various diameters D


i


, D


o


, D


w


and d


2


. In accordance with other embodiments contemplated as part of the invention, these diameters may be non-circular inner and outer dimensions, such as oval or square shaped. For example, a cannula


20


modified to a square cross-section would still provide a large working channel, such as working channel


25


. Likewise, a corresponding fixture


30


have a square cross-section would also provide a large working channel opening D


w


. In the case of non-circular configurations, the fixture


30


in accordance with the present embodiment would be unable to rotate around the circumference of the cannula


20


, as permitted by the circular configurations. On the other hand, even the non-circular configurations will permit axial movement of the optical viewing element and rotation of the viewing element about its own axis, as set forth more fully herein.




In accordance with a further variation of the present invention, the cannula


20


can be replaced by a similar device that is capable of maintaining a large working channel


25


. For example, the cannula


20


can be replaced by an expanding cannula or dilator apparatus. In one specific embodiment, the apparatus can be a spiral wound tube that is unwound or expanded to provide the working channel dimension. Alternatively, multiple tissue dilators, such as speculae, can be expanded to create a working space. In these configurations, the fixture


30


may still be used to support the optical viewing element


50


once the expandable dilator or tissue retractor reaches its full working channel dimension.




Although standard micro-surgical instruments may be used with the present invention, this invention also contemplates 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


20


.




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 substantially parallel to the length B of the body


76


.




Preferably, the curved plate


84


subtends an arc A


1


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 arc A


2


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 A


3


between the second opposite edges


120


′ that is different from the first arc A


2


in this embodiment. Preferably, the first arc A


2


subtends an angle of less than 180 degrees and the second arc A


3


subtends an angle of more than 180 degrees. Most preferably, the first arc A


2


subtends an angle of about 90 degrees and the second arc A


3


subtends an angle of about 270 degrees.




The retractors of this invention may be provided with means for engaging the retractors


70


,


100


within the working 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


I


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 while another surgeon is drilling into a bone. The curvature of the body


76


,


106


of the retractors


70


,


100


provides more working space and increases visibility. Another feature is that the long axis of the component can be placed in the working channel


25


while a bend in the handle portion keeps hands away from the channel


25


so that more than one surgeon can work in the channel


25


and more tools can be placed in the channel


25


. The retractors shown in

FIGS. 4-8

each comprise an arm


71


,


101


attached to the proximal first end


77


,


107


of the body


76


,


106


. Preferably, as shown in

FIGS. 4-8

, the arm


71


,


101


is at an angle ax which is less than 180 degrees from the longitudinal axis of the length L of the body


76


. Most preferably, the angle a is about 90 degrees so that the arm


71


,


101


is substantially perpendicular to the length L of the body


76


,


106


. Preferably, the arm


71


,


101


has a gripping surface


72


,


102


to facilitate manipulation of the retractor


70


,


100


.




The present invention also provides tissue dilators usable with the device


10


. Any dilator which is insertable into the working channel


25


of the cannula


20


is contemplated; however, a preferred dilator provided by this invention is depicted in

FIG. 12. A

dilator


130


preferably includes a hollow sleeve


135


defining a channel


131


. The channel


131


allows the dilator


130


to be placed over a guidewire (not shown) or other dilators. The hollow sleeve


135


has a working end


136


defining a first opening


132


in communication with the channel


131


and an opposite end


137


defining a second opening


133


. The working end


136


is tapered to a tapered tip


138


to atraumatically displace tissue. Preferably, a gripping portion


140


is provided on the outer surface


141


of the sleeve


135


adjacent the opposite end


137


. In one embodiment, the gripping portion


140


is defined by a plurality of circumferential grooves


142


defined in the outer surface


141


. The grooves


142


are configured for manual gripping of the dilator


130


to manipulate the dilator


130


through tissue. Preferably, the grooves


142


are partially cylindrical. In the embodiment shown in

FIG. 9

, the gripping portion


140


includes a number of circumferential flats


143


each of the circumferential grooves


142


. The grooves


142


have a first width W


1


along the length of the sleeve


135


and the flats


143


have a second width W


2


146 along the length. Preferably, the first and second widths W


1


and W


2


are substantially equal.




The present invention has application to a wide range of surgical procedures, and particularly spinal procedures such as laminotomy, laminectomy, foramenotomy, facetectomy and discectomy. Prior surgical techniques for each of these procedures has evolved from a grossly invasive open surgeries to the minimally invasive techniques represented by the patents of Kambin and Shapiro. However, in each of these minimally invasive techniques, multiple entries into the patient is required. Moreover, most of the prior minimally invasive techniques are readily adapted only for a posterolateral approach to the spine. The devices and instruments of the present invention have application in an inventive surgical technique that permits each of these several types of surgical procedures to be performed via a single working channel. This invention can also be used from any approach and in other regions besides the spine. For instance, the invention contemplates apparatus appropriately sized for use in transnasal, transphenoidal and pituitary surgeries.




The steps of a spinal surgical procedure in accordance with one aspect of the present invention are depicted in FIG.


10


. As can be readily seen from each of the depicted steps (a)-(i), the present embodiment of the invention permits a substantially mid-line or medial posterior approach to the spine. Of course, it is understood that many of the following surgical steps can be performed from other approaches to the spine, such as posterolateral and anterior. In a first step of the technique, a guidewire


150


can be advanced through the skin and tissue into the laminae M of a vertebral body V. Preferably, a small incision is made in the skin to facilitate penetration of the guidewire through the skin. In addition, most preferably the guidewire, which may be a K-wire, is inserted under radiographic or image guided control to verify its proper positioning within the laminae L of the vertebra V. It is, of course, understood that the guidewire


150


can be positioned at virtually any location in the spine and in any portion of a vertebra V. The positioning of the guidewire is dependent upon the surgical procedure to be conducted through the working channel cannula of the present invention. Preferably, the guidewire


150


is solidly anchored into the vertebral bone, being tapped by a mallet if necessary.




In subsequent steps of the preferred method, a series of tissue dilators are advanced over the guidewire


150


, as depicted in steps (b)-(d) in FIG.


10


. Alternatively, the dilators can be advanced through the incision without the aid of a guidewire, followed by blunt dissection of the underlying tissues. In the specific illustrated embodiment, a series of successively larger dilators


151


,


152


and


153


are concentrically disposed over each other and over the guidewire


150


and advanced into the body to sequentially dilate the perispinous soft tissues. Most preferably, the tissue dilators are of the type shown in

FIG. 9

of the present application. In a specific embodiment, the dilators have successively larger diameters, ranging from 5 mm, to 9 mm to 12.5 mm for the largest dilator. Other dilator sizes are contemplated depending upon the anatomical approach and upon the desired size of the working channel.




In the next step of the illustrated technique, the working channel cannula


20


is advanced over the largest dilator


153


, as shown in step (e), and the dilators and guidewire


150


are removed, as shown in step (f). Preferably, the working channel cannula


20


has an inner diameter D


I


of 12.7 mm so that it can be easily advanced over the 12.5 mm outer diameter of the large dilator


153


. Larger working channel cannulas are contemplated depending upon the anatomical region and surgical procedure.




With the cannula


20


in position, a working channel is formed between the skin of the patient to a working space adjacent the spine. It is understood that the length of the cannula


20


is determined by the particular surgical operation being performed and the anatomy surrounding the working space. For instance, in the lumbar spine the distance between the laminae M of a vertebra V to the skin of the patient requires a longer cannula


20


than a similar procedure performed in the cervical spine where the vertebral body is closer to the skin. In one specific embodiment in which the cannula


20


is used in a lumbar discectomy procedure, the cannula has a length of 87 mm, although generally only about half of the length of the cannula will be situated within the patient during the procedure.




In accordance with the present surgical technique, the working channel cannula


20


is at least initially only supported by the soft tissue and skin of the patient. Thus, in one aspect of the preferred embodiment, the cannula


20


can include a mounting bracket


27


affixed to the outer surface of the cannula (FIG.


10


(


f


), FIG.


11


). This mounting bracket


27


can be fastened to a flexible support arm


160


, which can be of known design. Preferably, the flexible support arm


160


is engaged to the bracket


27


by way of a bolt and wing nut


161


, as shown in FIG.


10


(


i


) and in more detail in

FIG. 11

, although other fasteners are also contemplated. This flexible arm


160


can be mounted on the surgical table and can be readily adjusted into a fixed position to provide firm support for the cannula


20


. The flexible arm


160


is preferred so that it can be contoured as required to stay clear of the surgical site and to allow the surgeons adequate room to manipulate the variety of tools that would be used throughout the procedure.




Returning to

FIG. 10

, once the cannula


20


is seated within the patient, the fixture


30


can be engaged over the proximal end of the cannula


20


. The fixture


30


, as shown in

FIGS. 2 and 3

and as described above, provides an optics bore


60


for supporting an elongated viewing element, such as element


50


shown in step h. In accordance with the invention, the viewing element


50


is advanced into the fixture


30


and supported by the optics bore


60


(FIG.


2


). In one specific embodiment, the element


50


is most preferably a fiber optic scope, although a rod lens scope, “chip on a stick” or other viewing scopes may be utilized. In the final step (i) of the procedure shown in

FIG. 10

, the flexible arm


160


is mounted to the bracket


27


to support the cannula


20


which in turn supports the optical viewing element


50


. This final position of step (i) in

FIG. 10

is shown in more detail in FIG.


11


. The viewing element


50


can be of a variety of types, including a rigid endoscope or a flexible and steerable scope.




With the viewing element or scope


50


supported by the fixture


30


the surgeon can directly visualize the area beneath the working channel


25


of the cannula


20


. The surgeon can freely manipulate the viewing element


50


within the working channel


25


or beyond the distal end of the cannula into the working space. In the case of a steerable tip scope, the second end


52


of the viewing element


50


, which carries the lens


55


, can be manipulated to different positions, such as shown in FIG.


11


. With virtually any type of viewing element, the manipulation and positioning of the scope is not limited by the working channel


25


, in contrast to prior systems.




Preferably, the positioning capability provided by the fixture


30


is utilized to allow extension of the lens


55


into the working space or retraction back within the cannula


20


, as depicted by the arrows T in FIG.


1


. Also the fixture preferably accommodates rotation of the element


50


about its own axis (arrows R in

FIG. 1

) to vary the viewing angle provided by the angled lens


55


, or rotation of the entire viewing element


50


about the cannula


20


and around the circumference of the working channel


25


, as shown by the arrows N in FIG.


1


. In this manner, the surgeon is provided with a complete and unrestricted view of the entire working space beneath the working channel


25


. In instances when the fixture


30


is rotated about the cannula


20


, the viewing orientation of the optics (i.e., left-right and up-down) is not altered so the surgeon's view of the procedure and surrounding anatomy is not disturbed.




Another advantage provided by the single working channel cannula


20


of the present invention, is that the cannula can be readily positioned over an appropriate target tissue or bone, to thereby move the working space as necessary for the surgical procedure. In other words, since the working channel cannula


20


is freely situated within the patient's skin and tissue, it can be manipulated so that the working space beneath the cannula


20


is more appropriately centered over the target region of the spine. Repositioning of the cannula


20


can be performed under fluoroscopic guidance. Alternatively, the cannula may be fitted with position sensing devices, such as LEDs, to be guided stereotactically. As the cannula is being repositioned, the surgeon can also directly visualize the spine through the viewing element


50


.




Once the position of the cannula


20


is established and a working space is oriented over the proper target tissue, a variety of tools and instruments can be extended through the working channel


25


to accomplish the particular surgical procedure to be performed. For instance, in the case of a laminotomy, laminectomy, foramenotomy or facetectomy, a variety of rongeurs, curettes, and trephines can be extended through the working channel opening


35


(see

FIG. 2

) and through the working channel


25


of the cannula


20


(see

FIG. 11

) into the working space. It is understood that these various tools and instruments are designed to fit through the working channel. For instance, in one specific embodiment, the working channel


25


through the cannula


20


can have a maximum diameter d


2


of 12.7 mm. However, with the viewing element


50


extending into the working channel


25


, the effective diameter is about 8 mm in the specific illustrated embodiment, although adequate space is provided within the working channel


25


around the viewing element


50


to allow a wide range of movement of the tool or instrument within the working channel. The present invention is not limited to particular sizes for the working channel and effective diameter, since the dimensions of the components will depend upon the anatomy of the surgical site and the type of procedure being performed.




Preferably, each of the tools and instruments used with the working channel cannula


20


are designed to minimize obstruction of the surgeon's visualization of and access to the working space at the distal end of the working channel cannula. Likewise, the instruments and tools are designed so that their actuating ends which are manipulated by the surgeon are displaced from the working channel cannula


20


. One such example is the tissue retractor shown in

FIGS. 4-8

. with these retractors, the handles that are manually gripped by the surgeon are offset at about a 90 degree angle relative to the longitudinal axis of the tool itself.




In accordance with once aspect of the present invention, the surgical procedures conducted through the working channel cannula


20


and within the working space at the distal end of the cannula are performed “dry”—that is, without the use of irrigation fluid. In prior surgical techniques, the working space at the surgical site is fluid filled to maintain the working space and to assist in the use of the visualization optics. However, in these prior systems the visualization optics were fixed within the endoscope. In contrast, the device


10


of the present invention allows a wide range of movement for the viewing element


50


so that the lens


55


can be retracted completely within the working channel


25


of the cannula


20


to protect it from contact with the perispinous tissue or blood that may be generated at the surgical site.




Moreover, since the viewing element


50


is removable and replaceable, the element


50


can be completely removed from the fixture


30


so that the lens


55


can be cleaned, after which the viewing element


50


can be reinserted into the fixture and advanced back to the working space. Under these circumstances, then, the need for irrigation is less critical. This feature can be of particular value when cutting operations are being performed by a power drill. It has been found in prior surgical procedures that the use of a power drill in a fluid environment can cause turbulence or cavitation of the fluid. This turbulence can completely shroud the surgeon's view of the surgical site at least while the drill is being operated. With the present invention, the dry environment allows continuous viewing of the operation of the power drill so that the surgeon can quickly and efficiently perform the necessary cutting procedures.




While the present invention permits the surgeon to conduct surgical procedures in the working space under a dry environment, irrigation may be provided separately through the working channel


25


. Alternatively, the viewing device


50


itself may include a tube


54


supported by the fitting


53


through which modest amounts of fluid can be provided to keep the visualization space clear. In addition, during a discectomy, aspiration of the excised tissue is preferred, and irrigation will frequently assist in rapid removal of this tissue. Thus, separate irrigation and aspiration elements can also be inserted through the working channel


25


as required by the procedure.




As necessary, aspiration can be conducted directly through the working channel


25


of the cannula


20


. In one specific embodiment, an aspiration cap


165


is provided as shown in

FIGS. 11 and 12

. The cap


165


includes a body


166


which defines a mating bore


167


having an inner diameter d


b


larger than the outer diameter D


h


of the housing


31


of fitting


30


. A tool opening


168


is provided in communication with the mating bore


167


. When the aspiration cap


165


is mounted over the housing


31


, as shown in

FIG. 11

, the tool opening


168


communicates directly with the upper bore


41


and provides the same entry capabilities as the working channel opening


35


of the housing


31


. The aspiration cap


165


is also provided with a tube receiver bore


169


which intersects the mating bore


167


. The receiver bore


169


is configured to receive an aspiration tube through which a vacuum or suction is applied. In certain instances, the tool opening


168


may be covered while suction is applied through the tool receiver bore


169


and mating bore


167


, and ultimately through the working channel


25


. Covering the opening


168


can optimize the aspiration effect through the working channel.




Returning again to the surgical technique of one embodiment of the present invention, once the working channel cannula


20


and the optics


50


are in position, as depicted in

FIG. 10

step (i) and

FIG. 11

, the paraspinous tissue can be reflected using instruments as described above, and a laminectomy performed using various rongeurs, curettes and drills. As necessary, the cannula


20


can be angled to allow a greater region of bone removal, which may be necessary for access to other portions of the spinal anatomy. In some instances, access to the spinal canal and the posterior medial aspects of the disc annulus may require cutting a portion of the vertebral bone that is greater than the inner diameter of the working channel


25


. Thus, some manipulation of the cannula


20


may be necessary to permit removal of a greater portion of bone. In other operations, multi-level laminectomies or foramenotomies may be necessary. In this instance, these multi-level procedures can be conducted by sequentially inserting the working channel cannula


20


through several small cutaneous incisions along the spinal mid-line. Alternatively, several working channel cannulas


20


can be placed at each of the small cutaneous incisions to perform the multi-level bone removal procedures.




Again, in accordance with the preferred illustrated surgical technique, an opening is cut into the laminae M of the vertebra V providing direct visual access to the spinal canal itself. As necessary, tissue surrounding the spinal nerve root can be removed utilizing micro surgical knives and curettes. Once the spinal nerve root is exposed, a retractor, such as the retractors shown in

FIGS. 4-8

, can be used to gently move and hold the nerve root outside the working space. In one important aspect of the two retractors


70


,


100


, the portion of the retractor passing through the working channel


25


generally conforms to the inner surface of the cannula


20


so that the working channel


25


is not disrupted by the retractor tool. Specifically, the effective diameter within the working channel


25


is reduced only by the thickness of the curved plates


84


,


114


of the retractors


70


,


100


. In one specific embodiment, this thickness is about 0.3 mm, so it can be seen that the tissue retractors do not significantly reduce the space available in the working channel


25


for insertion of other tools and instruments.




With the tissue retractor in place within the working channel


25


, bone within the spinal canal, such as may occur in a burst fracture, can be removed with a curette or a high speed drill. Alternatively, the fractured bone may be impacted back into the vertebral body with a bone impactor. At this point, if the spinal procedure to be performed is the removal of epidural spinal tumors, the tumors can be resected utilizing various micro-surgical instruments. In other procedures, the dura may be opened and the intradural pathology may be approached with micro-surgical instruments passing through the working channel cannula


20


. In accordance with the specific illustrated technique, with the nerve root retracted posterior medial disc herniations can be readily excised directly at the site of the herniation.




In another embodiment of the invention, a working channel cannula, such as cannula


20


, is provided with a fixture


170


for supporting optics and irrigation/aspiration components. In accordance with this embodiment, the fixture


170


includes a scope body


171


which is shown most clearly in

FIGS. 13

,


14


,


16


and


17


. The scope body


171


includes a clamping ring


172


configured to encircle the outer surface


23


of the cannula


20


. In particular, the clamping ring


172


includes an inner clamping surface


175


(see FIG.


14


). That clamping surface


175


has substantially the same configuration and dimension as the outer surface


23


of the cannula


20


. The clamping ring


172


includes clamp arms


173




a, b


at the free ends of the ring. The clamp arms


173




a, b


define a slot


174


(see

FIG. 17

) therebetween.




The clamping ring


172


is integral with a support column


176


forming part of the scope body


171


. A column slot


177


is formed in the support column


176


, with the column slot


177


being contiguous with the slot


174


between the clamp arms


173




a


, b. As described in more detail herein, the slots


174


and


177


permit the clamp arms


173




a


, b to be compressed toward each other to thereby compress the clamping surface


175


of the ring


172


about the outer surface


23


of the cannula


20


. In this manner, the fixture


170


can be affixed at a specific position on the cannula


20


. It is understood that when the clamping ring


172


is loosened, the fixture


170


is free to rotate about the circumference of the cannula


20


in the direction of the arrow N. In addition, the fixture


170


can translate along the longitudinal length of the cannula


20


in the direction of the arrow T. Of course, the direction of the travel distance of the fixture


170


along the length of the cannula


20


is limited by the proximal end


22


and the bracket


27


used to engage a supporting flexible arm


160


as described above.




Returning to

FIGS. 13-17

, additional details of the fixture


170


can be discerned. In particular, the fixture


170


includes an optics mounting body


178


that is supported by and preferably integral with the support column


176


. The optics mounting body


178


defines a stop edge


179


at the interface between the support column


176


and the mounting body


178


. This stop edge defines the height of the support column from the clamping ring


172


to the stop edge


179


. The stop edge


179


of the optics mounting body


178


can be used to limit the downward travel of the fixture


171


in the direction of the arrow T, which can be particularly important in embodiments of the cannula


20


that do not include the bracket


27


,.




In accordance with the present embodiment, the optics mounting body


178


defines an optics bore


180


which is configured to receive and support an optics cannula


190


. The optics bore


180


can communicate with an illumination port


181


which can receive an illumination source, such as a fiber optic light cable. The optics bore


180


also communicates with an optics coupling bore


182


projecting from a front face of the fixture


170


. In accordance with one specific embodiment, the fixture


170


also includes a coupling body


183


that is preferably press-fit within the optics coupling bore


182


. As shown in

FIG. 15

, the coupling body


183


can be engaged by a coupler


184


to support a camera


185


thereon.




In a further aspect of the optics mounting body


178


, an aspiration port


186


and an irrigation port


187


can be provided that communicates with the optics bore


180


. Preferably, the optics cannula


190


includes channels along its length to correspond to the various ports in the optics mounting body


178


. In one specific embodiment, the port


181


is not used, with the port


186


being used to receive an illumination element. As shown more particularly in

FIG. 23

, the port


187


can be connected to an aspiration circuit. In particular, the port


187


can be engaged to an aspiration tube


225


which carries a flow control valve


226


and Luer® fitting


227


at its free end. The Luer® fitting


227


can engage a source of irrigation fluid or aspiration vacuum pressure depending upon the particular use envisioned for the port


187


and a corresponding channel within the optics cannula


190


.




In accordance with a method of the present invention, the port


187


is used as an aspiration port with the Luer® fitting


227


connected to a vacuum source. It is understood that the port


187


is in fluid communication with a corresponding channel in the optics cannula


190


so that suction applied through the tube


225


and port


187


is drawn through the distal or working end


192


of the optics cannula


190


. The working end


192


is at the surgical site so that the suction draws air through the working channel


25


of the cannula


20


, to the surgical site and through the aspiration/irrigation channel in the optics cannula


190


. It has been found that providing aspiration suction in this manner eliminates smoke that may be developed during operation of certain instruments, such as a Bovie. Moreover, the suction applied through the port


187


can draw air across the lens


191


(see

FIG. 14

,


15


) of the optics cannula


190


, to prevent fogging of the lens. If a separate aspiration tube is extended through the working channel, defogging of the lens


191


is best achieved with the opening of the aspiration tube adjacent the lens. In this manner, the provision of aspiration vacuum through the working channel and working space virtually eliminates the need to retract the optics cannula


190


to clean the lens


191


. This is in contrast to prior devices in which either the lens had to be removed from the surgical site for cleaning or devices in which substantial flow of fluid is required to keep the lens clean and clear.




Looking now to

FIGS. 18-22

, details of a barrel clamp mechanism


195


are shown. The barrel clamp mechanism


195


compresses the arms


173




a, b


of the clamping ring


172


together to clamp the fixture


170


to the cannula


20


. The barrel clamp mechanism


195


includes a barrel cam


196


disposed immediately adjacent one of the clamp arms


173




b


, and a lever arm


197


that operates to compress the barrel cam


196


against the clamp arm


173


. A shoulder screw


198


fixes each of these components together. Specifically, the shoulder screw


198


includes a threaded shank


199


that is configured to engage a mating threaded bore


202


in one of the clamp arms


173




a.


The shoulder screw


198


includes a bearing shank


200


that is smooth or non-threaded. The bearing shank


200


is received within a bearing bore


203


in the clamp arm


173




b


, a colinear bearing bore


204


in the barrel cam


196


, and a bearing bore


205


in the lever arm


197


. The shoulder screw


198


further includes an enlarged head


201


which is preferably received within a head recess


206


in the lever arm


197


(see FIG.


19


). Preferably, the enlarged head


201


of the shoulder screw includes a driving tool recess to mate with a driving tool to thread the threaded shank


199


of the screw into the mating threaded bore


202


of the clamp arm


173




a


. It is understood that the barrel cam


196


and lever arm


197


are free to rotate about the bearing shank


200


of the shoulder screw


198


.




Referring specifically to

FIGS. 18-19

, the lever arm


197


includes an arm


210


that is integral with a body


211


. The bearing bore


205


and head recess


206


are defined in the body


211


. The body


211


defines a pair of projections


212


on opposite sides of the bearing bore


205


. As depicted in

FIG. 19

, each of the projections


212


includes a rounded tip


213


to provide a smooth sliding surface.




Referring specifically to

FIGS. 20-21

, the barrel cam


196


includes a flat face


215


that faces the clamp arm


173




b


. Preferably, the flat face provides for smooth rotation of the barrel cam


196


relative to the stationary arm


173




b


. The opposite face of the barrel cam


196


is a cam face


216


that includes a pair of diametrically opposite cam portions


217


. In accordance with the preferred embodiment, the cam portions


217


define a ramp


218


that is inclined upward to a detent recess


219


. Each detent recess


219


terminates in a stop


220


that is higher relative to the base detent recess


219


than the ramp


218


.




In the assembled configuration, the barrel clamp mechanism


195


operates to compress the arms


173




a, b


of the clamping ring


172


together when the lever arm


197


is rotated about the shoulder screw


198


. Specifically, as the lever arm


197


is rotated, the projections


212


slide on their rounded tip


213


along the ramps


218


until the rounded tips


213


fall within the opposite detents


219


. As the projections


212


move up the ramps


218


, the projections


212


push the barrel cam


196


toward the clamp arms


173




a, b


. More specifically, since the opposite clamp arm


173




a


is held relatively fixed by the threaded shank


199


of the shoulder screw


198


, the movement of the barrel cam


196


presses the clamp arm


173




b


against the relatively stationary clamp arm


173




a


. As this occurs, the clamping ring


172


is tightened around the outer surface


23


of the cannula


20


. When the projections


212


are seated within the recesses


219


of the barrel cam


196


, the fixture is locked onto the cannula


20


. It is understood that the recesses


219


are shallow enough to permit ready manual disengagement of the projections


212


from the recesses


219


as the lever arm


197


is rotated in the opposite direction.




In one specific embodiment, the detent recesses


219


are 180° opposite each other. The ramps


218


are curved and subtend an angle of about 90°. Thus, the lever arm


197


rotates through 90° to move the projections


212


from one end of the cam ramps


218


to the recesses


219


. In the preferred embodiment, the lever arm ninety degree movement (arrow J in

FIG. 15

) moves the arm from a first position in which the arm


197


is substantially parallel to the cannula, to a second position in which the arm is substantially perpendicular to the cannula. Most preferably, in the second position the arm is oriented immediately adjacent the cannula, rather than projecting away. In the first and second positions, the lever arm


197


maintains a low profile so as not to interfere with the surgeon's manipulation of tools and instruments through the working channel. In a specific embodiment, the first position of the lever arm corresponds to the loose or unlocked position of the barrel clamp mechanism


195


, while the second position corresponds to the locked configuration.




In order for the barrel clamp mechanism


195


to function properly, it is preferred that the barrel cam


196


remain stationary relative to the moveable lever arm


197


, with the exception that the barrel cam


196


is free to translate along the length of the shoulder screw


198


. Consequently, the clamp arm


173




b


includes a recess


222


that has a configuration substantially similar to the outer periphery of the barrel cam


196


. In this manner, the barrel cam can be slightly indented within the clamp arm


173




b


so that the cam is unable to rotate about the shoulder screw


198


as the lever arm


197


is pivoted.




In accordance with one specific embodiment of the invention, the components of the fixture


170


are formed of a flexible and resilient material. For example, the scope body


171


can be formed of a plastic, such as polycarbonate. The scope body


171


lends itself particularly well to typical plastic molding techniques. Likewise, the barrel cam


196


and lever arm


197


can be molded from a plastic material. In one specific embodiment, these components are formed of Delrin®, since Delrin® provides a smooth surface for the relative movement between the projections


212


on the lever arm


197


and the cam face


216


of the barrel cam


196


.




It is understood that the travel of the barrel clamp mechanism


195


can be calibrated sufficient to tightly compress the clamping rings


172


about the cannula


20


. It is also understood that this compression must not be so great as to compromise the integrity or strength of the cannula


20


. In one specific embodiment, the slot


174


is larger than the maximum travel of the barrel clamp mechanism


195


so that the projections


212


of the lever arm


197


can rest solidly within the detent recesses


219


of the barrel cam


196


. In accordance with one specific embodiment, the slot


174


has a dimension of 2.0 mm while the throw of the barrel clamp mechanism


195


achieved by the barrel cam


196


is 1.0 mm.




In accordance with the present embodiment of the invention, the fixture


170


supports an optics cannula


190


in a fixed orientation relative to the scope body


171


. In other words in this specific embodiment, the optics cannula


190


is not permitted to rotate about its axis as could the scope


50


of the embodiment shown in FIG.


1


. The lens


191


is therefore mounted at an angle B relative to the distal end of the optics cannula


190


. In one specific embodiment, the lens


191


is situated at an angle B of 30°. In addition, in the specific embodiment, the lens has an optical axis that is angled toward the center of the working space


25


or the cannula


20


. While the lens


191


has a fixed orientation relative to the scope body


171


, the lens can still be rotated around the working space by rotation of the fixture


170


about the outer surface


23


of the cannula


20


. In addition, the lens


191


and the optical system provide a depth of field of view that allows the surgeon to view anatomy outside the working channel


25


.




Even in the present specific embodiments, the fixture


170


allows rotation of the optics cannula


190


around the working space and translation of the optics cannula


190


and


191


along the longitudinal axis of the working channel


25


. Of course, it is understood that the surgeon can achieve these motions by releasing the barrel clamp mechanism


195


and then re-engaging the clamp by rotating the lever arm


197


to its locked position. Preferably, the optics cannula


190


is sized so that the lens


191


can project beyond the distal end


21


of the cannula


20


. Similarly, in the preferred embodiment, the fixture


170


allows the retraction of the lens


191


and optics cannula


190


within the working channel


25


and cannula


20


.




In one specific embodiment, the fixture


170


permits up to 15 mm travel along the direction of the arrow T with 7.5 mm of the travel being within the working space


25


and 7.5 mm of the travel being beyond the distal end


21


of the cannula


20


. In accordance with the specific embodiment, this 15 mm travel distance is related to the height of the support column


176


from the top of the clamping ring


172


to the stop edge


179


of the optics mounting body


178


. The amount of extension of the lens


191


of the optics cannula


190


beyond the distal end


21


of the cannula


20


is also based upon the overall length of the optics cannula


190


relative to the overall length of the working channel cannula


20


. In one specific embodiment, the optics cannula


190


has a length of 100 mm measured from the lens


191


to the stop edge


179


of the optics mounting bore


178


. Of course, it is understood that the optics cannula is longer than this 100 mm distance because a portion of the cannula is supported within the optics bore


180


of the optics mounting body


178


. Again in the specific embodiment, the cannula


20


has an overall length of 92 mm from its distal end


21


to its proximal end


22


(see FIG.


15


).




In a further aspect of the invention, the overall length of the cannula, and consequently the optics cannula


190


, is determined, in part, by the spinal anatomy. In particular, for applications of the present invention in the field of spinal surgery, it has been found that placement of the proximal end


22


of the working channel


25


too distant from the surgical site at the distal end


21


, causes the surgeon to lose tactile feel while manipulating certain instruments. In other words, when the surgeon passes instruments through the working channel and manipulates them at the surgical site, a certain amount of “feel” is required so that the surgeon can accurately perform the respective operations with the instrument. If the distance between the surgical site and the manual end of the instrument is too great, the surgeon will not be able to stably and comfortably operate the instrument.




In accordance one beneficial aspect of the present invention, it has been found that the working channel cannula


20


must have a length that is limited relative to the distance L (

FIG. 24

) between the vertebral laminae and the surface of the skin. In the lumbar region of the spine, this distance is approximately 65-75 mm. Consequently, in one embodiment of the invention, the working channel cannula


20


has first portion of its length somewhat less than the anatomic distance. In one specific embodiment, this length of the first portion is about 66 mm from the distal end


21


to the mounting bracket


27


. In some surgical applications, the mounting bracket


27


may actually rest against the skin of the patient so that the distal end


21


of the working channel cannula can be closer to the surgical site.




Further in accordance with the present invention, the remaining second portion of the length of the cannula


20


above the mounting bracket


27


is minimized. In accordance with the invention, this distance must be sufficient to permit extension and retraction of the lens


191


relative to the distal end


21


of the cannula


20


. As described above, the travel of the optical lens


191


is preferably 15 mm, so that the remaining length of the cannula


20


is about 26 mm to accommodate this travel and to provide adequate surface for engagement by the clamping ring


172


. Thus, in the preferred embodiment, the working channel cannula


20


has an overall length of 92 mm. In accordance with one aspect of the invention, it has been found that the relative length between the first portion of the cannula disposed within the patient to the second portion of the cannula length situated outside the patient have a ratio of 2:1 to 3:1. In other words, the length of the first portion is between two to three times longer than the length of the second portion.




It has also been found that it is desirable to minimize the height of the fixture


170


beyond the end of the working channel cannula


20


. In accordance with the present invention, the optics mounting body


178


has a height of about 21 mm between the stop edge


179


and the top face of the body


178


. This distance is not so great that the surgeon is restrained from manipulating instruments directly above the fixture


170


. Of course, it is preferable that the surgeon manipulate the instruments directly above the proximal end


22


of the working channel


20


immediately adjacent to the fixture


170


.




In the present preferred embodiment, the working channel cannula has an inner diameter of about 15 mm and an outer diameter of about 16 mm. Alternatively, the cannula can be provided in a smaller size for other regions of the spine. In a further specific embodiment, the cannula inner diameter is 12.7 mm with a 14 mm outer diameter. In another aspect of the invention, the overall length and diameter of the working channel cannula


20


is calibrated again relative to the distance L of the spinal anatomy. With the larger diameter working channel, the surgeon can orient certain instruments at an angle relative to the longitudinal axis of the cannula


20


. In specific embodiments, this angle is approximately 5-6°. It has been found that this angle, together with the large working channel


25


, gives the surgeon greater flexibility and mobility within the surgical site to perform various operations. To that end, the length and diameter of the working channel cannula


20


is appropriately sized to maintain this flexibility, without getting too large. A working channel cannula


20


that has too large a diameter is less adaptable to the spinal anatomy.




In accordance with preferred methods using the device


10


of the present invention, the working space is generally limited to the region directly adjacent the laminae of a vertebra. A cannula having a diameter that is too large will interfere with the spinous process when the working space is created, and will require resection of greater amounts of tissue than is preferred for an optimal percutaneous procedure. Therefore, in accordance with one aspect of the invention, the working channel cannula has a relationship between its length and its diameter to permit tool angles through the cannula of between 5-8°. In accordance with one specific aspect of the present invention, the cannula can have a length to diameter ratio of between about 5.5:1 to 7:1. Further in accordance with the present invention, the working channel cannula has a length that is no more than 20-30 mm greater than the distance L (

FIG. 24

) between the laminae and the skin of the patient.




One important feature of the present invention is achieved by the large diameter of the working channel


25


in the cannula


20


. This large diameter allows the surgeon or surgeons conducting the surgical procedure to introduce a plurality of instruments or tools into the working space. For example, as described above, a tissue retractor and discectomy instruments can be simultaneously extended through the working channel. In that illustrated embodiment, the discectomy instruments could include a trephine for boring a hole through the disc annulus and a powered tissue cutter for excising the herniated disc nucleus. Likewise, the present invention contemplates the simultaneous introduction of other types of instruments or tools as may be dictated by the particular surgical procedure to be performed. For example, an appropriately sized curette and a rongeur may be simultaneously extended through the working channel into the working space. Since all operations being conducted in the working space are under direct visualization through the viewing element


50


, the surgeon can readily manipulate each of the instruments to perform tissue removal and bone cutting operations, without having to remove one tool and insert the other. In addition, since the surgical procedures can be conducted without the necessity of irrigation fluid, the surgeon has a clear view through the working space of the target tissue. Furthermore, aspects of the invention which permit a wide range of motion to the viewing element


50


allow the surgeon to clearly visualize the target tissue and clearly observe the surgical procedures being conducted in the working space.




The surgeon can capitalize on the same advantages in conducting a wide range of procedures at a wide range of locations in the human body. For example, facetectomies could be conducted through the working channel by simply orienting the working channel cannula


20


over the particular facet joints. The insertion of vertebral fixation elements can also be accomplished through the device


10


. In this type of procedure, an incision can be made in the skin posterior to the location of the vertebra at which the fixation element is to be implanted. Implementing the steps shown in

FIG. 10

, the cannula


20


can be positioned through the incision and tissue directly above the particular location on the vertebra to be instrumented. With the optics extending through the working channel, an insertion tool holding the vertebral fixation element can be projected through the cannula


20


and manipulated at the vertebra. In one specific embodiment, the fixation element can be a bone screw. The working channel


25


has a diameter that is large enough to accept most bone screws and their associated insertion tools. In many instances, the location of the bone screw within the vertebra is critical, so identification of the position of the cannula


20


over the bony site is necessary. As mentioned above, this position can be verified fluoroscopically or using stereotactic technology.




In many prior procedures, cannulated bone screws are driven into the vertebra along K-wires. The present invention eliminates the need for the K-wire and for a cannulated screw. The working channel itself can effectively operate as a positioning guide, once the cannula


20


is properly oriented with respect to the vertebra. Moreover, the device


10


allows insertion of the bone screw into the vertebra to be conducted under direct vision. The surgeon can then readily verify that the screw is passing into the vertebra properly. This can be particularly important for bone screws being threaded into the pedicle of a vertebra. The working channel cannula


20


can be used to directly insert a self-tapping bone screw into the pedicle, or can accept a variety of tools to prepare a threaded bore within the pedicle to receive a bone screw.




The device


10


can also be used to prepare a site for fusion of two adjacent vertebrae, and for implantation of a fusion device or material. For example, in one surgical technique, an incision can be made in the skin posterior to a particular disc space to be fused. The incision can be made anteriorly, posteriorly or posterior laterally. If the incision is made anteriorly for anterior insertion of the working channel, it is anticipated that care will be taken to retract tissues, muscle and organs that may follow the path of the incision to the disc space. However, the device


10


of the present invention allows this tissue retraction to occur under direct vision so that the surgeon can easily and accurately guide the cannula


20


to the disc space without fear of injury to the surrounding tissue. As the tissue beneath the skin is successively excised or retracted, the working channel cannula


20


can be progressively advanced toward the anticipated working space adjacent the vertebral disc. Again under direct vision, the disc space can be prepared for implantation of fusion materials or a fusion device. Typically, this preparation includes preparing an opening in the disc annulus, and excising all or part of the disc nucleus through this opening.




In subsequent steps, a bore is cut through the disc annulus and into the endplates of the adjacent vertebrae. A fusion device, such as a bone dowel, a push-in implant or a threaded implant can then be advanced through the working channel of device


10


and into the prepared bore at the subject disc space. In some instances, the preparatory steps involve preparing the vertebral endplates by reducing the endplates to bleeding bone. In this instance, some aspiration and irrigation may be beneficial. All of these procedures can be conducted by tools and instruments extending through the working channel cannula


20


and under direct vision from the viewing element


50


.




In some instances, graft material is simply placed within the prepared bore. This graft material can also be passed through the working channel cannula


20


into the disc space location. In other procedures, graft material or bone chips are positioned across posterior aspects of the spine. Again, this procedure can be conducted through the working channel cannula particularly given the capability of the cannula to be moved to different angles from a single incision site in the skin.




The present invention provides instruments and techniques for conducting a variety of surgical procedures. In the illustrated embodiments, these procedures are conducted on the spine. However, the same devices and techniques can be used at other places in the body. For example, an appropriately sized working channel device


10


can be used to remove lesions in the brain. The present invention has particular value for percutaneous procedures where minimal invasion into the patient is desirable and where accurate manipulation of tools and instruments at the surgical site is required. While the preferred embodiments illustrated above concern spinal procedures, the present invention and techniques can be used throughout the body, such as in the cranial cavity, the pituitary regions, the gastro-intestinal tract, etc. The. ability to reposition the viewing optics as required to visualize the surgical site allows for much greater accuracy and control of the surgical procedure. The present invention allows the use of but a single entry into the patient which greatly reduces the risk associated with open surgery or multiple invasions through the patient's skin.




In accordance with yet another aspect of the present invention, a tissue retractor apparatus


230


is provided that combines a tissue retractor


231


with an optical viewing device


232


. Referring to

FIGS. 25-26

, the retractor apparatus


230


includes a retractor plate


234


that is affixed to a grip


235


for manual support of manipulation of the retractor. The grip


235


is at the proximal end


236


of the plate. The distal end


237


of the retractor plate preferably has a blunt tip


238


to avoid trauma to tissue upon insertion and manipulation of the tissue retractor. Preferably, the blunt tip


238


is angled slightly away from the plate


234


. The retractor plate


234


defines an outer retraction surface


239


that can be configured according to the type of surgery being performed. In a preferred embodiment, the plate


234


is semi-cylindrical in configuration to permit atraumatic retraction of tissue adjacent a surgical site. In addition, the retractor plate


234


defines a channel


240


that helps define a working channel. As thus far described, the retractor


231


is substantially similar to the retractor


70


depicted in

FIGS. 4-6

and as described above.




In accordance with this embodiment of the invention, an optical viewing device


232


is supported within the retractor


231


by way of a number of C-clips


245


. Preferably, the C-clips


245


are formed of a resilient material, such as plastic or thin flexible metal, and are affixed to the channel


240


of the retractor plate


234


. In accordance with one specific embodiment, two such C-clips


245


are provided to stably mount the optical viewing device


232


relative to the retractor


231


. Preferably, the clips


245


are sized to support an optical viewing device


232


that is configured substantially identical to the viewing device


50


described above. In the preferred embodiment, the viewing device


232


has a distal tip


52


with an angled lens


54


. In accordance with this embodiment, the C-clips


245


provide a resilient friction fit to the optical viewing device


232


while still permitting relative sliding and rotation of the viewing device


232


relative to the retractor


231


.




In accordance with the present invention, the tissue retractor apparatus


230


can be used in a variety of applications, including non-spinal applications. For example, this tissue retractor can have application in transnasal and transphenoidal surgeries, and in pituitary procedures. In surgeries of this type, it is not necessarily desirable to provide a closed cannula, such as the working channel cannula


20


. Moreover, the smaller working space does not lend itself to the use of a closed cannula which would tend to restrict the space available for manipulation of surgical instruments. Consequently, a tissue retractor or speculum of the type shown in

FIGS. 25-26

may be very adequate for surgeries of this type. In this instance, then the working channel is defined in part by the patient's body itself, and in part by the tissue retractor. The optical viewing device


232


is supported relative to the retractor to permit the same degrees of motion as are available with the device


10


described above.




While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.



Claims
  • 1. A method for performing a spinal surgical procedure in a patient's body, comprising:inserting a cannula into a patient through skin and tissue to create a working channel to the spine; creating a working space in communication with the working channel and adjacent the spine; providing a viewing element having a lens at its distal end and a body with a ring sized to substantially encircle the cannula; inserting the viewing element through the working channel to position the lens at the working space; mounting the viewing element to the cannula by clamping the ring about the cannula; providing an aspiration channel with an opening adjacent the working space; and aspirating through the aspiration channel to draw air through the working channel and the working space.
  • 2. The method according to claim 1, further including orienting the opening of the aspiration channel such that air is drawn past the lens of the viewing element during aspiration.
  • 3. The method according to claim 2, wherein providing an aspiration channel further comprises alternately irrigating through the aspiration channel to clean the lens of the viewing element.
  • 4. The method according to claim 1, further comprising providing the cannula with a distal end opening, a proximal end opening, and a working channel extending therebetween, wherein aspirating through the aspiration channel includes aspirating through the proximal end opening into the working channel of the cannula.
  • 5. A method for performing a spinal surgical procedure in a patient's body, comprising:inserting a cannula into a patient through skin and tissue to create a working channel to the spine; creating a working space in communication with the working channel and adjacent the spine; providing a viewing element having a lens at its distal end and a body with a ring sized to substantially encircle the cannula; inserting the viewing element through the working channel to position the lens at the working space; mounting the viewing element to the cannula by clamping the ring about the cannula; providing an aspiration/irrigation channel with an opening adjacent the working space; and alternately aspirating and irrigating through the aspiration irrigation channel to keep the lens clear while it is adjacent the working space.
  • 6. The method according to claim 5, further comprising providing the cannula with a distal end opening, a proximal end opening, and a working channel extending therebetween, wherein alternately aspirating and irrigating includes aspirating through the proximal end opening of the cannula.
  • 7. A method for performing a spinal surgical procedure in a patient's body, comprising:providing a cannula having a proximal end opening, a distal end opening, and a working channel extending therebetween; inserting the cannula into a patient through skin and tissue so the distal end of the cannula is adjacent the spine; providing a body having a ring sized to substantially encircle the cannula, the body including an optics cannula having a lens at a distal end thereof and an aspiration port extending therethrough in communication with an aspiration channel having an opening adjacent the lens; mounting the body by clamping the ring about the cannula with the optics cannula in the working channel and extending towards the distal end of the cannula to view the location; and aspirating through the aspiration channel to draw air through the proximal end opening of the cannula and into the opening of the aspiration channel.
  • 8. The method according to claim 7, further including orienting the opening of the aspiration channel such that air is drawn past the lens of the optics cannula during aspiration.
  • 9. The method according to claim 7, wherein aspirating through the aspiration channel further comprises alternately irrigating through the aspiration channel.
  • 10. The method according to claim 7, further comprising extending a power tool through the working channel.
  • 11. The method according to claim 7, wherein the aspiration channel is formed by a tube extending beside the optics cannula.
RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 08/736,626, filed on Oct. 24, 1996, now issued as U.S. Pat. No. 5,902,231; which is a continuation-in-part of application Ser. No. 08/620,933, filed on Mar. 22, 1996, now issued as U.S. Pat. No. 5,792,044; each entitled “Devices and Methods for Percutaneous Surgery.”

US Referenced Citations (86)
Number Name Date Kind
465161 Chase Dec 1891
2235979 Brown Mar 1941
2255657 Freedman Sep 1941
2482116 Lanahan Sep 1949
2575253 Bicek Nov 1951
2666428 Glenner Jan 1954
2756742 Barton Jul 1956
2829649 Glenner Apr 1958
2886004 Morrison May 1959
3486505 Morrison Dec 1969
3570498 Weighton Mar 1971
3626471 Florin Dec 1971
3651800 Wilbanks Mar 1972
3941127 Froning Mar 1976
3964480 Froning Jun 1976
4049000 Williams Sep 1977
4232660 Coles Nov 1980
4344419 Burgin Aug 1982
4350151 Scott Sep 1982
4461281 Carson Jul 1984
4498902 Ash et al. Feb 1985
4545374 Jacobson Oct 1985
4562832 Wilder et al. Jan 1986
4573448 Kambin Mar 1986
4586491 Carpenter May 1986
4638799 Moore Jan 1987
4655216 Tischer Apr 1987
4674501 Greenberg Jun 1987
4678459 Onik et al. Jul 1987
4700694 Shishido Oct 1987
4736738 Lipovsek et al. Apr 1988
4750475 Yoshihashi Jun 1988
4750487 Zanetti Jun 1988
4762120 Hussein Aug 1988
4875897 Lee Oct 1989
4899729 Gill et al. Feb 1990
4905082 Nishigaki et al. Feb 1990
4919113 Sakamoto et al. Apr 1990
4947896 Bartlett Aug 1990
4972827 Kishi et al. Nov 1990
5004457 Wyatt et al. Apr 1991
5020514 Heckele Jun 1991
5071410 Pazell Dec 1991
5125396 Ray Jun 1992
5158543 Lazarus Oct 1992
5167220 Brown Dec 1992
5170774 Heckele Dec 1992
5171279 Mathews Dec 1992
5195541 Obenchain Mar 1993
5201729 Hertzmann et al. Apr 1993
5225001 Manni et al. Jul 1993
5242444 MacMillan Sep 1993
5313962 Obenchain May 1994
5334150 Kaali Aug 1994
5354302 Ko Oct 1994
5357983 Mathews Oct 1994
5376076 Kaali Dec 1994
5380291 Kaali Jan 1995
5392766 Masterson et al. Feb 1995
5395317 Kambin Mar 1995
5396880 Kagan et al. Mar 1995
5437637 Lieber et al. Aug 1995
5439449 Mapes et al. Aug 1995
5439464 Shapiro Aug 1995
5441041 Sauer et al. Aug 1995
5443058 Ough Aug 1995
5445142 Hassler, Jr. Aug 1995
5448990 De Faria-Correa Sep 1995
5472426 Bonati et al. Dec 1995
5512034 Finn et al. Apr 1996
5534009 Lander Jul 1996
5549541 Muller Aug 1996
5551947 Kaali Sep 1996
5562696 Nobles et al. Oct 1996
5569205 Hart et al. Oct 1996
5588949 Taylor et al. Dec 1996
5603688 Upsher Feb 1997
5667472 Finn et al. Sep 1997
5667473 Finn et al. Sep 1997
5667478 McFarlin et al. Sep 1997
5695448 Kimura et al. Dec 1997
5728046 Mayer et al. Mar 1998
5735792 Vanden Hoek et al. Apr 1998
5772661 Michelson Jun 1998
5891013 Thompson Apr 1999
5954635 Foley et al. Sep 1999
Foreign Referenced Citations (12)
Number Date Country
1 566 116 Jan 1970 DE
2 222 979 Nov 1973 DE
3936811 A1 Sep 1990 DE
0 303 824 A2 Feb 1989 EP
0 528 562 A2 Jul 1992 EP
2 701 379 A1 Aug 1994 FR
2 714 285 Jun 1995 FR
2 234 906 Feb 1991 GB
WO9219146 Nov 1992 WO
WO 9314801 Aug 1993 WO
WO 9315647 Aug 1993 WO
WO 9522285 Aug 1995 WO
Non-Patent Literature Citations (5)
Entry
Laparoscopic Bone Dowel Surgical Technique Sofamor Danek “The Spine Specialist” 1995.
Laparoscopic Bone Dowel Instruments Sofamor Danek “The Spine Specialist” 1995.
Micro-Endo Systems . . . Creating the Future of Spinal Endoscopy Sofamor Danek “The Spine Specialist” 1994.
Spinal Endoscopy Evolution, Applications, & Foundations Hallett H. Mathews, M.D.
Med™ System Surgical Technique Video.
Continuation in Parts (1)
Number Date Country
Parent 08/620933 Mar 1996 US
Child 08/736626 US