Surgical retractor with removable scissor arms

A retractor having interchangeable or replaceable blades facilitates the expansion of a surgical site below an incision in the skin, and establishes a work-through surgical space. The retractor includes a frame connected to two collar arms, a pair of blades connected to the collar arms, a sheath for encompassing the blades and providing a circumscribed working space, and a device for rotating the collar arms, thereby displacing the blades and any tissue surrounding them.

BACKGROUND OF THE INVENTION

The present invention relates to a device used to retract tissue within the body of a patient. More specifically, the present invention relates to a retractor that facilitates enlarging a surgical cavity and providing a work-through channel to the surgical site.

Since it is advantageous to perform surgery in ways that minimize tissue trauma, the present minimally invasive approach facilitates a smaller incision, less tissue trauma, and faster patient rehabilitation, as compared to traditional incision and retraction techniques.

The various embodiments of the present invention are particularly useful for orthopedic surgery of the spine, but are envisioned to be limitlessly applicable to other surgical techniques and other parts of the body.

SUMMARY OF THE INVENTION

An aspect of the present invention provides an apparatus for conducting a less invasive surgical procedure by making a relatively small incision in a patient's skin and forming a larger surgical cavity below the incision. The surgical retractor according to this aspect of the invention includes a mount having a frame connected through two translating pivot points to two collar arms, where the two collar arms are attached together at at least one hinge, a pair of blades connected to the collar arms, and an actuator for rotating the two collar arms along the hinge axis, thereby displacing the blades. Preferably, the actuator is located close to the hinge connecting the collar arms, and is not a separate instrument. Also preferably, the actuator is at an angle relative to the frame in order to provide clearance with the patient's skin when the axis of the retractor is not perpendicular to the skin. Another aspect of the present invention provides that at least a portion of the actuator is part of the frame.

One aspect of the actuator includes a screw threadably associated with a housing that is part of the frame. In this aspect, when the screw is turned, or actuated, it moves distally and bears on both collar arms, thus pushing them downwardly and forcing the blades to open.

Another preferred aspect of the actuator further includes a ball in communication with the screw and in communication with a hinge pin linking the collar arms together. Optionally, a guide may be attached to the pin, wherein the guide provides a contact surface for the ball. Thus, when the screw is turned, it translates and bears on the ball, which itself moves and bears on the guide, which, because of its connection to the hinge pin, forces the hinge pin and hinge of the two collar arms to move distally, thereby pushing both collar arms downwardly and forcing the blades to open.

Yet another preferred aspect of the invention includes a tool, such as a screwdriver or an Allan key, that engages the actuator to move the actuator and thus cause the blades to move, either to separate or to come together.

In yet another aspect, the mount is preferably situated above the skin of the patient and has an opening therethrough allowing entry into the surgical cavity.

Another aspect of the present invention provides a mount comprising two collar arms attached at two hinge points. The mount includes an opening through its center leading to a channel, whereby a portion of the opening resides on each of the two collar arms. In a preferred embodiment, the opening is of an oval cross-section. However, this opening can be of any diameter, shape, or cross-sectional area. Additionally, the mount can be of any size or shape and the opening in the mount may or may not correspond to the shape of the tube created by the blades that are attached to the collar arms.

Another aspect of the present invention further provides blades having a shape and a length. In a preferred embodiment, the blades are curved, whereby together, they form an oval tube when in a non-expanded position. Upon rotation of the collar arms, the blades move outwardly, thereby displacing tissue and enlarging the surgical cavity. The major and minor diameters of the oval tube can be of any size. It should be noted that the blades can be of any shape and may or may not correspond to the shape of the mount. For example, the curvature of the blade may differ from that of the opening. Similarly, the blades can be of any length thereby creating surgical cavities with different depths. Additionally, the blades have tapered ends which facilitate progressive tissue penetration. This allows for improved control during insertion and less damage to the tissue.

Another aspect of the present invention further provides blades that are easily detachable from the mount. In a preferred embodiment, the blades are attached to the mount through the use of male and female connectors. These connectors facilitate easily attaching and detaching the blades from the mount. The blades may be attached by compressing them to fit within the opening, and then allowing them to spring back to original shape and engage the respective connectors. Detachment may be similarly achieved by compressing the blades to disassociate the respective connectors, thereby freeing the blades for removal and/or replacement. Other connection configurations are also envisioned.

The blades may be constructed of any sturdy material, and preferably from a radiolucent or semi-radiolucent material. In a preferred embodiment, thin, semi-radiolucent aluminum is employed. This allows for improved visualization of the surgical site when viewed on an X-ray with the retractor in place. In another embodiment, a non-autoclavable or non-sterilizable material may also be utilized.

The blades, as well as the collar, may also be constructed of a light-conducting material, such as acrylic, for example. Preferably a cable transfers light from a light source to the collar and blades, which then illuminate the working space.

It is also contemplated, in a preferred embodiment, that the blades are easily interchangeable. This allows for quick changes in length, depth, or shape of the blades depending upon a particular surgical situation. Thus, among other advantages, the desired length, depth, or shape of blades can be changed without having to utilize an entirely new device.

In another preferred embodiment, the blades can be disposable, either in addition to the interchangeable feature, or independent of that feature. In this regard, in a preferred embodiment, the blades may be removable for disposability, or the blades and the collar to which they are connected may be disposable. Preferred methods contemplate the interchangeability, illumination and/or the disposability features in various forms.

Another aspect of the present invention further provides a sheath that covers the blades. The sheath expands when the blades are extended outwardly thereby creating an enlarged surgical cavity that is enclosed by the retractor and sheath. The sheath also contracts along with the inward retraction of the blades. In a preferred embodiment, the sheath is constructed of pliable elastic material, such as silicone rubber, thereby allowing for both its expansion and contraction. It is envisioned that the sheath can be made of any material and can be any length, thickness, or shape, as well as transparency or opaqueness. In a preferred embodiment, the sheath fits snuggly over the blades in both the retracted and expanded positions. The sheath material can be such that it facilitates easy assembly onto, and removal from, the blades. The sheath may also be disposable, and a preferred method contemplates such disposability. Additionally, the sheath may cover any portion of the blades up to and including their entire surface area.

Another aspect of the present invention provides a bar for use with the retractor. The bar can be easily attached to a rigid, relatively fixed object on a first end and to the retractor on a second end. The bar is used to hold the retractor in position relative to the patient. Multiple bars may also be interconnected, thus forming a support assembly, to allow for discreet positioning of two or more retractors relative to each other. One example of a support assembly is the AF400 SpineTract System manufactured by Omni-Tract Surgical, a division of Minnesota Scientific. However, any type of bar or assembly can be used.

Another aspect of the present invention provides an apparatus for dilating an opening created by a small incision in the skin of a patient. The apparatus according to this aspect of the invention includes a guide and a variable number of dilators, whereby the first dilator fit over the guide and subsequent dilators of increasing size are sequentially fit over one another. In a preferred embodiment, the dilators are oval tubes having major and minor inside and outside diameters. Increasingly sized dilators are configured such that each larger dilator can fit over a smaller dilator. In a preferred method, the guide is inserted in an incision in the skin of the patient. Then a first dilator is moved down the guide thereby increasing the size of the surgical cavity. The first dilator has outside major and minor diameters which are slightly smaller than the inside major and minor diameters of the second dilator. The second dilator is then slid over the first dilator, thereby once again increasing the size of the surgical cavity. These steps are repeated until the desired surgical cavity size is achieved with a corresponding sized dilator, at which point the retractor, in its closed form, may be inserted into the surgical cavity over the largest dilator, the dilators removed therefrom, and the retractor expanded to further enlarge the surgical cavity below the incision.

Yet another aspect of the present invention further provides a surgical retractor having a mount and blades as described previously. With the mount in an unexpanded state, the blades form a tube having an opening extending through the mount. This tube has an inside cross-sectional shape larger than that of the largest dilator. This allows for the retractor to be placed over the largest dilator and into the enlarged surgical cavity. In a preferred embodiment, the opening in the mount, the tube formed by the blades of the retractor, and the dilators are all of an oval cross-sectional configuration. However, it is recognized that other shapes and sizes are possible.

Another aspect of the present invention provides for a method of creating a larger surgical cavity through a smaller incision in the skin of a patient. A preferred method includes making an incision in the skin of a patient, securing the guide to a portion of the patient, moving a first smaller sized dilator over the guide to expand tissue, adding further increasingly sized dilators over one another and progressively dilating the incision until the desired surgical cavity size is achieved with a correspondingly sized dilator, sliding the retractor over the largest inserted dilator, removing all of the dilators through the retractor, and by using the actuator, rotating the two collar arms of the mount along the hinge axis thereby displacing the blades laterally and moving the patient's tissue to enlarge a surgical cavity. Alternatively, the guide, and all but the largest dilator, may first be removed from the cavity prior to insertion of the retractor. The amount of rotation of the collar arms of the mount along the hinge axis determines the enlargement of the surgical cavity.

Another aspect of the present invention further provides for a method wherein the blades of the retractor are first covered with a sheath before they are introduced into the body of the patient. The sheath, as discussed previously, allows the retractor to form a surgical cavity enclosed by the apparatus. This, in turn, allows for better use of the surgical cavity as surrounding tissue can be prevented from entering the cavity. It is also noted that the sheath may be transparent thus allowing visualization of the expanded cavity outside of the sheath.

Another aspect of the present invention further provides for a method wherein, prior to displacing the blades of the retractor, a rod is connected to a rigid, relatively fixed object on the rod's first end, and to the retractor on the rod's second end. This step allows for enhanced control of the retractor before and after it is inserted into the body of the patient.

Another aspect of the present invention further provides that the retractor be inserted into the body of a patient so that the blades of the retractor displace in the same direction in which the muscles run in the area of the incision. This step facilitates minimizing the amount of damage to the muscle tissue upon the expansion of the blades of the retractor.

Yet another aspect of the present invention further provides for a method for creating a surgical cavity in a body wherein, various elements of the present retractor or the entire retractor, are disposable. In a preferred embodiment, additional steps of removing the retractor and disposing of the entire apparatus are performed. In another embodiment, additional steps of removing the retractor and disposing of a portion of it, for example, the blades are performed. In yet another embodiment, additional steps of sterilizing a portion of the retractor and attaching a non-autoclavable, or otherwise non-sterilizable portion, to the sterilized portion are performed. Subsequent to use of the retractor, the non-autoclavable, or otherwise non-sterilizable portion can be disposed.

Another aspect of the present invention provides for a kit including the various elements of the present invention. The kit comprises differently sized and shaped mounts, blades, and sheaths. The different elements may be interchanged to conform to the given surgical situation. In another embodiment, a method is contemplated wherein elements of desired shape and size are selected and connected to one another to provide a retractor best suited to create the proper surgical cavity.

DETAILED DESCRIPTION

FIG. 1depicts one embodiment of the mount10with a first collar arm11and a second collar arm12rotatable around hinge axis13. Collar arms11and12are rotatably connected to each other at forward hinge point14and rearward hinge point15, and connected to frame19at first hinge49and second hinge50. Specifically, first collar arm11is connected to frame19at first hinge49by a first hinge pin52that extends through a first slot56in frame19. Similarly, second collar arm12is connected to frame19at second hinge50by a second hinge pin54that extends through a second slot57in frame19. Hinge points14and15, as well as hinges49and50, allow for the rotational movement of collar arms11and12. Additionally, slots56and58on frame19accommodate hinges49and50, respectively, and allow for the horizontal translation of hinges49and50with respect to frame19. Actuator17is oriented on frame19such that its rotational actuation causes it to translate distally (identified as DT inFIG. 7). Thus, as actuator17translates distally, it acts upon collar arms11and12causing the rotation of collar arms11and12around hinge axis13, and causing hinge axis13, itself, to translate distally. Rotation around hinge axis13is facilitated and accompanied by rotation of collar arms11and12around hinges49and50, respectively, as well as translation of hinges49and50toward the center of frame19along slots56and58, respectfully. All this motion, in turn, causes the expansion of the apparatus. Other actuating mechanisms for expanding and contracting the retractor1are also envisioned.

Mount channel18is oval in shape and located centrally between first and second collar arms11and12. Mount channel18facilitates movement of instruments and other materials into and out of the surgical cavity created by the present invention. Mount channel18further comprises mount connection points20,21,22, and23that allow for the connection between collar arms11and12and blades24and25(FIGS. 2,3, and4).

FIGS. 2–5show views of first blade24, which is a mirror image of second blade25(shown inFIG. 6, for example). First blade24has a proximal end26, a distal end36, an inner portion68and a peripheral portion70. Blade24also has blade connection points27and28, hole72, rearward slit64and forward slit66. Additionally, as seen inFIGS. 3 and 4, the distal end36of blade24is tapered toward its periphery70to facilitate easier insertion through tissue.

As shown in assembled form inFIGS. 13 and 14, for example, proximal end26of blade24is connected at blade connection points27and28, as well as at hole72, to corresponding connection points22and23, as well as pin76, on first collar arm11. Blade24gets connected to collar arm11by compressing proximal end26, therefore moving blade connection points27and28toward each other, so as to prepare for assembly with connection points22and23on collar arm11. Slits64and66facilitate this compression. It is recognized that compression of points27and28may be achieved by other configurations, and/or in other ways as well.

Once proximal end26is released from compression, blade24regains its original shape and firmly attaches to collar arm11through connections27to22,28to23, and72to76. The male/female relationship of these connections, as well as the friction fit, allows the blade24to remain attached to the first collar arm11upon release of the compressive force that had been applied to the proximal end of blade24.

Since first blade24is a mirror image of second blade25, it is understood that the above description equally applies to the connection of second blade25to second collar arm12. It is further recognized that many other connection configurations from the ones described above are possible. Such configurations may permit for interchangeability of blades24and25, or just the removability of the blades for sterilization or disposability. Interchangeability allows a surgeon to readily change blades24and25depending upon, for example, the desired surgical cavity depth and/or cross-sectional area. Thus a surgeon may be provided with a kit of variably sized and shaped blades from which desired blades may be selected for a particular surgery or technique. Additionally, disposability of the blades allows for easier post-use handling techniques.

FIG. 5shows a top view of first blade24where the blade's curvature is readily apparent. When placed together, blades24and25form a tube that is open at both the proximal and distal ends, with an oval channel therebetween. As shown inFIG. 6, this is the case when actuator17has not been translated distally and collar arms11and12have, therefore, not been rotated around hinge axis13.

Actuator17comprises a screw60that is threadably assembled in housing62, which is part of frame19. As best seen inFIG. 7, in opening the retractor1, upon distal translation DT of screw60through housing62, collar arms11and12rotate around hinge axis13as hinge axis13is moved distally. In conjunction with this motion, first collar arm11rotates in direction r1around first hinge49as hinge49translates in direction t1in slot56(FIG. 1), and second collar arm12rotates in direction r2around second hinge50as hinge50translates in direction t2in slot58(FIG. 1). In this manner, blades24and25are displaced in respective retraction directions R1and R2, and retractor1is opened. The displacement of blades24and25spreads apart tissue within the original incision and creates a larger surgical cavity, allowing for a larger working space for a surgeon. Additionally, as shown inFIGS. 3 and 6, for example, the distal ends36of blades24and25are tapered so as to allow easier insertion into the body of a patient.

It is recognized that the screw60may be engaged by a tool, such as screwdriver or an Allan key, to cause it to turn. Additionally, it is envisioned that multiple variations of the type of tool, interface with the screw, as well as screw types, or even the absence of a screw, are possible to accomplish moving the blades of the retractor towards and away from each other.

The material used in the construction of blades24and25is generally of a rigid type to support the spreading of the body tissue, such as aluminum, for example. In a preferred embodiment, the material is radiolucent or semi-radiolucent thereby allowing for the improved visualization of the anatomy when viewed on an X-ray with the retractor1in place. In other embodiments, the material may be non-autoclavable or otherwise non-sterilizable, and disposable. This further allows for the interchangeability of blades24and25, to suit a particular surgical cavity.

FIG. 8shows an embodiment of a sheath29of the present invention. Sheath29is preferably made of a pliable, elastic, and translucent material, such as silicone rubber, and fits snugly around blades24and25. Preferably, sheath29is assembled over blades24and25when the retractor1is in the unexpanded condition, such as inFIG. 6. Upon distal translation DT of screw60of actuator17, and displacement R1and R2of blades24and25, sheath29stretches and forms an enclosure around blades24and25, as shown inFIG. 9. This enclosure allows for a more manageable surgical cavity by preventing tissue from entering the cavity. Sheath29may also be made of a completely clear material, so that when in the expanded condition, a surgeon may see tissue and objects through sheath29when it is in the surgical cavity.

Preferably, to prevent sheath29from riding up on blades24and25during the opening of the retractor1, the sheath29is sized slightly shorter than the length of the longest vertical peripheral dimension of blades24and25, as seen inFIG. 3. In this configuration, when retractor1is opened, the distal end of sheath29stretches over and hooks onto the distal central edges of the blades24and25, thus preventing the sheath's movement up the blades.

Upon the reverse translation of screw60and the return of blades24and25to their original state, sheath29returns to its original form as well. Depending on the pliability of the material used to construct sheath29, the sheath may aid in bringing blades24and25back to their original, unexpanded condition. In any event, the tissue surrounding the blades24and25aids in compressing the blades back to their unexpanded condition. It should be noted that various materials with the above desirable properties for the sheath29may improve the cost-effectiveness of the sheath's29disposability. Additionally, the sheath29may be of any shape or size and may cover any area of the retractor1, thereby creating any portion of covered and non-covered areas of blades24and25.

FIG. 10shows dilator assembly30. This assembly is utilized prior to the introduction of retractor1into the body of the patient. Dilator assembly30includes guide31and increasingly sized dilators32,33,34, and35. Each of these dilators is a tube with an outside cross-section and an inside cross-section. The inside cross-section of each dilator is slightly larger than the outside cross-section of the next smallest dilator, while the outside cross-section of each dilator is slightly smaller than the inside cross-section of the next largest dilator. This allows for successive dilators to be placed over one another. Initially, guide31is inserted through an incision and secured within the body of a patient. Dilator32is then slid over guide31into the incision, thereby spreading the incision, and creating a surgical cavity having an area corresponding to the size of the dilator's outside cross-section. This step is repeated with successive dilators33,34, and35until the desired surgical cavity is achieved. It should be noted that any quantity of variously-sized dilators may be used to achieve this surgical cavity. Additionally, the dilators may be of any size or shape as long as they interact with one another as described above and allow the surgical cavity to be created and enlarged.

With reference toFIG. 11, subsequent to inserting all the desired dilators into the incision, retractor1is inserted over the largest dilator35in the cavity. This is done while blades24and25are together, whereby they form a passage extending distally from mount channel18. This passage is large enough to accommodate the largest dilator35within it. Additionally, the tapered distal ends36of blades24and25facilitate easier insertion through the tissue.

Once retractor1is in place over the largest dilator35, the guide31and all dilators32–35are removed from the surgical cavity. This leaves an opening corresponding to the passage extending from the proximal ends26to the distal ends36of the blades24and25. Blades24and25of retractor1may then be expanded, thus enlarging the surgical cavity. It is also contemplated that retractor1may be inserted into the body in an orientation allowing blades24and25to displace in the same direction in which the muscles run in the area of the surgical site. Orienting retractor1in this fashion helps minimize muscle tissue damage and contributes to a faster recovery time from surgery for the patient. However, retractor1may be oriented in any fashion necessary to create a larger surgical cavity, in any area of the body. The introduction of retractor1into the body of a patient allows for the preservation of a small portal at the skin's surface.

FIGS. 12–14show another preferred embodiment of a retractor2of the present invention. This retractor2features a different frame80and actuator arrangement90from frame19and actuator17of retractor1. Here, actuator90comprises a screw96threadably engaged in an actuator housing94, and a ball100within the housing94. The ball100rides on a bearing element106that resides on hinge pin102. Hinge pin102couples the first and second collar arms11and12together at rearward hinge point15, while hinge pin104couples collar arms11and12together at forward hinge point14. Both hinge pins,102and104, are on the same hinge axis13. It is understood, however, that other variations are also possible.

The housing94is part of frame80, but is oriented at an angle that is other than parallel to hinge axis13. Additionally, the exterior92of housing94is shaped to serve the same function as retractor connection segment16of retractor1, which is to facilitate coupling the retractor to a support structure that aids in maintaining the position of the retractor in place relative to the patient. The proximal interior of housing92contains a stop ring98which serves as a restriction to retraction of screw96beyond the proximal end of housing94, to prevent screw96from being inadvertently removed from housing94during the closing of retractor2.

Further, collar arms11and12also have cutouts82and84, respectfully, which aid in attaching and removing blades24and25to collar arms11and12, by providing additional manipulation space for the proximal ends26of blades24and25.

Beginning with the closed arrangement of retractor2inFIG. 13, to expand the blades24and25of the retractor2, screw96is advanced distally in housing94. As screw96is advanced, it pushes on ball100, which, in turn, pushes on bearing element106. Bearing element106is coupled to hinge pin102which is part of rearward hinge point15. Hinge pin102rotatably joins collar arms11and12, and hinge point15is capable of moving distally. Thus, as screw96is advanced, ball100pushes downwardly on bearing element106. Bearing element106then moves downwardly together with hinge pin102, which causes hinge point15to move distally and, therefore, blades24and25to expand from the closed configuration inFIG. 13to the open configuration inFIG. 14. The amount of distal movement of hinge point15is the same as the vertical component of the movement of ball100from its position inFIG. 13to its position inFIG. 14. Thus, in opening the retractor2, ball100moves from an elevated rearward position on bearing element106, as shown inFIG. 13, to a lowered forward position on bearing element106, as shown inFIG. 14.

Preferably, ball100is made of a ceramic material, and has a low-friction surface. The ceramic material is used for the resulting strength of the ball100, while the low-friction surface is to diminish the undesirable friction forces associated with the functioning of actuator90, which otherwise increase the effort required to open the retractor2. Bearing element106and screw96may be made of any suitable material, and have any suitable surface finish, to compliment and improve the functionality and compatibility of the retractor2, given the above parameters. For example, the tip of screw96that contacts ball100, may have a low-friction surface to further diminish the frictional forces involved in advancing ball100along bearing element106.

FIG. 15shows a typical configuration where one or more retractors are used in conjunction with a support assembly47. The support assembly47comprises a first bar37connected to a first retractor43through a first holder38. Optionally, there is a second bar44connected to a second retractor45through a second holder46. The first and second bars are joined together at coupling48. The support assembly47is ultimately attached to a rigid structure that facilitates maintaining the retractors43and45in relative position with respect to the patient.

An example of a support assembly of this type is the AF400 SpineTract System manufactured by Omni-Tract Surgical, a division of Minnesota Scientific. However, different support assemblies can be used, including but not limited to single support assemblies, where only one retractor is utilized.

It is further contemplated that the retractor of the present invention may be utilized on any part of the patient where a small incision but large subcutaneous operating area is desirable.

It is also contemplated that objects including but not limited to surgical instruments, surgical implants, and connection devices can be introduced into the body of a patient through the retractor of the present invention. The methods of use, as described above, may be performed with one or more retractors, with or without support assemblies, and in sequences different from those described. Additionally, the steps utilizing dilators may or may not be performed. Alternatively, various quantities, sizes, or shapes of dilators may be utilized. Finally, the present invention may be a kit encompassing the various elements disclosed above. This kit may include, but is not limited to, differently sized and shaped mounts10, blades24and25, and sheaths29. Any or all of these different elements may be interchanged to suit the desired surgical cavity. Depending upon the conditions, a surgeon may select different mounts10, blades24and25, and sheaths29for assembly and use.