Abstract:
A tissue retractor device for retracting tissue includes a base and a plurality of blades connected to and distributed around said base. Each of the blades is outwardly movable from the base and includes a respective sloped portion on an interior region of the blades. The tissue retractor includes a pusher engaged to the base. A portion of said pusher abuts the sloped portion of each of the blades. Movement of the pusher in a longitudinal direction engages a portion of the pusher against said sloped portion of each of the blades to move the blades and angularly displace the blades between a respective closed position and an open position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Divisional of U.S. patent application Ser. No. 13/657,516 filed on Oct. 22, 2012, titled “Tissue Retractor” to Alan G. Ellman, all of which is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    This present application relates to a surgical tissue retractor. 
       BACKGROUND 
       [0003]    The present invention relates to a device and method for expanding an enclosure such as tissue to expose the operative field in a patient. Entering an operative field such as in connection with specialized back surgery on or in-between vertebrae of the spine and on spinal discs involves various meticulous surgical procedures which can be challenging even for experienced surgeons who specialize in this particular surgery. Minimally invasive techniques are preferred over traditional open surgical procedures which require extensive operating time and post-operative recovery time. 
         [0004]    When employing such minimally invasive surgical techniques, one of the challenging requirements relates to safe retraction of patient tissue in the target area or operative field to provide sufficient space for implementation of these techniques. For example, nerve roots are plentiful in this operative field and extreme care must be exercised by the surgeon to avoid accidentally damaging or even severing any of these roots when retracting tissue in this operative field. An example of a tissue retractor which does not include improvements, advancements and advantages of the present invention is provided in U.S. Pat. No. 7,374,534 issued on May 20, 2008 to Dalton, which is incorporated herein by reference in its entirety. The present invention provides an improved retractor device which improves chances of avoiding undesired results and thereby greatly improves chances of achieving a successful patient outcome. Furthermore, the present invention provides greater control, precision, ease of use and may have utility in surgical procedures performed in operative fields other than those discussed herein. Other advantages and features will become apparent from the description of the invention. 
       SUMMARY 
       [0005]    In summary, an embodiment of relates to a tissue retractor device and/or to a method for performing a surgical procedure using that device on a patient by a surgeon. The device includes a base hinged to a number of blades circumferentially distributed around the base. In one embodiment, each of the blades is spring-biased so that the blades close upon themselves in the default state. Each of the blades is rotatable relative to its respective hinge when utilizing the retractor device under the control of the surgeon. In one embodiment, one of the blades is longer than all of the other blades, thereby providing an advantageously-smaller device-tip configuration by which the surgeon can better control such longer blade to maneuver around, and between, nerve roots and other critical elements lying in its path after the device has been surgically inserted into the patient. 
         [0006]    In one aspect, the device further includes a pusher mechanism which is threadably and concentrically connected within the base. Again, after the device has been surgically inserted into the patient, the pusher interacts with the blades in a manner to controllably and angularly displace each of the blades from its respective closed position about its respective hinge, responsive to the surgeon&#39;s manually-rotating the pusher in the threaded connection relative to the base. 
         [0007]    To facilitate the surgical insertion or implantation of the device, the device further includes a dilator mechanism thread-ably and concentrically connected within the pusher. The dilator, in one embodiment, includes a concentrically located shaft having a tip at the end of the shaft which protrudes beyond the end of the largest one blade. The dilator tip is suitable for penetrating or pushing into the body of the patient while each of the blades is in its respective closed position and before the surgeon operates the pusher to displace the blades. And, the tip is particularly suitable for maneuvering between adjacent vertebrae in the spine of the patient if back surgery is being performed. However, it will be understood that the present embodiment may be used in broader surgical procedures beyond spinal surgery including OB/GYN, or even non-surgical procedures where one desires to expand a particular area. 
         [0008]    In another embodiment, a method relates to first inserting a guide-wire into the spinal area of a patient to a desired depth. Then the above-described tissue retracting device including the dilator having a tip protruding beyond any other structure of that device is slid over the guide-wire. The device is inserted into the patient to a desired depth, the surgeon maneuvering the tip between target vertebrae, the maneuvering including clockwise and counter clockwise rotation of the device while the blades remain closed. Under certain circumstances, the guide-wire may be removed from the patient, either prior to, concurrently with, or subsequent to the dilator tip maneuvering. However, if the guide-wire was not previously removed, after the dilator tip is properly positioned (wherefore ends of the blades are properly positioned), the dilator and the guide-wire are both removed together from the device, leaving an inserted portion of the remainder of the device including at least a portion of its blades in the patient. The non-inserted portion includes the accessible circularly-shaped base noted above, hinged to the inserted blades, where one of the blades is longer than the other two equally-sized blades. The surgeon maneuvers the one blade beyond and around nerve roots that are in the vicinity of the target vertebrae, thereby safely clearing a pathway between and amongst those nerve roots which otherwise obstruct the surgeon&#39;s performance. The surgeon then operates the pusher mechanism by rotating its knob relative to the base and controllably displaces each of the blades from its respective closed position to cause tissue of the patient&#39;s body to be retracted. This provides space at the location of the operative field for surgical activity. Finally, the surgeon inserts a surgical tool, perhaps inserting one of several tools in sequence, into the device when the device&#39;s blades are displaced, and uses each such tool to perform the necessary surgery. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a top plan view of an exemplary embodiment of a retractor device including its dilator, configured for insertion into a patient; 
           [0010]      FIG. 2  is an end view of the configuration of  FIG. 1 ; 
           [0011]      FIG. 3  is a perspective view of the embodiment of  FIG. 1 ; 
           [0012]      FIG. 4  is a cross-sectional view of the embodiment of  FIG. 1 , sliced by vertical plane  4 - 4 ; 
           [0013]      FIG. 5  is a top plan view of the exemplary embodiment of  FIG. 1  after the dilator has been removed; 
           [0014]      FIG. 6  is an end view of the configuration of  FIG. 5 , being the same end view as that of  FIG. 2  but with the dilator removed; 
           [0015]      FIG. 7  is the same perspective view as that presented in  FIG. 3 , but with the dilator removed; 
           [0016]      FIG. 8  is a cross-sectional view of the embodiment of  FIG. 5 , sliced by vertical plane  8 - 8 ; 
           [0017]      FIG. 9  is a top plan view of the exemplary embodiment of  FIG. 5 , after the blades have been outwardly displaced or spread apart; 
           [0018]      FIG. 10  is an end view of the configuration of  FIG. 9 , being the same end view as that of  FIG. 6  but with the blades spread apart; 
           [0019]      FIG. 11  is the same perspective view as that presented in  FIG. 7 , but with the blades outwardly displaced; 
           [0020]      FIG. 12  is a cross-sectional view of the embodiment of  FIG. 9 , sliced by the vertical plane  12 - 12 ; 
           [0021]      FIG. 13  is a top plan view of the exemplary embodiment of  FIG. 9 , but after a surgical tool had been inserted into the embodiment; 
           [0022]      FIG. 14  is an end view of the configuration of  FIG. 13 , being the same end view as that of  FIG. 10  but with the surgical tool in place; 
           [0023]      FIG. 15  is the same perspective view as that presented in  FIG. 11 , but with the surgical tool in place; 
           [0024]      FIG. 16  is a cross-sectional view of the embodiment of  FIG. 13 , sliced by the vertical plane  16 - 16 ; 
           [0025]      FIG. 17  is another perspective view, similar to, but axially rotated from, that of  FIG. 7 , to more clearly show that one blade is longer than the other blades, and more clearly show the base finger-tab or handle permanently aligned with the longer blade; 
           [0026]      FIG. 18  is an exploded view of the embodiment of  FIG. 17 , but axially rotated therefrom to more clearly show certain detailed mechanical features of the embodiment; 
           [0027]      FIG. 19  is a perspective view of the pusher mechanism shown in cross section in  FIGS. 4 ,  8 ,  12  and  16 ; 
           [0028]      FIG. 20  is a side view of the pusher mechanism depicted in  FIG. 19 ; 
           [0029]      FIG. 21  is an exploded view similar to that of  FIG. 18 , but also showing the dilator depicted in cross section in  FIG. 4 ; and 
           [0030]      FIG. 22  is a perspective view of an alternative embodiment of the retractor device. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    In this description, the same reference numeral in different Figs. refers to the same entity. Otherwise, reference numerals of each Fig. start with the same number as the number of that Fig. For example,  FIG. 3  has numerals in the “30” category and  FIG. 4  has numerals in the “40” category, etc. 
         [0032]      FIG. 1  is a top plan view of tissue retractor device  10  according to one embodiment of the present invention. Retractor device  10  may be constructed from stainless steel and/or hard or elastic or plastic and/or other materials suitable for use as, or within, a surgically invasive tool for use in surgical procedures upon a human body. Alternatively, retractor  10  may be constructed from a material that is compatible with a visualization system, e.g., a fluoroscope or a magnetic resonance imaging (MRI) machine, where the tip of its longest blade (discussed below) is radio opaque to allow the user to visualize, in real time as the surgery is progressing, exactly where the end of that device blade is located in the body of the patient. 
         [0033]    Base  11  can be a circular structure and includes screw-threads formed therein (threads  180  in  FIG. 18 ) for thread-ably engaging threads  18  which are formed on the outside of pusher mechanism  14 . (Base  11  includes certain structure which is analogous to a nut having threads formed therein which can receive threads of a compatibly-mated bolt, the latter being analogous to a portion of the pusher). Of course, base  11  may be any other configuration depending on the desired result such as square or shaped to interconnect with a wrench or other suitable tool. 
         [0034]    In the present embodiment, three retractor blades  12  are spaced circumferentially around base  11 . Each blade  12  includes extended portion  12   a  and hinge portion  12   b , wherein each blade  12  is hinged by a respective hinge-pin  13  (located in hinge portion  12   b , to base  11 . One skilled in the art, however, will understand that any number of blades  12  may be employed. In one embodiment, blades  12  are spring-biased toward a closed position, as shown, by springs  19 . Each blade has its own spring  19  associated with its respective hinge pin, and discussed in further detail below. Although the use of independent coil springs are shown in the respective figures, one skilled in the art will readily understand that alternative spring means may be employed. For example, elastic membranes or materials (rubber for example) may be used in place of the springs. In one embodiment, an elastic washer (e.g., an O-ring) is circumferentially disposed, encircling areas between base  11  and hinge portion  12   b  of all three hinge portions  12 . Thus, when any of the blades is moved into an open or retracted position, the washer provides elastic force in response thereby biasing the blades  12  toward their closed position. The use of a singular O-ring may have advantages in manufacturing costs or assembly. In another alternative embodiment, the blades  12  may be molded together with base  11  with a plastic material where the blades are biased inward based on the elasticity of the plastic material used. 
         [0035]    Pusher mechanism  14  is threadably engaged to base  11  for movement in and out thereof. The Pusher mechanism  14  is manually rotatable by grasping by a user (e.g., a surgeon, aid, or device) and turning knob finger tabs  15 . In an alternative embodiment, the dilator mechanism (including knob  16 ) may be welded to pusher mechanism  15 . Operation of the entire retractor device including the pusher mechanism shall be discussed below. 
         [0036]    Dilator mechanism knurled knob  16  (hereinafter knob  16 ) is threadably engaged with pusher mechanism  15 , similar to the thread-able engagement between pusher  15  and base  11 , and is shown in  FIG. 1  in its tightened-down position (completely inserted into pusher mechanism  15 ). Pusher mechanism threads  190 , with which dilator mechanism thread-ably engages, are shown in perspective  FIG. 19 . Dilator mechanism knurled knob  16  may be welded, adhered or attached by any other means as well. Dilator mechanism tip  16   t , at the left hand side of  FIG. 1 , is open at its center (to ride over the guide-wire) and is connected to knob  16  by a hollow dilator tube  42  (See  FIG. 4  and  FIG. 21 ). The dilator tube  42  and tip  16   t  form a completely open interior to accommodate insertion of a guide-wire (not shown) therethrough. Finger tab  17  is fixedly connected to base  11  to provide a protuberance for firm grasping by the user or other individual using the device. In one embodiment, the finger tab  17  is located at a position on the base  11  in alignment with one of the three blades which is longer than the other two blades (not shown in  FIG. 1 ). By noting location of tab  17 , the user knows the location of the longer blade. The significance and functionality of this longer blade length variation is discussed below. It will be understood, however, that the blades  12  may be all the same length, varying lengths or any combination therebetween and the present description should not be construed as limiting. In another embodiment, finger tab  17  may be located at a specific radial position (164 degrees from some reference point for example) to aid in a specific surgical procedure. It will be understood that finger tab  17  may be located at any radial position suitable for its desired purpose. 
         [0037]      FIG. 2  is an end view of retractor device  10  shown in  FIG. 1 . In this Fig. three finger-tabs  15 ,  15   a  and  15   b  are shown spaced evenly around and extending from dilator knob  16 . Also shown is finger-tab  17  which is fixedly connected to base  11 . In operation, after a stab incision is made by the user and after a guide-wire is inserted into the stab incision to determine appropriate penetration depth, location or other desired use of the guide-wire, hollow tip  16   t  ( FIG. 1 ) is inserted over the guide-wire and pushed into the body of the patient. To accomplish this penetration, the user or other individual using the device may use any of the finger-tabs  15 , finger tab  17  and/or knob  16  to provide a good structure for grasping. One will understand that grasping may be done by either human or mechanical means (for example wrench or robotic device). In one embodiment, a rotary motion, clockwise and counterclockwise of the entire retractor device  10 , and other motions can thus be used to work the retractor device  10  into the patient and into its needed position to position tip  16   t  at the optimum location in the operative field. The guide-wire (not shown) protrudes from aperture  20  and can be withdrawn through aperture  20  when the optimum location is obtained, or before or after that occurrence or with the removal of the dilator itself. During this portion of the operation, blades  12  are in the closed position as shown in  FIG. 1 . The tip  16   t  may also be used to auto-position the device at the desired location. When used in spinal disc surgery, the tip  16   t  may be auto-located inside the disc at the desired location such that when the dilator assembly  14 ,  15 ,  16  is removed, the blades  12  are in the correct position to be opened at the desired location. In one embodiment, this is accomplished through positioning the tip  16   t  between vertebras. 
         [0038]      FIG. 3  is a perspective view of the embodiment of  FIG. 1 . Blade  12   L  is the longer blade noted above and, as depicted, it aligns with finger tab  17  affixed to base  11  (although it may be at any radial position). Longer blade  12   L  may be considered a multipurpose blade for use during a procedure generally providing for retraction of specific anatomy, identification/targeting specific anatomy, sweeping an area to move away anatomy, and identification of the device within the patient (e.g., under various imaging modalities), as discussed herein. 
         [0039]      FIG. 4  is a cross-sectional view of the embodiment of  FIG. 1 , taken along the section  4 - 4 . The hinge pin  13  depicted as a black dot is shown axially and is the hinge pin associated with longer blade  12   L  and about which blade  12   L  rotates. Spring  19  is shown seated in a recessed portion of base  11  and presses against shoulder  40  of blade  12   L , wherefore spring  19  is biased in a manner to keep blade  12   L  closed, as shown (such may be the same for remaining blades  12 ). As discussed above, other biasing means may be used instead of spring  19  shown herein. Pusher tube (or expander tube)  41  extends from pusher  14  to a distal location between the blades  12 . Pusher tube  41  has a distal end  41   a  that is set in length from pusher  14  such that when pusher mechanism  14  is fully tightened into and bottomed out in base  11 , distal end  41   a  will either be positioned at or above section  51  of any of the blades  12  or between section  51  for reasons that will be discussed and depending on the desired operation. In the embodiment shown in  FIGS. 1 and 4 , distal end  41   a  is positioned at or above section  51  such that in its tightened position, distal end  41   a  does not abut section  51  and therefore the blades  12  are not expanded. In this configuration, the retractor device  10  is positioned into a patient while the blades  12  are in their contracted position. 
         [0040]      FIG. 5  is a top plan view of the embodiment of  FIG. 1  according to another embodiment. In this embodiment, the pusher assembly (collectively pusher  14 , pusher tube  41 , dilator tube  42  and knob  16 ) is replaced with a second pusher assembly  15 . Alternatively, instead of the entire pusher mechanism, the dilator including its knob  16 , tube  42  and tip  16   t  may be removed leaving the remaining items of the pusher assembly. Blades  12  are still in a closed position. Blades  12  each have three sections  50 ,  51  and  52 , shown in  FIG. 5 . Section  50  extends substantially uniform in diameter such that pusher tube  41  is positioned along the interior in a non-interfering way between blades  12 . Section  51  has a tapered configuration to abut against distal end  41   a  as will be discussed. Section  52  forms an extended tapered configuration with blades  12  as needed for working the device  10  into the operative area. The relationship between cylindrical configuration  50  and conic configuration  51 , both configurations formed by the three blades while in a closed position, is responsible for spreading the blades, and is discussed in detail below. However, one skilled in the art will understand that the tube  42  may interact with blades  12  through any other means known in the art to expand the blades  12 . For example, tube  12  could include gear teeth that mate with teeth on blades  12  to cause gear like rotation of blades  12  about the hinge. 
         [0041]      FIG. 6  is an end view of the configuration of  FIG. 5 . Two blades  12  and one blade  12   L  are visible in the center of the Figure. Light posts  60  are attachments for light fibers or light cables (not shown) used for illuminating the surgical site. The light posts also serve as detents for control of surgical instruments (not shown in this Fig.) used with the configuration of  FIG. 5 , to be discussed below.  FIG. 7  is the same perspective view as that presented in  FIG. 3 , but with the dilator removed. 
         [0042]      FIG. 8  is a cross-sectional view of the embodiment of  FIG. 5  taken along the section  8 - 8 . Pusher tube  41  is shown to have a length which, while the pusher  14  is in a relatively unthreaded and non-bottomed out position, does not enter section  51  of the blades. As such, springs  13  maintain sufficient force onto shoulders  40  to hold blades  12  and  12   L  in closed positions as shown. The structure through which hinge pin  13  is inserted has hard edge  80  which serves as a limit stop to the advancement of pusher  14  as it is threaded into base  11 , operation of which is discussed below. 
         [0043]    With reference to  FIGS. 8 and 12 , the operation of the embodiment is described. In  FIG. 8 , the pusher  14  is in its unthreaded state. Next, pusher  14  is threaded into base  11  such that distal end  41  engages section  51 . As can be seen in  FIG. 12 , distal end  41   a  abuts section  51  and expands blades  12  apart and against the biasing of springs  19 . The pressure against section  51  by distal end  41   a  and the counter force by springs  19  create a degree of rigidity that holds blades  12  in place. Of course, one will understand that springs are not necessary and only distal end  41   a  against section  51  may be employed. The angle of section  51  may be chosen such that an optimum force or speed of retraction may be achieved. For example, the angle of section  51  may be chosen shallow such that more rotation of pusher  14  is required for each degree of opening for blades  12 . This will provide a relatively larger amount of torque where opening the operative area is difficult and needs more force. Likewise, where speed is desired, the angle of section  51  may be steeper such that a greater degree of opening will be achieved with each rotation of pusher  14 . Additionally, the sections  51  of each blade  12  may be pitched differently to cause blades  12  to open at different rates per rotation of pusher  14 . 
         [0044]      FIG. 9  is a top plan view of the embodiment of  FIG. 5  after the blades have been outwardly displaced or spread apart. At the left-hand side of the drawing, it can be readily seen that the end of blade  12   L  extends beyond the ends of blades  12  and that all blades are spread apart. In  FIG. 9 , it can be seen that pusher  14  has been screwed or threaded into base  11  to the maximum extent possible. It will be noted that the depth of pusher threaded into base  11  or the degree of stop between shoulder  40  against base  11  may be set to ensure the blades  12  open only a predetermined amount. 
         [0045]      FIG. 10  is an end view of the configuration of  FIG. 9 , being the same end view as that of  FIG. 6  but with the blades in their open and expanded configuration. Two blades  12  and one blade  12   L  are shown, Open space  61  is provided between the blades in  FIG. 10  representing vision into the operative area that allows the user or the user to access the targeted for surgical intervention. Tabs  15  are shown in the same position in which they appeared in  FIG. 6 . For ease of presentation; however, it should be understood that after pusher  14  has been screwed into base  11  to the desired distance to achieve the desired expansion of the blades  12 , as shown, there is no requirement that tabs  15  on the pusher maintain the same relative position with respect to tab  17  on the base  11 , although that may coincidentally occur.  FIG. 11  is the same perspective view as that presented in  FIG. 7 , but with the blades outwardly displaced, shown at end  110  of blades  12  and  12   L - FIG. 12  is a cross-sectional view of the embodiment of  FIG. 9 , the view taken along the section  12 - 12 . Pusher  14  is shown as coincidentally being completely threaded into base  11  while structure of base  11  simultaneously abuts limit stop edge  80 . However, in one embodiment, limit stop  80  is the primary mechanism to prevent further movement of pusher tube  41  and corresponding expansion of the blades  12 . Further, in another embodiment, the limit stop  80  is positioned such that it is reached before spring  19  is fully compressed to ensure that no excessive wear or damage results to spring  19 . It should be noted that pusher tube  41  has necessarily advanced to the left in  FIG. 12  and, by that translational motion, it is pressing against the inside walls of section  51  of the blades. This motion against section  51  causes the blades to spread apart, against counterforce spring resistance from springs  19  as shown by the contact between blade-shoulder  40  and spring  19 . The ends of the blades  110  are shown spread apart. The spreading of the blades is constrained to an outward displacement limit as determined by the transverse movement limit of pusher tube  41  which, in turn, is determined by limit stop  80 . In an alternative embodiment, in the structure containing hinge pin  13  ( FIG. 8 ), the face of that structure opposite to that of limit stop  80  can be extended to the left to further reduce motion of shoulder  40  and, if extended sufficiently can be an alternative limit stop to that provided by face  80 . 
         [0046]    Different retractors can be designed for different surgical tasks. Different retractors can have different outward blade displacement limits as functions of different pusher tube lengths and/or as functions of different degrees of taper of section  51 . Typically, these displacements may be in the two (2) to twelve (12) millimeter range, but is not limited to any particular displacement amount. The more severe the taper of section  51 , the greater the blade displacement is obtained per angle of rotation of pusher tabs  15 . With other parameters being equal, however, a greater taper to section  51  yields a greater effort than otherwise is required by the user in rotating pusher tabs  15  to achieve that greater blade displacement. Conversely, the less severe the taper of section  51 , the smaller the blade displacement is obtained per angle of rotation of pusher tabs  15  with other parameters being equal. However, with a lesser taper to section  51 , a lesser effort than otherwise is required by the user in rotating pusher tabs  15  to achieve that lesser blade displacement. Different retractors having these different mechanical advantages requiring greater or lesser effort are advantageously used in different surgical scenarios. Moreover, the opening distance between blades  12  may be adjustable for various procedures. The adjustment may be predetermined based on the dimensions of the components, or it may be adjustable during a procedure by utilizing pusher tubes  41  of various lengths. In an example, a larger opening retractor device may be used by OB/GYN procedures. Examples of opening distances may include two millimeters (2 mm) to eighteen millimeters (18 mm), or more. The opening distances (see ends  110  of  FIGS. 11 and 12 ) of the blades  12 , and the associated size of all components, may be smaller or larger for any given procedure and are not limited by the exemplary embodiments described herein. 
         [0047]      FIG. 13  is a top plan view of the exemplary embodiment of  FIG. 9 , but after a surgical tool is inserted into the embodiment. Surgical tool  130  is threadably and concentrically connected to pusher  14  similarly to how dilator knob  16  was threadably and concentrically connected to pusher  14 . Surgical tool  130  is intended to represent a generic tool, and its end  131  protrudes beyond the ends  110  of blades  12  and  12   L . The device  10  can be a conduit used, for example, to allow illumination and viewing if operatively connected to fiber optic light sources (via light terminals  60  in  FIG. 14 ). Or, device  10  can be used to allow a different device to perform suction, or it could be used to allow other instrumentation to occupy the conduit to function as a clipper, a caliper, a pincher, a cauterizer, etc., depending on what is threadably attached to pusher  14  and what is inserted into the conduit. 
         [0048]      FIG. 14  is an end view of the configuration of  FIG. 13 , being the same end view as that of  FIG. 10 , but with the surgical tool in place. Surgical tool  130 , regardless of its utility or function, can be configured with a plurality of handle-indentations  131  to serve as both convenient hand-grips and detents relative to light posts  60 . In other words, light posts  60 , which supply fiber optic light paths to the surgical sight, also serve as posts which can provide mechanical detents to hold surgical tool  130  in place, after the user positions it to his/her liking.  FIG. 15  is the same perspective view as that presented in  FIG. 11 , but with surgical tool  130  in place, its end  131  showing beyond the ends  110  of the blades.  FIG. 16  is a cross-sectional view of the embodiment of  FIG. 13 , taken along the section  16 - 16 , with tool  130  in place. 
         [0049]      FIG. 17  is another perspective view of tissue retractor device  10  in a closed-blade state with it including pusher  14  but not dilator  16  as shown in  FIG. 1 . Tool  130  cannot be included within the device in this view, because the device is in a closed-blade state. Longer blade  12   L  is clearly visible in this view and is aligned with tab  17  on the base. 
         [0050]      FIG. 18  is an exploded view of the embodiment of  FIG. 17 , but axially rotated therefrom to more clearly show certain detailed mechanical features of the embodiment. Each blade-shoulder  40  is held in place by hinge pin  13  when inserted into apertures  13   a . As can be seen from the Fig., each spring  19  pushes against its respective shoulder  40  from the side opposite to the side seen in the Fig., and because of the location of hinge pin  13  and its apertures  13   a  relative to the point of force from spring  19  onto the shoulder, each blade  12  is pressed against the other two blades which are similarly biased. In other words, all three blades are pressed against each other as a result of the three springs pushing, respectively, against the three shoulders. The interior surfaces, or a portion of an interior surface, of blades  12 ,  12   L  may be finished to provide reduced glare from illumination or to provide improved illumination conditions. The color of the interior surface may also be selected to provide improved illumination depending on the procedure. Examples of finishes may include a flat finish, a mirrored finish, and/or a colored finish. 
         [0051]      FIG. 19  is a perspective view of the pusher mechanism shown in cross section in  FIGS. 4 ,  8 ,  12  and  16 . Threads  190  are shown which are arranged to receive, concentrically, first the dilator  16  and, after that fulfills its purpose and is removed (unscrewed), then surgical tool  130 .  FIG. 20  is a side view of the pusher mechanism depicted in  FIG. 19 . Pusher tube or expander tube  41  is cylindrical in shape, and readily fits within the generally cylindrical shape  50  formed by the three blades. However, the diameter of cylindrical pusher tube  41  is larger than radially-taken cross sectional diameters of the three blades providing conical shape  51 . Therefore, the blades are forced open against opposing bias forces of springs  19  when the pusher handle tabs  15  are rotated because that causes pusher tube  41  to acquire translational motion and advance towards blade ends  110 , thereby spreading those blades to allow that translational motion. 
         [0052]      FIG. 21  is an exploded view similar that of  FIG. 18 , but also showing the dilator depicted in cross section in  FIG. 4 . Knob  16  is shown, along with dilator tube  42  and dilator tip  16   t . Knob  16  screws into pusher mechanism  14  which, in turn, screws into base  11 . 
         [0053]      FIG. 22  is a perspective view of an alternative embodiment  220  of the retractor device. Additional features may include a window  222  through blade  12   L  where a user may access tissue from the side for sampling. The windows may be located, for example, to allow access by biopsy devices placed through pusher tube  41 . The windows may also be configured to allow tissue to protrude through one or more of blades  12  such that inspection and/or sampling of the tissue may be performed (biopsies for example). As shown, window  222  is aligned with the blade  12   L  that is also aligned with finger tab  17  that provides the position to the user. Additionally, blades  12  may include a number of windows (e.g., openings therethrough) to provide additional opportunities for tissue inspection, resection, reduce weight and/or alter structural rigidity and strength. Moreover, blades  12  may be partially or substantially skeletonized. 
         [0054]    In operation of the above-described embodiment, referring to all Figures collectively, the user first makes a stab incision and may insert a guide-wire to determine depth of penetration. Then, if a guide-wire is used, the user inserts the device  10  in  FIG. 1 , including the dilator mechanism having knob  16 , over the guide-wire which enters the dilator mechanism via the hole in tip  16   t . The user grasps base  11  including tab  17  with one hand and grasps pusher/pusher tabs/knob combination  14 / 15 / 16  with the other hand and, without rotating pusher  14  relative to base  11 , slides device  10  down the guide-wire and works device  10  into the body of the patient by clockwise and counterclockwise and other motion. These tabs offer a secure gripping configuration for the user. All blades  12  and  12   L  remain closed during this portion of the procedure by force of springs  19 . If no guide-wire is used, the same procedure may be followed without interacting with the guide-wire. After tip  16   t  is positioned in the correct position, and this can be determined by any known means in the art including fluoroscopy or other means in combination with a radio opaque tip  16   t  or a radio opaque end of blade  12   L , dilator assembly and the guide-wire can be removed. Alternatively, the retractor may be auto-located with or without the use of imaging as discussed herein. 
         [0055]    Then, with the blades remaining closed, the user, in one embodiment, uses longer blade  12   L  to maneuver around nerve roots and/or other structure(s) in his/her path (this may be done before or after removal of the guide wire), without damaging nerves or causing an unwanted result. The longer blade  12   L  is advantageous for this purpose because it offers a small effective tip at the end of device  10  as compared with an embodiment having same-length legs  12  (e.g., substantially equal length legs). This smaller tip permits easier maneuvering around nerve root obstructions and the like which, importantly, supports better patient outcomes. Other embodiments may include retractor devices having two or more blades. In practice, the longer blade  12   L  may be used to sweep an area such that the user to move aside specific anatomy (e.g., an exiting nerve root). The sweep procedure may be performed by turning the retractor. Additionally, the longer blade  12   L  may be used to retract or specify certain anatomy or to provide improved targeting during imaging using a radio opaque material near the distal end. An example of specifying particular anatomy, the longer blade  12   L  may be used to target an exiting nerve root and controllably retract/push it aside. 
         [0056]    Next, the user installs the dilator assembly shown in  FIG. 8  that includes a longer pusher tube  41 . The user rotates tabs  15  relative to tab  17  to advance pusher tube  41  into the vicinity of section  51 . The rotational motion of tabs  15  and, thus, rotational motion of threads  18 , provide translational motion to pusher tube  41  which, in turn, presses against section  51 , thereby spreading blades  12  and  12   L  against force of springs  19 . The spreading of these blades pushes patient tissue out of the way so the user can have clear access to the site  61  as shown in  FIG. 10 , such as vertebrae or discs, upon which surgical procedures shall be performed. Surgical tools and/or instrumentation are introduced through the opening to site  61  which can be held in place by detents in combination with light terminals  60 . 
         [0057]    In this specification, various preferred embodiments may have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The present invention is thus not to be interpreted as being limited to particular embodiments and the specification and drawings are to be regarded in an illustrative rather than restrictive sense. 
         [0058]    It will be appreciated that the system and methods described herein have broad applications. The foregoing embodiments were chosen and described in order to illustrate principles of the methods and apparatuses as well as some practical applications. The preceding description enables others skilled in the art to utilize methods and apparatuses in various embodiments and with various modifications as are suited to the particular use contemplated. In accordance with the provisions of the patent statutes, the principles and modes of operation of this invention have been explained and illustrated in exemplary embodiments. 
         [0059]    It is intended that the scope of the present methods and apparatuses be defined by the following claims. However, it must be understood that this invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. It should be understood by those skilled in the art that various alternatives to the embodiments described herein may be employed in practicing the claims without departing from the spirit and scope as defined in the following claims. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future examples. Furthermore, all terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. In sum, it should be understood that the invention is capable of modification and variation and is limited only by the following claims.