Abstract:
A minimal incision maximal access system allows for maximum desirable exposure along with maximum access to the operative field utilizing a minimum incision as small as the METRx and Endius systems. Instead of multiple insertions of dilating tubes the design is a streamlined single entry device to avoid repetitive skin surface entry. The system offers the capability to expand to optimum exposure size for the surgery utilizing hinged bi-hemispherical or oval working tubes applied over an introducer obturator which is controllably dilated to slowly separate muscle tissue. Deeper end working and visualization areas with maximum proximal access and work dimensions are provided to makes the operative procedure safer in application and shorten the surgeons&#39;s learning curve because it most closely approximates the ability to use open microdiskectomy techniques.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to improvements in the field of minimal access lumbar posterior surgery and more particularly to instrumentation which allows for maximal access to the surgical field through the smallest possible incision. Greater access is allowed into the working field while enjoying the reduction of trauma and disturbance to surrounding tissues, which results in a reduced the time necessary to complete the operative procedure, increased safety of the procedure, and increased accuracy by providing an expanded working field. 
       BACKGROUND OF THE INVENTION 
       [0002]    Microscopic Lumbar Diskectomy techniques were developed and championed by Dr. Robert Williams in the late 1970&#39;s and by Dr. John McCullough in the late 1980&#39;s and 1990&#39;s. For the first time since the advent of Lumbar Disc Surgery by Mixter and Barr in 1934 a method was introduced allowing Lumbar Disc Surgery to be performed through a small incision safely resulting in faster patient recovery and converting a two to five hospital stay procedure virtually to an outpatient procedure. 
         [0003]    The special retractors developed by Drs. Williams and McCullough however were often difficult to maintain in optimum position and relied on the interspinous and supraspinatus ligaments for a counter fixation point severely stretching the structures. This stretching along with the effects of partial facectomy, diskectomy, removal of the ligamentum flavum and posterior longitudinal ligament contributed to the development of Post Diskectomy Instability. Taylor retractors were also used but were cumbersome, required larger incisions and often injured the facet joints. 
         [0004]    Dr. William Foley in 1997 introduced a tubular system mated to an endoscope which he labeled a Minimal Endoscopic Diskectomy (MED) system. It featured sequentially dilating the Lumbar Paraspinous Muscles allowing a working channel to be advanced down to the level of operation through which nerve root decompression and Diskectomy Surgery could be performed with a small incision and less muscle trauma. Improvements were made by Dr. Foley in his second generation METRx system. However, there were several disadvantages to the MED and METRX systems. 
         [0005]    In the MED and METRX systems, the cylindrical working channel considerably restricted visualization and passage of instruments. It also compromised the “angle of approach” necessary for safe usage of the operating instruments. This problem was proportionately aggravated with the long length of the tube. This compromised visualization contributed to the following problems, including nerve injury, dural tear, missed disc fragments, inadequate decompression of the lateral recess, increased epidural bleeding, difficulty controlling epidural bleeding, inadequate visualization of the neuroforamen, and inadequate decompression of neuroforamen. 
         [0006]    The repetitive introduction of successively larger dilators caused skin abrasion with the potential for carrying superficial skin organisms down to the deeper tissue layers hypothetically increasing the risk of infection. The learning curve for operating in a two dimension endoscopic field proved to be arduous and contributed to the above complications. 
         [0007]    The attempted use of the METRx system for more complex procedures such as fusion was further hazardous by inherent limitations. 
         [0008]    Endius in September of 2000 then introduced a similar device which differed by having an expandable foot piece to allow greater coverage of the operative field. However, the enlarged foot piece was unwieldy and difficult to seat properly. Exposure of the angle of approach was also limited by having to operate through a proximal cylindrical tube with its limitations as described before. In comparison to the METRX system the working area was improved but access was again restricted by the smaller proximal cylinder. 
         [0009]    Both systems offered endoscopic capability but many spine surgeons chose to use an operating microscope or loupes to maintain 3-Dimensional visualization rather than the depth impaired 2-Dimensional endoscopic presentation. Keeping debris off of the endoscopic lens has also proved to be a troubling challenge. 
       SUMMARY OF THE INVENTION 
       [0010]    The system and method of the invention, hereinafter minimal incision maximal access system, includes a surgical operating system that allows for maximum desirable exposure along with maximum access to the operative field utilizing a minimum incision as small as the METRx and Endius systems. The minimal incision maximal access system disclosed offers advantages over the METRx and Endius systems in several respects. First, instead of multiple insertions of Dilating Tubes the Invention is a streamlined single entry device. This avoids repetitive skin surface entry. Second, the minimal incision maximal access system offers the capability to expand to optimum exposure size for the surgery utilizing hinged bi-hemispherical or oval Working Tubes applied over an introducer Obturator which is controllably dilated to slowly separate muscle tissue. 
         [0011]    Third, the minimal incision maximal access system maximizes deeper end working and visualization area with maximum proximal access and work dimensions significantly greater than either the METRx or Endius devices and methods. Fourth, the minimal incision maximal access system provides expanded visual and working field to makes the operative procedure safer in application and shorten the surgeons&#39;s learning curve because it most closely approximates the open microdiskectomy techniques. Fifthly, the minimal incision maximal access system has a tapered ended Obturator which allows for tissue spread rather than muscle tissue tear and subsequent necrosis. 
         [0012]    Sixth, the minimal incision maximal access system controls muscle oozing into the operative field which is controlled by simply opening the tubes further. This also thereby controls the bleeding by pressure to the surrounding tissues. Seventh, in contrast to the cylindrical tube based systems such as the METRx and Endius the minimal incision maximal access system offers a larger working area in proportion to the working depth. For the first time this allows for a minimal access technique to be applied to the large or obese patients. The enlarged footprint of the longer tubes in the minimal incision maximal access system is a major difference from any other minimal access system. 
         [0013]    An eighth advantage of the minimal incision maximal access system is that ist expandable design allows for excellent exposure for more complex procedures such as fusion and instrumentation including TLIF, PLIF, and TFIF (Transfacet Interbody Fusion), as well as allowing application for anterolateral lumbar disc surgery. The minimal incision maximal access system can also be used for cervical surgery posteriorly (foraminotomy, lateral mass instrumented fusion) as well as anterior cervical diskectomy and fusion. The minimal incision maximal access system can also be used for anterior lumbar interbody fusion be it retroperitoneal, transperitoneal or laparoscopic. 
         [0014]    A ninth advantage of the minimal incision maximal access system is that the medial oval cutout of the retractors, or sleeve forming the working tube, allows more central docking on the spine which is problematic for other devices. A medialized docking provides access for easier and better and safer dural retraction to address midline pathology. A tenth advantage is had by including an anti-reflective inner surface of the retractor sleeves which eliminates unwanted glare. 
         [0015]    An eleventh advantage of the minimal incision maximal access system includes the slanted and contoured distal end of the retractor sleeve which allows minimal resistance for entry and advancement to the docking site. A twelfth advantage minimal incision maximal access system is the provision of a variety of retractor tips specific for different surgical procedures. 
         [0016]    A thirteenth advantage of the minimal incision maximal access system is the provision of oval retractor sleeves for larger access requirements such as pedicle to pedicle exposure and especially in the case where pedicle screw instrumentation is to be applied. This minimizes unnecessary muscle spread by providing a smaller waist profile than a circular system. A fourteenth advantage of the minimal incision maximal access system is that the larger retractor sleeve also features one or two “skirts” to cover the lateral aperture created by the spread of the two retractor sleeves when opened. This prevents soft tissue and muscle ingress into the working cone. The skirts are attached to the working tube either at the hinge or on one of the two halves of the sleeve. 
         [0017]    A fifteenth advantage of the minimal incision maximal access system is the provision of a modular design in which the retractor sleeves can be quickly removed, changed and reapplied. In this version the proximal port can also be modular and changeable to fit the needs of a specific surgical procedure. A sixteenth advantage of the minimal incision maximal access system is that the retractor sleeves can be made out of metal, ceramic or plastic, can be opaque or translucent, and can have tips of different shapes for different applications. A seventeenth advantage is the provision of snap lock connections of the major parts of the Invention provides for easy assembly and disengagement for cleaning and sterilization purposes. 
         [0018]    Further, the Obturator is cannulated for carrying a central Guide Pin Passage. It has a Handle component which remains superficial to the skin. The obturator houses an internal hinge device which allows for spread of the two obturator tips. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which: 
           [0020]      FIG. 1  is a perspective view of a working tube with an angled upper section and shown in position with respect to an obturator insertable into and workable within the working tube; 
           [0021]      FIG. 2  is a perspective assembled view illustrating the relative positions of the obturator and working tube; 
           [0022]      FIG. 3  is a perspective assembled view illustrates the position of the obturator after it has been inserted into the working tube; 
           [0023]      FIG. 4  is a view taken along line  4 - 4  of  FIG. 2  and looking into the working tube of  FIG. 1 ; 
           [0024]      FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 2  and looking into the hinge of working tube of  FIG. 1 , illustrating its hinge connections; 
           [0025]      FIG. 6  is an side end view of the working tube of  FIGS. 1-5  and illustrating predominantly one of the rigidly connected halves of the invention; 
           [0026]      FIG. 7  is a side sectional view taken along line  7 - 7  of  FIG. 6  and showing the internal bearing pivot; 
           [0027]      FIG. 8  is a side sectional view taken along line  8 - 8  of  FIG. 5  and illustrating a option for external bevel for the working tube; 
           [0028]      FIG. 9  is a side view of the working tube of  FIGS. 1-8  shown with the lower portions in parallel alignment and the upper portions angled with respect to each other; 
           [0029]      FIG. 10  is a side view of the working tube as seem in  FIG. 9  and shown with the lower portions in an angled relationship and the upper portions in a closer angled relationship with respect to each other; 
           [0030]      FIG. 11  is a side view of the working tube as seen in  FIGS. 9 and 10  and shown with the lower portions in a maximally angled relationship and the upper portions in parallel alignment signaling maximal spread of the lower portions in bringing the upper portions into parallel alignment; 
           [0031]      FIG. 12  is a side view of the obturator of  FIG. 1  and seen in an assembled view and emphasizing a through bore seen in dashed line format; 
           [0032]      FIG. 13  is a side view of the obturator of  FIG. 11  as seen in an assembled view but turned ninety degrees about its axis and emphasizing the through bore; 
           [0033]      FIG. 14  shows a side view of the obturator  33  of  FIG. 13  with the spreading legs in an angled apart relationship; 
           [0034]      FIG. 15  is a sectional view taken along line  14 - 14  of  FIG. 12  and gives a sectional view from the same perspective seen in  FIG. 14 ; 
           [0035]      FIG. 16  is a view of the obturator similar to that seen in  FIG. 15 , but turned ninety degrees along its axis and illustrates the wedge as having a narrower dimension to lend internal stability; 
           [0036]      FIG. 17  is a closeup view of the external hinge assembly seen in  FIG. 1  and illustrates the optional use of a plug to cover the exposed side of a circular protrusion; 
           [0037]      FIG. 18  is a view taken along line  18 - 18  of  FIG. 11  and illustrates the use of an optional skirt having flexible members which spread from an initial curled position to a straightened position to better isolate the surgical field; 
           [0038]      FIG. 19  is a view of the lower tube hemicylindrical portions  65  and  69  in a close relationship illustrating the manner in which the skirts sections within their accommodation slots areas; 
           [0039]      FIG. 20  is a cross sectional view of the a patient and spine and facilitates illustration of the general sequence of steps taken for many procedures utilizing the minimal incision maximal access system disclosed; 
           [0040]      FIG. 21  illustrates a fascial incisor overfitting a guide pin and further inserted to cut through external and internal tissue; 
           [0041]      FIG. 22  illustrates the assembled Working Tube—Obturator being inserted into the area previously occupied by the fascial incisor and advanced to the operative level lamina; 
           [0042]      FIG. 23  illustrates the obturator  33  being actuated to a spread orientation to which automatically actuates the working tube to a spread orientation; 
           [0043]      FIG. 24  is a view of the working tube  35  is in place and supported, held or stabilized in the field of view by a telescopy support arm and engagement, the opposite end of the stabilizing structure attached to the operating table; 
           [0044]      FIG. 25  illustrates further details of the support arm seen in  FIG. 24 , especially the use of a ball joint; 
           [0045]      FIG. 26  illustrates a side view of the assembly seen in  FIG. 25  is seen with an adjustable clamp operable to hold the working tube open at any position; 
           [0046]      FIG. 27  is a top view looking down upon the adjustable clamp seen in  FIGS. 25-26  and shows the orientation of the working tube and adjustable clamp in fully closed position; 
           [0047]      FIG. 28  shows a variation on the obturator seen previously in  FIG. 1  and illustrates the use of handles which are brought together; 
           [0048]      FIG. 29  illustrates a further variation on the obturator seen previously in  FIG. 1  and illustrates the use of a central ball nut; 
           [0049]      FIG. 30  is a sectional view taken along line  30 - 30  of  FIG. 29  and illustrates the use of a central support block to support the central threaded surface; 
           [0050]      FIG. 31  is a top view of a thin, inset hinge utilizable with any of the obturators herein, but particularly obturators of  FIGS. 1 and 29 ; 
           [0051]      FIG. 32  is a sectional view of the obturator of  FIG. 1  within the working tube of  FIG. 1  with the wedge  51  seen at the bottom of an internal wedge conforming space; 
           [0052]      FIG. 33  illustrates the obturator seen in  FIG. 32  as returned to its collapsed state. 
           [0053]      FIG. 34  illustrates a top and schematic view of the use of a remote power control to provide instant control of the working tube using an adjustable restriction on the upper angled hemicylindrical portions of the working tube; 
           [0054]      FIG. 35  is a view taken along line  35 - 35  of  FIG. 34  and illustrating the method of attachment of the cable or band constriction; and 
           [0055]      FIG. 36  is a mechanically operated version of the nut and bolt constriction band seen in  FIG. 25 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0056]    The description and operation of the minimal incision maximal access system will be best described with reference to  FIG. 1  and identifying a general system  31 . System  31  includes an obturator  33  and a working tube  35 . The orientation of the obturator  33  is in a slightly displaced from a position of alignment with the working tube  35  for entry into working tube  35  and to provide the initial carefully controlled force for spreading the working tube  35 , as will be shown. 
         [0057]    Obturator includes an upper control housing  37  and a pair of spreading legs  39  and  41 . The spreading legs  39  and  41  are seen as coming together to form a conical tip and thus have hemi conical end portions. The spreading legs  39  and  41  overfit attachment leg portions  43  and  45 , respectively. At the top of the upper control housing  37  a boss  47  surrounds and supports the extension of a control shaft  49 . A knurled thumb knob  50  sits atop the control shaft  49  to facilitate controlled turning of the control shaft  49  to control the degree of spreading of the spreading legs  39  and  41 . Thus spreading can be controlled independently of pressure applied along the length of the obturator  33 . 
         [0058]    Below the upper control housing  37  is the bottom of the control shaft  49  which operates against a wedge  51 . The wedge  51  operates within a pair of opposing slots  52  in an upper portion  53  of the overfit attachment leg portions  43  and  45 . The lower ends of the overfit attachment leg portions  43  and  45  include insertion tangs  55  which fit within insertion slots  57  of the spreading legs  39  and  41 . The overfit attachment leg portions  43  and  45  are pivotally attached to the upper control housing  37  internally by pivot blocks  59  which fit within access apertures  60 . 
         [0059]    The working tube  35  has a first lower extending connection tang  61  and a second lower extending connection tang  63 . First lower extending connection tang  61  connects into a slot  64  of a lower tube hemicylindrical portion  65 . The first lower extending connection tang  61  is fixed to an upper angled hemicylindrical portion  67 . The second lower extending connection tang  63  connects into a slot  68  of a lower tube hemicylindrical portion  69 . Second lower extending connection tang  61  is fixed to and an upper angled hemicylindrical portion  71 . The upper angled hemicylindrical portion  67  has a reinforced wear plate  73  for applying upper pressure and force on the upper angled hemicylindrical portions  67  and  71  toward each other to cause the first and second lower extending connection tangs  61  &amp;  63  and their connected lower tube hemicylindrical portions  65  and  69  to be urged away from each other. 
         [0060]    At the side of the working tube  35  at the transition between the upper angled hemicylindrical portions  67  and  71  and a point just above the first and second lower extending connection tangs  61  &amp;  63  is an external hinge assembly  77 . Hinge assembly  77  may include an optional first guide plate  79  and first circular protrusion  81  attached to upper angled hemicylindrical portions  67 , and a first slotted plate  83  positioned adjacent to first guide plate  79  and having a slot partially surrounding the circular protrusion  81 . 
         [0061]    Upper angled hemicylindrical portion  71  has a pair of spaced apart facing surfaces facing a matching pair of facing surfaces of the upper angled hemicylindrical portion  67 , of which a dividing line  85  is seen. Upper angled hemicylindrical portions  67  and  71  are be brought together to cause the first and second lower extending connection tangs  61  &amp;  63  and their connected lower tube hemicylindrical portions  65  and  69  to spread apart. 
         [0062]    In the View of  FIG. 1 , the first and second lower extending connection tangs  61  &amp;  63  are shown in a spread apart relationship. A locking pin  87  is seen which can be used to engage angularly spaced apart apertures in the circular protrusion  81  to provide a detent action to hold the working tube  35  in various degrees of spread. Also seen is a slight exterior bevel  89  on the lower tube hemicylindrical portions  65  and  69 . 
         [0063]    Note the angled separation of the upper angled hemicylindrical portions  67  and  71  and exposing opposing surfaces  91 . The angle of the opposing surfaces  91  equals the angle of spread of the first and second lower extending connection tangs  61  &amp;  63 . 
         [0064]    Referring to  FIG. 2 , a perspective assembled view illustrates the relative positions of the obturator  33  and working tube  35  in a position for the obturator  33  to be inserted into the working tube  35  and before any spreading takes place. 
         [0065]    Referring to  FIG. 3 , a perspective assembled view illustrates the position of the obturator  33  after it has been inserted into the working tube  35  and again before any spreading takes place. Note that the pivot axes of the first and second lower extending connection tangs  61  &amp;  63  are on par with the pivot axes of the insertion tangs  55 . The tip of the obturator  33  extends slightly beyond the bottom most part of the working tube  35  so that the completed assembly can be smoothly urged past muscle and other tissue. 
         [0066]    Referring to  FIG. 4 , a view taken along line  4 - 4  of  FIG. 1  is a view looking down into the working tube  35 . Other features seen include a wear plate  93  located on the upper angled hemicylindrical portion  71 . In both of the wear plates  73  and  93  a universal port  94  is provided as a bore for insertion of a tool or lever to assist in bringing the upper angled hemicylindrical portions  67  and  71  into a tubular relationship. Further, an identical hinge assembly  77  on the side opposite that seen in  FIG. 1  is shown with the same numbering as the components which were seen in  FIG. 1 . 
         [0067]    Also seen are a pair of opposing surfaces  95  on upper angled hemicylindrical portion  71  and a pair of opposing surfaces  97  on upper angled hemicylindrical portion  67 . Also seen is a central working aperture  99 . 
         [0068]    Referring to  FIG. 5 , a view taken along line  5 - 5  of  FIG. 1  is a sectional view looking down into the working tube  35 . The connectivity of the structures seen in  FIG. 4  are emphasized including the connection of circular protrusion  81  to the upper angled hemicylindrical portion  71 , and the connection of first slotted plate  83  to upper angled hemicylindrical portion  67 , and which is indicated by the matching section lines Further, an identical hinge assembly  77  on the side opposite that seen in  FIG. 1  is shown with the same numbering as the components which were seen in  FIG. 1 . 
         [0069]    Referring to  FIG. 6 , a view of one end of the working tube  35  illustrates predominantly the second angled half portion  63 . Elements seen in  FIGS. 1 and 2  are made more clear in  FIG. 3 . 
         [0070]    Referring to  FIG. 7 , a side sectional view taken along line  7 - 7  of  FIG. 6  and shows the internal bearing pivot consisting of a slightly greater than hemispherical side bump projection  101  located on upper angled hemicylindrical portion  71 , and a slightly less than hemispherical side circular groove  103  located on upper angled hemicylindrical portion  67 . Also seen is the interconnect slots  64  and  68  as well as the first and second lower extending connection tangs  61  and  63 . In the showing of  FIG. 7  an external bevel  105  is utilized 
         [0071]    Referring to  FIG. 8 , a side semi-sectional view taken along line  8 - 8  of  FIG. 5  illustrates the integral connectivity of circular protrusion  81  with the upper angled hemicylindrical portion  71 . Seen for the first time in isolation are a pair of pin apertures  107  for engaging the locking pin  87 . 
         [0072]    Referring to  FIG. 9 , an illustration of a side plan view and in which the lower tube hemicylindrical portions  65  and  69  are in matching straight alignment and forming a lower tube shape, while the upper angled hemicylindrical portions  67  and  71  are angled apart. 
         [0073]    Referring to  FIG. 10 , a midpoint of movement is illustrates wherein the lower tube hemicylindrical portions  65  and  69  have begun to move apart widening the lower tube shape previously formed into an angled apart opposing hemicylindrical shape, while the upper angled hemicylindrical portions  67  and  71  are brought closer together to have a closer though angled apart an angled apart opposing hemicylindrical shape. 
         [0074]    Referring to  FIG. 11 , a completed movement, with respect to the view of  FIG. 4  illustrates a state where the lower tube hemicylindrical portions  65  and  69  have moved apart to their maximum extent into a maximally angled apart opposing hemicylindrical shape, while the upper angled hemicylindrical portions  67  and  71  are brought completely together to form an upper tube shape. It is the position of  FIG. 6  which is the ideal working position once the lower tube hemicylindrical portions  65  and  69  are within the body, and provides an expanded working field at the base of the working tube  35 . Surgical work is ideally performed through the upper, abbreviated axial length tube shape formed by the upper angled hemicylindrical portions  67  and  71 . 
         [0075]    Referring to  FIG. 12 , a side view of the obturator  33  of  FIG. 1  is seen in an assembled view and emphasizing in dashed line format a through bore  111  which extends though the obturator  33  from the knurled knob  50  through to the tip of the pair of spreading legs  39  and  41 . 
         [0076]    Referring to  FIG. 13 , a side view of the obturator  33  of  FIG. 11  is seen in an assembled view but turned ninety degrees about its axis, and again emphasizing in dashed line format the through bore  111  which extends though the obturator  33  from the knurled knob  50  through to the tip of the pair of spreading legs  39  and  41 . It is from this position that further actuation will be illustrated. 
         [0077]    Referring to  FIG. 14 , a side view of the obturator  33  of  FIG. 13  is seen but with the spreading legs  39  and  41  in an angled apart relationship. An optional support  112  is supported by the upper control housing  37  to enable independent support and locationing of the obturator  33  should it be needed. Once the knurled knob  50  is turned, the wedge  51  seen in  FIG. 1  is driven downward causing the spreading of the spreading legs  39  and  41 . 
         [0078]    Referring to  FIG. 15 , a sectional view taken along line  14 - 14  of  FIG. 12  gives a sectional view from the same perspective seen in  FIG. 14 . Pivot blocks  59  are seen as having pivot bores  113  which enable the upper portions  53  to pivot with respect to the upper control housing  37  and which enable the downward movement of the wedge  51  to translate into a spreading of the spreading legs  39  and  41 . 
         [0079]    As can be seen, the knob  50  and control shaft  49  and the wedge  51  have the through bore  111 . In the configuration shown, the control shaft  49  includes a threaded portion  113  which engaged an internally threaded portion  115  of an internal bore  117  of the upper control housing  37 . The boss  47  is shown to be part of a larger insert fitting within a larger fitted bore  119  within the upper control housing  37 . This configuration pushes the wedge  51  downwardly against an internal wedge conforming space  123  to cause the insertion tangs  55  and upper portions  53  to spread apart. The wedge conforming space  123  need not be completely wedge shaped itself, but should ideally have a surface which continuously and evenly in terms of area engages the wedge  51  to give even control. Further, the wedge  51  can be configured to be rotatable with or independently rotationally stable with respect to the control shaft  49 . As can be seen, the through bore  111  continues below the internal wedge conforming space  123  as a pair of hemicylindrical surfaces  125  in the upper portion  53 , as well as a pair of hemicylindrical surfaces  127  in the pair of spreading legs  39  and  41 . 
         [0080]    Referring to  FIG. 16  a view of obturator  33  similar to that of  FIG. 15 , but turned ninety degrees along its axis is seen. In this view, the wedge  51  is seen as having a narrower dimension to lend internal stability by narrowing the bearing area of the wedge  51  action in opening the pair of spreading legs  39  and  41 . 
         [0081]    Referring to  FIG. 17 , a closeup view of the external hinge assembly  77  seen in  FIG. 1  illustrates the optional use of a plug  131  to cover the exposed side of the circular protrusion  81 . 
         [0082]    Referring to  FIG. 18 , a view taken along line  18 - 18  of  FIG. 11  illustrates a view which facilitates the showing of an optional skirt, including a skirt section  133  welded or otherwise attached to lower tube hemicylindrical portion  65 , and a skirt section  133  welded or otherwise attached to lower tube hemicylindrical portion  69 . The skirts sections  133  and  135  are made of thin flexible metal and interfit within a pair of accommodation slots  137  and  139 , respectively. 
         [0083]    Referring to  FIG. 19 , a view of the lower tube hemicylindrical portions  65  and  69  in a close relationship illustrates the manner in which the skirts sections  133  and  135  fit within the accommodation slots  137  and  139  when the lower tube hemicylindrical portions  65  and  69  are brought together to a circular configuration. 
         [0084]    Referring to  FIG. 20 , a cross sectional view of the a patient  151  spine  153  is shown for illustration of the general sequence of steps taken for any procedure utilizing the minimal incision maximal access system  31 . There are several procedures utilizable with the minimal incision maximal access system  31 . Only a first procedure will be discussed using illustrative figures. Other procedures will be discussed after minor variations on the minimal incision maximal access system  31  are given below. 
       Procedure I: Diskectomy and Nerve Decompression 
       [0085]    The patient  151  is placed prone on radiolucent operating table such as a Jackson Table. The patient  151  is then prepared and draped. The operative area is prepared and localized and an imaging device is prepared. A guide pin  155  is insert through the patient&#39;s skin  157 , preferably under fluoroscopic guidance. In the alternative and or in combination, the patient  151  skin can be incised with a scalpel. Other features in  FIG. 20  include the dural sac  159 , and ruptured intervertebral disc  161 . 
         [0086]    Referring to  FIG. 21 , a fascial incisor  169  overfits the guide pin  155  and is further inserted to cut through external and internal tissue. The fascial incisor  169  is then removed while the guide pin  155  is left in place. Next, using the obturator  33 , the surgeon clears the multifidus attachment with wig-wag motion of the obturator  33  tip end. Next the obturator  33  is actuated to gently spread the multifidus muscle, and then closed. 
         [0087]    Referring to  FIG. 22 , next the assembled Working Tube  35 —Obturator  33  is inserted into the area previously occupied by the fascial incisor  169  and advanced to the operative level lamina and remove the obturator  33 . As an alternative, and upon having difficulty, the obturator  33  could be initially inserted, followed by an overfit of the working tube  35 . In another possibility, a smaller size of obturator  33  and working tube  35  or combination thereof could be initially utilized, followed by larger sizes of the same obturator  33  and working tube  35 . The assembled Working Tube  35 —Obturator  33  in place is shown in  FIG. 22  with the working ends very near the spine. 
         [0088]    Referring to  FIG. 23 , the obturator  33  is actuated to a spread orientation, which automatically actuates the working tube  35  to a spread orientation. Spread is had to the desired exposure size. The obturator  33  is thin actuated to a closed or non-spreading position. The obturator and working tube is then again advanced to dock on the spine. The working tube  35  is then fixed to assume an open position either by utilization of the locking pin  87  or other fixation device to cause the working tube  35  to remain open. Then, once the working tube  35  is locked into an open position, the obturator  33  is actuated to a closed or non-spread position and gently removed from the working tube  35 . 
         [0089]    Referring to  FIG. 24 , the working tube  35  is in place. The working tube  35  may be secured by structure ultimately attached to an operating table. The working tube  35  may be held or stabilized in the field of view by a support  181  which may have an engagement sleeve  183  which fits onto the working tube. As can be seen, the operative field adjacent the spine area is expended even though the incision area is limited. The deeper a given size of working tube  35  is inserted, the smaller its entrance area. After the working tube  35  is stabilized, the surgeon will typically clear the remaining multifidus remnant at the working level and then set up and insert an endoscope or use operating microscope or loupes. The surgeon is now ready to proceed with laminotomy. 
         [0090]    Referring to  FIG. 25 , further detail on the support  181  and engagement sleeve  183  is shown. A base support  185  may support a ball joint  187 , which may in turn support the support  181 . The support  181  is shown as supporting a variation on the engagement sleeve  183  as a pivot point support engagement end  188  having arm supports  189  and  191 . The arm supports  189  and  191  engage the external pivot structure on the working tube  35  which was shown, for example, in  FIG. 1  to be the external hinge assembly  77 . 
         [0091]    As a further possibility, the upper angled hemicylindrical portions  67  and  71  are shown as being engaged about their outer periphery by an adjustable clamp  195 . Adjustable clamp  195  includes a band  197  encircling the upper angled hemicylindrical portions  67  and  71 . The ends of band  197  form a pair of opposing plates  199  and are engaged by a nut  201  and bolt  203  assembly. 
         [0092]    Referring to  FIG. 26 , a side view of the assembly seen in  FIG. 25  is seen with the adjustable clamp  195  operable to hold the working tube  35  open at any position. Referring to  FIG. 27 , a top view looking down upon the adjustable clamp  195  seen in  FIGS. 25-27  shows the orientation of the working tube  35  and adjustable clamp  195  in fully closed position. When used in conjunction with the adjustable clamp  195 , the Reinforced wear plates  73  and  93  are eliminated so as to provide a smooth interface against the exterior of the upper angled hemicylindrical portions  67  and  71 . 
         [0093]    Referring to  FIG. 28 , a variation on the obturator  33  is seen. An obturator  215  has handles  217  and  219  which operate about a pivot point  221 . A working tube  222  is somewhat simplified but is equivalent to the working tube  35  and is shown as including upper angled hemicylindrical portions  67  and  71 . Handle  219  has a ratchet member  223  extending from it and a latch  227  pivotally connected about pivot point  229  to handle  217 . 
         [0094]    Referring to  FIG. 29 , a variation on obturator  33  is seen as an obturator  241  having an upper housing  243 , control shaft  245  having a threaded section  247  and operating through a ball nut  249 . A wedge  251  is extendable down through an operation space made up of a half space  253  in a leg  255  and a half space  257  in a leg  259 . Hinge structures  261  are shown attaching the legs  255  and  259  to the upper housing  243 . A through bore  111  is also seen as extending from the knob  261  through to the bottom of the wedge  251 . An access groove  263  is carried by the leg  259  while An access groove  263  is carried by the leg  259  while an access groove  265  is carried by the leg  255 . 
         [0095]    Referring to  FIG. 30 , a sectional view taken along line  30 - 30  of  FIG. 29  illustrates the use of a central support block  271  to support the a central threaded surface  273  and the legs  255  and  259 . 
         [0096]    Referring to  FIG. 31 , a view of a thin, inset hinge  281  utilizable with any of the obturators, but particularly obturators  33  and  241 , is shown. In the case of obturator  33 , by way of example, upper portions  53  accommodate control shaft  49  with its through bore  111 . Inset hinge  281  may be implaced with an inset  283  and secured with machine screws  285 . Inset hinge  281  may be made of a “living hinge” material such as a hard plastic, or it can have its operations base upon control bending of a pre-specified length of steel, since the angle of bend is slight. The connection between the upper portions  53  and the upper control housing  37  may be by any sort of interlocking mechanism, the aforementioned pivot blocks  59  or other mechanism. 
         [0097]    Referring to  FIG. 32 , a sectional view of the obturator  33  within the working tube  35  is seen. The wedge  51  is seen at the bottom of the internal wedge conforming space  123 . Once the spreading of the working tube  35  is accomplished the working tube  35  is kept open by any of the methods disclosed herein. Also seen is a pivot ball  116  to allow the control shaft  49  to turn with respect to the wedge. The pivot ball will continue to support a central aperture bore  111 . Once the working tube  35  is stabilized in its open position, the obturator  33  is returned to its collapsed state as is shown in  FIG. 33 . 
         [0098]    Provision of electro-mechanical power to the operation of the working tube  35  can provide a surgeon an additional degree of instant control. Referring to  FIG. 34 , a top and schematic view of the use of a remote power control to provide instant control of the working tube  25 , similar to the view seen in  FIG. 25  illustrates the use of a remote annular control cable  301  using an internal cable  303  which is closely attached using a guide  305  and which circles the upper angled hemicylindrical portion  67  and  71 , terminating at an end fitting  307 . 
         [0099]    The annular cable  301  is controlled by a BATTERY MOTOR BOX  311  having a forward and reverse switch  313  (with off or non actuation being the middle position). This enables the surgeon to expand the surgical field as needed and to collapse the surgical field to focus on certain working areas. BATTERY MOTOR BOX  311  is configured with gears to cause the cable  303  to forcibly move axially within the annular cable  301  to transmit mechanical power to the working tube  35 . 
         [0100]    Referring to  FIG. 35 , a view taken along line  35 - 35  of  FIG. 34  illustrates how the cable  303  is held in place and a closeup of the end termination  307 . 
         [0101]    Referring to  FIG. 36 , a mechanically operated version of the nut  201  and bolt  203  constriction band seen in  FIG. 25 . The mechanical power linkage can be provided remotely as by a rotating annular cable, but the basic mechanical setup shown illustrates the mechanical principles. On the bolt  203 , a gear head  325  is implaced, either by attachment or by the provision of a threaded member and gear head made together. A second gear head  327  is utilized to show the possibility of providing a right angle power take-off in the event that the power connection interferes with the area around the surgical field. A shaft  329  extends from a BATTERY MOTOR BOX  331 . The BATTERY MOTOR BOX  331  has a forward and reverse switch  333 , (with off or non actuation being the middle position). Shaft  329  could be flexible and connected directly into axial alignment with the threaded member of bolt  201  or an integrally formed threaded member. 
       Advantages Over Existing Surgical Techniques 
       [0102]    In terms of general advantages, there are differences between the minimal incision maximal access system  31 , and its components as described in all of the drawings herein (but which will be referred throughout herein simply as the minimal incision maximal access system  31 , or simply system  31 ) and other devices and procedures. 
         [0000]    1. With regard to the Traditional microdiskectomy technique, the minimal incision maximal access system  31  allows for at least the same, if not better visualization access of the operative field. System  31  offers the same 3-Dimensional work ability or, if preferred, an endoscope can be utilized. System  31  minimizes muscle injury with spread versus extensive cautery dissection. System  31  has clear advantage on the challenging obese and very large patient where the traditional microdiskectomy technique is almost impossible to be applied.
 
2. With regard to open pedicle screw insertion procedures, system  31  offers muscle approach minimizing muscle devascularization and denervation. The traditional approach had required at least one level proximal and one level distal additional exposure causing extensive muscle injury often leading to “fibrotic” muscle changes resulting in chronic painful and stiff lower back syndrome. System  31  offers the most direct approach to the pedicle entry point selecting the avascular plane between the longissimus and multifidus muscles.
 
3. With regard to the Sextant Procedure, system  31  offers clear advantage over the Sextant procedure. First, the system  31  offers a procedure which is not a blind pedicle screw technique. System  31  can be applied to larger and more obese patients in which the Sextant procedure cannot be utilized. In this procedure using system  31  oosterolateral fusion can be performed along with insertion of the pedicle screws. The sextant procedure is strictly a tension band stabilization.
 
         [0103]    In general, the components of the minimal incision maximal access system  31  are very simple the hemispherical shapes used for the working tube can be round or oval. A keying system can be had to align the obturator  33  to the working tube  35 . In the case of an oval system, the alignment would be automatic. 
         [0104]    The minimal incision maximal access system  31  is a modular system with interchangeable parts for both the working tube  35  and the obturator  33 . The guide Pin  155  is of simple construction, as is the fascial incisor  169 . The working tube  35  has a limited number of basic parts, and can be made in the simple, two main piece version of  FIG. 28 , or the multi-piece version of  FIG. 1 , which enables retractor-sleeve substitution. A hinge and stabilization mechanism completes the simplified construction. 
         [0105]    The obturator  33  is also of simple construction, with upper control housing  37 , pair of spreading legs  39  and  41 , and an internal hinge, whether the pivot blocks  59  or hinge  281  and its ability to support a control shaft  49  having a bore  111  for a guide pin  155 . Guide pin  155  may preferably have a size of from about 0.3 mm to 0.40 mm diameter and 30 cm to 40 cm in length. The fascial incisor may preferably be cannulated for usage with the guide pin  155  and have a width of about 2 mm more than the associated retractor. The overall cutting head length of about 1.2 cm has a shape as indicated in the Figures and has a thickness slightly larger than that of the guide pin  155 . 
         [0106]    The working tube  35  can have several variations and added details including the simplest shapes as dictated by intended usage. Working tube  35  can have a simple fluted hemitube shape or a Slanted box shape. Further, the possibility of a fluted oval shape is dictated when the approach is more angular. The working tube  35  can have an attachment for an endoscope. Working tube  35  can also have a non-symmetric appearance as by having longitudinal cross sectional shape with half of its shape being rounded and one half of its shape being rectangular or box shaped. This could also give rise to a similarly shaped obturator  33 . The working tube  35  should have an anti-reflective inner coating and may be of modular construction. 
         [0107]    The preferred lower dimensions for the lower tube hemicylindrical portions  65  and  69  include an overall shape which is semi tubular round or oval and having a width of from about 1.6-3.0 cm and a length of from about 4.0-18 cm. Hemicylindrical portions  65  and  69  may have custom cut outs depending upon planned application. 
         [0108]    The hinge assembly  77  may have male-female post or male-female dial lock design, as well as a hinge housing and a bias (by spring or other mechanism) to keep angular displaceable portions of the working tube  35  closed. A “universal” port provides a point of attachment of an endoscopic or stabilizer bar. 
         [0109]    The obturator  33  may be any controlled opening device including a circular band or cable, force Plates, or a device attached to hinge assembly  77  or other hinge assembly. 
         [0110]    All sleeve attachments including the attachable legs  39  and  41 , as well as the lower tube hemicylindrical portions  65  and  69  should be of the friction grip type or snap and lock type or other suitable connection method or structure. 
         [0111]    Obturator  215  may have squeeze grip scissor style handles  219  and  217  and a controlled dilator. It may utilize an enclosed design with a handle cover having a no-slip surface. It may be attached to the hinge housing of the working tube or separate hinge housing. In fact, it may be of a design to be held in place solely by the working tube  35 . Ideally a cavity will be provided through the center axis to contain the shaft for the dilator mechanism if applicable. 
         [0112]    The central bore  111  of the obturator  33  may have a diameter of from about 5-10 mm, depending upon the size of the obturator  33  utilized. Obturator  33  should be provided in various widths and length to match working tube. The working tips of the spreading legs  39  and  41  may be changeable according to surgical procedures as described in the operative procedures herein. It may have an inner chamber, or internal wedge conforming space  123  slanted in shape wider proximal and more narrow distal to accommodate the wedge  51 . The internal wedge conforming space  123  can be enclosed with expanding, contracting sleeve. 
       Other Procedures 
       [0113]    Many other procedures can be facilitated with the use of the inventive minimal incision maximal access system  31  and methods practiced therewith. Procedure I, a diskectomy and nerve decompression procedure was described above with reference to the Figures. Other procedures are as follows: 
       Procedure II: Facet Fusion 
       [0114]    1. Patient prone on Jackson Table with normal lordosis preserved. This can be increased by placing additional thigh and chest support to increase lumbar lordosis. 
         [0115]    2. Insert percutaneous special guide pin perpendicular to the floor at a point 1 cm caudal to the Alar-Superior facet notch. 
         [0116]    3. Apply a flag guide to a first guide pin  155  # 1 . 
         [0117]    4. Measure skin to bone depth from the scale on guide pin  155  # 1 . 
         [0118]    5. Slide drill guide mechanism on the flag guide to match the skin bone distance. 
         [0119]    6. Insert guide pin  155  # 2  through the drill guide to dock on the superior facet. 
         [0120]    7. Make a small skin incision for the obturator  33 . 
         [0121]    8. Working tube  35  should be small oval or round with medial cutout to maximally medialize the working tube  35 . 
         [0122]    9. Advance the working tube  35  to the L5-S1 joint and dock. 
         [0123]    10. Drill the guide pin across the joint medial to lateral, rostral to caudal. If in proper position, advance across the joint to engage the ala. 
         [0124]    11. Drill across the joint with a cannulated drill. 
         [0125]    12. Check depth flouroscopically and measure. 
         [0126]    13. Pick appropriate screw length. 
         [0127]    14. Insert specially designed facet screw and protective bracket, secure tightly. 
       Procedure III: Posterior Lumbar Interbody Fusion (PLIF) 
       [0128]    1. First half of the procedure similar to microdiskectomy (Procedure I) except for the use of a larger diameter sized working tube  35 . Use a 20-25 mm round or elliptical diameter working tube  35  with a medial cutout to allow docking as close to midline as possible. 
         [0129]    2. Following diskectomy enlarge the laminotomy to accommodate the tools use for the specific PLIF such as Brantigan cage or Tangent. 
       Procedure IV: Transfacet Interbody Fusion (TFIF) 
       [0130]    1. Follow the same procedure as the PLIF in terms of selecting and inserting the Working Tube  35 . 
         [0131]    2. Following the diskectomy, resect the facet joint. 
         [0132]    3. Approach the posterolateral disc space through the medial ⅔ of the facet joint. Take care not to injure the exiting root above. 
         [0133]    4. Proceed with Brantigan cage instruments and interbody cages. 
       Procedure V: Pedicle Screw Instrumentation Technique 
       [0134]    1. Place the patient  151  Prone position on a Jackson Table. 
         [0135]    2. Guide pin  155  is docked on facet joint angled 30 degree lateral to medial in the plane between the longissimus muscle longitudinally and multifidus muscle medially. 
         [0136]    3. Make skin incision. 
         [0137]    4. Fascial incisor introduction. 
         [0138]    5. Introduce the obturator  33  working tube  35  assembly between the longissimus and multifidus and progressively open the obturator  33  tip ends of the legs  39  and  41   p , gradually reaching from the joint above and the joint below. 
         [0139]    6. Advance the working tube  35  and retract the obturator  33 . 
         [0140]    7. Use the elliptical Working Tube size 2.5 cm wide and open up to 5 cm. 
       Procedure IV: Anterior Lateral Lumbar Diskectomy Fusion 
       [0141]    1. Mid lateral decubitus position left side up. Place a “waist roll” to prevent sag of the mid lumbar spine. 
         [0142]    2. Identify proper level of surgery fluoroscopically. 
         [0143]    3. Insert a guide pin  155  # 1  percutaneously into the superior facet perpendicular to the spine. 
         [0144]    4. Measure depth skin to joint on the scaled guide pin  155  # 1 . 
         [0145]    5. Insert cannulated flag guide over guide pin  155  # 1 . 
         [0146]    6. Slide the drill guide to match the depth. 
         [0147]    7. Insert a guide pin  155  # 2  down to the disc space. 
         [0148]    8. Make skin incision and insert fascial cover. 
         [0149]    9. Insert the working tube  35  and Obturator  33  combination. 
         [0150]    10. Progressively dilate the obturator  33 . 
         [0151]    11. Advance the working tube  35 . 
         [0152]    12. Perform anterolateral diskectomy and interbody fusion as taught above. 
         [0153]    13. Use a round or oval shaped retractor or lower tube hemicylindrical portion  65  and  69  as inserts preferably with distal end cutouts in each. 
       Procedure VII: Posterior Cervical Foramenotomy and Lateral Mass Plating 
       [0154]    1. The patient is placed in a prone position on a Jackson table. 
         [0155]    2. Fluoroscopic identification of the level of surgery is had. 
         [0156]    3. Percutaneously insert guide pin  155  with AP and lateral fluoroscopic views. 
         [0157]    4. Make the initial skin incision. 
         [0158]    5. Apply the working tube  35  with obturator  33  into the incision. 
         [0159]    6. Perform slow dilation of the muscle. 
         [0160]    7. Advance the working tube  35  and collapse and remove the obturator  33 . 
         [0161]    8. Proceed with surgery. Type of sleeve or lower tube hemicylindrical portion  65  should be round or oval with slanted and to match the slanted lamina. 
         [0162]    9. For application for Lateral mass plating use an oval working tube  35  for a greater exposure. 
       Procedure VIII: Anterior Cervical Diskectomy Fusion 
       [0163]    1. Begin with standard anterior cervical diskectomy fusion approach with a incision on the left or right side of the neck. 
         [0164]    2. Blunt finger dissection is performed between the lateral vascular structures and the medial strap muscle and visceral structures down to the prevertebral fascia. 
         [0165]    3. Establish the correct level to be operated on fluoroscopically and the guide pin  155  inserted into the disc. 
         [0166]    4. Apply the working tube  35  and obturator  33  combination and dock at the proper level of the anterior spring. 
         [0167]    5. Open the working tube  35  and obturator  33 . 
         [0168]    6. Mobilize longus colli muscle. 
         [0169]    7. Use special Bent Homen Retractor specifically design to retract the longus colli. 
         [0170]    8. Proceed with surgery. 
       Procedure IX: Anterior Lumbar Interbody Fusion 
       [0171]    1. Begin with the standard approach whether it is retroperitoneal, transperitoneal or laparoscopic. 
         [0172]    2. Apply the special anterior lumbar interbody fusion working tube  35  and obturator  33 . This is a design with a medial lateral opening. It is oval shape and preferably with skirts  133  and  135 . The distal end of the retractor sleeve is slightly flared outward to retract the vessels safely. There is a skirt  133  or  135  applied to the cephalad side and possibly to the caudal side. 
         [0173]    3. With the vessels and the abdominal contents safely retracted out of harms way, proceed with diskectomy and fusion. 
         [0174]    While the present system  31  has been described in terms of a system of instruments and procedures for facilitating the performance of a microscopic lumbar diskectomy procedure, one skilled in the art will realize that the structure and techniques of the present system  31  can be applied to many appliances including any appliance which utilizes the embodiments of the instrumentation of the system  31  or any process which utilizes the steps of the system  31 . 
         [0175]    Although the system  31  has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the system  31  may become apparent to those skilled in the art without departing from the spirit and scope of the system  31 . Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.