Abstract:
An improved cannula that provides improved visibility at a surgical site through the continuous flow of fluid through a cannula positioned in direct proximity of the surgical site, the improved cannula including a handle, a pair of portals, and a trephine.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is broadly directed to improvements in instruments for arthroscopic surgery and, more particularly, to a device which provides improved visibility of the surgical site during arthroscopy on the vertebral pedicle. 
       BACKGROUND OF THE INVENTION 
       [0002]    Modern surgery tends toward minimally invasive techniques whenever possible because they reduce pain and accelerate healing. Although often more complicated in some ways for the surgeon, minimally invasive techniques result in less trauma to the patient and less scarring because of much smaller incisions thereby promoting faster healing and reducing possibilities for infections. In general, minimally invasive surgeries involve making one or more small incisions at appropriate locations and inserting tubular devices through the incisions to the surgical site. Arthroscopic surgery typically requires visibility of the surgical site, and in many cases, it is necessary to inspect the surgical site prior to performing a procedure. During the procedures, byproducts from use of instruments, debris, and blood can enter the space around the surgical site and cause poor visual clarity. 
         [0003]    Depending on the procedures, different techniques are relied upon to maintain good visibility. To help improve visibility, some surgeons rely upon the cannulae or the effective removal of debris. However, when there is limited room to maneuver within a surgical site, and because of the close proximity, it is desirable to maintain accessibility while limiting any visual obstructions from the surgical site. One feature of good visibility is the effective removal of surrounding debris. Another is that the user has an unobstructed view of the instrument in contact with the tissue and the view of the tissue not be obscured by the instrument. 
         [0004]    In a typical procedure, removal of debris from the visual field is accomplished by aspirating debris from the surgical site via an inner rotating lumen, which is connected to an external vacuum source. However, in some procedures the surgical site is too delicate and small for surgical tools that aspirate debris and remove that debris through an external vacuum source. Moreover, many procedures create little debris, and the use of an external vacuum source is unnecessary. When there is minimal debris and the visual field is primarily obstructed by blood flow, devices relying on external suction are ineffective. Such procedures would require different tools and different methods for maintaining visibility of the surgical site than those currently known in the art. As such, there is currently a problem with maintaining visually clarity in a small and delicate surgical site. 
         [0005]    There is a need for an improved cannula, which provides for improved visibility during surgery while not obstructing contact with the tissue. In addition, there is a need for an improved cannula with characteristics to prevent and remove blood from entering the surgical site, which enhances the surgeon&#39;s visibility in procedures where visibility is required. 
         [0006]    The current invention addresses this problem by visual clarity of a surgical site with the use of the present invention. In one embodiment, the current invention provides a continual flow of fluid to a surgical site, allowing for removal of visually obstructing debris and blood from the surgical site and providing for improved visual clarity at the surgical site. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is a cannula that provides improved visibility at a surgical site through the continuous flow of fluid through a cannula positioned in direct proximity of the surgical site. The invention includes a handle, a pair of portals, and a trephine. 
         [0008]    An embodiment of the invention includes a handle communicating with a trephine terminating distally therefrom. The handle will remain external to the patient, while the trephine will be inserted through an incision toward the surgical site. A side portal and a rear portal, respectively, communicate with the handle. Generally, the rear portal is aligned with the trephine but spaced from the trephine by the handle. Internally, the handle contains a central mixing chamber that allows for simultaneous fluidic communication between the side portal, the rear portal, and the surgical site through the trephine. The trephine is configured to establish and maintain a hermetic seal with a membrane of the surgical site such as a vertebral pedicle. 
         [0009]    The trephine includes a conical trephine body terminating distally in a trephine tip, which may be conically tapered. The trephine tip contains a plurality of flow apertures adaptable for the inflow or outflow of fluid at the surgical site. In an alternative embodiment the trephine tip includes a plurality of elongated slots which are adapted for the inflow and outflow of fluid. The trephine has an internal trephine mixing chamber with a diameter sufficient for receipt of endoscopic instruments while is passed simultaneously therethrough. The trephine may be constructed from any suitable material, such as stainless steel, a polymer, or the like. 
         [0010]    The present invention is used to provide visibility to a surgical site through the controlled continual flow of fluid, while endoscopic instruments are extended through the trephine chamber and beyond the trephine tip into the surgical site. The trephine is inserted through an incision and forms a hermetic seal with a membrane or barrier to the surgical site. In operation, an endoscopic instrument may be inserted through the rear portal and passed through the trephine chamber for placement along the trephine. A pressurized fluid source may be secured to the side portal of the handle. The fluid from the fluid source enters through the side portal of the handle, travels through the internal mixing chamber to the trephine and exits through the trephine tip into the surgical site providing improved visibility. The pressurized fluid source may include an irrigant such as water, a saline solution, or other solution of a type that would be used to irrigate a surgical site. The fluid source generally provides a positive pressure to the surgical site, the fluid source presenting a pressure greater than the patient&#39;s blood pressure which may range between 60 and 160 mm of Hg. 
         [0011]    In an alternative embodiment, a trocar or other endoscopic surgical instrument is received by the rear portal of the handle and extended through the trephine chamber beyond the trephine tip. The trocar having a rear cap and trocar body extending distally therefrom with a length greater than the cannula. The rear cap is capable of communicating with the rear of the handle to form a lock, which holds the trocar in place. The trocar being adapted for extension through the trephine chamber and beyond the trephine tip into the surgical site. 
         [0012]    In an exemplary embodiment of the invention, the trephine is inserted into a patient&#39;s pedicle with the outer surface at the distal end of the trephine making a hermetic seal with the proximal end of the patient&#39;s pedicle. The trocar is then received by the rear port of the handle and inserted through the trephine. The trocar cannulates the pedicle and in doing so, compresses cancellous bone tissue within the pedicle centrifugally thereby reducing blood flow from the internal surface area of the pedicle. The fluid source is connected to the side portal of the handle and fluid travels into the internal area of the patient&#39;s pedicle. The hermetic seal prevents fluid from escaping and keeps the pressure of the fluid higher than the patient&#39;s blood pressure. An internal endoscope is then positioned along the internal surface of the trephine towards the surgical site in such a manner that still allows for fluid to flow in the same direction. The fluid continues to flow into the internal area of the patient&#39;s pedicle when the internal endoscope is moved beyond the trephine tip and allows for a clear view of the internal bony surface of the patient&#39;s pedicle. The surgeon may then visually inspect the internal area of the patient&#39;s pedicle. 
         [0013]    Additionally, the trocar is slightly larger in diameter than the endoscope, which allows the endoscope to be telescoped through the path created by the trocar in the pedicle. 
         [0014]    Various objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings submitted herewith constitute a part of this specification, include exemplary embodiments of the present invention, and illustrate various objects and features thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a top elevation view of an embodiment of the present invention. 
           [0016]      FIG. 2  is a side elevation view of  FIG. 1 . 
           [0017]      FIG. 3  is a cross-sectional view taken on line A of  FIG. 2 . 
           [0018]      FIG. 4  is a side elevation view of an embodiment of the present invention with a surgical instrument. 
           [0019]      FIG. 5 . is a side elevation view of an alternative embodiment of the present invention. 
           [0020]      FIG. 6  is a side elevation view of the cap. 
           [0021]      FIG. 7  is a side elevation view of the trocar. 
           [0022]      FIG. 8 . is a side elevation view of the trocar with an alternative tip. 
           [0023]      FIG. 9 . is a side elevation view of the trocar with an alternative tip. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0025]    Referring to the drawings in more detail, the reference numeral  10  generally designates an embodiment of the biflow spinal cannula instrument (hereinafter “cannula”). The cannula includes a handle  20  with a trephine  30  extending distally therefrom. 
         [0026]    As depicted in  FIGS. 1-3 , an embodiment of the cannula  10  includes a handle  20  that contains a central mixing chamber  26 . The handle  20  is acorn-shaped with a plurality contoured elongations along the surface for grip. A side portal  22  radially extends outward from the handle and is adapted for receipt of a fluid source. A first chamber  23  extends inwardly from the side portal  22  through the handle  20  to the central mixing chamber  26  for fluidic communication therebetween. A rear portal  24  extends proximately from the rear of the handle  20  and is adapted for the receipt of other endoscopic instruments, including a trocar  40  or visual instrument. A second chamber  25  that extends inwardly from the rear portal  24  through the handle  20  to the central mixing chamber  26  for communication therebetween. 
         [0027]    The rear portal chamber  25  may also include an o-ring  28  presenting a hermetic seal limiting fluid flow through the rear portal while permitting removable receipt of a plurality of various surgical instruments, including but not limited to a trocar or optical instrument received at the rear portal  24 . 
         [0028]    A trephine  30  extends from the handle  20  with the trephine  30  being axially aligned with the rear portal  24 . Both the side portal  22  and the rear portal  24  may include repeatable releasable locking mechanisms (not shown) to hold fluid sources and/or instruments received by the cannula  10  in place during use. One such example may include but is not limited to a leur lock. 
         [0029]    In one embodiment of the cannula  10 , the trephine  30  extends forwardly from the handle  20  and includes a conical trephine body  32 , which terminates distally at a trephine tip  34 . The proximal end of trephine body  32  has a barbed flange which is adjacent to the handle  20 . As illustrated in  FIGS. 1-5 , a plurality of flow apertures  35  also referred to as sidewall apertures are located on opposite sides of the trephine top  34  and are adapted for the inflow and outflow of fluid as desired during surgical procedure where the trephine tip may be obstructed with, for example, a surgical instrument or surrounding tissue or bone. 
         [0030]    Alternative flow apertures (not shown) may be positioned along the outer surface including a plurality of elongated slots or apertures (not shown) being positioned near the trephine tip  34  and further adapted for the inflow and outflow of fluid from the surgical site. 
         [0031]    The trephine  30  illustrated in  FIGS. 1-3  contains a chamber  36  that extends continuously with a constant radius from the central mixing chamber  26  and through the trephine body  32  terminating at the trephine tip  34 . The trephine  30  contains an outer surface  32  and the trephine chamber  36  contains an inner surface  37 , the outer surface and inner surface being radially separated by a sidewall thickness, which generally corresponds to the thickness of the trephine  30  and may vary according to the desired fabrication methods and desired operational characteristics. The trephine chamber  36  is in fluidic communications with the central mixing chamber  26  and is adapted for simultaneous receipt of fluid from the fluid source at the side portal  22  and surgical instruments received from the rear portal  24 . 
         [0032]    As illustrated in  FIG. 5 , an alternative trephine  60  may include a plurality of vertically spaced indicia  62 , the indicia circumscribing the trephine  60 , with each indicia extending along the trephine outer surface near the distal end of the trephine  64 . Each indicia corresponds to a given location. By way of example, the indicia illustrated in  FIG. 5  are positioned coaxial to the side portal  22  and generally allow for localization of fractures or other pathology associated with the surgical site. 
         [0033]    The central mixing chamber  26  simultaneously communicates with each of the side portal chamber  23 , the rear portal chamber  25 , and the trephine chamber  36 , independently. In this manner, the trephine chamber  36  can simultaneously communicate with the side portal  23  and the rear portal  25 . Thus, the trephine chamber  36  can simultaneously and continuously receive fluid from the fluid source at the side portal chamber  23  and surgical instruments from the rear portal chamber  25 . 
         [0034]    In an alternative embodiment, a trocar  40  can be inserted into the rear portal  24  through the central mixing chamber  26  and the trephine chamber  36  and into the surgical site. The trocar has body  42 , a tip  44  at the distal end, and a top  46  at the proximal end. The tip  44  may have multiple embodiments as shown in  FIGS. 7-9 . The tip may be sharp  44   a  or blunt  44   b  based upon the desired operational characteristics. 
         [0035]    In an additional embodiment, a cap  50  may be placed on the rear portal  24  in order to shorten the working length of surgical instruments received by the rear portal  24 . The cap  50  contains an aperture  52  adapted for receipt of surgical instruments including the trocar  40 . The cap  50  may also include an o-ring  54  adapted for creating a hermetic seal with received surgical instruments. Further, the cap contains a locking mechanism  56 , such as but not limited to a leur lock so that it may be held in place when adapted to the rear portal  24 . 
         [0036]    It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.