Patent Publication Number: US-2012029280-A1

Title: Arthroscopic System

Description:
This application is a continuation-in-part of U.S. Application No. 13/106,078 filed May 12, 2011, which is a continuation-in-part of U.S. application Ser. No. 12/846,747 filed on Jul. 29, 2010. 
    
    
     FIELD OF THE INVENTIONS 
     The inventions described below relate to the field of arthroscopic surgical instruments. 
     BACKGROUND OF THE INVENTIONS 
     Arthroscopic surgery involves using optical instruments, such as an arthroscope, to visualize an operating field inside or near a joint of a patient. The same instrument or other instruments may be used to perform a surgical procedure in the operating field. 
     Known inflow and outflow arthroscope systems generally consist of several elements, which include a flexible or rigid tube, a light that illuminates the area the doctor wants to examine (where the light is typically outside of the body and delivered via an optical fiber system), a lens system that transmits an image to the viewer from the arthroscope and another channel that allows the entry of medical instruments or manipulators. The lens systems typically use pre-manufactured square or rectangular shaped CCD chips. Traditionally, arthroscopes are circular so that the arthroscope does not have sharp edges that may cause trauma to tissue. When the chips are housed within the arthroscope, this results in a great amount of wasted space between the square chips and the circular arthroscope that houses the chips. 
     In addition, current arthroscopes that use metal sheaths are prone to damage if the metal is touched with an RF wand. This stray RF current can damage the lens of the arthroscope or damage an imaging chip. 
     SUMMARY 
     The devices and methods described below provide for an arthroscope having square or rectangular lateral cross section herein after referred to as a rectangle or rectangular. The arthroscope can be used in an arthroscopic system that also includes a scope sheath that is matched to the dimensions of the arthroscope. The system includes a flow system, which sends fluid out of the end of the endoscope and brings debris and other fluid behind the field of view, thus allowing the surgeon to have a clear field of view while using the system. 
     This architecture allows the arthroscope to have a low profile thus making it less traumatic once introduced into anatomic spaces. Further, configuring the arthroscopic cross-section into the shape of the pre-manufactured CCD chip image configurations reduces costs associated with the manufacture of the scope. 
     To enhance the effectiveness of the systems, the arthroscope includes a protective cap for use over the distal tip of the arthroscope. The cap is constructed of a non-conductive polymer. The portion of the cap that covers a view port on the arthroscope is transparent. The cap protects the distal end of the arthroscope from accidental damage and also emits light from the tip of the arthroscope. The cap contains two tubes or pipes that terminate in openings on the cap. The cap also contains LEDs positioned on the proximal end of the tubes or pipes. Positioning the LEDs at the proximal end of the tubes or pipes provides the advantage that the imaging chip does not require a ring of LEDs around the cap and thus provides more space for the imaging chip which advantageously increases the space available for the imaging chip. It also provides the advantage that the imaging chips can allow for high light sensitivity with low illumination requirement from the LEDs. Also, the position of the LEDs allows irrigation fluid passing through the inflow channel to cool off the imaging chips and imaging sensor, resulting in less image noise. In addition, because the cap is constructed of a non-conductive polymer, the imaging chip is isolated and therefore protected from stray RF current. 
     The device provides for variable view angles in a single endoscope. The most common angles of view in an endoscope are 0 degrees (cystoscopy) 30 degrees (the most common arthroscope view angle) and 70 degrees (for difficult to visualize areas). A range of view angles may be produced in one scope, eliminating the need for having multiple view angle scopes in stock, or needing to remove and replace the scope to switch viewing angles. One way to achieve this is to deflect the chip view plane to the desired angle, by means of, for example, a pushrod. In another embodiment, two or more cameras are mounted to an angled face and the user selects a camera corresponding to the desired viewing angle. 
     The digital scope embodiments lend themselves to the ability to bend the scope shaft to gain access to anatomy not accessible with a straight rigid scope. Because of the architecture of the scope, the endoscope has the ability to have a variable angle of view, with the scope shaft bent at an angle. The angle of the shaft may either be pre-molded and fixed, or malleable and the bend angle and radius may be selected by the user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an arthroscope having a sheath that encloses an elongated core that has a square radial cross section, the elongated core has an imaging element on the distal end. 
         FIG. 2  illustrates a cross-sectional view along Line A-A of  FIG. 1 . 
         FIG. 3  illustrates an arthroscope having an optical cap. 
         FIG. 4  illustrates the features of the arthroscope pulled apart. 
         FIGS. 5   a  and  5   b  illustrate the elongated core of the arthroscope before it is folded into its final configuration. 
         FIG. 6  illustrates the elongated core of the arthroscope in its final folded configuration. 
         FIGS. 7   a  and  7   b  illustrate another elongated core before it is folded into its final configuration. 
         FIG. 8  illustrates another elongated core configuration. 
         FIG. 9  illustrates an elongated core with a square tube or solid mandrel for additional rigidity. 
         FIG. 10  illustrates a method of performing arthroscopic surgery on a patient using an arthroscope containing an elongated core with a square radial cross section. 
         FIG. 11  illustrates an arthroscope where the fluid management is contained in a grommet-type cannula. 
         FIG. 12  illustrates an arthroscope that can be used without requiring a user to hold it, providing the user the opportunity to use the arthroscope hands free. 
         FIG. 13  illustrates an arthroscope with a molded optical cap and 3-D positioning sensors. 
         FIG. 14  illustrates an optical cap for use with an arthroscope system and its features. 
         FIG. 15  illustrates a side view of the optical cap. 
         FIG. 16  illustrates an arthroscope having a variable view angle. 
         FIG. 17  illustrates the distal end of the arthroscope of  FIG. 16 . 
         FIG. 18  illustrates the distal tip of the arthroscope of  FIG. 16 . 
         FIG. 19  illustrates a top view of  FIG. 18 . 
         FIG. 20  illustrates a cross-sectional view of the distal tip shown in  FIG. 18 . 
         FIGS. 21 and 22  illustrate a nitinol mechanism for deflecting the camera. 
         FIG. 23  illustrates an arthroscope having a solid state variable view angle. 
         FIG. 24  is an exploded view of the distal tip of the arthroscope of  FIG. 23 . 
         FIG. 25  is an exploded cross-section view of  FIG. 23 . 
         FIGS. 26 and 27  illustrates an arthroscope with an angled shaft. 
         FIG. 28  illustrates a cross section view of  FIG. 27 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTIONS 
       FIG. 1  shows an arthroscope  1  having a sheath that encloses an elongated core having a square radial cross section (see  FIG. 2 ). Contained centrally within a sheath  2 , the elongated core has a square imaging chip  3  located at the distal end of the elongated core. The elongated core and the imaging chip together form the imaging core of the arthroscope. An atraumatic tip  4  at the distal end may also encase the imaging chip. The elongated core has a square radial cross section that allows for the largest possible rectangular chip image package to be used in combination with the smallest possible round fluid sheath outside diameter. This combination allows a clear pocket flow system, which sends fluid out of the end of the arthroscope and brings debris and blood behind the operator&#39;s field of view. The system contains fluid outflow  5  and fluid inflow channels  6 . These channels are defined by the space created between the elongated core and the circular sheath surrounding it. 
       FIG. 2  illustrates a cross-sectional view along Line A-A of  FIG. 1 . Fluid enters the inflow channels  6  and flows axially into the joints. Fluid exits through the outflow channels  5  and comes behind the distal end of the arthroscopic sheath system and pulls blood and debris behind the field of view of the user. The fluid flow is perpendicular to the system creating a pocket of clear fluid in front of the system where it is needed the most. An elongated core having square radial cross section  7  is inserted into the sheath  2 . The inner surface of the sheath  2  can have an extruded profile for mating with the outer surface of the elongated core  7 . The outer surface of the elongated core has tabs  8  that mate tightly with the inner surface of the sheath in order to ensure that the elongated core does not rotate within the sheath. The force of the elongated core pushing against the inner surface of the sheath forms a seal between the elongated core  7  and the inner surface of the sheath  2 . As shown, fluid inflow  5  channels and fluid outflow channels  6  are created between the outer sheath  2  and the elongated core  7 . 
       FIG. 3  illustrates an arthroscope  1  having an optical cap  9 . The arthroscope has an ergonomic handle  10  for user comfort. The handle contains user control switches  11  that can provide focusing means for controlling the optical zoom of the system. At the distal end, the arthroscope also contains an electronics cable  12  and fluid inflow and outflow tubing  13 . Positioning of the electronics and fluid tubing eliminates clutter of conventional arthroscopes. The optical cap  9  is made of a plastic material and is located at the distal end of the arthroscope. The optical cap  9  may serve as the objective lens if one is not integrated into the imaging chip and associated package. Alternatively, the cap  9  may serve as a protective window, either optically clear or with optical modifying properties such as polarization or color filtering. The arthroscope also contains a fluid drain and sensor window  14 . A clear pocket flow of fluid flows axially to the system outflow from the distal end of the system. Drainage flows through openings  15  in the sheath  2 . Flow in this direction creates a clear fluid pocket in front of the arthroscope where it is required the most. 
       FIG. 4  illustrates the features of the arthroscope  1  pulled apart. The distal end of the elongated core has a multifunction connector  16  for use with the video, pressure and temperature sensors. A round fluid sheath  2  is placed over the elongated core  7  and connected via a hub  17 . The hub can be coupled to a multi-channel fluid manifold. The outside diameter of the sheath closely matches the radial cross section of the elongated core to minimize the shape of the arthroscope. When engaged, the inner surface of the external sheath and the outer surface of the elongated core define a plurality of fluid channels extending longitudinally within the arthroscope. The fluid sheath can also have a rectangular radial cross section closely matching the radial cross section of the elongated core. 
       FIGS. 5   a  and  5   b  illustrate the elongated core  7  of the arthroscope before it is folded into its final configuration.  FIG. 5   a  illustrates the base of the elongated core. The elongated core is constructed onto a flat molded backing  18 . The backing  18  contains folds to create hinge points  19  that allow the backing to fold into the square configuration. The degree to which the folds are rotated allows the angle of the imaging chip to vary according to user preference. Pivot points  20  are contained at each end of the backing for connection of the top and bottom faces of the elongated core.  FIG. 5   b  illustrates the molded backing  18  with a flex circuit  21  laminated onto the molded hinge backing. The flex circuit  21  contains a pressure sensor  22  and a temperature sensor  23  as well as an imaging chip and its sensor module and associated lens  24 . The lens can be made of plastic or other similar material to assist in insulating the imaging chip and the inside electronics from damage. In addition, an edge connector  25  is contained on one end of the molded backing for connection to desired system input or power devices. 
       FIG. 6  illustrates the elongated core of the arthroscope in its final folded configuration. At the distal end the elongated core houses the digital image CCD or CMOS chip and a sensor module  24  to enhance image magnification clarity and color. At the proximal end, the elongated core contains a multifunction edge connector  25  for use with the temperature  23  or pressure signal  22  connectors and to carry video signal. This elongated core is open on both sides. The elongated core  7  is formed by folding over the backing  18  and connecting the top and bottom backing faces at the pivot points  20 . The elongated core shape is dictated by the combination of the square chip and associated chip package that are of pre-determined sizes and commercially available. The elongated core may contain one or multiple digital image chips within a single arthroscope. Longitudinal movement of a first face of the backing relative to a second face of the backing changes the angle of digital image CCD or CMOS chip to vary relative to the radial plane of the elongated core. The imaging end enables an indefinitely adjustable view angle from 0 degrees to 90 degrees in a single scope. The arthroscope can also accommodate for a 180 degree or retrograde view where the arthroscope has a flat top construction and a rotatable or living hinge rectangular arthroscope architecture. The elongated core  7  can be releasably mounted to a base such that the core can be sterilized and reused for a number of surgical procedures. 
       FIGS. 7   a  and  7   b  illustrate another elongated core  7  before it is folded into its final configuration.  FIG. 7   a  illustrates the backing  18  of the elongated core. The elongated core is constructed onto the molded backing  18  that contains protrusions  26  spaced apart at a predetermined distance. The protrusions on each face are matched to mate when in a folded configuration. When folded, the protrusions construct a solid elongated core. The elongated core has a square radial cross section with a proximal end, a distal end spaced from the proximal end for insertion into a body, a top surface, a bottom surface. The elongated core also has two opposite side surfaces adjacent to the top and bottom surfaces. At least one of the surfaces may contain a metal strip bonded to the top of the surface. The metal strip may be a spring steel or nickel-titanium alloy with a preformed radius of curvature. The metal alloy may alternatively be a malleable metal such as aluminum or may be a nickel-titanium (nitinol) alloy with a shape memory feature. The metal strip allows the elongated core to reliably bend in one plane of curvature. Where the memory backing is spring-steel or nitinol, it may bend to a shape if malleable, or may be made steerable with a nitinol shape-memory component. 
     The elongated core contains planes that provide structural rigidity to the elongated core. The protrusions can have a locking taper construction. In addition, the protrusions can be joined with an adhesive or can be welded together thermally or with ultrasonic welding techniques. The elongated core also contains an imaging device chip fitted at the distal end of the elongated core where the imaging surface is arranged in a viewing direction of the elongated core. In addition, the elongated core has an illumination source at the proximal end for illuminating a surgical site at which the arthroscopic sheath system is directed. The core backing  18  contains folds that create hinge points  19  to allow the backing to fold into a rectangle. Pivot points  20  are contained at each end of the backing for connection of the top and bottom faces of the elongated core.  FIG. 7   b  illustrates the molded backing  18  with a flex circuit  21  laminated onto the molded hinge backing. The flex circuit  21  contains the pressure and temperature sensors  22 ,  23  as well as the imaging chip and its associated LED package  24 . In addition, the edge connector  25  is contained on one end of the molded backing. 
       FIG. 8  illustrates another elongated core configuration. The distal end of the elongated core  7  houses the digital image CCD or CMOS chip and sensor module  24 . The distal end can also contain imaging modalities other then visible light devices such as ultrasonic transducers and optical coherence tomography (OCT) imagers in addition to the CCD and CMOS video imagers. At the proximal end, the elongated core contains a multifunction edge connector  25  for use with temperature or pressure signal connectors. The intermediate body of the elongated core is in the form of vertebrated or specifically profiled sections  27  located at a predetermined distance from each other to enhance steerability of the elongated core when inserted into the patient. The elongated core is transversely slotted along its entire length to form this configuration. 
       FIG. 9  illustrates an elongated core with a square tube or solid mandrel for additional rigidity. The rectangular mandrel may serve as an illumination conduit. The assembly has an optically transparent light pipe center core  28  that allows light to pass through. Illumination light emanating from a light source apparatus passes through the transparent core, is converged by a lens, and falls on the opposing end surface of the illumination conduit. The illumination light is transmitted to the arthroscope over the illumination conduit, passes through the arthroscope, and is emitted forward through the distal end of the arthroscope. Thus, an object in the patient&#39;s body cavity is illuminated. An image represented by the light reflected from the illuminated object is formed by the arthroscope. A resultant object image is projected by the imaging means through the scope. The optically transmitting center core is a rectangular shaped housing or mandrel made of a molded plastic material that can transmit light from the proximal end and out of the distal end. The center core is made of any clear molded polycarbonate or acrylic plastic material that can be easily molded. The molded plastic mandrel has an LED illumination module  29  at the proximal end and the assembly circuitry  30  is wrapped around the center core. The edge connector  25  is also contained at the proximal end of the assembly. The chip imaging module  24  is contained at the distal end of the assembly. In addition, the distal end of the assembly serves as the transmitting end of the light pipe created by the center core. The advantage to the assembly is that it has a small cross-section, but is very robust and easy to use. The assembly is inexpensive to manufacture and provides adequate illumination to the arthroscope. 
       FIG. 10  shows a method of performing arthroscopic surgery on a patient  31  using an arthroscope in an atraumatic sheath  2 . Various anatomical landmarks in the patient&#39;s knee  32  are shown for reference, including the femur  33 , patella  34 , posterior cruciate ligament  35 , anterior cruciate ligament  36 , meniscus  37 , tibia  38  and fibula  39 . During surgery, the surgeon introduces the arthroscope into the knee via a first incision  40  in order to visualize the surgical field. A trimming instrument  41  is introduced through a second incision  42  to remove or trim tissue that the surgeon determines should be removed or trimmed. 
       FIG. 11  illustrates an arthroscope where the fluid management is contained in a grommet-type cannula. The arthroscope has an angle set collar  45  and an elastomeric portal cannula  46 . When the collar is not pressed to the elastomeric cannula, the scope set perpendicular to the portal. When the sleeve is pushed forward, the scope is angled in the portal. Where the collar is rotated, the arthroscope can be directed to an area of interest radially within the surgical space. The ability to translate, rotate and hold the scope can be accomplished with a ball gimbal or other similar means. This frees the hands of the surgeon to use their instruments rather than have to hold the arthroscope in position. 
       FIG. 12  illustrates an arthroscope that can be used without requiring a user to hold it, providing the user the opportunity to use the arthroscope hands free. The arthroscope has an angle set collar  45 , an elastomeric portal cannula  46  and a grommet cannula  47  to allow for fluid inflow and outflow through the grommet cannula. The fluid and gas management connections are removed from the arthroscope. The arthroscope also contains a wireless scope  48  that accommodates for multiple scopes to communicate on a network. This allows the arthroscope to be wireless and untethered by either wires or fluid tubes and instead to be aimed and held on a point of interest. This provides the advantage that the surgeon can use both hands while operating on a patient and can be useful in telemedicine applications. The arthroscope is wireless and can be networked together with a ZigBee, MESH or Bluetooth wireless network. 
       FIG. 13  illustrates an arthroscope with a molded optical cap and 3-D positioning sensors. Spatial positioning and tracking sensors  49  can be attached to 3 of the 4 orthogonal sides of the arthroscope. These sensors can read optically, ultrasonically, or with an RFID system. The positioning and tracking system allows the arthroscope to be positioned accurately in space and can be used to guide surgical instruments and provide accurately guided cutting of tissue. In addition, due to the arthroscope&#39;s flat surface, a linear encoder  50  can be added to the arthroscope using circuit printing lithography techniques. This can be used to accurately gauge the depth of penetration of the scope into the surgical field. A reader  51  for the linear encoder is disposed within an access cannula. The data from the 3-D positioning and tracking means  49  and linear encoder  50  may be transmitted for display and processing either wired, or wirelessly. The 3-D and linear positioning encoders may be on two or more arthroscopes and can communicate and network together with a ZigBEE MESH network, Bluetooth 802.11 or other wireless protocol. The 3-D positioning and tracking can be useful for robotic surgery, virtual template aided surgery, augmented reality surgical visualization and high-risk surgery, or implant surgery where geometrically accurate cutting is essential to the proper alignment of a device such as an orthopedic implant. The system also has an optical cap  52  to protect the imaging chip from fluids. The cap is molded of acrylic, polycarbonate, or other appropriate optically clear plastic. The cap may be molded with a spherical lens, an aspheric lens, or a split stereoscopic lens that projects a binocular image on to the imaging chip. The central square rod may have a structural center core (e.g. stainless steel or titanium), to give the scope strength, and the perimeter of the rod may be clad with an optically clear light pipe of a light-transmitting plastic. The rod is illuminated at the proximal end with an LED light source or a fiber optic cable, and the light is transmitted through a pipe light, through the optical cap  52  out the distal end to illuminate the surgical field. On the perimeter, the optical cap may have a condensing lens feature, or a light diffusion means to tailor the illumination to the clinical needs of the surgeon. The system may be used with a fluid management sheath and means previously disclosed. Also the ability to build 100% polymer and non-ferrous arthroscope allows its use in radiology guided applications where the materials must be non-magnetic, such as under MRI applications. 
       FIG. 14  illustrates an optical cap  54  for use with an arthroscope system. The optical cap  54  has a cap face  55  that is optically clear and can have a plain transparent viewing window  56  or can be molded as a lens element. The optical cap is made of any optically clear biocompatible and moldable polymer, acrylic, optical polycarbonate, or other moldable optically clear plastic or non-conductive polymer. The optical cap may also be made of any optically clear silicon. The cap protects the distal end of the arthroscope from accidental damage and also emits light from the distal tip of the arthroscope. The cap face contains fluid channels  57  to allow the inflow of fluid into the surgical space. The cap also includes at least two inserted molded tubes or pipes  58 ,  59  for transport of light through the tubes with minimal loss of light. The tubes or pipes  58  can be light pipes or prisms that terminate at openings  60  at the distal end of the cap located on the cap face. Each light pipe contains a 45 degree prism or mirror  61  at the proximal end of the light pipe that directs light from the LEDs out of the end of the optical cap into the surgical space to facilitate the emission of light from the distal tip of the arthroscope. The cap also includes a first LED  62  and second LED  63  (shown in  FIG. 15 ) where each LED is located on the proximal end of the tubes or pipes  58 . The LEDs may also be mounted on the flat, flexible circuit board laminated to the molded and foldable mandrel shown in  FIG. 7   b.    
     The LEDs are preferably mounted in a direction orthogonal to the direction of emission of light from the distal end of the cap. The openings on the cap face allow for light output and also condense projected light from the LEDs. The cap may also include an indentation or molded-in lens to condense projected light. Light reflected off the prisms or mirrors is transmitted out of the front of the cap at the distal end of the arthroscope. The emitted light from the LEDs shine onto and reflect off of the prism or mirror and projects out from the distal tip of the arthroscope. The LEDs produce white light in the ultraviolet (UV) and the near infrared (NIR) ranges. Each light pipe is coated with an anti-dispersive coating or cladding to facilitate shining of light through the interior of the arthroscope. 
       FIG. 15  shows a side view of an optical cap. The cap contains at least two light pipes  58 ,  59 , each light pipe having an angled prism or mirror  61  at the proximal end of each light pipe. Each light pipe contains an LED positioned at the proximal end of the tube or pipe. Light emitted from the LEDs is reflected off of the mirror surfaces and projected out of the distal end of the arthroscope. The cap face is positioned over the distal tip of the arthroscope to protect the arthroscope from damage. The cap face can be of various viewing angles according to the surgical application viewing requirements. The cap face can have a 0 degree or blunt face for use with hysteroscopes. A 30 degree tip angle can be used for arthroscopes while a 70 degree tip angle can be used for special viewing applications in arthroscopy. The distal end of the cap can also include a molded in lens on the larger optical cap surface or fly eye to allow light to be locally focused. The smaller molded in lens on the larger cap surface eliminates the need for secondary assembly procedures. Additionally, the arthroscopic system can include an accessory channel for delivering fluent medications, tissue adhesives, needles, anchors or sutures. 
       FIG. 16  illustrates an arthroscope which provides for variable angle viewing. An angle of view selector  70  is embedded in the handle  71 . The variable angle of view may range from 0 to 90 degrees, and in particular, 0, 30 and 70 degrees are the most common viewing angles used in arthroscopic surgery. The distal tip provides a digital imager (detailed in  FIG. 17 ). This embodiment uses an articulated video module in conjunction with features previously described, including the square scope, the optical cap, fluid inflow and outflow, all within a minimal cross-section fluid tube. This embodiment also supports temperature and pressure sensing previously described. The device also contains a position encoder for the video module pushrod, which senses the viewing angle of the scope. The proximal end  72  provides for fluid, electronic and video connection, as well as flow, temperature and pressure measurements. 
       FIGS. 17 and 18  detail the distal tip of the instrument.  FIG. 17  shows the variable angle arthroscope of  FIG. 16 . One way to achieve the variable angle viewing is to deflect the chip view plane to the desired angle. As shown, a chip camera module is actuated with a pushrod to provide for different viewing angles. The pushrod  73  enclosed within square support core  74  swings a pivoting camera  75  in positions ranging from 0 degrees to 90 degrees, in particular, 0, 30 and 70 degree viewing angles. Though a pushrod is shown, other mechanisms may be used for deflecting the imaging chip, such as a pullwire or jackscrew. A curved optical cap  76  allows for camera swing. A curved window  77  eliminates optical distortion. The cap contains fluid channels  78  to allow the inflow of fluid into the surgical space. Fluid flows out through sheath  79  via the outflow port  80 . Encoders may also be used to communicate to a video processor the angle of view. The view angle is displayed on a video monitor (not shown). A variable viewing angle allows the surgeon to change from a 0 to a 30 to a 70 degree angle of view without the need to change scopes. The surgeon can also pan the anatomy to get a better view of an arthroscopic workspace. 
       FIG. 19  illustrates a top view of the distal tip of the arthroscope shown in  FIG. 16 .  FIG. 20  shows a cross-sectional view of  FIG. 19 . The variable angles of the imaging camera are shown. 
     Other mechanisms may be employed to swing the pivoting camera. As shown in  FIGS. 21 and 22 , the camera may be deflected using a shape-memory nitinol wire or shape memory spring that is resistively heated to change its length or generate push or pull force, and thus provide the actuating force to deflect the camera. This has the advantage of being able to pan the camera without the need for a mechanical pullwire or pushrods mechanically actuated from the proximal handle. This allows for reliable actuation even when the shaft is bent at an acute angle, as the actuation is generated with an electric current via a wire  87 . The nitinol shape memory actuator  88  is trained such that, when heated, it shortens to pull on the pivoting camera  75  to deflect it (as shown in  FIG. 22 ). (Conversely, the actuator may be trained to lengthen upon heating, and push the camera to make it pivot.) A biasing spring  89  pulls the camera to “home” position when the resistive heating current stops and the nitinol actuator returns to its original longer shape (as shown in  FIG. 21 ). 
     In the embodiment shown in  FIGS. 23 and 24 , a variable view angle is achieved by means of two or more imaging devices that are attached to planar surfaces at a pre-set viewing angles (item  90 ). In the example shown, the endoscope has three pre-sets for 0 degrees, 30 degrees, and 70 degrees, as shown in  FIGS. 24 and 25 . The user selects the imaging device at the desired angle of view  91  (discrete angle view). The imaging devices may also operate simultaneously and the images stitched together in software to generate a panoramic view  92  (stitched view). 
     The digital scope has a clear optical cap. The cap may contain focusing lenses or optical filters including polarization, and wavelength filtering. The endoscope has a light source that illuminates the surgical field through the optical cap. The optical cap  93  with fluid management capability  94  covers the imaging devices, and a fluid management tube  95  covers the shaft of the endoscope. This produces two or more fluid channels with the outer tube circumscribing the rectangular core of the endoscope. 
       FIGS. 26 ,  27 , and  28  illustrate an arthroscope which provides for variable angle viewing in a bent shaft  100  configuration. This embodiment allows the viewing angle of the camera at the distal end to be changed, and allows the camera shaft to be bent at an angle. The pullwire  101  to actuate the view angle lie in tracks in the i-beam shaped extrusion, and the wiring for the camera module goes through the conduit track  102  in the center of the extrusion. This allows enough slack in the data wires to allow movement of the video module at the distal end. The angle of view is controlled with a steering device  103  on the handle  104 . The angled shaft may be either rigid and fixed, or the shaft may be malleable, and set to a desired angle by the user. The angled shaft embodiment may have a fluid management tube and an optical cap with a fluid management means as previously described. 
     The digital scope embodiments lend themselves to the ability to bend the scope shaft to gain access to anatomy not accessible with a straight rigid scope. Because of the architecture of the scope, the endoscope has the ability to have a variable angle of view, with the scope shaft bent at an angle, as well as all of the other capabilities previously noted. The angle of the shaft may either be pre-molded and fixed, or malleable and the bend angle and radius selected by the user. 
     In use, a surgeon inserts the elongated core into the sheath of corresponding size. The elongated core creates the most space efficient configuration in that the insertion of the elongated core into the smallest complimentary circular shaped sheath eliminates wasted space. In addition, the arthroscope allows for an efficient clear pocket view flow of fluid inflow and outflow to create a clear field of view for the surgeon. Also, the arthroscope can be used as a retractor once inserted in the patient. 
     Alternatively, in use, a surgeon inserts the optical cap over the arthroscopic system in viewing direction of the arthroscopic system before inserting the entire system into a patient. The LEDs are activated so that light is emitted from the LED at the proximal end of the light pipes. Light emitted from the LEDs is reflected off the 45 degree prism or mirror of the light pipes and projects from the distal tip of the arthroscope. The position of the LEDs allows irrigation fluid passing through the inflow channel to cool off the imaging chips and imaging sensor, resulting in less image noise. In addition, because the cap is constructed of a non-conductive polymer, the imaging chip is isolated and therefore protected from stray RF current. The optical cap insulates the imaging chip located on the elongated core of the arthroscopic system from damage from radiofrequency surgical devices commonly used in surgery. 
     The arthroscope architecture allows the largest possible elongated core to be used in the smallest scope sheath. The elongated core dimensions are matched to the scope sheath to accommodate for a low profile system. Further, the arthroscope allows for a flat rectangular scope with a panoramic view, as well as 3-D viewing where two chips are placed side-by-side. In addition, multiple arthroscopes can be used at the same time in a single application system. Two or more arthroscopes can be aimed at a particular area of interest and the user can switch between the arthroscopic cameras with a selector device such as a footswitch. This frees up the user&#39;s hands to focus on other surgical instruments such as an arthroscopic shaver or stitcher without requiring use of his hands to hold the camera in place. The multiple arthroscope configuration can be held in place by a portal plug device. The plug can have an angled foot and be rotated to place the arthroscope at the desired angle. A plug can anchor the surgical portal as well as provide a means for sealing the portal to prevent leakage of fluid or gas. The plug can have a square inner lumen to seal against a square arthroscope that does not have an outer round sheath. The two or more cameras can be switched back and forth to cover multiple locations from a central console. The cameras can be of different focal lengths or have imaging capabilities such as narrow-light band imaging, near infra-red, optical coherence tomography miniature radiology device or other non visible light imaging modalities. 
     The imaging chip that generates video may also be incorporated to have the capability to pick up infrared. Thus, a chip camera can read temperature in a joint without the need for a thermocouple. The chip is programmed to dedicate a small area of the chip as an “area of interest” and the IR on the surface of what the chip is looking at is read, and interlaced between video frames, thus reading temperature. This data can be gathered simultaneously with recording a video image, and does not interfere with capturing the video image. 
     In conjunction with the fluid temperature management platform, this chip can read temperature, and this inter-articular temperature reading may be used to control a fluid pump that incorporates cooling (to prevent RF heat damage to tissue) and warming (to prevent patient hypothermia during arthroscopy). This could be in addition to the scope having an on-board MEMS pressure sensor for accurate inter-articular pressure measurement. These data may be transmitted to the irrigation pump temperature and pressure control unit by means of a wired connection or a wireless connection such as Bluetooth or 802.11. 
     The word arthroscope used herein includes a family of instruments, including endoscopes, laparoscopes and other scopes. The scopes may use rod optics, fiber optics, distally mounted CCD chips, or other optical systems. Thus, while the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.