Patent Publication Number: US-2007106128-A1

Title: Computer assisted surgery system

Description:
FIELD OF THE INVENTION  
      The present invention relates to a computer assisted surgery system or CAS platform. In particular, the present invention relates to a CAS platform which includes a camera, a computer and a visual display.  
     BACKGROUND TO THE INVENTION  
      Generally, in conventional computer assisted surgery systems, a measurement mark is fixed to a bone, an anatomic element of a patient or a tool used by the surgeon and its motions are followed by means of a position sensor, also known as a locating system or a tridimensional positioning system. Such a position sensor may be a set of cameras which locate the position and orientation of the measurement mark which may be formed of at least three infra-red diodes or reflective markers. Alternatively, the position of the measurement mark may be obtained by acoustic or magnetic technologies.  
      Images captured by the cameras are sent to a computer linked to a display screen which provides images to assist the surgeon for the preparation of a surgical operation or during a surgical operation. Usually, the cameras are fixed to the top of a mast so that images can be captured even though persons move in the operating room. Moreover, an input interface, such as a keyboard, a mouse or a foot assembly is provided so that the surgeon customizes the images displayed on the display screen.  
      Such computer-assisted surgery systems are usually bulky since they include the mast with the camera at its top, the screen and a holder thereof, the computer and the input interface used by the surgeon. Moreover, a specialist is required to install and dismantle such systems since many electrical and mechanical connections have to be made. This means that when a failure of the system occurs, an on-site specialist is needed to replace the failing part. Such on-site maintenance is uneasy to implement efficiently.  
      The computer-assisted surgery system provided by Orthosoft under the name Navitrack® Sesamoid™ includes a mast, the bottom of which is mounted to a base comprising four wheeled feet. The cameras are mounted at the top of the mast. A monitor with built-in computer is attached directly to the mast when minimal place is available. Such a computer assisted surgery system occupies a limited space.  
      However, a specialist is still required to install or dismantle such system since the base, the wheeled feet, the mast, the camera and the monitor have to be connected together mechanically and electrical connections have to be made at least between the monitor and the mast. Moreover, once mounted, it is not easy to move such a system over large distances since it would require a box of having large dimensions to contain it. It would also be necessary to dismantle it and mount it again at the new location, requiring the intervention of a specialist.  
     SUMMARY OF THE INVENTION  
      One aim of the present invention is to provide a computer assisted surgery system which is mountable without the intervention of a specialist.  
      Another aim of the present invention is that the computer assisted surgery system is easily transportable.  
      To achieve these and other objects, the present invention provides a computer assisted surgery system comprising a base; a telescopic mast, movable between an unextended state and an extended state, having at least first, second and third elongated portions, the third elongated portion being inserted at least partially into the second elongated portion and the second elongated portion being inserted at least partially into the first elongated portion in the unextended state, the first elongated portion being linked to the base; a monitor; and sensing means linked to the third elongated portion, such that when the telescopic mast is in the unextended state with the sensing means in a determined position, the system is contained in a parallelepiped of dimensions 1000 mm by 700 mm by 600 mm.  
      According to an embodiment of the present invention, the monitor is linked to the second elongated portion.  
      According to an embodiment of the present invention, the second elongated portion has a first and a second end, the first end being closer to the base than the second end, the monitor being linked to the second elongated portion at the second end.  
      According to an embodiment of the present invention, the third elongated portion has a first and a second end, the first end being closer to the base than the second end, the sensing means being linked to the third elongated portion at the second end.  
      According to an embodiment of the present invention, the system comprises an arm having first and second ends, the first end being linked to the third elongated portion according to a at least one degree of liberty of rotation link, the sensing means being linked to the second end of the arm according to a at least one degree of liberty of rotation link.  
      According to an embodiment of the present invention, the monitor is linked to the second elongated portion according to at least a one degree of liberty of translation and one degree of liberty of rotation link.  
      According to an embodiment of the present invention, the system comprises at least three elongated feet, each elongated foot having first and second ends, each elongated foot being pivotally linked to the base at the first end and being linked at a pivotal wheel at the second end, the elongated feet being adapted to be folded away to be adjacent to a face of the base.  
      According to an embodiment of the present invention, the sensing means comprises at least a camera.  
      According to an embodiment of the present invention, the monitor includes a built-in computer.  
      According to an embodiment of the present invention, the system comprises a connection part linking the monitor to the second elongated portion, the connection part comprising a slide attached to the monitor and a guide pivotally linked to the second elongated portion, the slide being slidably mounted into the guide.  
      According to an embodiment of the present invention, the system comprises at least one electrical converter attached to the base and electrically linked to the monitor or/and to the sensing means by electrical conducting means at least partially located inside the telescopic mast.  
      According to an embodiment of the present invention, the system comprises means for moving the second elongated portion of the telescopic mast with respect to the first elongated portion of the telescopic mast.  
      According to an embodiment of the present invention, the system comprises a hydraulic cylinder arranged to move the second elongated portion of the telescopic mast with respect to the first elongated portion of the telescopic mast.  
      The present invention also provides a method for folding a computer assisted surgery system from an operation configuration to a transport configuration wherein the system is contained in a parallelepiped of dimensions 1000 mm by 700 mm by 600 mm, the computer assisted surgery system comprising a base, a telescopic mast having at least first, second and third elongated portions, the first elongated portion being linked to the base, a monitor linked to the second elongated portion, and sensing means linked to the third elongated portion, the method comprising the insertion of the third elongated portion at least partially into the second elongated portion; the insertion of the second elongated portion at least partially into the first elongated portion; and the displacement of the sensing means closer to the first elongated portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The aims, characteristics and advantages, as well as other aspects of the present invention, will be described in detail in the following description with reference to a number of examples, and with reference to the attached figures in which:  
       FIGS. 1 and 2  are respectively a front view and a rear view of a computer assisted surgery system according to an example of the present invention in an operation configuration;  
       FIG. 3  is a detailed view of a part of the computer assisted surgery system of  FIG. 2 ;  
      FIGS.  4  to  6  are respectively a front view, a rear view and an underside view of the system of  FIGS. 1 and 2  in a transport configuration; and  
       FIG. 7  is a front view of the computer assisted surgery system according to another example of the present invention in an operation configuration. 
    
    
      For reasons of clarity, same elements in the figures have been referenced with the same reference numbers throughout the figures.  
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION  
       FIGS. 1 and 2  are respectively a front view and a rear view of a computer assisted surgery system  10  according to an example of the present invention in an operation configuration. System  10  includes a base  12 , which, in the present example, has a generally rectangular shape. The base  12  comprises a bottom face  14  on which are mounted four pivotal feet  16 . Each foot  16  has the shape of a slightly incurved rod  18 . One end  20  of the rod  18  is pivotally connected to the bottom face  14  of the base  12  with respect to a vertical axis. A wheel  22  is pivotally mounted to the other end  24  of the rod  18  with respect to a vertical axis. The base  12  comprises a top face  26  opposite to the bottom face  14 .  
      A locking mechanism, not shown, is incorporated into the feet  16  such that when each foot  16  reaches a certain angular position, it is locked into place mechanically and can only be folded back in by releasing or forcing the locking mechanism. Such a locking mechanism is realized, for example, by using a ball stop component integrated in the end  20  or rod  18  of each foot  16 , where the ball falls into a recess at a certain angular position, locking the foot  16 . The feet  16  can be locked in either the extended or retracted position, by placing the recesses correspondingly. Additionally, the feet  16  can be inter-connected with a pivoting linkage mechanism or a gear mechanism, not shown, such that when one foot  16  is unfolded, all feet unfold simultaneously.  
      A telescopic mast  28 , extending in the vertical direction in the present example, comprises a lower portion  30 , a middle portion  32  and an upper portion  34  and is fixed to the base  12  at an end of the lower portion  30 . The three portions  30 ,  32 ,  34  are cylindrical in shape and are formed as sleeves adapted to fit into each other so that, in an unextended position, the middle portion  32  is nearly completely inserted into the lower portion  30  and the upper portion  34  is nearly completely inserted into the middle portion  32 , then also into the lower portion  30 . An end piece  36  is pivotally mounted at the upper end of the upper portion  34  of the mast  28  so that it is rotatable around the axis of the mast, that is to say the vertical axis in the present example. An articulated arm  38  is pivotally mounted to the end piece  36  so that it can be rotated with respect to the end piece  36  around an axis perpendicular to the axis of the mast  28 , that is to say a horizontal axis in the present example. The arm  38  includes a first elongated portion  40 , predominantly straight, which extends to a second portion  42  which is inclined with respect to the first portion  40  with a 90° angle. The end of portion  42  is pivotally fixed to the end piece  36 . The system  10  comprises a box  44  containing one or several cameras (two cameras  45  are shown in the figures) and being generally shaped as a parallelepiped. The camera box  44  is mounted at the end of portion  40  of the arm  38  by means of a connection part  46  which is described more precisely below. The connection part  46  allows three degrees of liberty of rotation of the camera box  44  with respect to the arm  38 .  
      A monitor  48  with built-in computer is fixed to the middle portion  32  of the telescopic mast  28  by means of a connection part  50 . The monitor  48  comprises a screen  49 , such as for example a touch screen, and the different common elements of a computer. For example, it can include a disk reader. As will be described below, the connection part  50  allows a displacement of the monitor  48  parallel to the middle portion  32  of the mast  28  along the axis of the mast, an inclination of the monitor  48  with respect to the middle portion  32  of the mast  28  along an axis perpendicular to the axis of the mast  28 , that is to say a horizontal axis in the present example, and a swivel of the monitor  48  with respect to the axis of the mast  28 .  
       FIG. 3  shows in more detail the connection part  50  which includes a ring  52  positioned at the top of the middle portion  32  and which has a protrusion  54  extending from it. The ring  52  is pivotally mounted to the middle portion  32  of the mast  28  so that it can rotate with respect to the axis of the mast  28 . The connection part  50  also includes a holder  56  fixed to the rear face of the monitor  48 . The holder  56  includes a plate  58  attached to the rear face of the monitor  48 , a flange  59  which is fixed to the plate  58 , a handle  60  which is fixed to the plate  58  and which projects out from the top of the monitor  48  and two parallel shafts  62 , fixed at one end to the plate  58  by means of the flange  59  and which extend parallel to each other and parallel to the plate  58 . The connection part  50  also includes an inclinable part  64  which comprises a basis  66  with two lugs  68  extending perpendicularly to the basis  66 . The lugs  68  are pivotally mounted to the protrusion  54  around a shaft  70 . At least one of the lug  68  includes an opening  72  incurved around the axis of shaft  70 . A pin, not shown, extends from the protrusion  54  and enters the opening  72 . The cooperation of the pin and the opening  72  defines the range of allowable inclination of the inclinable part  64  with respect to the protrusion  54 . The inclinable part  64  comprises a guide  74 , fixed on the opposite side of the basis  66  with respect to the lugs  68 . The guide  74  has two parallel cylindrical openings  76 . The shafts  62  are slidably mounted into the openings  76  so that the relative position between the holder  56  and the inclinable part  64  can be modified.  
      The electrical supply to the cameras  45  and to the monitor  48  is provided by converters  78 ,  80  (or transformers) fixed to the base  12 . Each converter  78 ,  80  is connected to a general supply network, not shown, through power supply leads  82 ,  84 , only the ends of which are shown in the figures. The general supply network is connected to the hospital power supply with a single plug (not shown). Thus the monitor with built-in computer  48 , the cameras  45 , and other components can all be powered with only a single power cable. Additionally, a medial grade power supply (not shown) can be incorporated into the base  12  to provide uninterruptible power to the converters. The converter  78  is connected to the monitor  48  by means of an electrical power and communication signal cable  86 , only the end of which is shown in the figures. The converter  80  is connected to the cameras  45  of the camera box  44  by means of an electrical power and communication signal cable  88 , only the end of which is shown in the figures. The electrical power and communication signal cables  86 ,  88  to the monitor  48  and the camera box  44  can be routed either in the interior or the exterior of the hollow mast  28 . For example, rings (not shown) on the exterior of the telescopic mast  28  can be used to guide the cables  86 ,  88  and to keep them close to the mast  28 , similar to the rings on a fishing rod or pole. For example, one ring per mast portion could be used. Alternatively, the cables  86 ,  88  can be coiled on the inside of the mast  28 , for example, around a hydraulic cylinder used to extend the mast  28  as will be described later, such that when the mast  28  is extended or retracted, the pitch of each coiled cable increases or decreases, respectively. When the mast  28  is in the fully retracted position, each cable can be completely coiled such that the coil pitch is equivalent to the thickness of the cable, thus occupying the minimal axial length.  
      Even though the monitor  48  may comprise a touch screen through which the surgeon inputs commands, a pedal assembly  90 , actuated by the surgeon with his feet, is provided in the present example of the invention. The pedal assembly  90  includes, for example, two pedals and is connected to the monitor  48  by means of a wire  92 , only the end of which is shown in the figures, which extends, for example, inside the mast  28 , from the bottom of the lower portion  30  up to the monitor  48  through the connection part  50 .  
      The computer assisted surgery system  10  is shown on FIGS.  1  to  3  in the operation configuration, that is to say ready for use. According to the embodiments of the present invention, the computer assisted surgery system  10  having the features described above can be “folded” in order to occupy a space within a parallelepiped volume with the dimensions 1000 mm by 700 mm by 600 mm, preferably 900 mm by 600 mm by 500 mm, and more preferably 800 mm by 500 mm by 350 mm. In such a configuration, the computer assisted surgery system  10  can then be placed inside a box in order to be transported. Moreover, according to embodiments of the present invention, the global weight of the computer assisted surgery system  10  and the box containing it does not exceed about 25 kg so that it can be easily transported by conventional means of transport. The portability of the computer assisted surgery system  10  in the transport configuration can be extremely useful, for example, in the following situations: 
          the computer assisted surgery system  10  can be taken as checked luggage on an airplane;     the computer assisted surgery system  10  can be easily folded up by a nurse and sent back to the manufacturer by standard courier, in case of malfunctioning parts for example;     the computer assisted surgery system  10  can easily be transported by sales representatives to give demonstrations in different locations; and     the computer assisted surgery system  10 , in transport configuration, does not take up a lot of storage space in the hospital or in the operating room, and can easily be transferred from one department to another.        

      FIGS.  4  to  6  are respectively a front view, a rear view and an underside view of the system of  FIGS. 1 and 2  in the transport configuration. In the transport configuration, the mast  28  is unextended. This means that the upper portion  34  and the middle portion  32  are inserted into the lower portion  30 . The axial lengths of portions  30 ,  32 ,  34  are chosen such that, in the transport configuration, only the top of the middle portion  32 , to which the connection part  50  is attached, remains outside the lower portion  30  and that only the end piece  36  at the top of the upper portion  34  remains outside the middle portion  32 .  
      In the transport configuration, the monitor  48  is moved parallel to the middle portion  32  of the mast  28  so that it is placed in the lowest position possible with respect to the middle portion  32 . This corresponds to the position wherein the flange  59  abuts the guide  74 . In such a position, the monitor  48  rests above the converters  78 ,  80  at a certain distance from them. The monitor  48  is positioned vertically, such that the pedal assembly  90  is lodged between the lower portion  30  of the mast  28  and the monitor  48 . For example, a holding means is provided at the back of the monitor  48  to attach the pedal assembly  90  in the transport configuration.  
      The arm  38  is pivoted with respect to the end piece  36  so that the straight portion  40  is brought to the closest position possible to the mast  28 . The dimensions of portion  42  are determined so that, in the transport configuration, the portion  40  extends globally parallel to the mast  28 , nearly in contact with it. The camera box  44  is orientated so that its longest edge extends globally parallel to the mast  28 , that is to say vertically in the present example, one side of the camera box  44  lying on the top face  26  of the base  12  or being close to the top face  26  of the base  12 .  
       FIG. 6  represents the positions of the feet  16  of the computer assisted surgery system  10  in the transport configuration. The feet  16  are folded away under the base  12  so that no part of the feet protrudes from the underside of the base  12 . The curved shape of the feet  16  makes the folding away of the feet  16  easier by preventing the feet  16  to contact to each other.  
      As shown on  FIGS. 1 and 5 , the connection part  46  includes a cylindrical part  94  which is pivotally linked to the arm  38  with respect to an axis perpendicular to the axis of the mast  28 , that is to say, in the present example, vertically in the operation configuration and horizontally in the transport configuration. The connection part  46  also includes an inclinable part  96  which comprises a cylindrical basis  98  attached to the camera box  44 . Two lugs  100  extend perpendicularly to the basis  98  and are pivotally mounted on the cylindrical part  94  around a shaft  102 . At least one of the lug  100  includes an opening  104  incurved around the axis of shaft  102 . A pin, not shown, extends from the cylindrical part  94  and enters the opening  104 . The cooperation of the pin and the opening  104  defines the range of allowable inclination of the camera box  44  with respect to the cylindrical part  94 .  
       FIG. 7  is a front view of a computer assisted surgery system  100  according to another example of the present invention in the operation configuration. System  100  includes a cover  102  fixed to the base  12 . The cover  102  protects the converters used for the voltage supply of the monitor  48  and the cameras  45 . The cover  102  also enhances the visual aspect of the system  100 . The cover  102  comprises a recess  104  in which is placed a part of the camera box  40  in the transport configuration. In this example, a supplementary handle  106  is fixed to end piece  36  to facilitate the extension of the upper portion  34  of the mast  28  with respect to the middle portion  32  and/or to facilitate the rotation of arm  38  with respect to the mast  28 . Moreover, a supplementary handle  108  is fixed to camera box  44  to facilitate the positioning of the camera box  44  extension with respect to the arm  38 .  
      An exemplary method for “unfolding” the computer assisted surgery system  10  from the transport configuration, wherein the system  10  is placed into a transport case, not shown, to the operation configuration comprises the following steps: 
          open the case;     unfold two feet  16 ;     roll out the system  10  from the case;     unfold the other two feet  16 ;     extend the upper portion  34  of the mast  28  from the middle portion  32 ;     deploy the arm  38 ;     extend the monitor  48  with the handle  60 ;     extend the middle portion  32  of the mast  28  from the lower portion  30 ;     deploy the pedal assembly  90  and the power cable of the system  10 ;     plug in the power cable; and     switch the system  10  on.        

      Precise positioning and orientation of the camera box  44  and of the monitor  48  is performed during or after the “unfolding” operation. Once unfolded, the feet  16  provide good stability to the system  10 . The system  10  can then be moved towards any desirable location.  
      An exemplary method to “fold” the computer assisted surgery system  10  from the operation configuration to the transport configuration comprises the following step: 
          switch the system  10  off;     unplug the converters  82 ,  84 ;     insert the middle portion  32  of the mast  28  into the lower portion  30  of the mast  28 ;     unfold the arm  38  and orientate the camera box  44  so that it is globally parallel to the mast  28 ;     insert the upper portion  34  of the mast  28  into the middle portion  32 , that is to say also into the lower portion  30  of the mast  28 ; and     fold the feet  16  away under the base  12 .        

      In the above methods, the extension of the mast  28  is made manually or by means of an actuation mechanism, for example a hydraulic-based, a cable based or a pinion based actuation mechanism contained inside the mast  28 . For example, the actuation mechanism used to lift the mast  28  is in the form of a hydraulic cylinder contained inside the hollow mast  28 , similar to the hydraulic cylinder commonly used to actuate an office chair. The hydraulic cylinder comprises a cylinder and a piston placed inside the cylinder and movable with respect to the cylinder along the axis of the cylinder. The cylinder is fixed to the lower portion  30  of the mast  28  or to the base  12  and the piston is fixed to the middle portion  32 , with the long axis of the cylinder parallel to the long axis of the telescopic mast  28 . The cylinder contains compressed gas, and a button or foot switch (not shown) is used to release the piston such that the pressurised gas contained in the cylinder expands, moving the piston lifting the middle portion  32  of the mast  28  relative to the lower portion  30 . To retract the mast  28 , the button is depressed and the piston can be retracted in the cylinder by pushing down on the upper elements of the mast  28  such as the middle or the upper portions  32 ,  34  or handle  60 , for example. Similarly, upper portion  34  can be automatically raised and lowered relative to the middle portion  32  using a hydraulic cylinder. Furthermore, said button can be connected to either one or both hydraulic cylinders using for example an ordinary mechanical cable such as those commonly found on the brakes of a bicycle.  
      Moreover, when the monitor  48  is positioned and oriented with respect to the middle portion  32  of the mast  28  and when the camera box  44  is positioned and oriented with respect to the upper portion  34  of the mast  28 , the final chosen positions and orientations can be maintained by the friction alone between the mechanical parts. Alternatively, stop means are provided, such stop means being activated when the desired positions and orientations of the connection parts  46 ,  50  and of the arm  38  are achieved to block the connection parts  46 ,  50  and the arm  38 .  
      The above described embodiment of the present invention has a number of advantages:  
      first, the computer assisted surgery system according to the above described embodiment of the present invention provides a complete system wherein the monitor with built-in computer and the cameras are fixed to a telescopic mast, hence occupying a minimal volume in transport configuration when the mast is unextended;  
      second, the computer assisted surgery system according to the above described embodiment of the present invention can be quickly and efficiently positioned according to the surgeon&#39;s wishes since the monitor with built-in computer and the cameras are separately positionable and orientable with respect to the mast and the system itself is mounted on wheels; and  
      third, the folding and unfolding methods do not involve any mechanical connection operations or electrical connection operations (except the plugging or the unplugging of the converters) and as such are implementable by a non specialist person.  
      According to another example of the present invention, the monitor is not attached to the telescopic mast, but is attached to a separate mast. In this case, the computer assisted surgery system has the structure described above, without the monitor, such monitor being provided separately. Indeed, in some conditions, it is preferable to place the monitor and the camera box at different locations.  
      It will be apparent to those skilled in the art that different connection parts  46 ,  50  to those previously described could be used. For example, a ball joint could be used to link the camera box  44  to the arm  38  instead of connection part  46  or to link the guide  74  to the protrusion  54  in connection part  50 . Moreover, the telescopic mast  28  could have more than three portions.  
      Having thus described at least one illustrative embodiment of the invention, various alterations, modifications and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements are intended to be within the scope of the invention. Accordingly, the foregoing description is by way of example only and is not intended to be limiting. The invention is limited only as defined in the following claims and the equivalent thereto.