Abstract:
The present invention discloses an endoscope positioning system for maneuvering, orienting and positioning an endoscope relative to an organ within a patient&#39;s body during an endoscopic operation. The endoscope positioning system comprises a gripper that reversibly attaches the positioning system to the patient&#39;s body while allowing full adjustment of the endoscope in four degrees of freedom.

Description:
FIELD OF THE INVENTION 
     This invention relates to a structure for supporting a surgical instrument, such as an endoscope, and more particularly to a structure which provides for repositioning of the instrument during surgery without stressing an incision through which the instrument extends. 
     BACKGROUND OF THE INVENTION 
     Laparoscopic surgery is a procedure in which surgical instruments and a viewing scope, referred to generally as an endoscope and more specifically as a laparoscope, are inserted through small puncture wounds or incisions into the abdominal cavity of a patient. A small video camera is attached to the laparoscope and connected to a television monitor for viewing the procedure. 
     The instruments and the laparoscope are inserted through cannulae which are first inserted through the incisions. Cannulae are hollow tubes with gas valves. The cannulae are left in the puncture wounds throughout the procedure. This allows the instruments and scope to be removed and reinserted as necessary. 
     To aid in visualizing the intra-abdominal structures, gas is inserted through one of the cannulae to raise the abdominal wall. Seals are required at the exit points of the scope and instruments to prevent the gas from escaping. 
     The viewing laparoscope is inserted through a cannula which is usually inserted through an incision made in the umbilicus. The scope is then directed toward the pelvis for pelvic surgery or toward the liver for gallbladder surgery. 
     Throughout the procedure it is necessary for the surgeon, assistant surgeon, or a scrub nurse to hold the scope and direct it at the target of the surgery. It is constantly being repositioned to obtain the best view. This process ties up one hand of the surgeon or assistant surgeon, if either holds the scope. The scrub nurses also have other tasks to perform, and holding the scope interferes with performing these tasks. It is also difficult for the surgeon to direct others to position the scope for the best view. When the scope is not held by the surgeon, it is often misdirected. 
     The support of a laparoscope has been provided through the use of robotic retractors. Retractors hold instruments in fixed positions, such as for holding an incision open to allow a surgeon access to the underlying body parts. The retractors are fixedly clamped to a mechanical skeleton. This skeleton has also been used to hold a laparoscope in a fixed position. When it is desired to move the scope, the clamp must be readjusted, and usually the skeleton linkages must also be adjusted to accommodate a change in the angle of insertion of the laparoscope. 
     U.S. Pat. No. 5,571,072 (&#39;072) discloses a cannula and an associated endoscope secured to an operating table by a mechanical linkage assembly having linear and angular connections. These connections are adjustable for supporting an endoscope extending through an incision. According to &#39;072, two angular connections are friction joints that allow manual repositioning of the scope by pivoting about respective orthogonal axes that intersect at a point along the scope that is coincident with the location of the incision. 
     U.S. Pat. No. 7,048,745 (&#39;745) teaches surgical tool robotic manipulator. As taught by &#39;745 embedded computer means can perform a number of functions when the tool is loaded on the tool manipulator: (1) providing a signal verifying that the tool is compatible with that particular robotic system; (2) identifying the tool-type to the robotic system so that the robotic system can reconfigure the programming; or (3) indicating tool-specific information, including measured calibration offsets indicating misalignment of the tool drive system, tool life data, or the like. 
     Patent Application WO2006111966 (&#39;966) to the inventor, which is incorporated as a reference, discloses a computerized system enabling operative precise positioning laparoscopic surgical tools. The system comprises a manipulator providing displacement in four degree of freedom. The system consists of two main components: the first part has an arc shape in which the endoscope can be driven back and forth and at the same time can be moved from side to side; the second part is characterized by zoom and rotation properties. 
     Laparoscopic orthopedic surgeries differ from abdominal laparoscopic surgeries in their dynamic nature: it is common in orthopedic surgeries to move the limbs of the patient from side to side to bend the knee or the shoulder, or to stretch the patient&#39;s joints. Traditional endoscope holders are fixed to the operation table and do not let the endoscope follow the limb movement and therefore are not used in these kinds of procedures. Today, endoscopic orthopedic procedures are performed by the surgeon holding the endoscope in one hand and using a tool in the other hand. When the surgeon needs to use two tools at the same time, he requires an assistant to hold and aim the endoscope for hint. Hence, a system providing rigid fixation of the laparoscope relative to the human limb and laparoscope precise moving, especially a system with four or more degrees of freedom is still a long-felt need. 
     SUMMARY OF THE INVENTION 
     It is one object of the present invention to provide an endoscope positioning system (EPS,  300 ) for maneuvering, orienting and positioning an endoscope  500  relatively to an organ being operated within a patient&#39;s body; said EPS is especially used during orthopedic operations such that said organ is constantly moved during said operation;
         said EPS comprising:
           a. at least four freedom degree mechanisms (FDFM) ( 100 ); said FDOF are adapted to actuate the distal portion of said endoscope by maneuvering the proximal portion of said endoscope; said FDFM comprises at least a first, second, third and fourth means for providing said four degrees of freedom:
               i. said means of first degree of freedom is a rotation gab-mechanism  310  adapted to rotate said endoscope around its longitudinal axis;   ii. said means of second degree of freedom is a tilting sub-mechanism  320 , comprising:
                   a. at least one transmission  116  in mechanical communication with arc  150 ; said arc  150  is in mechanical communication with said endoscope; and,   b. at least one motor  157   b  in reversible mechanical communication with said transmission  116 ; said transmission  116  is adapted to transmit rotational motion from said motor  157   b  to said arc  150  such that said arc  150  is titled at an angle of interest;   
                   iii. said means of third degree of freedom is an arc sub-mechanism  330 , comprising:
                   a, at least one nut  151  adapted to linearly move along at least one screw ( 155 );   b. a chain comprising a plurality of links, said chain is characterized by having a distal end and a proximal end; each of said links is in mechanical communication with at least one of its neighboring links; said chain is at least partially located in semicircular guides ( 154 );    said at least one nut  151  is in mechanical communication with at least one first link ( 152   a ) in said proximal end of said chain;    a gimbal ( 170 ) through which said endoscope passes is in mechanical communication with at least one link located in said distal end of said chain;    wherein said linear movement of said nut ( 151 ) is adapted to affects said first link ( 152   a ) in said chain such that the remaining links in said chain are forced to move along said    semicircular guides  154  so as to move said gimbal  170  and said endoscope  500  along said arc  150 ;   
                   iv. said means of fourth degree of freedom is a zoom sub-mechanism  340 ;   
                each of said first, second, third and fourth degree of freedom is characterized by an independent movement;   b. at least one body adapter gripper ( 201 ) adapted to reversibly and firmly attach said EPS to said patient&#39;s body;
 
wherein said EPS is conformed to said movements of said organ by means of said gripper  201  such that the orientation of said endoscope is adjustable accordingly to said movement.
   
               

     It is another object of the present invention to provide the EPS as defined above, wherein said EPS is adapted to maintain a constant orientation of said endoscope relatively to said organ by means of said gripper  201 , such that alteration in said orientation as a result of said movements of said organ is prevented. 
     It is another object of the present invention to provide the EPS as defined above, wherein at least one of said first, second, third and fourth means for providing degrees of freedom is activated by a mechanical or electrical motoring means. 
     It is another object of the present invention to provide the EPS as defined above, wherein said gripper are selected from a group consisting of strips, magnets, screws, hooks, zips, fasteners, clips, flaps, claspers, springs, grips, hooks-and-loops (especially Velcro™-type fasteners), hooks, hooks and eyes, straps, strings, wires, cables, tabs, links, poppers, nails, buttons, brackets, buckles or any combination thereof. 
     It is another object of the present invention to provide the EPS as defined above, wherein said motoring means activates at least one of said first, second, third and fourth means for providing degrees of freedom by maneuvering said first, second, third and fourth means relative to said gripper  201 . 
     It is another object of the present invention to provide the EPS as defined above, wherein said motoring means comprises a plurality of motors, at least two motors are adapted to simultaneously actuate said at least a first, second, third and fourth means for providing degrees of freedom. 
     It is another object of the present invention to provide the EPS as defined above, wherein said motoring means and said at least a first, second, third and fourth means for providing degrees of freedom are reversibly interconnected. 
     It is another object of the present invention to provide the EPS as defined above, wherein said tilting sub-mechanism  320  is characterized in that the reciprocal movement of gimbal  170  along arc  150 , and tilting of arc  150  are completely independent movements. 
     It is another object of the present invention to provide the EPS as defined above, wherein said zoom sub-mechanism  340  comprises:
         a. at least one worm gear  181 ;   b, at least one drum  182  mechanically connected to said worm gear  181 ; said drum  182  is characterized by a main longitudinal axis; said drum  182  is adapted to rotate a wire  183  around said main axis, such that the distance between said drum  183  and a gimbal  170  is shortened and a zoom motion is obtained.       

     It is another object of the present invention to provide the EPS as defined above, additionally comprising a quick locking sub-mechanism  350 , adapted to enable or disenable said arc sub-mechanism  330 . 
     It is another object of the present invention to provide the EPS as defined above, additionally comprising a quick fixing sub-mechanism  370  adapted to reversibly connect said endoscope  500  from semicircular guides ( 154 ); said quick fixing sub-mechanism  370  comprising:
         a. gimbal  170  through which said endoscopes passes;   b. at least one screw  161 ;   c. a cylinder  162  adapted to partially and reversibly accommodate said screw  161 ;   d. at least one clamping means  163  reversibly housed within said cylinder  162 ; said clamping means  163  being in mechanical communication with said screw  161 ; said clamping means  163  are adapted to reversibly apply pressure on said cylinder such that said gimbal  170  is reversibly housed within said cylinder  162 .       

     It is another object of the present invention to provide a method for maneuvering, orienting and positioning an endoscope  500  relative to an organ being operated within a patient&#39;s body, during orthopedic operations such that said organ is constantly moved during said operation. The method comprises steps selected inter alia from:
         a. obtaining an endoscope positioning system (EPS,  300 ); said EPS comprising:
           i. at least four freedom degree mechanisms (FDFM) ( 100 ) comprising at least a first, second, third and fourth means for providing said four degrees of freedom:
               a. said means of first degree of freedom is a rotation sub-mechanism  310  adapted to rotate said endoscope around its longitudinal axis;   b. said means of second degree of freedom is a tilting sub-mechanism  320 , comprising:
                   i. at least one transmission  116  in mechanical communication with arc  150 ; said arc  150  is in mechanical communication with said endoscope; and,   ii. at least one motor  157   b  in reversible mechanical communication with said transmission  116 ;    said transmission  116  is adapted to transmit rotational motion from said motor  157   b  to said arc  150  such that said arc  150  is titled at an angle of interest;   
                   c. said means of third degree of freedom is an arc sub mechanism  330 , comprising:
                   i. at least one nut  151  adapted to linearly move along at least one screw ( 155 );   ii. a chain comprising a plurality of links, said chain is characterized by having a distal end and a proximal end; each of said links is in mechanical communication with at least one of its neighboring links; said chain is at least partially located in semicircular guides ( 154 );    said at least one nut  151  is in mechanical communication with at least one first link ( 152   a ) in said proximal end of said chain;    a gimbal ( 170 ) through which said endoscope passes is in mechanical communication with at least one link located in said distal end of said chain;    wherein said linear movement of said nut ( 151 ) is adapted to affects said first link ( 1 . 52   a ) in said chain such that the remaining links in said chain are forced to move along said semicircular guides  154  so as to move said gimbal  170  and said endoscope  500  along said arc  150 ;   
                   d. said means of fourth degree of freedom is a zoom sub-mechanism  340 ;   each of said first, second, third and fourth degree of freedom is characterized by an independent movement;   
               ii. at least one body adapter gripper ( 201 );   
           b. reversibly and firmly attaching said EPS to said patient&#39;s body via said body adapter gripper ( 201 );   c. maneuvering the proximal portion of said endoscope in a movement selected from a group consisting of rotating, tilting, arcing or zooming thereby actuating and orienting the distal portion of said endoscope;   wherein said step of reversibly and firmly attaching said EPS to said patient&#39;s body conforms said EPS is to said movements of said organ by means of said gripper  201  such that the orientation of said endoscope is adjustable accordingly to said movement.       

     It is another object of the present invention to provide the method as defined above, wherein said step of reversibly and firmly attaching said EPS to said patient&#39;s body maintains said endoscope of said EPS in a constant orientation relatively to said organ by means of said gripper  201 , such that alteration in said orientation as a result of said movements of said organ is prevented. 
     It is still an object of the present invention to provide the method as defined above, wherein said step of actuating and orienting the distal portion of said endoscope is performed by mechanical or electrical motoring means  110 . 
     It is lastly an object of the present invention to provide the method as defined above, additionally comprising step of selecting said gripper from a group consisting of strips, magnets, screws, hooks, zips, fasteners, clips, flaps, claspers, springs, grips, hooks-and-loops (especially Velcro™ m-type fasteners), hooks, hooks and eyes, straps, strings, wires, cables, tabs, links, poppers, nails, buttons, brackets, buckles or any combination thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The objects and advantages of various embodiments of the invention will become apparent from the following description when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an isometric view of a four degree mechanism with an adapter; 
         FIG. 2  is a schematic view representing four degree displacement; 
         FIGS. 3   a - 3   c  are schematic views showing optional working arrangements for shoulder ( 3   a ) and knee ( 3   b  and  3   c ) surgery; 
         FIG. 4  is a schematic view showing optional displacement provided by a sliding adapter; 
         FIG. 5  is a schematic overview of a displacement mechanism; 
         FIG. 6  is a schematic diagram of a sub-mechanism of arc reciprocal displacement: 
         FIG. 7  is a detailed view of a sub-mechanism of arc reciprocal displacement; 
         FIG. 8  is a detailed view of a tilting sub-mechanism; 
         FIG. 9  is a detailed view of a zoom sub-mechanism; 
         FIG. 10  is a detailed view of a rotation sub-mechanism: 
         FIG. 11   a  is an isometric view of a locking sub-mechanism; 
         FIG. 11   b  is an isometric view of a locking sub-mechanism in the locked position; 
         FIG. 11   c  is an isometric view of a locking sub-mechanism in the unlocked position; 
         FIG. 12   a  is a detailed view of a coupling/decoupling sub-mechanism; 
         FIG. 12   b  is an enlarged view of a screw of the coupling/decoupling sub-mechanism; 
         FIG. 13   a  is a schematic view representing an endoscope fixing sub-mechanism on the arc guides; and, 
         FIG. 13   b  is a schematic view representing an endoscope gripping unit alone. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The following description is provided in order to enable any person skilled in the art to make use of said invention and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, will remain apparent to those skilled in the art, since the generic principles of the present invention have been defined specifically to provide (i) an endoscope positioning system (EPS) essentially consisting at least four freedom degree mechanism (FDFM); (ii) a method of manipulating an endoscope in at least four degrees of freedom by the EPS; and (iii) method for applying endoscopic surgery. 
     The terms “endoscope” and “laparoscope” refer interchangeably hereinafter to a fiber optical device that consists of a flexible tube. Glass or plastic filaments allow the internal refraction of light for viewing. This medical device is used in laparoscope, endoscope, laparoscopic and endoscopic surgeries. It is also in the scope of the invention wherein the term refers also to any means for looking within body cavities, especially inside the human body and mammalian body for medical reasons using an instrument; and especially to means for minimally invasive diagnostic medical procedure, such as rigid or flexible endoscopes, fiberscopes, means for robotic surgery, trocars, surgical working tools and diagnosing means etc. 
     The terms “endoscopic surgery” and “laparoscopic surgery” interchangeably refer hereinafter to modern surgical technique in which operations into the body of a patient, e.g., in the abdomen, are performed through small incisions (usually 0.5 to 1.5 cm) as compared to larger incisions needed in traditional surgical procedures, or via natural cavities of the body. Laparoscopic surgery includes e.g., operations within the abdominal, pelvic or joint cavities. Endoscopy surgery involves, inter alia, operations in the gastrointestinal tract, e.g., in the oesophagus, stomach and duodenum (esophagogastroduodenoscopy), small intestine, colon (colonoscopy, proctosigmoidoscopy), bile duct, endoscopic retrograde cholangiopancreatography (ERCP), duodenoscope-assisted cholangiopancreatoscopy, intraoperative cholangioscopy, the respiratory tract, the nose (rhinoscopy), the lower respiratory tract (bronchoscopy), the urinary tract (cystoscopy), the female reproductive system, the cervix (colposcopy), the uterus (hysteroscopy), the Fallopian tubes (falloscopy), normally closed body cavities (through a small incision), the abdominal or pelvic cavity (laparoscopy), the interior of a joint (arthroscopy) organs of the chest (thoracoscopy and mediastinoscopy), during pregnancy, the amnion (amnioscopy), the fetus (fetoscopy), plastic surgery, panendoscopy (or triple endoscopy), combining laryngoscopy, esophagoscopy, and, bronchoscopy; and various non-medical uses for endoscopy. It is also in the scope of the invention wherein the term also refers also to any manipulation of laparoscopes and endoscopes as defined above into the body of a patient. 
     The invention concerns an endoscope positioning system suited for all kinds of laparoscopic surgeries. It is best suited for orthopedic surgeries as defined below. Laparoscopic orthopedic surgeries differ from abdominal laparoscopic surgeries in their dynamic nature: it is common in orthopedic surgeries to move the limbs of the patient from side to side; to bend the knee or the shoulder; or to stretch the patient&#39;s joints. Traditional endoscope holders are fixed to the operation table and therefore do not allow the endoscope to follow the limb movement and thus are not used in these kinds of procedures. 
     Today, endoscopic orthopedic procedures are performed by the surgeon holding the endoscope in one hand and using a tool in the other hand. When the surgeon needs to use two tools at the same time, he requires an assistant to hold and aim the endoscope for him. 
     The present invention provides a quick and optimal endoscope setup, automatic and precise positioning of the endoscope, which allows the surgeon to use both his arms for simultaneously operating two tools at the same time, without interfering with the flow of the operation process. 
     The term “Degrees of freedom” (DOE) refers hereinafter to a set of independent displacements that specify completely the displaced position of the endoscope or laparoscope as defined above. In three dimensional space, there are six DOE, three DOE of linear displacement and three rotational DOB, namely, moving up and down, moving left and right, moving forward and backward, tilting up and down, turning left and right, tilting side to side. The present invention refers to a system essentially comprising means for at least four DOE selected from any of those defined above. 
     The terms “distal portion” and “proximal portion” refer hereinafter to the side of the endoscope within the body of the patient, and outside the body of the patient, respectively. 
     Reference is now made to  FIG. 1 , illustrating a typical endoscope positioning system  300  comprising a four freedom degree mechanism (FDFM) that moves the endoscope  500  and the body adapter  200 , thus enabling an optimal placement of the mechanism. The mechanism  100  comprises a rotation sub-mechanism  310 , a tilting sub-mechanism  320 , an arc sub-mechanism  330 , and a zoom sub-mechanism  340 . The sub-mechanisms  310 ,  320 ,  330 , and  340  are activated by a motor box  110 . 
     Reference is now made to  FIG. 2  showing the mechanism  300  enabling displacement of the endoscope  500  with FDFM. FDFM  300  is used for linearly and angularly positioning the endoscope  500  relative to a joint incision. 
     Reference is now made to  FIG. 3 , illustrating optional arrangements of the endoscope positioning system  300  on human limbs. The adaptor grippers  201  of body adapter  200  embrace a human arm  400  ( FIG. 3   a ) and a human leg  410  ( FIGS. 3   h  and  3   c ). By using the adapter stripes or grips ( 201 ) the adapter is fixed firmly to the patient&#39;s body allowing the mechanism to move the endoscope to the desired position. 
     Reference is now made to  FIG. 4 , presenting the motor box  110  which is adapted to move relative to the adapter  200 . This option allows the surgeon to attach the first gripper  201  firmly to the patient&#39;s limb, and then to position the mechanism  300  in the optimal arrangement relative to a joint incision (not shown) and finally to fix mechanism  300  by the second gripper  201 . 
     Reference is now made to  FIG. 5 , disclosing a motor box  110  that contains the four motors. The transmission  115  transmits motion from the motors located in the motor box  110  to a tilting sub-mechanism  320  and to the arc sub-mechanism  330 . Driving the zoom and rotation sub-mechanisms is performed by means of flexible shafts  199 . The endoscope  500  passes through a transmission box  180  and a gimbal  170 . 
     Reference is now made to  FIG. 6  illustrating the arc sub-mechanism  330 . A nut  151  is connected to a first link  152   a . Hinges  153  are used for coupling links  152   b ,  152   c , etc. Said hinges  153  and links  152   a ,  152   b  et cetera are located in semicircular guide  154 . The number of the links  152   b ,  152   c , etc., illustrated does not limit the described embodiment. The gimbal  170  is coupled with hinge  153  to the distal end of the last link in the chain. The endoscope  500  passes through the inner part of the gimbal  170 . When the screw  155  rotates, the nut moves along the screw, thereby causing the first link  152   a  in the chain to move in tandem. The other links are forced to move along the semicircular track  154 , thus moving the gimbal  170 . Due to its being fixed to the gimbal  170 , the endoscope  500  moves along the arc  150 . 
     Reference is now made to  FIG. 7 , illustrating the transmission.  115  transmits rotational motion from a motor  157   a  to the screw  155 . The nut  151  moves along the screw  155  and acts upon the link  152   a . The nut is connected to a chain of links  152  by means of a fast release mechanism (not shown). The link chain  152  is connected to the gimbal  170  that moves the endoscope  500  along the arc. 
     Reference is now made to  FIG. 8  showing the main components of the tilting sub-mechanism  320 . The transmission  115  transmits rotational motion from a motor  157   b  to the arc  150  tilting the arc  150  at an angle of interest. Reciprocal movement of the gimbal  170  along the arc  150  and tilting the arc  150  are completely independent. 
     Reference is now made to  FIG. 9  presenting the zoom sub-mechanism  340 . A flexible shaft  199   a  couples a motor  157   e  located in the motor box  110  (not shown) to an axle  184  of a worm gear  181 . A drum  182  mechanically connected to the worm gear  181  winds the wire  183  up, so that the distance between the drum  182  and the gimbal  170  becomes shorter. When the motor stops moving, the spring  185  maintains tension in wire  183 . The structure of the worm gear prevents the spring  185  from causing undesired displacement of the transmission box  180 . During zoom down movement, the motor  157   c  rotates in the opposite direction. The unwrapped wire  183  lets the spring  183  extend. As a result the zoom box transmission rises. 
     Reference is now made to  FIG. 10  showing the rotation sub-mechanism  310 . A flexible shaft  199   b  couples a motor  157   d  located in motor box  110  (not shown) to an axle  202  of a worm gear  186  which rotates a cogwheel  187 . A part of the transmission, the cogwheel  187 , allows the endoscope to pass through a hole in its center. The friction between the cogwheel  187  and the endoscope is high enough not to allow circular sliding between them. The aforesaid cog wheel  187  has a centered passage for a proximal portion of the endoscope  500 . A locking sub-mechanism (not shown) is adapted to fix and release the endoscope  500 . 
     Another option is to use the housing  188  in order to transmit the rotation from the cogwheel by using the housing to apply the moment on the endoscope head. 
     Reference is now made to  FIGS. 11   a ,  11   b , and  11   c , presenting a quick locking sub-mechanism  350  for enabling or disenabling the arcing mechanism  330 . The sub-mechanism  350  consists of a lever  190  furnished with two perpendicular slots  196  and  197 . The lever  190  can rotate around an axis  191  ( FIG. 11   a ). 
     In a locked position, the hinge  153  of link  152   a  is trapped within slot  196  (see  FIG. 11   b ). In an unlocked position the lever is rotated (around axis  191 ) and enables insertion of link  152   a  into the slot  197  (see  FIG. 11   c ). An appropriate position of the lever  190  is kept by openings  194  and  195 . The openings  194  and  195  are fixed by the screw  155 . 
     Reference is now made to  FIG. 12   a  and  12   b , showing a coupling/decoupling sub-mechanism  360 . The sub-mechanism  360  connects and disconnects the arcing mechanism  330  of the endoscope positioning device. The mechanism  360  connects/disconnects the arcing mechanism  330  to/from the motor to which it is connected to enable manual movement of the arcing mechanism  330 . 
     The mechanism  360  consists of a screw  198  that couples/decouples the screw  155  to the transmission  115 . 
     Clockwise rotation of the screw  198  pushes the screw  155  backward, leading to separation of the screw  155  from the transmission  115  and thus disconnection from motor  157   e . Conversely, counterclockwise rotation of the screw  198  results in engagement of the screw  155  with transmission  115  and thus engagement with motor  157   e . By coupling/decoupling of the transmission  115   a  to/from motor  157   e , the operator can transform to/from a manual mode of operation (or alternatively from/to automatic mode of action). 
     Reference is now made to  FIGS. 13   a  and  13   b , disclosing a quick fixing sub-mechanism  370  that enables connection and disconnection of the endoscope  500  and the gimbal  170  to/from arc  151 . This feature is of great significance for such operations when the surgeon needs/wants to switch modes or to clean the endoscope  500 . 
     The gimbal  170  is mechanically coupled to a cylinder  162  that serves as a hinge. The cylinder  162  abuts against clamping means (e.g., balls)  163  which apply pressure on the gimbal  170 , thus prohibiting its release from cylinder  162 . 
     Disconnection of the gimbal  170  from the cylinder  162  is attained by rotating the screw  161  counterclockwise. The pressure applied by the clamping means (balls  163 ) on the gimbal is eliminated, such that gimbal  170  and cylinder  162  can be pulled out from screw  161 . 
     When screw  161  is rotated clockwise, balls  163  are pushed out towards cylinder  162  thereby applying pressure on said cylinder. The pressure applied on the cylinder prevents gimbal  170  from disconnecting. 
     As stated above, the endoscope positioning system  300  is installed on the human limb. Precise positioning provided by the four freedom degree mechanism  100  enables alignment of the position of the endoscope  500  before insertion into a human joint and displacement of a distal end of the endoscope  500  inside the human joint. Rigid fixing of the endoscope  500  relative to the human limb provides freedom for the surgeon&#39;s hands from holding or maneuvering the endoscope  500  during a surgical operation.