Patent Publication Number: US-2007102008-A1

Title: Table mounted thigh harness

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to a leg support for a surgical procedure. More particularly, the present invention relates to a table mounted harness for securing a knee in a flexed position for a surgical procedure.  
      Several methods have been developed for securing a knee in a flexed position for a surgical procedure such as a knee replacement surgery. The knee is preferably positioned into the flexed position to gain access to the ends of both the femur and tibia. Providing access to the ends of both the femur and tibia allows the damaged ends to be replaced with implants.  
      One method for securing the leg in a selected flexed position for a surgical procedure includes clamping the upper leg, also referred to as a thigh, to a surgical table with a clamping device that is positioned about the upper leg. With the thigh secured in the selected position, the knee joint is located proximate an edge of the surgical table. The lower leg hangs downward from the edge of the table, thereby flexing the knee for the surgical procedure.  
      Another method of securing the knee in a flex position for a surgical procedure is to insert a foot of the leg in a boot type structure attached to the table. The boot is moved while retaining the torso of the patient in a selected position, thereby causing the knee to flex into the selected position. Alternatively, the boot can be attached to the table and the position of the patient&#39;s torso is adjusted to cause the knee to flex into the selected position.  
      Another method of securing the knee in a flexed position is to provide a support apparatus that is positioned under the leg with the knee positioned in a selected flexed position. The leg is supported by the apparatus with the knee in the selected flexed position.  
      Utilizing any of the methods previously described to retain the knee in a selected flexed position requires a clinic or hospital to purchase a series of differently sized devices to accommodate patients of different sizes. Having to purchase a series of devices to perform the same procedure increases the costs to equip a clinic or hospital.  
     SUMMARY OF THE INVENTION  
      The present invention includes an apparatus for supporting a leg during a surgical procedure. The apparatus includes a support for mounting to a surgical table and a harness for attaching to the support. The harness positions about the thigh and secures to the support thereby supporting the thigh in an elevated position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a top view of a leg harness of the present invention attached to a thigh;  
       FIG. 2  is a perspective view of the leg harness of the present invention in a separated configuration;  
       FIG. 3  is another perspective view of the leg harness of the present invention in a separated configuration;  
       FIG. 4   a  is a partial perspective view of the leg harness of the present invention in a separated configuration;  
       FIG. 4   b  is a partial perspective view of the leg harness of the present invention in an attached configuration;  
       FIG. 5   a  is a partial sectional view of a leg support of the present invention in a separated configuration;  
       FIG. 5   b  is a partial sectional view of the leg support of the present invention in an attached configuration; and  
       FIG. 6  is a partial exploded view of the leg support of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      An apparatus for supporting a leg during a surgical procedure of the present invention is generally illustrated at  10  in  FIG. 1 . The apparatus  10  includes a leg support  11  that is mounted to a support apparatus  12  having arms  21  that are positioned on opposite sides of a leg  14  of a patient that is preferably bent at a knee joint  16 . The support apparatus  12  is mounted to a post  13  that is attached to a rail  17  of a surgical table  18 .  
      A harness  28  attaches the thigh  15  to the leg support  11 . By harness is meant a fastener that retains an object, such as a thigh, in a selected position where at least a portion of the fastener has flexible characteristics. By flexible is meant capable of conforming to a surface of an object, such as a thigh.  
      The leg support  11  includes a shaft  20  that extends over the surgical table  18 . A docking mechanism  23 , such as a plate  26  attaches to a distal end  22  of the shaft  20 . The plate  26  is positioned proximate the thigh  15  and preferably has an arcuate surface  25  that generally conforms to the shape of the thigh  15 .  
      Referring to  FIG. 2 , the plate  26  is secured to the thigh  15  with the harness  28  that is positioned about a circumference of the thigh  15  and over at least a portion of the plate  26 . The harness  28  secures the plate  26  on a selected position of the thigh  15  to provide access to a surgical site, such as the knee joint  16 . Although the harness preferably attaches to the plate, it is with the scope of the present invention for the harness to attach to another docking mechanism  23  including, but not limited to, one or more bars, hooks, or loops.  
      An exemplary harness  28  includes surgical tape. However, other harnesses are also within the scope of the present invention including, but not limited to, a rope, a strap, a cloth strip, a mesh strip and an elastic bandage such as an Ace® bandage manufactured by Becton, Dickinson and Company of Franklin Lakes, N.J., and a polymeric material. The harness  28  may have elastic, extendible properties, rigid portions attached to flexible portions or non-elastic, flexible properties.  
      The harness  28  secures the thigh  15  to the plate  26  with any suitable attaching device such as a pressure sensitive adhesive, a loop and hook mechanism such as that sold under the VELCRO trademark, a buckle, a snap, a pin, a hook or a drawstring. Other fastening devices are also within the scope of the present invention.  
      The shaft  20  includes a stub shaft  32  that attaches to a main portion  38 . The stub shaft  32  includes a pivot ball  34  that is positioned within a housing  27  that is attached to the plate  26 . The housing  27  rotates about the pivot ball  34  to rotatably adjust a position of the plate  26 .  
      The stub shaft  32 , having a substantially circular cross-section, includes a proximal end  36  that positions within a substantially circular cross-section cavity  40 . The cavity  40  opens from a distal end  41  of the main portion  38  substantially along a central axis  42 . The distal end  41  of the main portion  38  outwardly flares to aid in positioning the stub shaft  32  within the cavity  40 . A non-flared distal end  41  and a non-circular cross-section cavity  40  and stub shaft  32  are also within the scope of the present invention provided that the stub shaft  32  is positionable within the cavity  40 .  
      Referring to  FIGS. 4A, 4B ,  5 A and  5 B, a peg  43  extending from a plate  44  positions within an annular groove  33  in the stub shaft  32  to return the stub shaft  32  within the cavity  40 , as best illustrated in  FIGS. 4B and 5B . A compression spring  45  biases the plate  44  toward the cavity  40  to retain the peg  43  within the annular groove  33 .  
      As best illustrated in  FIGS. 4A and 5A , the peg  43  is displaced from the annular groove  33  by applying manual force to a knob  46  that is attached to a plunger  47  that engages the plate  44 . As the plunger  47  engages the plate  44 , manual force overcomes the bias of the compression spring  45  and causes the peg  43  to move from the cavity  40  and exit the annular groove  33 .  
      The plunger  47  is positioned within a through bore  37  in the retaining mechanism  39  that intersects the cavity  40 . The plunger  47  is retained within the through bore  37  through engagement of a shoulder  49  on the plunger  47  with a threaded nut  35  that threadably engages the threaded through bore  37 .  
      With the peg  43  displaced from the annular groove  33 , the stub shaft  32  disengages from the cavity  40  with manual force. The stub shaft  32  repositions within the cavity  40  by applying manual force to the knob  46  which forces the plunger  47  into the plate  44  and displaces the peg  43  from the cavity  40  by overcoming the bias of the compression spring  48 . The stub shaft  32  repositions within the cavity  40  such that the annular groove  33  aligns with the peg  43 . With the annular groove  33  aligned with the peg  43 , manual force is removed from the knob  46  and the compression spring  48  forces the peg  43  into the annular groove  33  and thereby retains the stub shaft  32  to the main portion  38 .  
      Referring to  FIG. 3 , the main portion  38  of the shaft  20  is slidably adjustable within a through bore  52  of a clamp  50  attachable to a support apparatus clamp  11 . The support apparatus clamp  11  includes apertures that accept a post  54  extending from the clamp  50 . The post  54  retains the clamp  50  to the support apparatus clamp  11 . The post  54  and the surface defining the apertures preferably have flat surfaces that engage and prevent the post  54  from rotating within the apertures. However, it is within the scope of the present invention for the post  54  to rotate with respect to the support apparatus clamp  11 .  
      Referring to  FIGS. 3 and 6 , the main portion  38  is secured in a selected position by rotating a knob  60  attached to a camming mechanism  64 . The mechanism  64  includes an eccentric portion  66  having an axis  68  offset from the axis  78  of rotation of the camming mechanism  64 . As the camming mechanism  64  rotates, a surface of the eccentric portion  66  engages a substantially flat surface  70  on the main portion  38 . The engagement of the surface of the eccentric portion  66  with the substantially flat surface  70  frictionally secures the main portion  38  in the selected position.  
      The main portion  38  preferably includes a proximal portion  72  having the flat surface  70  and a distal portion  74  pivotally attached to the proximal portion  72 . However, the main portion  38  may also be constructed of a single member. A pivot pin  76  is positioned within aligned apertures (not shown) in the proximal portion  72  and the distal portion  74  to pivotally attach the distal portion  74  to the proximal portion  72 . The pivot pin  76  frictionally engages the proximal portion  72  and the distal portion  74  such that manual force is required to adjust a position of the distal portion  74  with respect to the proximal portion  72 .  
      A back surface  78  of the distal portion  74  engages a substantially vertical surface  80  on the proximal portion  72  to limit an upward movement of the distal portion  74 . The back surface  78  of the distal portion  74  engages a slanted surface  82  of the proximal portion  72  to limit downward movement of the distal portion  74 .  
      An angle defined by the substantially vertical surface  80  and the slanted surface  82  limits the rotational range of movement of the distal portion  74 . The distal portion  74  may be adjusted within the range of movement to provide access to the cavity  40  when the thigh  15  is in the selected position.  
      In operation, the stub shaft  32  separates from the main portion  38  of the shaft  20  and the plate  26  is positioned in a selected position on the thigh  15 . The plate  26  is secured to the thigh  15  with the harness  28 , preferably with surgical tape. The harness  28  is wrapped around the circumference of the thigh  15  and also covers at least a portion of the plate  26  to secure the plate  26  to the thigh  15 .  
      The post  54 , extending from the clamp  50 , is positioned within the apertures in the support apparatus clamp  11  to secure the clamp  50  in the selected position. Alternatively, the clamp  50  may be positioned in a selected position along the lengths of the support arms  21  and secured thereto with a clamp or another securing device.  
      With the clamp  50  secured in the selected position, the main portion  38  is slidably positioned within the through bore  52  in the clamp  50  to position the distal end  41  in the selected position. The camming mechanism  64  rotates to frictionally secure the main portion  38  in the selected position by engaging the flat surface  70  with the eccentric portion  66 .  
      The thigh  15 , having the stub shaft  32  secured thereto, is elevated by articulating the knee joint  16  and thereby positioning the proximal end  36  of the stub shaft  32  with the cavity  40  in the distal end  41  of the main portion  38 . Manual force applied to the knob  46  overcomes the bias of the compression spring  48  to displace the peg  43  from the cavity  40 . The proximal end  36  of the stub shaft  32  is positioned into the cavity  40  such that the annular groove  33  is aligned with the peg  43 . Manual force is removed from the knob  46  such that the compression spring  48  biases the peg  43  into the annular groove  33  and thereby secures the stub shaft  32  to the main portion  38 . With the stub shaft  32  secured to the main portion  38 , the thigh  15  is secured in the selected elevated position with the knee joint  16  in a bent position.  
      To adjust the position of the thigh  15  and the knee  16 , the camming mechanism  64  is rotated to release the frictional engagement between the surface of the eccentric portion  66  and the substantially flat surface  70  such that the main portion  38  is slidably positioned through the clamping bore  52 . With the thigh  15  and the knee  16  in the selected position, the camming mechanism  64  is rotated and the main portion  38  is secured in the selected position with the frictional engagement. Additionally, the position of the thigh  15  is adjusted by pivoting the distal portion  74  of the main portion  38  about the pivot pin  76 . By pivotally moving the distal portion  78 , the thigh  15  is raised or lowered into a selected position.  
      Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.