Abstract:
A femoral distractor includes a top post for positioning under a patient&#39;s knee and a bottom pin for fixed attachment to a hospital bed rail. A vertical rod extends between the top post and horizontal bottom pin to move the knee joint in the vertical direction upon operation of a trigger assembly.

Description:
BACKGROUND OF THE INVENTION 
     Devices such as described within U.S. Pat. No. 5,116,338 entitled “Apparatus for Knee Prosthesis” and U.S. Pat. No. 5,308,350 entitled “Femoral Distractor for Use in Knee Surgery” are currently available for assisting a surgeon in knee surgery by employing means for insertion within the knee joint to retract or distract the femur from the tibia. 
     The use of such sterile pins, rods, or sterile spreaders and the like to provide insertion requires considerable time and effort to insure insertion in a precise and antiseptic manner within the joint space and thereby create enough space for instruments and implantable devices. 
     It would be highly advantageous to be able retract or distract the femur from the tibia during such knee surgery without having to insert any pins, rods, or sterile spreaders into the joint space thereby obscuring vision and occupying instrument space. 
     On purpose of the instant invention is to describe a simple and effective approach to femur distraction during knee surgery that is performed external to the knee joint, per se, for increasing surgical vision and surgical space when preparing to implant a prosthetic device. 
     SUMMARY OF THE INVENTION 
     A femoral distractor includes a top post at one end for positioning under a patient&#39;s knee when the knee has been incised to expose the femur and tibia and a bottom pin at the opposite end for fixed attachment to a hospital bed rail or a knee positioner unit. A vertical rod extends between the top post and horizontal bottom pin for controlled movement of the top post to move the knee joint in the vertical direction upon operation of a hand-operated and spring-loaded trigger assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of the femoral distractor unit in accordance with the invention; and 
         FIG. 2  is a front perspective view of the components of the femoral distractor of  FIG. 1  prior to assembly. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in  FIG. 1 , the femoral distractor unit  10  includes a knee support bar  11  at one end for supporting a patient&#39;s knee during surgery and a base support bar  12  at the opposite end for attaching to a support base  13 , similar to that described within U.S. Pat. No. 7,003,827 entitled “Operating Table Support Clamp”, which patent is incorporated herein for purposes of reference. 
     An outer cylinder  19  interconnects between the support bar  11  and support base  13  via the support bar  12  at one end and the U-shaped support  21  at the opposite end thereof. The support bar  12  is attached to the support base  13  via connector pin  15  in press-fit relation to allow the unit  10  to move along the knee positioner carriage rail (not shown) via the extended slot  14 . 
     Although the unit  10  is arranged herein for attachment to the knee positioner, device, per se, as described in the aforementioned U.S. Pat. No. 7,003,827, for example, it is to be understood that the unit could be directly attached to an operating table side rail, via a modified clamp (not shown.) 
     The driver rod  18  extends within the outer cylinder  19  and is attached to the support bar  11 , via screw  17  to move the support bar  11  in the indicated vertical direction against the bias of the compression spring  9  arranged within the U-shaped support  21 . A sterile foam cylinder  27  is arranged on the support bar  11  to insure sterile contact with the patient&#39;s knee (not shown). 
     The lever  26 , arranged on the driver rod  18  in press-fit relation, extends, at one end, under the lever pin  25 . 
     The handle lever  22  is pivotally attached to the flange  23  extending from the U-shaped support  21  via pivot pin  24 . When the handle lever  22  is moved toward the outer cylinder  19 , lever pin  25  drives the spring lever  26  and the attached driver rod  18  in the vertical direction against the bias of the compression spring  9  to thereby move the attached support bar  11  in the vertical direction. The relative movement of the handle lever  22  towards the outer cylinder  19  governs the associated movement of the driver rod and attached support bar  11  in a controlled manner. 
     Maintaining the handle lever  22  in a determined position relative to the outer cylinder  19  holds the support bar in an associated determined position, during knee surgery, which is an important feature of the instant invention. 
     When the patient&#39;s knee (not shown) is arranged over the support bar  11  and the knee is incised to separate the femur and tibia, movement of the handle lever  22  controls the position of the knee and accordingly determines the precise distance that the femur is separated from the tibia, during the course of the knee surgery. 
     To move the femur toward the tibia, tension on the handle lever  22  is controllably released to allow the compression spring  9  to force the driver rod  18  and attached support bar  11  to thereby move the femur in the opposite vertical direction. 
     The arrangement of the components within the femoral distractor unit  10  is best seen by now referring to  FIG. 2 . 
     The outer cylinder  19  having the support bar  12  welded at the end, receives the connector pin  15  for attachment to a knee positioner, as described earlier, along with a threaded opening  19 B for allowing the attachment of the outer cylinder  19  to a surgical knee positioner unit (not shown) via threaded bolt  16 . 
     The U-shaped support  21  is welded at the opposite end of the outer cylinder  19  and receives the driver spring  9  and release spring lever  26 , which includes an opening  26 A for receiving the driver rod  18  in press-fit relation. 
     The handle lever  22  includes apertures  22 A, for attachment to the U-shaped support  21  via aperture  28  and pivot pin  24  along with apertures  22 B for receiving lever pin  25  that is positioned under one end  26 B of the spring lever  26  for the purposes described earlier with reference to  FIG. 1 . 
     The driver rod  18  extends thru aperture  11 A, at one end of the support bar  11 , for attachment to the support bar via screw  17 . Prior to surgery, the sterile foam cylinder  27  is positioned over the support bar  11  to provide sterile contact with the patient&#39;s knee (not shown). 
     A simple and efficient arrangement has been described herein whereby a patient&#39;s femur can be precisely separated from the tibia during knee surgery without requiring insertions of pins, rods, spreaders and the like into the femur/tibia space or medullar canal as often required with prior knee surgery operations.