Patent Publication Number: US-2021161571-A1

Title: K-wire depth measurement

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to methods and apparatus for measuring depth of a Kirschner wire (K-wire) that passes through a surgical tool, such as but not limited to, screwdrivers, taps, bores, awls, probes, jamshidi needles, and others. 
     BACKGROUND OF THE INVENTION 
     For example, in certain surgical procedures, a K-wire or similar guide wire (the terms being used interchangeably throughout) is used in combination with a cannulated surgical tool, such as a screwdriver, tap, bore, awl, probe, or jamshidi needle, to name some. The K-wire is positioned through the pedicle and into the vertebral body to indicate or establish the position of subsequent screw placement. Once the proper positioning of the K-wire is confirmed by X-rays, the screw connected to the screwdriver is guided over the K-wire through the lumen (cannula) of the surgical tool and penetrates into the bone, which if not done properly can injure the patient, particularly if the K-wire encounters certain sensitive tissues. The procedures often require the use of force which can cause an otherwise properly positioned K-wire to move forward into the surgical site, which if excessive can move into contact where contact is to be avoided. 
     Measurement of the depth of the K-wire, that is, the amount the tip of the K-wire protrudes from the distal end of the surgical tool, is critical for patient safety. In a normal screw placement over a K-wire, the K-wire is placed to the desired depth, and then the screw is advanced over the K-wire. The surgeon must make sure the tip of the K-wire is not pushed further distally towards the anterior cortex of the vertebral body. If the K-wire tip were to puncture through the vertebra it could damage major blood vessels and cause major bleeding. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide an improved device for measuring the depth of a K-wire, as described more in detail hereinbelow. 
     The term K-wire throughout the specification and claims encompasses any slender, elongated piece with a tip used for entering bone, such as a K-wire or Steinmann pin or guidewire. 
     There is thus provided in accordance with an embodiment of the present invention an assembly including a surgical device including a distal interface member and a proximal handle, the distal interface member including a connecting element for connecting to a surgical tool, and a K-wire that passes through a central passageway of the surgical device distally through the distal interface member into a lumen of the surgical tool, and a wire depth measurement tool that includes a handle interface member that assembles to the handle and one or more graduated scales that extend proximally from the handle interface member, the one or more graduated scales including depth graduations for indicating an amount a tip of the K-wire protrudes from a distal end of the surgical tool. 
     In accordance with an embodiment of the present invention the handle interface member includes a threaded connection and a knob, wherein the threaded connection mates with the handle and is tightened or loosened by turning the knob. 
     In accordance with an embodiment of the present invention the K-wire is locked in place in the handle by means of a locking element. 
     In accordance with an embodiment of the present invention the one or more graduated scales include a plurality of scales that face different directions. 
     In accordance with an embodiment of the present invention the wire depth measurement tool is formed with a lumen for the K-wire to pass through. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: 
         FIG. 1  is a simplified illustration of a surgical tool assembled with a wire depth measurement tool, constructed and operative in accordance with an embodiment of the present invention; 
         FIG. 2  is a simplified illustration of the wire depth measurement tool assembled on a handle of the surgical tool; 
         FIGS. 3 and 4  are simplified plan-view and perspective illustrations, respectively, of the wire depth measurement tool, in accordance with a non-limiting embodiment of the present invention; and 
         FIG. 5  is a simplified exploded illustration of the surgical tool, wire depth measurement tool and K-wire. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Reference is now made to  FIGS. 1-2 and 5 , which illustrate a surgical device  10  assembled with a wire depth measurement tool  30 , constructed and operative in accordance with a non-limiting embodiment of the present invention. 
     Surgical device  10  may be, but not necessarily, constructed similarly to the tool described in PCT Patent Application PCT/IB2016/052074 (WO 2016/166662). 
     Surgical device  10  includes a distal interface member  12  and a proximal handle  14 . Distal interface member  12  includes a connecting element  16  for connecting to a surgical tool  18 , such as but not limited to, a cannulated pedicle awl, a screw, a screwdriver, a tap, a bore, a probe, or a jamshidi needle and the like. For example, connecting element  16  may be a quick-disconnect connector that secures to the proximal end of tool  18 . Surgical device  10  is formed with a central passageway or lumen formed through distal interface member  12  and handle  14 , and through surgical tool  18 . Two or more surgical tools may be connected to each other, such as a screwdriver connected to a pedicle screw. 
     A K-wire  20  passes through the central passageway of surgical device  10  distally through distal interface member  12  into the lumen of surgical tool  18 , and then can pass distally out the distal tip of surgical tool  18 . The K-wire  20  may be locked in place in the handle  14  by means of a locking element  22  (such as, but not limited to, a screw or nut). 
     The wire depth measurement tool  30 , shown particularly in  FIGS. 3 and 4 , includes a handle interface member  32  that assembles to the handle  14 . For example, handle interface member  32  may include a threaded connection  33  and a knob  34 . The male (or female) threaded connection  33  mates with a corresponding (female or male) threaded portion of handle  14  and is tightened or loosened by turning knob  34  in the appropriate direction. Alternatively, handle interface member  32  may connect to handle  14  or even to surgical tool  18  by other means, such as but not limited to, quick disconnect connections, press fit, snap fit, bayonet connections and others. 
     One or more graduated scales  36  extend proximally from handle interface member  32 . Each graduated scale  36  has depth graduations for indicating the depth of K-wire  20 , that is, the amount the tip of K-wire  20  protrudes from the distal end of the surgical tool  18 . There are preferably several graduate scales  36  that face different directions so the surgeon can easily see the depth graduations at any viewing angle. The wire depth measurement tool  30  is formed with a lumen  38  for the K-wire  20  to pass through. The wire depth measurement tool  30  is pre-calibrated such that when tool  30  is properly assembled on surgical device  10 , the graduated scale  36  accurately indicates the depth of K-wire  20 . 
     In another aspect of the invention, K-wire  20  includes one or more depth graduations  23 , which may be laser marked, etched or otherwise disposed at least partially around the circumference of K-wire  20 .