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The present invention generally pertains to a surgical wire inserting instrument adapted to insert a circular pros-thetic device into or through bones to provide support and fixation while the bone structure is mending ox to provide anchoxage for traction.
In the prior art a prosthetic wire device, usually -~
circular in cross-section, is generally inserted into the bone by means of a pre-drilled hole or more commonly by driving the wire with a suitable drill chuck and letting the wire bore its own hole by means of a spade or trocar tip. A trocar tip is the tip most commonly used on such wires. One such device which has been used to insert wires is a device called a Loth-Kirschner extension drill. The drlll is hand operated with the drill bit being rotated by suitable gearing which is turned by a handle much like that of a fishing reel.
Another device which has been used is a pneumatic wire , driver manufactured by the Stryker Corporation. This device is ; a hand held device with a trigger. An air supply, which is connected to the device by way of a hose, passes through the handle of the yun causing the wire to rotate so that it o~tains ` a sufficient torque to be driven into the bone.
General1y speaking the prosthetic wires which are used in both of these instruments and wires which are used in the operating room are circular in cross-section ranging from .028 to .062 inches in diameter and are provided with a ground spade point or a trocar point. ~ ~;
Because of the circular cross-section and small diameter of these wires, they are difficult to hold in a collet tightly enough to prevent slipping during installation.
According to the present invention, there is provided ,','.`' ~.
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5G68~i a portable surgical wire inserting instrument comprising a housing, the housing defining a handle and a drive casing, a power source cassette comprising motor means and switch means, the cassette being mounted in the housing and completely en-closed within the housing handle, the motor means being mounted in the cassette, a wire holding means mounted in the drive casing, the wire holding means being adapted to grab and hold a wire inserted in the wire holding means in a fixed position, gear mean~ for connecting the motor means to the wire holding means and rotating the wire holding means on activation of the motor means; and e~ternal trigger means movably mounted on the housing, the external trigger means being connected to the cassette switch means and adapted to engage the cassette switch means to activate the motor means.
A knob and cam mechanism may be provided for adjusting the instrument to surgical wires of different diameters.
Rotation of the knob to one o~ a number of different positions may, for example, be arranged to establish a number of different positions for the pivot points o thrust bars which act upon pins to draw the wire holding tube means into an in-ternally coned tube. The positions correspond to locations of the thrust bar pivots suitable for gripping wires of different respective sizes. Gripping of the wire is accomplished by rotating a cam which moves the thrust bars rearward against pins which move a draw tube rearward and further draws the wire holding tube means into the internally coned tube, causing ~aws of the wire holding tube means to s~ueeze in and grip the surgical wire.
The invention will be better unders-tood by referring to the following description of a preferred embodiment thereof . .,
- 2 -' '''i''~'''` '' ~ ~56~6 taken in connection with the accompanyiny drawings in which like reference numerals refer to like parts throughout ~he several views and in which:
Figure 1 is a side elevational view partially in section of a wire inserter instrument;
Figure 2 is a side elevational view partially ex-ploded and partially in section of the wire inserter instrument;
Figure 3 is a perspective view of the instrument head - of the wire inserter instrument partiaIly cut away;
Figures 4, 4a, 4b and 4c show an exploded sectional view of a split spring collet, collet tube and nose sub assembly, draw tube and spring cartridge sub-assembly of a wire . gripping mechanism of the wire inserter instrument;
Figure 5 is a side elevational view partially cut away and partially in section of an instrument head;
:. Figure 6 is a top~plan view partially in section and ~ partially cut away of the instrument head;
: Figure 7 is a top plan view of a removable power pack of the instrument showing the miter gear partially cut away;
Figure 8 is a side elevational view partially in ~ ~
~. section of the removable power pack of the instrument; ~ -:
: Figure 9 is a bottom plan view of the removable power :. pack of the instrument;
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~- Figure 10 is an exploded view of the wire inserter in- :
~ strument, power pack, introducer funnPl, battery, collet cap -~ :~
~: and surgical wire; and ~ ;
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::. Figure 11 is a view showing assembly of the wire in-serter instrument, power pack, introducer funnel, battery, .~ collet cap and surgical wire. ~ `
. 30 The wire which is used in the illustrated assembly .
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l~S6~l~6 preferably is formed with four flats formed as chords each sub-tending a center angle of 45 located in an equally spaced manner around the circumference of the wirle.
A wire inserter instrument 20 as shown in the Figures comprises a handle 22 and a head assembly 28 with a removable power pack. The handle 22 is hollow with a hinged cover 24 which is held closed by a lever operated latch 260 Mounted on ~ -the handle is the instrument head assembly 28 which contains the mechanism for gripping a surgical wire 21. A knob 40 on the top of the instrument head is used to initially adjust the in-strument for gripping different diameters o surgical wire, as will be more ully described later on in the specification. ;~
When a surgical wire is placed within the head assembly after it has been ad~usted to receive the wire, the mechanism is activated by moving a side lever 30 from the "RELEASEI' position to the IILOCKII position as i~ sh~wn in Figure 1. The lever movement causes a split collet 32 in the nose 34 ~
to retract and squeeze closed, thereby gripping the surgical wire 21 inserted into the collet.
; 20 A disposable soft plastic collet cap 36 is pressed onto the nose portion 34 of the head assembly. The cap 36 is formed with a thin membrane 38 which, when punctured by the surgical wire 21, forms a light wiping seal on the surgical wire to keep foreign material out of the head assembly 28.
j Contained within the hollow handle 22 is a removable power pack or cassette 42 comprising a support or frame member 43 (Figures 7-9), an electric motor 44 and associated gearing, - a switch 46 and associated cross-bar 52, and a rechargeable battery 48. When the trigger 50 which is mounted on the handle is pressed, the cross-bar 52, which is slidably mounted in the i - 4 ~ ~
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frame member 43, depresses button 54 on the switch 46 7 which completes an electrical circuit between the battery and the motor, eneryizing the motor. The motor turns a drive shaft and associated gearing, rotating the collet and the surgical wire it is gripping. The rechargeable battery 48 is retained in a cavity of the power pack frame and is connected electrically by two contacts 56 and 58 to the switch and motor. When the motor 44 is energized by the switch 46, a miter gear 60 i5 caused to rotate, which drives the collet mechanism as will be later described. The removable power pack 42 is held in the handle with the latched cover 24 which bears against a leaf spring 62 on the power pack. The power pack frame member 43 ?
is provided with a guide slot 45 which serves to fit over a projection (not shown) in the interior of the handle so that the power pack is always mounted into the handle in the correct :
- position.
~ A collet tube 64 is mounted in the nose 3~ by a thrust : . :
bearing 66 and a radial bearing 68 and is additionally supported by a Nylon* bushing 70. A miter gear 72 is mounted on the 20 collet tube and positioned to engage the miter gear 60 of the power pack so that the collet tube is driven to rotate when the motor is energized. As shown in Figure 4, a draw tube 74 ex-tends through the collet tube and engages the threaded portion 76 of the split spring collet 32. A hollow set-screw 78 is .. :, .
;~ adjustably mounted in the threaded bore of the draw tube 74 to j lock the collet 32 into a properly adjusted position. The end ;, of the set screw is provided with a hexagonal configuration so -~
that an allen wrench can be inserted into the interior of the draw tube to selectively position the set screw within the draw .,i :
, 30 tube.
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Rotation of the side lever 30 to the "LOCK" position rotates a cam rod 80 (Figure 3~. Flats 82 and 84 on the cam rod rotate against mating flats 86 and 88 on thrust bars 90 and 92.
The thrust bars are pivoted at their other end on pins 94 and 96.
Rotation of the cam rod causes the thrust bars to move rear-wardly (away from the nose) against pins 98 and 100 extending from thrust washer 102. Pre`ssure from the thrust ~ars onto ,;
these pins is transmitted to a ball bearing assembly 104 which is connected to the draw tube 74. Pressure from the pins is 10 transmitted to the bearing assembly 104 through a spring 106 contained within cartridge 108. The spring serves to limit -` the pressure which can be applied to the bearings and collet.
When the cam rod 80 is rotated to "LOCK" position, ., ^~ the bearing 104 is moved rearwardly, moving the draw tube rear- ~ ~
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wardly, which pull conical surfaces 109 of the split collet into mating conical inside surface 110 of the collet tube, causing jaws 112 of the split collet to squeeze closedj thereby gripping the surgical wire. The collet jaws 112 which engage the surgical wire are flat to correspond with lengthwise flats ~, 20 on the surgical wire, which prevents rotation and slipping of :~ .
the wire in the collet. A spline arrangement 114 causes the draw tube 74 and collet 32 to rotate with the collet tube 64 when the motor is energized. Crescent springs 116 and 118 : :;
~, cause the draw tube and collet to be returned to the forward ~;~ position when the cam rod is rPturned to the "RE1EASE" position. ;
The wire size adjustment knob 40 on the instrument : . ~
;~ head is connected to a follr faced cam 12Q which engages a dee hole 122 in draw bar 124, which carries the pivot pins 94 an~
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~!~ 96. Thus, when the knob 40 is rotated to the four positions in which the four cam faces of the cam 120 engage a flat surface ''' ':
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123 defining the dee hole 122 in the draw bar 124, the upper pivots 94 and 96 of the thrust bars 90 and 92 are adjusted selectively to one of four positions. As the flat surface of the dee hole 122 is moved rearwardly, the pivots 94 and 96 move rearwardly, Eorcing the thrust bars to move rearwardly, causing the draw tube to pull the collet into the collet tube. The engagement of the collet with the coned inner surface of the collet tube cause the collet jaws to close, so that varying sizes of smaller surgical wires can be gripped when the cam knob is rotated. Thus, the four positions of the cam result in four adjustments of the instrument for gripping four sizes ~dia-meters) of surgical wires which are preferably .028, .035, .045 and .062 inches. Additional micro adjustment of the instrument is accomplished by subsequently moving side lever 30 to the lock position as previously described.
As shown in Figure 10, the complete system consists of -a surgical wire 21, the wire inserter instrument 20 with re-movable power pack 42, rechargeable battery 48 and disposable collet cap 36. A stepped introducer funnel 128 is used to cover ;~ 20 the open end of the instrument handle so the non-sterile power pack can be installed into the sterile instrument without con- ~ `~
; 1,, taminating the outer surfaces of the instrument. The funnel is ~`
notched to allow installation of the funnel over the hinge cover.
Figure 11 shows the power pack being installed into ~ -the instrument handle through the introducer funnel 128 with ;;
surgical wire 21 and collet cap 36 in place. A guard ring 132 .
on the positive end of the battery 48 assures that the battPry can only be installed in the proper direction of the power pa~k.
., - , . , In operation, trigger 50 is pulled back towards the ~ `
handle moving ~he cross-bar 52. The button 54 of the micro .~ ~
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S6~6 switch 46 then energizes the motor 44.
The cover 24 can be released by turning latch 26 on the handle so that the power pack can be removed from the handle.
The removal of the power pack either allows a battery to be placed in the power pack or allows the instrument 20 to be auto-claved for sterile use. Thus, it can be seen that the instru-ment can b~ autoclaved in a conventional manner such as by heat and/or steam with no damage to the battery or to the motor. In addition, the power pack can be easily loaded into the handle without loss of instrument sterility through the use of the stepped funnel 128 as is shown in Figure 11. As shown in Figure ` 11 the instrument 20 is turned upside down with the cover 24 ~;
opened and the funnel mounted on the handle base over the hinge of the cover, allowing the power pack to be dropped into the handle in an aligned position.
,' The funnel is preferably constructed of aluminum and ~ ., .
the instrument housing and external parts are aluminum while the ' moving parts of the instrument are preferably constructed of stainless steel. However, plastic or brass or other suitable , 20 material components can be used if such is desired.
While the preferred embodiment of the invention has .,'' ~ ..
been disclosed, it is understood that the invention is not :....................................... .
limited to such an embodiment since it may be otherwise embodied in the scope of the appended claims.
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