CA1271998A

CA1271998A - Sighting instrument

Info

Publication number: CA1271998A
Application number: CA000516496A
Authority: CA
Inventors: Robert Frigg; Paul Gisin; Urs Jenny; Stephan M. Perren; Gebhard Ritter
Original assignee: Synthes USA LLC
Current assignee: Synthes USA LLC
Priority date: 1985-10-03
Filing date: 1986-08-21
Publication date: 1990-07-24
Also published as: US4803976A; CH671873A5

Abstract

Abstract A sighting instrument, particularly for surgical purposes, comprising a handle, a tool socket and a direction finder which may be held between a radiation source and a radiation receiver, the position of which can be represented visibly by means of an image converter, allowing continuous adjustment of its orientation.

Description

~ ~7~8 Siqhtinq I~stru~ent Field of thç Invention The invention refers to ~ 6ighting instrument, particularly for ~urgical purposes.

~açkqround ~f t~e Invention Certain 6urgical procedures require the use of ~ 6ighting device. For example, when an lntramedullary nail is inserted in the medullary canal of a bone, ~t may be necess~ry to lock the ond of the nall in place by inserting retaining pins, al60 called ~nt~rlocking scre~s or ~tud~, through lnterlocking holes at the di~t~l cnd of the nall. It ~ important ~n ~n~ertinq these 6tuds t~at one ~hould know the precise position of the inter~ocking hole~ ln the nail to avoid unnecess~ry damage to the bone.
Devlce6 are ~nown ln which a dr$11 template is adjusted and ultimately fixed in the desired position by means of an x-ray i~age nmpli~ier. For example, Swiss Patent CH-A5 635 998 discloses ~n aiming device which has ~n aiming head with a hole for the ln~ertion of a direction~l ocket. The aiming head ~ounting iB positioned in ~ holder that i6 connected to the x-ray -~achine and i6 6uspended from the x-ray machine. This arrangement ~akes it difficult to position the apparatus and to fix it in position, with resulting unsatisfactory target precision. In addition, the ~tationary arrangement limits operation.

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Becau6e of these problems, ~n aiming device has been devised thnt can be used independently of the x-ray ~achine. Thus, German industrial design patent Ul ~4 17 ~28 describes ~ device with A
~eceiving he~d that rest6 in ~ ~older And i6 permeable to x-rays, and which accept6 n drill bit or a drill wire. Even this improved device, ho~ever, has ma~or di6advantages. In particul~r, the ~lming process t~kes place during the drilling of the bone, which c~u6es considerable darkening of the working field ~nd low image reBO1UtiOn. A1BO~ ~he lack of ~ drill housing to protect the patient'~ ti6sue leads to dam~ge whenever the tool or ~nstrument being used ~B ch~nged.
In addition, ~ nown devices ~uffer from n serious flaw in thnt lt ls impossible to verify the t~rgeting procedure and to ~ake the nacessary corrections durlng the operation, Summ~rY of the Invçnt~Qn The present invention overcomes the dr~wbac~s of the prior Mrt dev1ces described above by providing n sighting instrument which allows ccntinuous control ~nd correction of the position of the ~xis of the tool socket and provides for optimum protection of the tissue. The ~nvention nl60 permits consider~bly improved picture resolution to be achieved.
By ~ean6 of the present invention, maximum precision can be achieved and the targeting process as a whole can be shortened, which is important for safety considerations in x-r~diation work.

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For example, in a typical intramedullary nail locking procedure, the period of x-radiation can be reduced from a few ~inutes to ten ~econds.
In accordAnce w~th the invention these resultfi are obtained by ~eans of a 6ighting instrument comprising a tool 60cket, a direction f$nder connected to said tool 60cket and a handle connected to 6aid direction finder ~nd tool socket, whereby the ocket and direction finder ~ay be ~alntalned in n defined po61tlon relatlve to OnQ another and ~ay be held between a radint~on ~ource and a rndi~tion receiver for adjusting the or$entat~on of caid dlrection finder and ~oc~et.
In another a~pect the invention includes an apparatus for drllllng a hole under condit$ons preventinq direct observation of the directlon of drllling ~hlch comprl6es a 60urce of radiatlon, a receiver for receivlng ~aid radiation, a converter for visually dlsplaying en ob~ect lylng in the radiatlon fleld between 6aid cource ~nd 6aid recelver, and a slghting ~nstrument comprising a drlll 60cket, a directlon ~inder connected to 6a$d dr$11 socket and ~eans for positlonlng sald drlll socket and direction finder in ~aid radiation fleld vhereby the directlon of n drill bit inserted in ~aid drlll ~ocket ~ay be controlled by controlling the orlentatlon of ~ald direction finder.
In 6till another aspect the invention includes a method for drilling a hole in a bone for the $nsertion of a transverse retaining pin or stud in A transverse hole in an intramedullary nail which comprises positioning the bone in a radiation field so ~ ~ 7~ ~3~

that t~e ~xis of the nail i6 tr~nsver6e to the direction of the ~ield and the nxi6 of the transverse hole is aligned with the direction of the field, positioning n 6ighting in6trument having tool socket nnd a direction finder with ~n axi8 p~rallel to the ~xis of the tool socket, ad~acent to the bone, 80 that the axis of the socket i6 ~ligned wlth the ~xis of the transverse hole, and drilling a hole in the bone, ~hile controlling the direction of drilling by ~eans of s~id dlrection ~inder.
~he invent$on will be ~urt~er described in the accomp~nying dr~wing~, ln ~hich:

P'~g. 1 ~6 view ln per6pective rhoving the ~ighting ~n6trument ~ccording to the invention and nssoci~ted x-ray oquipment u~ed ln in~erting retaining pin~ or locking ~tud6 ln ~n intr~medull~ry nail;
Fig. 2 16 pl~n view of a 6ighting instrument ~ccording to the invention;
Fig. 3 is a ~ide elevational view of a 6ighting instrument ~ccording to the inventlon with a pin inserted into the tool 60cket for determining the position point;
Fig. 4 is ~ plan view of the instrument according to the invention shown ~s in Fig. 3, in position but not yet ~ligned;

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Fig. 5 is a plan view of ~ 6ighting instrument according to the invention in position ~nd nliqned in the radiation field, with ~ drill bit inserted in the tool 60cket;
Fig. 6 i~
~ ~chematic repre~entation of the radiation field;
Fig. 7 is a cross-section through the tool 60cket and the direction finder of a ~odifled form of ~ sightlng ln~trument according to the invention;
Fig. ~ 1B
n plan vlew of ~ ~ghting ln~trument ~ccording to the invent~on wit~ an ~ddition~l drill bushing for in6erting the ~econd interlocklnq cre~;
Fig. 9 ~B
~n elevational ViQW ~een from the right 6ide of Fig. 8;
Fiq. 10 i6 an end elevational view of the device of Fig. 8;
Fig. 11 is a perspective vlew of the 6ighting instrument according to Figs. 8 to lo with an inserted first interlocking screw;
Fig. 12 is a monitor image of the ~ighting instrument according to Fig.
11 in a non-aligned position: and ^:

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Fig. 13 16 A monitor i~age of the sighting instrument according to Fig.
11 in an aligned position.

~ç,tailed Descrip~ion Fig. 1 shows A device ~ccording to the invention used for insert~ng retaining pins or studs in nn lntramedullary nail. As shown ln Flg. 1 it is used ln connection vith ~n x-ray source 3, and x-ray receiver 2, and an image converter 4, having n monitor 5, connected to x-ray receiYer 2.
In the r~di~tion ~leld 9 o~ t~e x-ray ~achine the patient' 6 thigh 7 ls shown positioned with ~n lntramedullary nail 6 already lnserted ln th~ ~edull~ of the femur 8. A sighting lnstrument 10 ~ccording to the lnYention iB used ~ith a tool 1, ln thi6 case an lectric drllllng devlce, to be used for drilllng through t~e femur 8.
The position of the drill tip with regard to the nail 6 and the ad~ustment of the slghting instrument 10 ln the radi~tion field 9 can be followed, and lf neces6ary corrected, by observing it~ l~age on the ronltor 5 of the l~age converter 4.
~ eferring to Figs. 2 and 3 the ~ighting lnstrument 10 according to the lnvention consists of a handle 11 having an extended shank lln to which a tool fiocket 12 is attached. A direction finder 13, having cross-hairs 13a, 13b is attached to the socket 12 by an arm 12a in such a way that lt can be pivoted around tool ~ocket 12, preferably with catches (not shown) that per~it a 90- pivot.

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The tool 60cket 12 consi~ts e~sentially of a hollow cylinder having two teeth 21. The cylinder i~ adapted to hold ~ pin 16 made of a radiation-permeable material, such as plastic, at the tip of which a reference component 17 is embedded. This reference component ~6 made of ~ radiation-impermeable material, 6uch as metal. In one embodiment of the invention, reference component 17 i6 ~pherical in 6hape.
Direction finder 13 i~ char~cterized by having two aiming elements lying ~n different pl~nes. For example, the direction ~Inder 13 may con~i~t o~ t~o ~ets o~ cro~s-hair6 13~, 13b angularly di6place~ 45- and ly~ng opposite each other in different plane~. Ot~er ~ppropriate aiming ~lement6 such a~ ~ circle ~nd a ~ot may ~l-o bc used.
Axia 20 of directlon finder 13 and the ~xis 18 of tool ~ocket 12 are co-planar. The di~tanco between tool socket 12 and dlrection ~lnder 13 1~ ~he came as the di6tance between the two interlocking holes, 1~ and 15, of nail 6.
The method of u~ing the 6iqht$ng lnstrument of the invention ln an intramedullary nail locking procedure is shown in Figs. 1, and 5.
Before the 6ighting instrument 10 according to the invention i~ u6ed, the relatlve po~ition of the nail 6 in relation to the x-ray device 2 and 3 is adjusted in ~uch manner that the interlocking holes 14 and 15 appear on monitor 5 to be round.
This happens when the axes of interlocking holes 14 and 15 lie parallel to radiation field 9. The interlocking hole which is to ~:71~9~
be pinned ~hould then lie in the center of t~e lower picture edge, so that the cro~s-h~ir~ of direction finder 13 ~tand in the center of the image. The thigh 7 i6 covered with a hield (not chown) to protect it from the x-rays. The 6h$eld h~s an opening corresponding to the ~rea to be ob erved. The radiation field must be within this opening.
Using the $mage converter for guidance, ~ cut i6 made through the ~kin lying exactly ~bove the interlocking hole after which the tool ~ocket 12 $nto which pin 16 h~s been $nserted, can be dr$ven through the cut IFig. ~).
Pin 16 s$mplifies the $ntroduct$on of the ln~trument through the ~oft portlon~ of the patient's t$65ue, because of it6 ~pher$cAl t$p. ~ter the $nsertion proce6s has been completed, t~e t$p of pin lC vith ~pherical refer2nce component 17 18 po61tioned o~er the center o~ the $nterlock$ng hole 14. ~his ~tep 1~ depicted ln Fiq. 4, and shows reference component 17 ly$ng exactly ln the center of tool ~ocket 12. ~he positlon of the component 17 can be observed ~n the lmage converter because the pin 16 i8 permeable to x-r~ys while the component 17 i6 not.
The direct$on finder 13 ~ 6 not u6ed at t~i6 time. When the reference co~ponent 17 lles preci~ely in the center of the lnterlocking hole, the 6ighting instrument i6 pressed firmly against femur 8, for example by tapping it with a ha~mer. The teeth 21 of tool 60cket 12 prevent the 6ighting instrument 10 from 61ipping off the femur 8. In this stage of the operation, care 6hould be taken that the 6ighting instrument 10 ls not turned ~ ~:71~

around the tool 60cket 12, 6ince the tool 60cket 12, which serves a6 protection for ~he patient's ti66ue, cont~cts femur 8 with the two teeth, not with ~ centr~l point.
After the 6ighting instrument 10 is positioned, the pin 16 is removed and a drill bushing, e.g., a 4.5mm bushing, is inserted into the tool 60cket 12. A drill bit i8 now inserted into this drill bushing, the tip of the bit lying precisely over the center o~ the interlocking hole. The drilling direction i6 checked on the ~onitor ~nd l~age converter and ~ay be ad~usted u~ing the direct~on finder 13 to keep the drill nligned. Thi6 ~tep i6 ~hown ln Flg. S, in which t~e directlon finder 13 ~8 poBitioned at right ~ngles to the radi~tion f~eld 9. Now the near cortex of the femur can be drilled into with the 4.5m~ drill bit. The drilling dlrection can be checked continuously with the image converter ~ and ~onitor 5. If necessary, the drilling direction c~n be corrected to ~aintain the correct ~ighting image.
As can be seen in Fig. 5, the interlocking hole i6 covered by the drill during thi~ ~tep ln the operation and direction i6 Daintained u~ing direction flnder 13. After drilling the near cortex the 4.5mm drill bit i8 removed from the 4.5mm drill bushing, and a 3.2mm headed drill bus~ing ls inserted ~s far ~5 the far cortex. The image converter 4 can now be cwung Away and the f~r cortex can be drilled with the 3.2mm drill bit. After the 3.2mm headed drill bushing is removed, the required 6tud length i6 measured with a depth gauge, a thread 16 cut in the far cortex, and the loc~ing 6tud is positioned. ~he 6ighting ~;~71~'3~

lngtrument may now be re~ov~d. For the insertion of the second locking stud the entire procedure described is repeated for the 6econd interlocking bole.
Depending on the particular embodiment, radlation 60urce 3 may emit radiation other than x-rays, 6uch ~s ultra-sound waves.
~or training purposes, it ~ay be desir~ble to use a radiation source 3 that e~its vi6$ble light ~nd~n r~di~tion receiver 2 ~hat compri~es a vldeo camerA.
~ he instruoent 1 used ~ith t~e sighting in~trument according to the invention c~n ~e o aw, ~ syringe, or snother surgic~l lnstru~ent ln6tead of the dr~ll described above. Although the ighting lnstrument according to the invention 16 appropriate for th~ ~urgical lnstrument~ and tool~ used ln orthopedics, arthro-ecopy, ~p~nal-column ~urgery, and tapping, the apparatus ~nd Dethod of the invention can al60 be used for non-surgical purposes.
Figure 7 show6 a way to increa6e the precision of the ~ighting ins~rument 10. ~he axi6 18 of ~ool socket 12 which lies ln e common plane witn axi5 20 of direction finder 13, can be At an ~ngle to it, in order to t~ke into ~ccount the divergence 19 of the rad~tion field 9 (Fig. 6). This embodiment, which improves the precision of the ~ighting lnstrument, can be constructed in e~ther fixed or ~djustable fashion.
A further improved embodiment of the sighting instrument according to the invention i~ represented in Figs. 8 to 11.

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Figs. 8 to 10 6how the construction of this embodiment, which rurther 6implifies the insertion of the ~econd interlocking 6crew.
The unit 22, a rect~ngular block, 16 pivotably mounted on the tool ~ocket 12 by ~eans of ~ coll~r 26, fixed to the block 22. The block 22 ~y ~e fixed to the 60c~et 12 by means of the set 6crew 25. The block 22 co~pri~es beside the direction finder 13 a drill bushing 23 for ln6ertion of A second interlocking screw.
The di6t~nce between the center6 of the drlll bushing 23 nnd tool ~ocket 12 corre6pond6 ex~ctly to the d~6tance between the centers ~ the two lnterloc~ing holes 14, 15 o~ nail 6 and the axis of the bu~hlng 23 i6 p~rallel to the axi6 of the ~ocket 12.
Sho direction r~nder 13 i~ arranged between ~e drill bushing 23 ~nd t~e tool socket 12, vhlch $~ otherwi~e constructed identlcally to the prcvlou~ly de~cribed embodi~ent of the lnventlon.
The unit 22 18 m~de from a radiation-permeable materi~l, ~uch as plastlc, and to ald ~n allgning unlt 22 parallel to the radiation fleld 9 of the x-ray device 2 and 3, ha6 two radiation-~mpermeable metalllc w$res 24 lying $n n plane parallel to the plane of the drawing, ~nd normal to the ~xes of the 60cket 12 and bushing 23.
The technic~l procedure for $nsertion of the ~econd lnterlocking screw by means of this $mproved embodiment of the invention i~ ~hown in Figs. 11 to 13.
Fig. 11 6hows the ~ighting instrument of Figs. 8-10 after insertion of the first interlocking ~crew according to the ~ ~7~9~3 6urgical technique already described. The corresponding monitor image ~hows typically an arrangement AS represented in Fig. 12, i.e., the ~etallic wires 24 embedded in the unit 22 ~re not yet allgned parallel to nail 6 but are at an angle to lt. Accordingly the lmages of the drill bushing 23 and of the second interlocking hole 14 are not 6uperimposed. Even though the plastic unit 22 is e66entially radiation-permeable, in practice its contour is feebly vi6ible on the monltor.
The surgeon then plvot6 unit 22 around the tool 60cket 12, which iB ~ir~ly connected to the bone 8, untll he has ~llgned the rcference ~etallic vires 24 parallel to nail 6 ~n tbe monitor l~age and fixes unit 22 ln thiB po6ition by ~a6tening the 6et cr~w 25.
The ~et crev 25 ha~ n ~exagonAl rocket ln lts head and the flxation of the unlt 22 ls occo~pll6hed by ~ean6 of ~n ordinary hexagonal ~ey 28 whic~ le inserted lnto the sccket of the fixation ~crew 25, a8 rhown ln Fig. 11.
Due to the divergence 19 o~ the radiation field 9 (Fig. 6), the dr$11 bushlng 23, and the second lnterlocking ~ole 14 do not appear circular, but elliptical, on the monltor. ~h~6 circumstance, ~o~ever, i6 not relevant for the ~lignment of unit 22, because the only condition to be observed 1~ the parallel alignment of the reference wires 24 with nail 6.
After fixation of unit 22 by means of the 6et ~crew 25 the surqeon can release his hold on the handle 11 of the 6ighting instrument 10 and use both hands for inserting the 6econd ~ ~71~ 3'L~

~nterlocking screw. For this purpose n ti6sue protecting bushing (not 6hown in the drawing) is inserted first into the drill bushing 23, into vhich the 4.5 mm bushing may then be lnserted.
Further procedures correspond to those described for the insertion of the first interlocking 6crew.
By means of this time-6aving nnd precision-increasing embodlment of the invention it i~ possible to further reduce the nlre~dy dimini6hed x-rny dose by nbout 50%.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A sighting instrument comprising a tool socket, a direction finder connected to said tool socket and a handle connected to said direction finder and tool socket, whereby the socket and direction finder may be maintained in n defined position relative to one another and can be held between a radiation source and a radiation receiver for adjusting the orientation of said direction finder and socket.

2. A sighting instrument according to claim 1 wherein the direction finder has an axis which is in the same plane as the axis of the tool socket.

3. A sighting instrument according to claim 2, wherein the axis of the direction finder is at an angle to the axis of the tool socket.

4. A sighting instrument according to claim 1 further comprising a pin made of radiation-permeable material for insertion into the tool socket, said pin having n reference component made of radiation-impermeable material.

5. A sighting instrument according to claim 4 wherein the reference component is spherical.

6. A sighting instrument according to claim 1, wherein the direction finder is pivotable around the tool socket.

7. A sighting instrument according to claim 6 further comprising catches that permit a 90° pivot.

8. A sighting instrument according to claim 1, wherein the direction finder comprises two aiming elements lying in different planes.

9. A sighting instrument according to claim 6, wherein the direction finder is arranged in a unit pivotable around the tool socket, said unit further comprising a drill bushing having an axis parallel to the axis of the tool socket.

10. A sighting instrument according to claim 9, wherein the direction finder is arranged between the drill bushing and the tool socket.

11. A sighting instrument according to claim 9, wherein said unit is made of radiation-permeable material and comprises radiation-impermeable reference means.

12. The sighting instrument claimed in claim 11 wherein the reference means comprises two parallel elongated elements, defining a plane generally normal to the plane defined by the axes of the tool socket and the bushing.

13. A sighting instrument for drilling holes through a bone for the insertion of two retaining pins in transverse interlocking holes in an intramedullary nail comprising a tool socket, a direction finder connected to the tool socket and a handle connected to said direction finder and tool socket, whereby the socket and direction finder can be held between a radiation source and a radiation receiver for adjusting the orientation of said direction finder and socket, the distance between the axes of said direction finder and socket being the same as the distance between the interlocking holes in said nail.

14. The instrument claimed in claim 13 and wherein the socket comprises a plurality of teeth for engagement with the bone to prevent slippage of the socket on the bone.

15. A sighting instrument for drilling holes through a bone for insertion of two retaining pins in transverse interlocking holes in in intramedullary nail comprising a block having a tool socket rotatably mounted in and extending through said block, a drill bushing in said block, the axis of said bushing being parallel to the axis of said socket and spaced from said socket at a distance equal to the distance between the holes in the nail, and a direction finder in said block and extending through said block.

16. The instrument claimed in claim 15 wherein the direction finder is between the socket and the bushing.

17. The instrument claimed in claim 15 wherein the block is made of radiation permeable material and comprises radiation impermeable reference means.

18. The instrument claimed in claim 17 wherein the reference means comprises two parallel elongated elements arranged in a plane normal to the axes of said socket end bushing.

19. An apparatus for drilling a hole under conditions preventing direct observation of the direction of drilling which comprises a source of radiation, a receiver for receiving said radiation, a converter for visually displaying objects lying in the radiation field between said source and said receiver and a sighting instrument comprising a drill socket, a direction finder connected to said drill socket, the axis of said direction finder being parallel to the axis of the socket, and means for positioning said drill socket and direction finder in said radiation field, whereby the direction of a drill inserted in said drill socket may be controlled by controlling the orientation of said direction finder.

20. The apparatus claimed in claim 19 wherein the radiation source is a source of x-radiation.

21. The apparatus claimed in claim 19, wherein the radiation source is a source of visible light and the radiation receiver is a video camera.

22. The apparatus claimed in claim 19 wherein the direction finder has two aiming elements located in different planes.

23. The apparatus claimed in claim 19 and comprising a pin for insertion into the socket for positioning the socket at the desired location for drilling.

24. The apparatus claimed in claim 19 wherein the pin is made of radiation permeable material except for a reference component made of radiation impermeable material.

25. A method for drilling a hole in a bone for the insertion of a transverse retaining pin in a transverse hole in an intramedullary nail which comprises positioning the bone in a radiation field so that the axis of the nail is transverse to the direction of the field and the axis of the transverse hole is aligned with the direction of the field, positioning a sighting instrument having a tool socket and a direction finder with an axis parallel to the axis of the tool socket adjacent to the bone so that the axis of the socket is aligned with the axis of the transverse hole, and drilling a hole in the bone, while controlling the direction of drilling by means of said direction finder.

26. The method claimed in claim 25 wherein the direction finder has two aiming elements in different planes and the direction of drilling is maintained by keeping said elements aligned with one another.

27. The method claimed in claim 25 further comprising inserting a pin having a body transparent to x-radiation and a tip impermeable to x-radiation through said socket to align said socket with said transverse hole.

28. The method claimed in claim 25 wherein said nail has two parallel transverse holes and the distance between the axis of the socket and the axis of the direction finder is equal to the distance between the axes of the transverse holes.

29. The method claimed in claim 25 wherein the socket is kept aligned with the axis of one hole during drilling by maintaining the axis of the direction finder aligned with the axis of the second hole.

30. The method claimed in claim 25 wherein the position of the direction finder during drilling is observed by viewing the alignment of the aiming elements on a image converter responsive to said radiation.