CA2050596A1 - External fixation device - Google Patents
External fixation deviceInfo
- Publication number
- CA2050596A1 CA2050596A1 CA002050596A CA2050596A CA2050596A1 CA 2050596 A1 CA2050596 A1 CA 2050596A1 CA 002050596 A CA002050596 A CA 002050596A CA 2050596 A CA2050596 A CA 2050596A CA 2050596 A1 CA2050596 A1 CA 2050596A1
- Authority
- CA
- Canada
- Prior art keywords
- fixation device
- external fixation
- clamp
- axis
- telescopic external
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
- A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
- A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
- A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like for external osteosynthesis, e.g. distractors, contractors
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- Health & Medical Sciences (AREA)
- Orthopedic Medicine & Surgery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Surgery (AREA)
- Biomedical Technology (AREA)
- Engineering & Computer Science (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Heart & Thoracic Surgery (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Surgical Instruments (AREA)
Abstract
The invention relates to an improved unilateral telescopic external fixator (10) comprising a telescoping unit (11) which includes telescopically engaging inner and outer parts (12, 13) arranged for limited axial reciprocal movement relative to one another along the longitudinal axis of the unit, the outer part (12) having a central bore extending therethrough, the inner part (13) engaging with sliding fit in the bore and extending the full length thereof, the inner part (13) being non-rotatable about said axis, wherein the bore comprises hard polymeric material whilst the inner part (13) is preferably formed of metal, a pair of orthopaedic pin clamp assemblies (20), one of which is carried by the inner part (13) adjacent its proximal end, the other being adjustably carried on the outer part (12) for selective positioning along the length thereof, and releasable locking means (60) for releasably locking said parts (12, 13) against said axial movement.
Description
WO9~/11149 PCT/A~'91/0003 "IMPROVEMENTS IN AND TO ~N EXTERNA~ FIXATION DEVICE"
This invention -e!ates to improvemen~s ln and to an external fixation device used in the trea.ment of bone ~ractures, and more specifically to an i~pro~ed unllateral- o-one-sided, telescopic, sinsle ~rame fixation de~ice which can provide dynamic axial motio~.
The purpose of an ex~ernal fixator is to hold together b~
means o. pins, the fragments or segments of a fractured ~o~e so that healing may progress while allowi~g the patients to retain mobility of neighbouring joints. To perform this task, the fixator must be sufficiently rigid or sti__ to suppor. ~he loads imposed on it without allowi~g excessive movement at the fractu_e site.
The use of external fixation d~ices is an established a~d recommended ~orm of tr~atment in many forms of limb injury and many diCferent fixation de~ices have been designed and are known to the applicants. While some of these are generally considered satisfactory, it is believed tha~ mos~ are unnacessarily complex aud do not pro~ide the degree o~ rigidity required for optimal bone healing. I a~ effor. to i~crease _igidity, designers have resortPd to multilateral or ~ulti- :
axial units (which i~clude more than one external fixation body) but such units are bulky and di-ficult to handle and are technically ~o~plicated. In addition their bulki~ess renders access to the wou~d as well as soft tissue management di~iCUlt.
Another drawback associated with known ~xternal fixa.io~
devices has been their inability to permit the pin clamps~nd :
thei- attachments ~o ~he main. body o~ the fixation uni~ to be easily a~d quiekly adjusted by the surgeon and th restri~ed ran~e of moveme~ts which such componen~ parts can undergo.
This has re~dered difficult the entry of the retainer pins and as well the ease with which any rotational misaiignme.n~ o the .
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SIJBSTI rUTE S~ ET
W091/111~9 PCT/A~191/00036 2 ~ ~ fl 1 ~ ~
f-ac~u-ed bone can be co--ected. I~ ad~.ion, the~e are limitatlons on .he extene to which the s?a~ial o-ie~tat~on of each set of -eta~ne- plr,s relative ~o the main body of the fixat on uni~ car. be var~ed, such ~a-ia~ion beins requi~ed to -e~able the unit .o be easily i~stalled a~d ta perm~t the body of the fixator to be posi~io~ed parallel to the lo~g axis of :-the bone, rega-dless of where the bone f-acture occur whether in a wide or ~ar-ow part of ~he bo~1e.
Whils~ ce-~ain prio~ ar~ exter~al .ixation devices are desig~ed ~o provide dy~a~ic axial motion, a p_oblem co~on to such de~ices is 'he hi~h bending moments which occur in the retaine- pi~s a~c therefo-e the main body o. t~e ixatio~ u~it, durin~ ambulatio~. Studies ha~e shown that these high be~ g 30me~ts cause t~e telescoping pa-~s 0c the uni~ to ja.
especially whe-e sliding f~iction is -elied upo~ and the t~lescoping pa-ts are ~ade of the ~ame ~etal, o~ metals ha~ing a high coef~icie~t of friction. ~hese units ~ay pro~ide a consistent dy~a~ic axial motion ti.e. axial telescoplng motion) at the f-~cture site by the applicatio~ o. a load through the ixator pins by an exter3ally applied ~oto- (refer-ed to as ~acti~e dynamisatio~U)~ but they ~a~no. ge~e~ally be relied .:
upon to pro~ide consisteut and reliable passi~e dy~a~isation throu~h ambulatio~.
It is i~o--ant that the fixa.o be su-Cicie~'ly stable o that dynamic axial motio~ is e~su-ed through telescoping of the d~ice a~d ~ot by i~stability o~ the 'ixator. Repeated axial ~o~e~ents may cause the telescoping u~it to loosen or jam with ti~e, whic~ i~ ~u~~ may alter drastlcally the -igi~ity of the~; ! ' ~ixato- and the e~ficacy o~ dy~a~satio~. For example, a sig~i'ica~~ problem wi~ certai~ prios a-t u~its is their-rotato~y i~stability. One solution to ~his p~oblem was to use a key-lock system, i.e. where the in~e- and oute- ~elescopi~g ~bers are par. cir~ula: and a key e~gages wi~hin a groove .:. .
ex~endi~g alo~g ~he inner membe-. ~nhanced -otato_y stability ~an be provided bv a tigh.e- it~ing key-lock, bu_ this _e~ul~s .:
::
WO9~ 9 PCT/A~'91/00036 -3- ~ 3 c;s ~ .~J r i in s~ictlon of the c~n~ac~ ar~s Oc the ~ey-loc~. Loose-fitting key-locks, whe~e a keyino pi~ engayes ln a key-way formed in the in~er mem~e-, pre~en. this complicatlon but cannot provide adequate rotatory stabili~y.
~ ixators have also been developed relyi~ on rolli~g friction between the telescopin~ parts rather than slidi~g frictio~, ~hese utilising roller bearings .rolling in ball bearins races. However, due to the fact that ~icromotion required for external flxators is in the order Oc lmm or less, such ball or roller bearings providi~s this motion will not roll ~ut rather rock a~d will therefore brinell. Such brinelli3g is a cause of i3stability a~d/or jamming, which s~ould be avoided'in dynamising ex~ernal fixators.
A still further defieie~cy of some known unilateral, , .:
telescopic external ~ixators is their inability to ~ary or , :
alter the rigidity o~ the device to axial motion of the ~ .
telescoping pa_ts during the course of fraeture heali~g. It has ~ ' bee~ fou~d that greater rigidity is required in the early ~ :
phases o. fracture healing and less rigidity later. It i5 desirable that means be provided so as to prevent p~ssi~e ''~' motio~ du-ing early stages o~ ~racture healing of t~e telescopi~g pa_ts of the fixator device until a set or ''.
predetermi~ed load is exceeded.
One object of the prP.sent i~vention therefore is to pro~ide a~ i~proyed unilateral, telescopic exter~al fixation de~ics which is of simple design, easy to hand}e and is more versatile in its ability to vary,,the orientatio~ a~d positioning o~ the pi~ clamps a~d in turn ~he orientation and positioni~g of the retainer pins fixed in the clamps.
:. ~
It is a~oth~- object of the.present invention to provide : an improved uni~ateral, teles~opic exter~al fixation,devl~e which can consistently, reliably and Pfficiently p_ovi~e S~ STllT~JTE ~1EE I
WO91/lll49 PCT/A-91/0003S
dynamisation (both active and passive) wlthout jamm~ns of the ~elescoping par~s.
It is yet anothe- object of the present in~en~ion to pro~ide an improved unilate~al, telescopic external fixat~on devi~e which can have its resistance ~o axial mo~ion readily :.
altered duri~g the course of fracture healins.
It is ye~ a fur_her object o~ the present inve~tion to provide an improved u~ilateral, teles~opic external fixation device which can provide an ext-emely stable, rigid s~ruc~ure thereby promoting mo~e rapid healing and early am~ulation.
Accordi~g to one aspect of this invention therefore, an .;:
improved u~ilateral, telescopic ex~ernal or~hopaedic rixation device comprises a~ elongate tel~scoping unit comprised of a :.
pair of telescopically engaging i3ner and outer parts adapted .
~or relative axial reciprocal mo~ement along a~ axis which coincides with the central longitudinal axis of said unit, a~d releasable locki~g means f 0- releasably locXing said parts agai~st rPlati~e axial movement, a pair of pin clamps respecti~ely carried o~ the telescopisg parts for clampi~g o~e o~ more orthopaedic retainer pins spaced lengthwise of the clamp and exte~di~ trans~ersely thereof, clamp co~ectio~
m@ans on each o~ the telescoping parts of said ~longate telssc~ping unit or con~ectin~ a respective said ~lamp thereto, each said clamp co~nection ~eans comprising a clamp holder having a first axis of rotation spaced radially rom said longitudinal axis of the telescoping unit whereby said elamp hol~er when in an u~locked co~dition, along with its associated sai~ cla~p can bodily-rotate about said fir t axis, `:.~
said clamp hslder being adjustably suppor~ed fo~ slidable~ :
moveme~t lengthwise along its said first axis whereby the .:~;
spatial po6ition of its associated s~id clamp can b~ varied by varyi~g the ra~ial distance (measu~ed along said irst axis) between said clamp and the telescoping unit, a~d wherein each said clamp is ro~atably supporte2 ~y said clamp holder so as to SU eS~ET~ 'T~
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PCI ~A ~191/00036 per~it the cla~p to bod~`ly -otate a~ou. a sece~d axis of rotation exten~ing leng.hwise the-eof and a~ _~ch- ansles te said fi_s~ axis.
With the above ar-angement, t~e p'~ cla~s o4 the _ixator together with the set of p~s can rota~e f-o~ a t-a~sve~se through to a ~ertical plane. This allows the pi~s to be placed horizontally at the e~d o~ the bone which is desira~le for met physical f-actures o~ long bones.
The ar_angeme~. alsc ~e-mi.s the pin cla~s to be tilted .h~ough a wide arc, which is requi-ed 40- spi-al a~d ve~-ical fractures which ~ay ha~e a wide ansula_ -ange o- the pla~e o~
the f raGtUre .
The abili.y Oc the clamps .o slide hor zon-ally allows ~ -rotation of the bone fragments without loss o~ axial alig~me~t of the fixator and also a wide ~ariation of ~he ansle of insertion of the pins i~to the bo2e. ~alaligame~t of the long~tudinal axis o~ the ixator f_o~ that o~ the tibia lesse~s the potential for dyna~ic axial ~otion o~ the de~ice. R~own dynamisi~g ~ixators allow ro~ation of the ~o~e fra~ment. only by axial de~iation of the ~Oay of '~he ~ixator from the loagitudi~al axis o the tibia.
P-eferably each said clamp co~ection ~ea~s (or at least that on the oute- telescopi~y pa-t~ ~u~_he~ comprises bracket or conneetor means slidably supported on its associated sai~
teles~opi~g past whe~eby the enti-e clamp connectio~ mea~s, whe~ i~ a~ u~lo~ked condition, along with its associated said clamp ca3 sl~de lo~gitudi~ally o~ sa~d telescopi~g u~it. T~e :~
; positio~ing of at leas~ one of the pin clamps a~ a~y lo~ati~n along th~ ~ull le~gth of the outer telescopi~g pa-t e~sures ~1 i~al ~paration of the in~er pi~s. Preferably, o~e o~ the bracXet ~ea~s is ~as- with the ~ee e~d of the inner ~eles~oping pa-~, wh~ls~ ~he othe- bra~ket means can ~lidably locate alo~g the lens~h o~ ~he ou~e telescopin~ pa~~. In 'hi~ :
S LJE3e~TlTUTE~ SHI ET
~
P(~/AIJ91/00036 ~i, way the separation O r the pin clamps anà the pins does no~
~ecessitate any adjustmen_ to the telescopi~g pa_ts whl~
co~t-asts with prio_ ar. ur.i~s which -eq~i-e rela~ive axial separatio~ t~ereo.. This also allows ~he te:lescopins pa_ts to be in conta~t with 02e a~other o~er a ~ajor portio~ of the le~g~h o~ the fixator, whieh gives r se to dlec_eased be~di~g movements and lesse~s the likelihood of the ujammi~g" of the unit duri~g dy~amic axial motion.
In another prefe -ed form of th~s in~e.. ~io~, sa~d b~ac~et ~.
~eans is ro~atably supported o~ its said telescopins pa-.
whereby said cla3p ~on~ec~ion mea~s ca~ be rota~isnally adjusted about a~ axis which coi~cides wit~ or s pa-allel wit~
the lon~itudi~al axis of said telescoping u~it, to assu~e di Serent angula_ positio~s -ela-ive to the telescop~s u~it. : ' . .
In another prefe~red form o thi~ i~veution, each said clamp co~nection means co~prises a swi~el blocX interconnected betwee~ the bracket means and the clamp holder and being rotatable, when i~ a~ u~loc~ed ~on~itio~, about a third axis wh~ch exteuds at _ight ansles to ~o~h ~he axis of ~he telescoping u~it a~d said ~irs~ axis. ~his pe~mits the bloc~
alo~g with its cla~ holde-, to swi~el about said thi-d axis and be set in a numDer o~ differen' a~sula_ positio~s relati~
to the telescopi3g u~it.
,:
Preferably the co~necto- o~ b_acket m~s comp-ises an :.
attachment body which encircles the associated telescoping pa-t a~d is pro~ided with a locki~g member, e.g. a cl~mping ~ w or ~olt which when ti~hte~ed, causes said boay to cl~pi3gly e~gage against ~aid teleseopi~g pæ~~ and locking ~he co~ecto~
~ea~s against both _ota~ional and longitudi~al move~ent , relati~e to the ~eLes~opi~g u~it. Preferably ~he body ~omprises a pair Oc hinged halves which are hingedly joined together alo~g an axis pa-allel to the axis of the fixator, with the cla~ping or locking screw cla~ping togethe- the fr~e en~s ~hereof o~ the opposi;e side o' the ~xa~o- body. ~is SUBST~ FU~ S~c .
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allows a clamp to De eas~ly removed f-om o- added to the f~xato- even wher~ ~he _xato- -emains a.~ached to a patient.
Pre~e-ably, .~e p~n clamps have a 360' horizontal a~gular range which pe-mi~s the body o. the _~xator ~.o be swu~g a-ound from o~e side of the leg to the othe~, thereby providi3g complete access to the wou~ds duri~g operative so~t tissue closu-e o- woun~ ca_e.
I~ yet a~othe_ ~refe_-ed em~oclme~, each said clamp holde- co~p-ises a t_ansve-sely ex.e~di~g shor~ le~g~~ pin or shaCt jo~r3alled ~o_ -o;?_iOr. abou~ said ci-s~ axis a~d ~ixedly carryi~g a; its distal end a pai~ o_ se~i-c~cula- ringers or . .
jaw membe-s, the i~ne- pe-i?he-al walls of which togethe-de~ine a th~ough ope~ins ln wAich is rotatably ~eceived a respective said clamp to enable said clamp ~o be rotat:ed ~rough 360-, this i~ tur3 permitting the o-ien'atio~ o~ the fixatos pi3s held therein to be simi la-ly ~aried.
Accordi3g to anothe- aspec~ o_ the pxesen_ inve~tio~, the:e is provided an i~proved u~i~ate-al telescopi~ exter~al ::
~ixatio~ de~ioe comprisl~g a m i~ telescopisly uni~ comprised of a pai~ o~ elongate teles~opically e~gaging pa~ s ada~ted ~o~
_elative axial slidi~s movement alo~g the lo~si~udinal axis of-said teles~oping u~it, the oute- o~e of said pa~ts co~s~ituti~g a housi~g having a bore exte~ding therethrou~h, the i~e- o~e of ~aid parts co3stituting a rod engagi3g with ~ Rliding ~lt i~
the bore and being ~o~-rotatable about said axis, the pro~ile of said rod a~d said bore each being n~n-circula- ha~i~g at leas~ o~e flat side, and whe_ein said rod is for~ed of metal, pre~e-ably stai~less stee'/ and the su-~2ce o~ sai~ hore ~o~p~isos hard polyme_ic ~ate-~al, whe-eby slidi~g r_ic~ion ~e~wee~ the parts, during said rela~i~e axial sliding move~e~t, ;.
i5 mi~imised. :
~ SUBSl~TUTE S~E~r ~ ~
~ :
WO 91/11149 PCr/A~91/00036 ~ -e~erably, ~he housing has 2 cy!lnd~~ca1 oute- wall sur'ace shaped and is ~omp-ised of ,wo ide~tical axial halves secured togethe~ ~y clampi~g sc-ews. T~e ~ousins may howeve-be fo-med as a unitary membe-.
:' By using dissimilar mate-ials for ~he i.~e_ rod a~d t~e bore sur_ace of the cyli~d~ al housl~g within whi~h the piston ~o~es, the slidi~s riction is ~ery much reduced (in eomparison ta uslng simila_ ~etals for example) a~d the_e is less li~elihood o the u~it ja~ing du-~g dy~a~isation t~ereo~.
Experime~ts conducted by the in~e~~o-s ha~e show~ th3t the combi~atio~ Or a suitable polymeric mate-ial an~ stai~le;s ~teel a:~o_ds a mos~ slg~i_ica~t i~proveme~t, i~ te~ms of ~ric_io~al resista~ce, in ~ompa~iso~ to pa~_s o_ si~ila- ~etals o- e~e~ dissimila- ~e~als, e.s. stzi~less steel/hard chrome ~:
stai~less s~eel, stainless steel/b_ass.
Pre~erably the bore of the cylindrical housi~g is li~ed :, with a laye_ of ~ard polymeric mate-ial, pxefe-ably acetal, a~d i3 particular mate~ial sold unde- the p~o~rieta~ ~ame ~E~ACEm~L", tpolyoxymethylene). ~e lin' g may be pro~ided by meaus o~ elo~gate flat s~rips i~serted in the bore and ~o-exte~sive therewith, eac~ st-ip beari~g agai s ~ a respe~tive pla~ar ~o~e sur4ace exte~di g along the le~g h o~ .he bore.
~y hard poly~e~ic mate_izl ha~ing high a~-asio~ and wear resista~ce and a low ~oe_~icient of ~ lc'.io~ would be suitable.
In addition to acetals, othe- exa~ples may i~clude hish density polyethylene and pol~propyle~e.
~ n a pr~fe-red arrangement, said bore is rec~a~gula-, and said rod has a recta~gula~ c~oss-s^ectional shape. ~he ~hape may also be t-iangula-.
other ~refe_red a_-angeme~t, ~aid rod co~p_ises flat : upper ~d lowe_ surfaces which are joined alo~g their lo~gitudinal ~arsins by cu_ved sidewall su__aces, a~d ~aid i~se~~ comp-ises a p ~_ oS dia~e~~~cally oppo~ec a~proxima~ely 1~_ .
.
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UO91/l11~9 PCT/A~'91/00036 f ~
_9_ D-shaped insert ~mbe-s fixedly secured to the cyl~nd-i~al bore with the planar 'aces o~ said insert me~bers enga~ing agains~
respective flat surfa~es of the rod, said 1nse~~ ~embers bei~s for~ed o~ hard polymeric ~aterial.
Preferably, said rod ~xtends through the entire length o the housing and is provided at its distal end with a limit wall which co-operates with a radial abutme~t surfa~e at the distal end o~ the housi~g to permit limited relative axial ~ovement only between the rod and the housing, su~h move~ent pref2ra~1y bei~g in the order of 5mm. In t~is ma~ne~, the rod maintains contac~ with the bore o~er a majcr portion of the le~th of the rod, which promotes stiffness and rigidity, and ~inimises the effect of possible bendi~g moments which in tur~ facilitates dy~amisation.
In yet a~other aspect of the present inven~ion/ an improved u~ilateral, external ~ixation device comprises a pneumatically operated or electric motor at the distal end of said cylindrical housing and bel~g co-axially aligned therewith, said ~o~or being adapted to provide dy~a~ic axial motion or dy~amic ~xial loadi~g of the bone fra~me~ts o the fractured bo~e.
~ referably the motor is arra~ged to provide micromotion at a fxequency of approximately 0.5 Hz a~d at an adjustable excussion of 0.1 ~m to 1.0 ~m.
. .
In a further aspect of this invention, the telescoping u~it is provided at its distal e~d with re~ovable calibrated : .:~
axial distraction means comprisi~g a longitu~inally extendi~s threaded rod arranged co-axially withi~ the u~it for effecti~g axial separation of the te~escoping parts a d i~ turn distraction o~ the bone parts, 80 as to allow bone lengthening procedures.
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WO91/11.J49 PCT/AU91/00036 ~r! J ~ c ~ Y
In yet anothe~ aspect arrangement, the telesGoping parts of the telescopi~g unit co-operate with an adjustable spri~g mechanism removably ~oused at the distal end of the outer part of the unit a~d arranged to provide an adjustable axial loading force to resist motio~ of the telescopi~g parts and to preYe~t relati~e axial movement of the t leseopi~g parts u~til a set (predete.rmined) load is exceeded. The adjustable spring will not allow dy~amic axial motion to oc~ur before ~aid set load is applied. ~is load will be set high during the early phase of .;
~ra~ture healing and set low duri~ the latte- phase of f~acture healing.
In order to more fully explain the Applica~ts' inventio~, several Pmbodi~e~ts are described hereu~der in som~ furthe-detail ~ut with reference to and illust-ated in the accompanying drawings in which;
FIG. l is a perspective ~iew o~ an external ~ixator according to a first embodiment of the inve~tion;
FIG. 2 is an e~d elevatio~al view of the fixator looki~g i~ the directio~ o~ arrow 2 of FIG. l;
FI~. 3 is a exploded perspective view of one of the clamp 7 assemblies show~ in FIG. l;
FIG. 4 is a longitudi~al sectional ~iew o~ the telescopi~g unit shown in ~IG. 1 (omitti~g the clamp assamblies for the sake of clarity~;
. . ~ .
FIG. S is a fragmentary perspecti~e ~iew, partly section, of the telescoping u~it of FIG. 4;
FIG. 6 is a radial cros~-sectio~al ~iew along the lines 6-6 of FIG. 4;
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W091/111~ P~T/~191/00036 FIG. 7 is a sec~ional v~ew slmi~a~ IG. 6 o~ a telesGopins uni~ acc~rd~ng to a secon~ embodimen- of ~he .i~vention;
FIG. 8 is a long~.udi~a1 section~l v~ew of an axial distra~tion uni~ fo- use w~th the .ix~tor shown in FIG. 1;
. .
FIG. 9 is a lonsltudinal sectional view o~ a~ axial loadi~g :
u~i~ fo- use wi~h ~he ~ xato_ show~ i~ FIG. 1; a d FIG. 10 is a schematic eleva~ional view of the fixato~ o~ .his in~e~tion which shows so~e o_ the adjus~men~s w~.ich can be ach~eved with the clamp assembly shown in FIG. 1.
I~ the embodime t illust_ated in FIGS. 1 to 4, a~
orthopaecic external fixation de~ice 10 comp_ises a main : . .
telescopi~g u it 11 which itself includes an ou e- cyli~d-ical housi~g 12 ia which is reciprocally housed a telescopi~s rod 13, clam~ connectors 15, 16 on the cylind-ical housing 12 and the head end o the rod 13 respec_i~ely, clamp holders 17, 18 associatec with each said clamp con~ec~or 15, 16 a~d ?i~
retainer cla~ps 19, 20 rotatably ~uppor~ed by the cla~p holders 17, 18 -espectiv~ly. Eac~ of t~e cla~ps lg, 20 comp-ises pai~s o opposed grooved cla~p plates 19', 19'' and 20', 20'', w~i~h are clamped togethe~ by means of clampins sc-ews 24 so as to fo~ t~ans~e~sely extending throush-openi~gs 25 fo_ -ecei~i~g 4ixato- retai~e- pins 27 a-ranged ~o ~e s~aced lens~hwise o~ ;;
the clamps 19, 20 and projecti~g t-a sve-sely thereof. The :;
pins 27 are of know~ co~struction.
.In ~his e~bodi~ent, the cl~p ~on~ectors 15, 16 each ~l .
~o~prises a pai- of hi~ged connec~or po-~ions 28, 29, a_-a~ged ~o e3ci-cl~ the ~ylind:~cal ~ousi~g 12 a~ -he c _cu} _ ~la_ged h~ad 30 (for~ed by two halves) at the ~-ee end o' the rod 13 respectively, ~he con~ec.or portio~s 28, 29, when in ~:
their 1006ened ~ondition, permittinS the cla~p ~onne~tor~ 15, 16~to be rotated about an axis which coincldes wi~h the ~ent-al lons eud~na1 axis of the ~elescop ~5 u..i- 11 anc, ~ he ca6~
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C I I R CT l ~ t IT I~
, '. ' . ' .' .'.. .. "' . ' . ' . ' ' . ~ ' .. :' ' . ' ... . '. ' . '. ' ' . ' '' WO 91/11149 PCI/A~I91/00036 . .
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of connecto- 15 also slidably d~splaced lons~tud~ally along the leng.h o_ the hous'ng 12. Wilh the clampins sc~ews 33 trefer FIGS. 2 and 3) in thei_ ti~htened cond~tion, the i~ne-bore sur~aces of the con3ector po_-io~s 28, 2~ clampingly engage a~ainst the oute- cylindrical surface of the ~ylin~rical housing 12 and thc pis~o~ head 30 respectively so as to i~mobilise the brac~e~s lS, 16.
As show~ in FIG. 3, each clamp 19, 20 is a 3~piece assembly comprisins two ide~tical plates 19~ and a u~i~a;v ~embe~ 31 co~tai~lng the plates lq''. ~he pieces mzy be die cast of alumi~ium o- alumi~iu~ alloy. With this a-ra~ae~le~, the pi~s 27 ca3 be removed withou- removing the clamp f_om its holder.
Suppor~ed on portio~ 28 Or the connectors 15, 16 are 8wi~el blocks 34, radially paced from ~he cyli3drical housi~g 12 of the telesGopi~g uni_ 11, each block 34, bei~g for~ed with -a tra~s~erse horizon~al slot 35 extendi~g i~wasdly ~rom o~e end of the block a~d co~mu~ica'i~g wi~h a trans~ersely exte~di~g cir~ular throu~h-openi~g 37 i~ which is rotatably recei~ed a solid cyli~ari al pi~ or shaæt 39 which ~orms pa-t of ~h~ cla~p holde_ 17, 18. Each block 34, is rotatably mou~ted on a stub shaft 3A ~rojecting radially from a side of por~io~ 28, and releasably locked therewith by ~eans of cla~ping screws 32, whereby, with the screws 32 loosened, the blocks 34, alo~g with the holde~s 17, 18 ca~ swi~el about a~ axis which i~tersects the cent~al axis of the u~it 10 a. ri~ht a~gles and is al~o at right angles to ~he axis O r the sha~t 39.
The rota~ion o' the holders 17, 18 along with their cla~ps 19~ 20 a~d pins 27 about the axis of ~he s~aft 39 per~its t~D pi~s ~0 be inse-ted longitu~inally o~ ~:a~versely, which is ~esira~le 1n si~ua,io~s involYing bo~es of ~arying diamet ~.
: SW~ST~TIJT SHEF.
. i ~O9l/ll149 PCT/A-91/0003~
f~ ~,. ,); ;, . . , -A cove- member 40 ha~ing a th_eaded s~em which th-eadably ensages in a th-eaded cen.-al bore formed in the shaf~ 38, preve~ts dislodgeme~t of the ~lock 3~.
Clamping screw 41, whe~ tightened, f_ic:tio~ally ~la~ps the shaft 39 agai~st bot~ rotatio~al a~d sli able ~ove~en~ relati~e to the block 34. It will of col~se be appreciated that whe~
the screw 41 is i~ its untightened ~o~di_io~, the clamp holde-s 17, 18 ca~ be rotated abous the ax~s Or the sha_' 39 a~d locked i~ any desired o-ie~ta~ion a~d also slida~ly adjusted le~gthwise Or the axis o the shaf~ 39.
Ea~h ~lam~ holder 17, 18 also i~ludes a pai~ of se~ni- -ci~cula- lugs ¢3, 43' which co-ope~a.e togethe- ~o ~orm a circula- opening for clampi~gly re~eivi~g .he clamps 19, 20. An adjustment screw 44 is used to faste~ the lugs 43, 43' together, and which, whe~ untightened, allows the clamp 19, 20 to be bodily rotated (along with its pi~s 27) to a~y desired ~:
a~gular set~i~g. ~-The ability o~ the cla~p holder 17, 18 to bo~h rotate about the ~xis cf s~af~ 39 a3d to slide lo~gi~udi~ally along ~ha~ ~is has bee~ ~hown to greatly ~aeilitate th~ pla~e~ent of the rstai~e- pin~ into the bone frag~es.s and also the ;~.
cor-ection of any rotatio~al misalign~en. of the bo~e fragments : :
withou~ altering the longitudinal alig~ment of the housins 12 to the axis of the bone, e.g. ti~a, whilst the a~ility of the cla~ps 1~, 20 to bodi}y rotate about an axis at right asgles t~
the axis of the sha~t 39 l~ds thie u~it ~uitable ~or approach-~g ~he bone th~oush a wide an~ula_ ra~ge. ~hese :.:
featu~es ca~ be clea-ly seen ~rom FIG. iO of the drawi~g6 whioh show~ ~ow the pi~ cla~p 19 can be horizon~ally di~placed ~-o~
th~ housing 12, and its orientation altered, which en~ure~ a wide ra~ge o4 a~ailable pin angl~s.
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SUBS~li lJTE SE~E~ t~ I
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u~I/III1') PCT/A~'9l/00036 ~ e ab~lity o- the clam~ conne~o~s 15, 16 to slide along the cylind~ical housfnc 12 'acili.ates optimal posl-ionins of the retai~er pins 27 rela~ive to the f_a~u~e si~e. I~ is a~
advan~age O r ~he p-esent ~ve~ioa that more tha~ o~e cla~p con~ecto_ ca~ be suppor~ed o~ the cyli~d_ical housins 12 a~ by virtue of the ~ersatility of the ra~ge o move~e~ts which the cla~p connector, hoLder an~ clam~ ca~ u~dergo, o~ is able to positio2 pias o~ oppo~ite ~ides of the hou6i~s~ 12 o the u~it 11, so as t~ allow n .-ia~gula~io~a a~d provide e~hanced rigidity.
The hi~ge 45 which plvotally joins the por ions 28, 29 of the con~ectors 15, 16 pe_mi~s .he co~nectors to be readily -emovea from the housi~s 12 even wi_h the u~i ! 11 att2ched to a bone. ~ .
.
Refer~i~g to FIGS. 4 to 6 of the drawi~gs, ~he rod 13 of the telescoping unit 11 is formed o~ stainle6s steel ha~'~g ~ighly polished outer sur'ace an~ is of square cross-sec~ion.
The roa 13 slidably engages with a sliding fi- in a bore ~6 which exte~ds through the rull le~g.h o~ the hou i~g 12 ~he bore 46 also bei~g of sgua_e oross section. he housins 12 is pseferably formçd o~ alu~i~iu~ a~d co~prises two dia~etral hal~es 12', 12'' secu-ed togethe~ bv screws 47. ~he bore 46 is lined by means o~ replaceable st-ips 49 of hard polymeric mate_ial, e.g. e-tacetal, which is abrasion resista~t, has a low co-e~icie~t o~ iriction and sood surface lubricity, 5uch :
an arrangemeut mi~imisi~g the sliai~g ~rictio~ betwee~ the rod 13 and the bore surface 46, as a result of which the moving pa_~s of ~h~ u~it 11 are less likely to ia~ whe~ subjected t~
bendi~g ~o~ents, in compa-ison with existi~g a~t. O~ ~our~s, the li~er 49 ~ay be i3 the form of a~gle i~se ts s~ugly ~itted iD~o the bore 46 of the housing 12. ~he fou- st-lps 49 are held loosely i~ the bore 46 agains~ respec~ive planar su-~aces ~or~ed the-ein and can be easily ~eplaced i- and whe~
~ecessa-Y . ',.
SUBSTlTlJT~ SHEE~T
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~091/1l1~9 PCT/A~9l/0003fi The oute- end Oc the _o~ 13 ~e~~. ~ates _n an e~la~ged head 30 fast ~herew~~h, a~d a-ound which is clamped connecto- 16, wh'ls~ the inne_ o- cis~al end of ~he rod 13 threadably co~nects to a lim ~ ~lock 50 via a .h-eaded s.em 52, co-axial therewi~h. The bloc~ 50 is housed in an exte~.sio~ piece 53 o~
t~e housing 12 a~d fixed thereto and is desi~ed to limit axial . -mo~eme~t of the rod 13 through a prese~ ra~ge, depe~di~g o~ the healing requirements o_ the f-actu-e, the bloc~ 50 co-operati~g with a radial abutme~ fla~ge 54 to co~s~-ain rod move~e~t i~
the extensio~ directio~. Move~en~ i~ the ret:-ac~on direc~ion of the rod is const-ai~ed bv the e~d wall of ~he rod 13 abut~i~g acai~s~ -he o~he- side o- ~he flz~ge 54. ~ .
The exte~sion piece 53 suppo-ts a slidable joi~iag colla-57 which has an in~er~a~ ead 58 _o- rece~vl~a a th-eaded e~d !:
plug.59.
TSe p-oximal end of the housins 12 is provided with a locking collar 60 whioh has an inter~al ~hread which threadingly en~ages a~ exter~al th-ead on end block 61 secured to the end of the housi~g 12, ~he bloc~ 61 ha~ing a ce~t_al openi~g throu~h which passes ~he -od 13. ~he arra~geme~t is such that as the locking collar 60 is rotated to its locked position, -~he e~d wall 62 o4 the collar 60 bears a~ai~s~ the .acl~g wall 64 on the head 30 of the rod 13 a~d upo~ ~u~the-tighte~ing, the -od 13 is axially displacea i~ t~e exte~sio~ :
direction un~ he limi_ block 50 abuts agai~st ~he ~lange 54, whereupon the rod 13 is locked agzius~ a~y ~ovemeut, ~he housi~g 12 a~d roa 13 thereby beiny ~ixedly secured with respec-. to o~e a~other. ~he lo~ed co dition is requ~red when a~y sho_~e~ g or colla~se of the ~od 13 is to be preve~d.
With the locking nut 60 in its loose~ed or unlocke~
conditio~, the u~i. can be subj~c~ed to dynamic axial loadi which ca~ elther be "passi~e" achieved t~rou~h ,he actio~ o~
a~bu~atio~ or "acti~e" er~e~ted -h~ough a moto- unit ~not ...
~how~) a~.ached ~ia t~e colla- 57 a_ ~he d~s~al end o. ehe SUBSTITUTE SHEET
WO91/11l~9 PCT/A-91/00036 t!~ ~ J ,~
l.6-cy~i~d-ical housing 1~ and co-axia!ly aligned _~erewi~h.
~refera~ly the moto~ ~s pneumatically o- elec~~ically operated.
In an alte~~ative embodimen, shown in ~'IG. 7 the -od 6S is for~ed with two flat sides jo~ned by two cu:~ed side walls, whilst the bore of the housi~g 12 is circula: a~d has fi~ed therein a pai~ of i~serts 66 formed of hard poly~erical ~aterial. ~he i~se_ts 66 a e D-shaped a~d are -es.~ai~ed agai~st rotation by ~ea~s of grub screws (~ot shown) exte~ g through the wall of ~he housing 12. O~ce asai~, the presence of the polyme~ic i~se~~s 66 signi_lca~tly recuces the eCrect of sli~ing f-iction.
I~ the above-desc-ibed e~bodiments, each of the cla~pi~g s~rews comprises a hexago~l -ecess or dep-ession i~ the head thereoC~ and rotatio~al adjustmen~ Oc such sc~ews is efCected by ~ea s of a k~ow~ hexagonal key spa~e-.
Refe--i~g to FIG. 8 Oc the d-awings, a calibrated leaa screw de~ioe 67 is shown and which can be attaehed to the unit : :
. 11 (by removing end plug 59) via the collz- 57, the device 67 ~o-operating with the rod 13 ~o ef~ect co~t-olled relati~e axial mo~eme~t ~etween ~he rod 13 a~d the cylinder 12 w~ich in tu-~ e~ ects d~s~-action o~ the bo~e ~agme~ts, t~is bei~g ~ecessa-y ~o al}ow the bone le~g~he~ing procedu-es. ~he de~ice 67 co~prises a~ ad jus-.me~ ~ membe_ 6a having a threaded stem 6 9 which is screwed i~tto a th-e~ded bore of body por~ion 70 whi~h in turn is scre~ con~tected to the co}la- 57. ~he stem 69 projects t~roush the ~ody postio~t 70 and bea s agai~tst an , ~, .
inte~ne~iate irLser~ lo~ated between the rod 13 (the bloc3c ~0 iDg been ~mo~ed ) . . .
Ref e-_ing to FIG . 9 o~ the drawlngs the~e is show~t an axial loadiD.g de~ice 71 a~eacha:ble to the coll - 57 o~ the u~it 11 to lie ~o-axi~l thereui .h, the de~ice 71 bei~g provided with rLn ~d jus.,a~le nu~ 72 which is screwe~ ~o a tubula- body 73, and a resilien~ oomp~ession sp~_ng 7~ housed w -".in the nu~ and the W O 91/111~9 PC~r/A~'91/00036 body 73, the sp-~ng 74 ir. ~u~n m~king pressu_e contac~ a~ains.
a pin 75 which p_ojects axlally _~om the e~d o_ the body 73 a~d bears a~ai~st the end of the rod 13, when the dev~ce 71 is so attache~. The de~ice 71 ~hus co-ac~s with the rod 13 to provide an adjustable spring resistance to ~o~eme~t of the rod 13 in such a ~an~er that a~y mo~ement of the rod 13 is inhibited u~til such ~ime as a set or predete:cmined load is exceeded. As explained herei~before, greate~ rigidity is recui-ed i~ the early phases of f-acture healing a~d less rigid~.y late~ or. The adjustable spr' ng mechanism is desig~ed 50 as ~o. to allow dy~amic axial mo~ion to occu- before the se~
load is applied. The reaui-ed load will be se~ kigh duri~g ~he early phase of f_acture healing a d i~ tu-n set low duri~g t~e late phase of _-ac~ure hezling.
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It will be realised t~at the material selection for the telescoping parts 12, 13 can be dir_eren. to that stated above.
Fo~ example, the xod 13 may be formed of ti'a ium or anocised aluMi~ium, w~ilst the housing 12 ~ay be oO a suitable ha_d plastics ~ate-ial. The rod 13 m2y eve~ be lined o- coated with a sul~able wea- resi~ta~ plastics material ha~i~g good ~urface lu~ricitv a d a low co-e,cicie~t of friction, e.~. te~lo~.
Still ~u-the-, it may be possible to coat t~e ~o~e su-face o_ the housing 12 with a layer o. hard polyme-ic ma~e-ial.
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A ~rie~ co~sideratio~ o~ ~he above-described e~bodiments will i~dicate that the inve~tio~ p-o~ides a~ improved ~ilateral exter~al fiJeation devic~ which is extremely ~e-sa~ile, co~pletely adjustable, easy to use a~d provides c04s1s e~t reliable a d e'fective d~nnamic axial ~o-ion.
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8UE~STlTlJTE SHEE~T
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This invention -e!ates to improvemen~s ln and to an external fixation device used in the trea.ment of bone ~ractures, and more specifically to an i~pro~ed unllateral- o-one-sided, telescopic, sinsle ~rame fixation de~ice which can provide dynamic axial motio~.
The purpose of an ex~ernal fixator is to hold together b~
means o. pins, the fragments or segments of a fractured ~o~e so that healing may progress while allowi~g the patients to retain mobility of neighbouring joints. To perform this task, the fixator must be sufficiently rigid or sti__ to suppor. ~he loads imposed on it without allowi~g excessive movement at the fractu_e site.
The use of external fixation d~ices is an established a~d recommended ~orm of tr~atment in many forms of limb injury and many diCferent fixation de~ices have been designed and are known to the applicants. While some of these are generally considered satisfactory, it is believed tha~ mos~ are unnacessarily complex aud do not pro~ide the degree o~ rigidity required for optimal bone healing. I a~ effor. to i~crease _igidity, designers have resortPd to multilateral or ~ulti- :
axial units (which i~clude more than one external fixation body) but such units are bulky and di-ficult to handle and are technically ~o~plicated. In addition their bulki~ess renders access to the wou~d as well as soft tissue management di~iCUlt.
Another drawback associated with known ~xternal fixa.io~
devices has been their inability to permit the pin clamps~nd :
thei- attachments ~o ~he main. body o~ the fixation uni~ to be easily a~d quiekly adjusted by the surgeon and th restri~ed ran~e of moveme~ts which such componen~ parts can undergo.
This has re~dered difficult the entry of the retainer pins and as well the ease with which any rotational misaiignme.n~ o the .
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SIJBSTI rUTE S~ ET
W091/111~9 PCT/A~191/00036 2 ~ ~ fl 1 ~ ~
f-ac~u-ed bone can be co--ected. I~ ad~.ion, the~e are limitatlons on .he extene to which the s?a~ial o-ie~tat~on of each set of -eta~ne- plr,s relative ~o the main body of the fixat on uni~ car. be var~ed, such ~a-ia~ion beins requi~ed to -e~able the unit .o be easily i~stalled a~d ta perm~t the body of the fixator to be posi~io~ed parallel to the lo~g axis of :-the bone, rega-dless of where the bone f-acture occur whether in a wide or ~ar-ow part of ~he bo~1e.
Whils~ ce-~ain prio~ ar~ exter~al .ixation devices are desig~ed ~o provide dy~a~ic axial motion, a p_oblem co~on to such de~ices is 'he hi~h bending moments which occur in the retaine- pi~s a~c therefo-e the main body o. t~e ixatio~ u~it, durin~ ambulatio~. Studies ha~e shown that these high be~ g 30me~ts cause t~e telescoping pa-~s 0c the uni~ to ja.
especially whe-e sliding f~iction is -elied upo~ and the t~lescoping pa-ts are ~ade of the ~ame ~etal, o~ metals ha~ing a high coef~icie~t of friction. ~hese units ~ay pro~ide a consistent dy~a~ic axial motion ti.e. axial telescoplng motion) at the f-~cture site by the applicatio~ o. a load through the ixator pins by an exter3ally applied ~oto- (refer-ed to as ~acti~e dynamisatio~U)~ but they ~a~no. ge~e~ally be relied .:
upon to pro~ide consisteut and reliable passi~e dy~a~isation throu~h ambulatio~.
It is i~o--ant that the fixa.o be su-Cicie~'ly stable o that dynamic axial motio~ is e~su-ed through telescoping of the d~ice a~d ~ot by i~stability o~ the 'ixator. Repeated axial ~o~e~ents may cause the telescoping u~it to loosen or jam with ti~e, whic~ i~ ~u~~ may alter drastlcally the -igi~ity of the~; ! ' ~ixato- and the e~ficacy o~ dy~a~satio~. For example, a sig~i'ica~~ problem wi~ certai~ prios a-t u~its is their-rotato~y i~stability. One solution to ~his p~oblem was to use a key-lock system, i.e. where the in~e- and oute- ~elescopi~g ~bers are par. cir~ula: and a key e~gages wi~hin a groove .:. .
ex~endi~g alo~g ~he inner membe-. ~nhanced -otato_y stability ~an be provided bv a tigh.e- it~ing key-lock, bu_ this _e~ul~s .:
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WO9~ 9 PCT/A~'91/00036 -3- ~ 3 c;s ~ .~J r i in s~ictlon of the c~n~ac~ ar~s Oc the ~ey-loc~. Loose-fitting key-locks, whe~e a keyino pi~ engayes ln a key-way formed in the in~er mem~e-, pre~en. this complicatlon but cannot provide adequate rotatory stabili~y.
~ ixators have also been developed relyi~ on rolli~g friction between the telescopin~ parts rather than slidi~g frictio~, ~hese utilising roller bearings .rolling in ball bearins races. However, due to the fact that ~icromotion required for external flxators is in the order Oc lmm or less, such ball or roller bearings providi~s this motion will not roll ~ut rather rock a~d will therefore brinell. Such brinelli3g is a cause of i3stability a~d/or jamming, which s~ould be avoided'in dynamising ex~ernal fixators.
A still further defieie~cy of some known unilateral, , .:
telescopic external ~ixators is their inability to ~ary or , :
alter the rigidity o~ the device to axial motion of the ~ .
telescoping pa_ts during the course of fraeture heali~g. It has ~ ' bee~ fou~d that greater rigidity is required in the early ~ :
phases o. fracture healing and less rigidity later. It i5 desirable that means be provided so as to prevent p~ssi~e ''~' motio~ du-ing early stages o~ ~racture healing of t~e telescopi~g pa_ts of the fixator device until a set or ''.
predetermi~ed load is exceeded.
One object of the prP.sent i~vention therefore is to pro~ide a~ i~proyed unilateral, telescopic exter~al fixation de~ics which is of simple design, easy to hand}e and is more versatile in its ability to vary,,the orientatio~ a~d positioning o~ the pi~ clamps a~d in turn ~he orientation and positioni~g of the retainer pins fixed in the clamps.
:. ~
It is a~oth~- object of the.present invention to provide : an improved uni~ateral, teles~opic exter~al fixation,devl~e which can consistently, reliably and Pfficiently p_ovi~e S~ STllT~JTE ~1EE I
WO91/lll49 PCT/A-91/0003S
dynamisation (both active and passive) wlthout jamm~ns of the ~elescoping par~s.
It is yet anothe- object of the present in~en~ion to pro~ide an improved unilate~al, telescopic external fixat~on devi~e which can have its resistance ~o axial mo~ion readily :.
altered duri~g the course of fracture healins.
It is ye~ a fur_her object o~ the present inve~tion to provide an improved u~ilateral, teles~opic external fixation device which can provide an ext-emely stable, rigid s~ruc~ure thereby promoting mo~e rapid healing and early am~ulation.
Accordi~g to one aspect of this invention therefore, an .;:
improved u~ilateral, telescopic ex~ernal or~hopaedic rixation device comprises a~ elongate tel~scoping unit comprised of a :.
pair of telescopically engaging i3ner and outer parts adapted .
~or relative axial reciprocal mo~ement along a~ axis which coincides with the central longitudinal axis of said unit, a~d releasable locki~g means f 0- releasably locXing said parts agai~st rPlati~e axial movement, a pair of pin clamps respecti~ely carried o~ the telescopisg parts for clampi~g o~e o~ more orthopaedic retainer pins spaced lengthwise of the clamp and exte~di~ trans~ersely thereof, clamp co~ectio~
m@ans on each o~ the telescoping parts of said ~longate telssc~ping unit or con~ectin~ a respective said ~lamp thereto, each said clamp co~nection ~eans comprising a clamp holder having a first axis of rotation spaced radially rom said longitudinal axis of the telescoping unit whereby said elamp hol~er when in an u~locked co~dition, along with its associated sai~ cla~p can bodily-rotate about said fir t axis, `:.~
said clamp hslder being adjustably suppor~ed fo~ slidable~ :
moveme~t lengthwise along its said first axis whereby the .:~;
spatial po6ition of its associated s~id clamp can b~ varied by varyi~g the ra~ial distance (measu~ed along said irst axis) between said clamp and the telescoping unit, a~d wherein each said clamp is ro~atably supporte2 ~y said clamp holder so as to SU eS~ET~ 'T~
, ; . . . . . .
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PCI ~A ~191/00036 per~it the cla~p to bod~`ly -otate a~ou. a sece~d axis of rotation exten~ing leng.hwise the-eof and a~ _~ch- ansles te said fi_s~ axis.
With the above ar-angement, t~e p'~ cla~s o4 the _ixator together with the set of p~s can rota~e f-o~ a t-a~sve~se through to a ~ertical plane. This allows the pi~s to be placed horizontally at the e~d o~ the bone which is desira~le for met physical f-actures o~ long bones.
The ar_angeme~. alsc ~e-mi.s the pin cla~s to be tilted .h~ough a wide arc, which is requi-ed 40- spi-al a~d ve~-ical fractures which ~ay ha~e a wide ansula_ -ange o- the pla~e o~
the f raGtUre .
The abili.y Oc the clamps .o slide hor zon-ally allows ~ -rotation of the bone fragments without loss o~ axial alig~me~t of the fixator and also a wide ~ariation of ~he ansle of insertion of the pins i~to the bo2e. ~alaligame~t of the long~tudinal axis o~ the ixator f_o~ that o~ the tibia lesse~s the potential for dyna~ic axial ~otion o~ the de~ice. R~own dynamisi~g ~ixators allow ro~ation of the ~o~e fra~ment. only by axial de~iation of the ~Oay of '~he ~ixator from the loagitudi~al axis o the tibia.
P-eferably each said clamp co~ection ~ea~s (or at least that on the oute- telescopi~y pa-t~ ~u~_he~ comprises bracket or conneetor means slidably supported on its associated sai~
teles~opi~g past whe~eby the enti-e clamp connectio~ mea~s, whe~ i~ a~ u~lo~ked condition, along with its associated said clamp ca3 sl~de lo~gitudi~ally o~ sa~d telescopi~g u~it. T~e :~
; positio~ing of at leas~ one of the pin clamps a~ a~y lo~ati~n along th~ ~ull le~gth of the outer telescopi~g pa-t e~sures ~1 i~al ~paration of the in~er pi~s. Preferably, o~e o~ the bracXet ~ea~s is ~as- with the ~ee e~d of the inner ~eles~oping pa-~, wh~ls~ ~he othe- bra~ket means can ~lidably locate alo~g the lens~h o~ ~he ou~e telescopin~ pa~~. In 'hi~ :
S LJE3e~TlTUTE~ SHI ET
~
P(~/AIJ91/00036 ~i, way the separation O r the pin clamps anà the pins does no~
~ecessitate any adjustmen_ to the telescopi~g pa_ts whl~
co~t-asts with prio_ ar. ur.i~s which -eq~i-e rela~ive axial separatio~ t~ereo.. This also allows ~he te:lescopins pa_ts to be in conta~t with 02e a~other o~er a ~ajor portio~ of the le~g~h o~ the fixator, whieh gives r se to dlec_eased be~di~g movements and lesse~s the likelihood of the ujammi~g" of the unit duri~g dy~amic axial motion.
In another prefe -ed form of th~s in~e.. ~io~, sa~d b~ac~et ~.
~eans is ro~atably supported o~ its said telescopins pa-.
whereby said cla3p ~on~ec~ion mea~s ca~ be rota~isnally adjusted about a~ axis which coi~cides wit~ or s pa-allel wit~
the lon~itudi~al axis of said telescoping u~it, to assu~e di Serent angula_ positio~s -ela-ive to the telescop~s u~it. : ' . .
In another prefe~red form o thi~ i~veution, each said clamp co~nection means co~prises a swi~el blocX interconnected betwee~ the bracket means and the clamp holder and being rotatable, when i~ a~ u~loc~ed ~on~itio~, about a third axis wh~ch exteuds at _ight ansles to ~o~h ~he axis of ~he telescoping u~it a~d said ~irs~ axis. ~his pe~mits the bloc~
alo~g with its cla~ holde-, to swi~el about said thi-d axis and be set in a numDer o~ differen' a~sula_ positio~s relati~
to the telescopi3g u~it.
,:
Preferably the co~necto- o~ b_acket m~s comp-ises an :.
attachment body which encircles the associated telescoping pa-t a~d is pro~ided with a locki~g member, e.g. a cl~mping ~ w or ~olt which when ti~hte~ed, causes said boay to cl~pi3gly e~gage against ~aid teleseopi~g pæ~~ and locking ~he co~ecto~
~ea~s against both _ota~ional and longitudi~al move~ent , relati~e to the ~eLes~opi~g u~it. Preferably ~he body ~omprises a pair Oc hinged halves which are hingedly joined together alo~g an axis pa-allel to the axis of the fixator, with the cla~ping or locking screw cla~ping togethe- the fr~e en~s ~hereof o~ the opposi;e side o' the ~xa~o- body. ~is SUBST~ FU~ S~c .
,~ .. .... . , . .; . . . ... ,. . . . ~ , . . .
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~ J~ J ~
allows a clamp to De eas~ly removed f-om o- added to the f~xato- even wher~ ~he _xato- -emains a.~ached to a patient.
Pre~e-ably, .~e p~n clamps have a 360' horizontal a~gular range which pe-mi~s the body o. the _~xator ~.o be swu~g a-ound from o~e side of the leg to the othe~, thereby providi3g complete access to the wou~ds duri~g operative so~t tissue closu-e o- woun~ ca_e.
I~ yet a~othe_ ~refe_-ed em~oclme~, each said clamp holde- co~p-ises a t_ansve-sely ex.e~di~g shor~ le~g~~ pin or shaCt jo~r3alled ~o_ -o;?_iOr. abou~ said ci-s~ axis a~d ~ixedly carryi~g a; its distal end a pai~ o_ se~i-c~cula- ringers or . .
jaw membe-s, the i~ne- pe-i?he-al walls of which togethe-de~ine a th~ough ope~ins ln wAich is rotatably ~eceived a respective said clamp to enable said clamp ~o be rotat:ed ~rough 360-, this i~ tur3 permitting the o-ien'atio~ o~ the fixatos pi3s held therein to be simi la-ly ~aried.
Accordi3g to anothe- aspec~ o_ the pxesen_ inve~tio~, the:e is provided an i~proved u~i~ate-al telescopi~ exter~al ::
~ixatio~ de~ioe comprisl~g a m i~ telescopisly uni~ comprised of a pai~ o~ elongate teles~opically e~gaging pa~ s ada~ted ~o~
_elative axial slidi~s movement alo~g the lo~si~udinal axis of-said teles~oping u~it, the oute- o~e of said pa~ts co~s~ituti~g a housi~g having a bore exte~ding therethrou~h, the i~e- o~e of ~aid parts co3stituting a rod engagi3g with ~ Rliding ~lt i~
the bore and being ~o~-rotatable about said axis, the pro~ile of said rod a~d said bore each being n~n-circula- ha~i~g at leas~ o~e flat side, and whe_ein said rod is for~ed of metal, pre~e-ably stai~less stee'/ and the su-~2ce o~ sai~ hore ~o~p~isos hard polyme_ic ~ate-~al, whe-eby slidi~g r_ic~ion ~e~wee~ the parts, during said rela~i~e axial sliding move~e~t, ;.
i5 mi~imised. :
~ SUBSl~TUTE S~E~r ~ ~
~ :
WO 91/11149 PCr/A~91/00036 ~ -e~erably, ~he housing has 2 cy!lnd~~ca1 oute- wall sur'ace shaped and is ~omp-ised of ,wo ide~tical axial halves secured togethe~ ~y clampi~g sc-ews. T~e ~ousins may howeve-be fo-med as a unitary membe-.
:' By using dissimilar mate-ials for ~he i.~e_ rod a~d t~e bore sur_ace of the cyli~d~ al housl~g within whi~h the piston ~o~es, the slidi~s riction is ~ery much reduced (in eomparison ta uslng simila_ ~etals for example) a~d the_e is less li~elihood o the u~it ja~ing du-~g dy~a~isation t~ereo~.
Experime~ts conducted by the in~e~~o-s ha~e show~ th3t the combi~atio~ Or a suitable polymeric mate-ial an~ stai~le;s ~teel a:~o_ds a mos~ slg~i_ica~t i~proveme~t, i~ te~ms of ~ric_io~al resista~ce, in ~ompa~iso~ to pa~_s o_ si~ila- ~etals o- e~e~ dissimila- ~e~als, e.s. stzi~less steel/hard chrome ~:
stai~less s~eel, stainless steel/b_ass.
Pre~erably the bore of the cylindrical housi~g is li~ed :, with a laye_ of ~ard polymeric mate-ial, pxefe-ably acetal, a~d i3 particular mate~ial sold unde- the p~o~rieta~ ~ame ~E~ACEm~L", tpolyoxymethylene). ~e lin' g may be pro~ided by meaus o~ elo~gate flat s~rips i~serted in the bore and ~o-exte~sive therewith, eac~ st-ip beari~g agai s ~ a respe~tive pla~ar ~o~e sur4ace exte~di g along the le~g h o~ .he bore.
~y hard poly~e~ic mate_izl ha~ing high a~-asio~ and wear resista~ce and a low ~oe_~icient of ~ lc'.io~ would be suitable.
In addition to acetals, othe- exa~ples may i~clude hish density polyethylene and pol~propyle~e.
~ n a pr~fe-red arrangement, said bore is rec~a~gula-, and said rod has a recta~gula~ c~oss-s^ectional shape. ~he ~hape may also be t-iangula-.
other ~refe_red a_-angeme~t, ~aid rod co~p_ises flat : upper ~d lowe_ surfaces which are joined alo~g their lo~gitudinal ~arsins by cu_ved sidewall su__aces, a~d ~aid i~se~~ comp-ises a p ~_ oS dia~e~~~cally oppo~ec a~proxima~ely 1~_ .
.
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: - . . .
UO91/l11~9 PCT/A~'91/00036 f ~
_9_ D-shaped insert ~mbe-s fixedly secured to the cyl~nd-i~al bore with the planar 'aces o~ said insert me~bers enga~ing agains~
respective flat surfa~es of the rod, said 1nse~~ ~embers bei~s for~ed o~ hard polymeric ~aterial.
Preferably, said rod ~xtends through the entire length o the housing and is provided at its distal end with a limit wall which co-operates with a radial abutme~t surfa~e at the distal end o~ the housi~g to permit limited relative axial ~ovement only between the rod and the housing, su~h move~ent pref2ra~1y bei~g in the order of 5mm. In t~is ma~ne~, the rod maintains contac~ with the bore o~er a majcr portion of the le~th of the rod, which promotes stiffness and rigidity, and ~inimises the effect of possible bendi~g moments which in tur~ facilitates dy~amisation.
In yet a~other aspect of the present inven~ion/ an improved u~ilateral, external ~ixation device comprises a pneumatically operated or electric motor at the distal end of said cylindrical housing and bel~g co-axially aligned therewith, said ~o~or being adapted to provide dy~a~ic axial motion or dy~amic ~xial loadi~g of the bone fra~me~ts o the fractured bo~e.
~ referably the motor is arra~ged to provide micromotion at a fxequency of approximately 0.5 Hz a~d at an adjustable excussion of 0.1 ~m to 1.0 ~m.
. .
In a further aspect of this invention, the telescoping u~it is provided at its distal e~d with re~ovable calibrated : .:~
axial distraction means comprisi~g a longitu~inally extendi~s threaded rod arranged co-axially withi~ the u~it for effecti~g axial separation of the te~escoping parts a d i~ turn distraction o~ the bone parts, 80 as to allow bone lengthening procedures.
~,....
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WO91/11.J49 PCT/AU91/00036 ~r! J ~ c ~ Y
In yet anothe~ aspect arrangement, the telesGoping parts of the telescopi~g unit co-operate with an adjustable spri~g mechanism removably ~oused at the distal end of the outer part of the unit a~d arranged to provide an adjustable axial loading force to resist motio~ of the telescopi~g parts and to preYe~t relati~e axial movement of the t leseopi~g parts u~til a set (predete.rmined) load is exceeded. The adjustable spring will not allow dy~amic axial motion to oc~ur before ~aid set load is applied. ~is load will be set high during the early phase of .;
~ra~ture healing and set low duri~ the latte- phase of f~acture healing.
In order to more fully explain the Applica~ts' inventio~, several Pmbodi~e~ts are described hereu~der in som~ furthe-detail ~ut with reference to and illust-ated in the accompanying drawings in which;
FIG. l is a perspective ~iew o~ an external ~ixator according to a first embodiment of the inve~tion;
FIG. 2 is an e~d elevatio~al view of the fixator looki~g i~ the directio~ o~ arrow 2 of FIG. l;
FI~. 3 is a exploded perspective view of one of the clamp 7 assemblies show~ in FIG. l;
FIG. 4 is a longitudi~al sectional ~iew o~ the telescopi~g unit shown in ~IG. 1 (omitti~g the clamp assamblies for the sake of clarity~;
. . ~ .
FIG. S is a fragmentary perspecti~e ~iew, partly section, of the telescoping u~it of FIG. 4;
FIG. 6 is a radial cros~-sectio~al ~iew along the lines 6-6 of FIG. 4;
$lJi3STlTlJTE $H~
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W091/111~ P~T/~191/00036 FIG. 7 is a sec~ional v~ew slmi~a~ IG. 6 o~ a telesGopins uni~ acc~rd~ng to a secon~ embodimen- of ~he .i~vention;
FIG. 8 is a long~.udi~a1 section~l v~ew of an axial distra~tion uni~ fo- use w~th the .ix~tor shown in FIG. 1;
. .
FIG. 9 is a lonsltudinal sectional view o~ a~ axial loadi~g :
u~i~ fo- use wi~h ~he ~ xato_ show~ i~ FIG. 1; a d FIG. 10 is a schematic eleva~ional view of the fixato~ o~ .his in~e~tion which shows so~e o_ the adjus~men~s w~.ich can be ach~eved with the clamp assembly shown in FIG. 1.
I~ the embodime t illust_ated in FIGS. 1 to 4, a~
orthopaecic external fixation de~ice 10 comp_ises a main : . .
telescopi~g u it 11 which itself includes an ou e- cyli~d-ical housi~g 12 ia which is reciprocally housed a telescopi~s rod 13, clam~ connectors 15, 16 on the cylind-ical housing 12 and the head end o the rod 13 respec_i~ely, clamp holders 17, 18 associatec with each said clamp con~ec~or 15, 16 a~d ?i~
retainer cla~ps 19, 20 rotatably ~uppor~ed by the cla~p holders 17, 18 -espectiv~ly. Eac~ of t~e cla~ps lg, 20 comp-ises pai~s o opposed grooved cla~p plates 19', 19'' and 20', 20'', w~i~h are clamped togethe~ by means of clampins sc-ews 24 so as to fo~ t~ans~e~sely extending throush-openi~gs 25 fo_ -ecei~i~g 4ixato- retai~e- pins 27 a-ranged ~o ~e s~aced lens~hwise o~ ;;
the clamps 19, 20 and projecti~g t-a sve-sely thereof. The :;
pins 27 are of know~ co~struction.
.In ~his e~bodi~ent, the cl~p ~on~ectors 15, 16 each ~l .
~o~prises a pai- of hi~ged connec~or po-~ions 28, 29, a_-a~ged ~o e3ci-cl~ the ~ylind:~cal ~ousi~g 12 a~ -he c _cu} _ ~la_ged h~ad 30 (for~ed by two halves) at the ~-ee end o' the rod 13 respectively, ~he con~ec.or portio~s 28, 29, when in ~:
their 1006ened ~ondition, permittinS the cla~p ~onne~tor~ 15, 16~to be rotated about an axis which coincldes wi~h the ~ent-al lons eud~na1 axis of the ~elescop ~5 u..i- 11 anc, ~ he ca6~
-: :
C I I R CT l ~ t IT I~
, '. ' . ' .' .'.. .. "' . ' . ' . ' ' . ~ ' .. :' ' . ' ... . '. ' . '. ' ' . ' '' WO 91/11149 PCI/A~I91/00036 . .
:
of connecto- 15 also slidably d~splaced lons~tud~ally along the leng.h o_ the hous'ng 12. Wilh the clampins sc~ews 33 trefer FIGS. 2 and 3) in thei_ ti~htened cond~tion, the i~ne-bore sur~aces of the con3ector po_-io~s 28, 2~ clampingly engage a~ainst the oute- cylindrical surface of the ~ylin~rical housing 12 and thc pis~o~ head 30 respectively so as to i~mobilise the brac~e~s lS, 16.
As show~ in FIG. 3, each clamp 19, 20 is a 3~piece assembly comprisins two ide~tical plates 19~ and a u~i~a;v ~embe~ 31 co~tai~lng the plates lq''. ~he pieces mzy be die cast of alumi~ium o- alumi~iu~ alloy. With this a-ra~ae~le~, the pi~s 27 ca3 be removed withou- removing the clamp f_om its holder.
Suppor~ed on portio~ 28 Or the connectors 15, 16 are 8wi~el blocks 34, radially paced from ~he cyli3drical housi~g 12 of the telesGopi~g uni_ 11, each block 34, bei~g for~ed with -a tra~s~erse horizon~al slot 35 extendi~g i~wasdly ~rom o~e end of the block a~d co~mu~ica'i~g wi~h a trans~ersely exte~di~g cir~ular throu~h-openi~g 37 i~ which is rotatably recei~ed a solid cyli~ari al pi~ or shaæt 39 which ~orms pa-t of ~h~ cla~p holde_ 17, 18. Each block 34, is rotatably mou~ted on a stub shaft 3A ~rojecting radially from a side of por~io~ 28, and releasably locked therewith by ~eans of cla~ping screws 32, whereby, with the screws 32 loosened, the blocks 34, alo~g with the holde~s 17, 18 ca~ swi~el about a~ axis which i~tersects the cent~al axis of the u~it 10 a. ri~ht a~gles and is al~o at right angles to ~he axis O r the sha~t 39.
The rota~ion o' the holders 17, 18 along with their cla~ps 19~ 20 a~d pins 27 about the axis of ~he s~aft 39 per~its t~D pi~s ~0 be inse-ted longitu~inally o~ ~:a~versely, which is ~esira~le 1n si~ua,io~s involYing bo~es of ~arying diamet ~.
: SW~ST~TIJT SHEF.
. i ~O9l/ll149 PCT/A-91/0003~
f~ ~,. ,); ;, . . , -A cove- member 40 ha~ing a th_eaded s~em which th-eadably ensages in a th-eaded cen.-al bore formed in the shaf~ 38, preve~ts dislodgeme~t of the ~lock 3~.
Clamping screw 41, whe~ tightened, f_ic:tio~ally ~la~ps the shaft 39 agai~st bot~ rotatio~al a~d sli able ~ove~en~ relati~e to the block 34. It will of col~se be appreciated that whe~
the screw 41 is i~ its untightened ~o~di_io~, the clamp holde-s 17, 18 ca~ be rotated abous the ax~s Or the sha_' 39 a~d locked i~ any desired o-ie~ta~ion a~d also slida~ly adjusted le~gthwise Or the axis o the shaf~ 39.
Ea~h ~lam~ holder 17, 18 also i~ludes a pai~ of se~ni- -ci~cula- lugs ¢3, 43' which co-ope~a.e togethe- ~o ~orm a circula- opening for clampi~gly re~eivi~g .he clamps 19, 20. An adjustment screw 44 is used to faste~ the lugs 43, 43' together, and which, whe~ untightened, allows the clamp 19, 20 to be bodily rotated (along with its pi~s 27) to a~y desired ~:
a~gular set~i~g. ~-The ability o~ the cla~p holder 17, 18 to bo~h rotate about the ~xis cf s~af~ 39 a3d to slide lo~gi~udi~ally along ~ha~ ~is has bee~ ~hown to greatly ~aeilitate th~ pla~e~ent of the rstai~e- pin~ into the bone frag~es.s and also the ;~.
cor-ection of any rotatio~al misalign~en. of the bo~e fragments : :
withou~ altering the longitudinal alig~ment of the housins 12 to the axis of the bone, e.g. ti~a, whilst the a~ility of the cla~ps 1~, 20 to bodi}y rotate about an axis at right asgles t~
the axis of the sha~t 39 l~ds thie u~it ~uitable ~or approach-~g ~he bone th~oush a wide an~ula_ ra~ge. ~hese :.:
featu~es ca~ be clea-ly seen ~rom FIG. iO of the drawi~g6 whioh show~ ~ow the pi~ cla~p 19 can be horizon~ally di~placed ~-o~
th~ housing 12, and its orientation altered, which en~ure~ a wide ra~ge o4 a~ailable pin angl~s.
,.' "
SUBS~li lJTE SE~E~ t~ I
,. ..
u~I/III1') PCT/A~'9l/00036 ~ e ab~lity o- the clam~ conne~o~s 15, 16 to slide along the cylind~ical housfnc 12 'acili.ates optimal posl-ionins of the retai~er pins 27 rela~ive to the f_a~u~e si~e. I~ is a~
advan~age O r ~he p-esent ~ve~ioa that more tha~ o~e cla~p con~ecto_ ca~ be suppor~ed o~ the cyli~d_ical housins 12 a~ by virtue of the ~ersatility of the ra~ge o move~e~ts which the cla~p connector, hoLder an~ clam~ ca~ u~dergo, o~ is able to positio2 pias o~ oppo~ite ~ides of the hou6i~s~ 12 o the u~it 11, so as t~ allow n .-ia~gula~io~a a~d provide e~hanced rigidity.
The hi~ge 45 which plvotally joins the por ions 28, 29 of the con~ectors 15, 16 pe_mi~s .he co~nectors to be readily -emovea from the housi~s 12 even wi_h the u~i ! 11 att2ched to a bone. ~ .
.
Refer~i~g to FIGS. 4 to 6 of the drawi~gs, ~he rod 13 of the telescoping unit 11 is formed o~ stainle6s steel ha~'~g ~ighly polished outer sur'ace an~ is of square cross-sec~ion.
The roa 13 slidably engages with a sliding fi- in a bore ~6 which exte~ds through the rull le~g.h o~ the hou i~g 12 ~he bore 46 also bei~g of sgua_e oross section. he housins 12 is pseferably formçd o~ alu~i~iu~ a~d co~prises two dia~etral hal~es 12', 12'' secu-ed togethe~ bv screws 47. ~he bore 46 is lined by means o~ replaceable st-ips 49 of hard polymeric mate_ial, e.g. e-tacetal, which is abrasion resista~t, has a low co-e~icie~t o~ iriction and sood surface lubricity, 5uch :
an arrangemeut mi~imisi~g the sliai~g ~rictio~ betwee~ the rod 13 and the bore surface 46, as a result of which the moving pa_~s of ~h~ u~it 11 are less likely to ia~ whe~ subjected t~
bendi~g ~o~ents, in compa-ison with existi~g a~t. O~ ~our~s, the li~er 49 ~ay be i3 the form of a~gle i~se ts s~ugly ~itted iD~o the bore 46 of the housing 12. ~he fou- st-lps 49 are held loosely i~ the bore 46 agains~ respec~ive planar su-~aces ~or~ed the-ein and can be easily ~eplaced i- and whe~
~ecessa-Y . ',.
SUBSTlTlJT~ SHEE~T
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~091/1l1~9 PCT/A~9l/0003fi The oute- end Oc the _o~ 13 ~e~~. ~ates _n an e~la~ged head 30 fast ~herew~~h, a~d a-ound which is clamped connecto- 16, wh'ls~ the inne_ o- cis~al end of ~he rod 13 threadably co~nects to a lim ~ ~lock 50 via a .h-eaded s.em 52, co-axial therewi~h. The bloc~ 50 is housed in an exte~.sio~ piece 53 o~
t~e housing 12 a~d fixed thereto and is desi~ed to limit axial . -mo~eme~t of the rod 13 through a prese~ ra~ge, depe~di~g o~ the healing requirements o_ the f-actu-e, the bloc~ 50 co-operati~g with a radial abutme~ fla~ge 54 to co~s~-ain rod move~e~t i~
the extensio~ directio~. Move~en~ i~ the ret:-ac~on direc~ion of the rod is const-ai~ed bv the e~d wall of ~he rod 13 abut~i~g acai~s~ -he o~he- side o- ~he flz~ge 54. ~ .
The exte~sion piece 53 suppo-ts a slidable joi~iag colla-57 which has an in~er~a~ ead 58 _o- rece~vl~a a th-eaded e~d !:
plug.59.
TSe p-oximal end of the housins 12 is provided with a locking collar 60 whioh has an inter~al ~hread which threadingly en~ages a~ exter~al th-ead on end block 61 secured to the end of the housi~g 12, ~he bloc~ 61 ha~ing a ce~t_al openi~g throu~h which passes ~he -od 13. ~he arra~geme~t is such that as the locking collar 60 is rotated to its locked position, -~he e~d wall 62 o4 the collar 60 bears a~ai~s~ the .acl~g wall 64 on the head 30 of the rod 13 a~d upo~ ~u~the-tighte~ing, the -od 13 is axially displacea i~ t~e exte~sio~ :
direction un~ he limi_ block 50 abuts agai~st ~he ~lange 54, whereupon the rod 13 is locked agzius~ a~y ~ovemeut, ~he housi~g 12 a~d roa 13 thereby beiny ~ixedly secured with respec-. to o~e a~other. ~he lo~ed co dition is requ~red when a~y sho_~e~ g or colla~se of the ~od 13 is to be preve~d.
With the locking nut 60 in its loose~ed or unlocke~
conditio~, the u~i. can be subj~c~ed to dynamic axial loadi which ca~ elther be "passi~e" achieved t~rou~h ,he actio~ o~
a~bu~atio~ or "acti~e" er~e~ted -h~ough a moto- unit ~not ...
~how~) a~.ached ~ia t~e colla- 57 a_ ~he d~s~al end o. ehe SUBSTITUTE SHEET
WO91/11l~9 PCT/A-91/00036 t!~ ~ J ,~
l.6-cy~i~d-ical housing 1~ and co-axia!ly aligned _~erewi~h.
~refera~ly the moto~ ~s pneumatically o- elec~~ically operated.
In an alte~~ative embodimen, shown in ~'IG. 7 the -od 6S is for~ed with two flat sides jo~ned by two cu:~ed side walls, whilst the bore of the housi~g 12 is circula: a~d has fi~ed therein a pai~ of i~serts 66 formed of hard poly~erical ~aterial. ~he i~se_ts 66 a e D-shaped a~d are -es.~ai~ed agai~st rotation by ~ea~s of grub screws (~ot shown) exte~ g through the wall of ~he housing 12. O~ce asai~, the presence of the polyme~ic i~se~~s 66 signi_lca~tly recuces the eCrect of sli~ing f-iction.
I~ the above-desc-ibed e~bodiments, each of the cla~pi~g s~rews comprises a hexago~l -ecess or dep-ession i~ the head thereoC~ and rotatio~al adjustmen~ Oc such sc~ews is efCected by ~ea s of a k~ow~ hexagonal key spa~e-.
Refe--i~g to FIG. 8 Oc the d-awings, a calibrated leaa screw de~ioe 67 is shown and which can be attaehed to the unit : :
. 11 (by removing end plug 59) via the collz- 57, the device 67 ~o-operating with the rod 13 ~o ef~ect co~t-olled relati~e axial mo~eme~t ~etween ~he rod 13 a~d the cylinder 12 w~ich in tu-~ e~ ects d~s~-action o~ the bo~e ~agme~ts, t~is bei~g ~ecessa-y ~o al}ow the bone le~g~he~ing procedu-es. ~he de~ice 67 co~prises a~ ad jus-.me~ ~ membe_ 6a having a threaded stem 6 9 which is screwed i~tto a th-e~ded bore of body por~ion 70 whi~h in turn is scre~ con~tected to the co}la- 57. ~he stem 69 projects t~roush the ~ody postio~t 70 and bea s agai~tst an , ~, .
inte~ne~iate irLser~ lo~ated between the rod 13 (the bloc3c ~0 iDg been ~mo~ed ) . . .
Ref e-_ing to FIG . 9 o~ the drawlngs the~e is show~t an axial loadiD.g de~ice 71 a~eacha:ble to the coll - 57 o~ the u~it 11 to lie ~o-axi~l thereui .h, the de~ice 71 bei~g provided with rLn ~d jus.,a~le nu~ 72 which is screwe~ ~o a tubula- body 73, and a resilien~ oomp~ession sp~_ng 7~ housed w -".in the nu~ and the W O 91/111~9 PC~r/A~'91/00036 body 73, the sp-~ng 74 ir. ~u~n m~king pressu_e contac~ a~ains.
a pin 75 which p_ojects axlally _~om the e~d o_ the body 73 a~d bears a~ai~st the end of the rod 13, when the dev~ce 71 is so attache~. The de~ice 71 ~hus co-ac~s with the rod 13 to provide an adjustable spring resistance to ~o~eme~t of the rod 13 in such a ~an~er that a~y mo~ement of the rod 13 is inhibited u~til such ~ime as a set or predete:cmined load is exceeded. As explained herei~before, greate~ rigidity is recui-ed i~ the early phases of f-acture healing a~d less rigid~.y late~ or. The adjustable spr' ng mechanism is desig~ed 50 as ~o. to allow dy~amic axial mo~ion to occu- before the se~
load is applied. The reaui-ed load will be se~ kigh duri~g ~he early phase of f_acture healing a d i~ tu-n set low duri~g t~e late phase of _-ac~ure hezling.
.
It will be realised t~at the material selection for the telescoping parts 12, 13 can be dir_eren. to that stated above.
Fo~ example, the xod 13 may be formed of ti'a ium or anocised aluMi~ium, w~ilst the housing 12 ~ay be oO a suitable ha_d plastics ~ate-ial. The rod 13 m2y eve~ be lined o- coated with a sul~able wea- resi~ta~ plastics material ha~i~g good ~urface lu~ricitv a d a low co-e,cicie~t of friction, e.~. te~lo~.
Still ~u-the-, it may be possible to coat t~e ~o~e su-face o_ the housing 12 with a layer o. hard polyme-ic ma~e-ial.
.....
A ~rie~ co~sideratio~ o~ ~he above-described e~bodiments will i~dicate that the inve~tio~ p-o~ides a~ improved ~ilateral exter~al fiJeation devic~ which is extremely ~e-sa~ile, co~pletely adjustable, easy to use a~d provides c04s1s e~t reliable a d e'fective d~nnamic axial ~o-ion.
:
.
8UE~STlTlJTE SHEE~T
'' :'',,.. ,.'',''' ,;'' ' ,`' ~. :'
Claims (27)
1. An improved telescopic external fixation device comprising a main telescoping unit itself comprised of a pair of elongate telescopically engaging parts adapted for relative axial sliding movement along the longitudinal axis of said unit, the outer one of said parts constituting a housing having a bore extending therethrough, the inner one of said parts constituting a rod housed with a sliding fit in the bore and being non-rotatable about said axis, said rod and said bore having a non-circular profile which has at least one planar surface, wherein the surface of said bore comprises hard polymeric material, whereby sliding friction between the parts during said relative axial sliding movement is minimised.
2. An improved telescopic external fixation device according to claim 1 wherein said rod and said bore have a profile which is rectangular or square.
3. An improved telescopic external fixation device according to claim 2 wherein each of the planar surfaces of the bore is lined with a layer of said hard polymeric material.
4. An improved telescopic external fixation device according to claim 2 comprising replaceable elongate flat strips of said polymeric material co-extensive with said bore and contiguous with the bore surface.
5. An improved telescopic external fixation device according to any one of the preceding claims wherein said rod is formed of metal, preferably stainless steel, and said polymeric material is acetal.
6. An improved telescopic external fixation device according to any one of the preceding claims wherein said housing has a cylindrical outer wall and comprises two identical axial halves secured together by securing means.
7. An improved telescopic external fixation device according to claim 6 wherein said securing means comprises screws.
8. An improved telescopic external orthopaedic fixation device comprising an elongate telescoping unit itself comprised of a pair of telescopically engaging inner and outer parts adapted for relative axial reciprocal movement along an axis which coincides with the central longitudinal axis of said unit, a pair of pin clamps respectively carried on the telescoping parts for clamping one or more orthopaedic retainer pins spaced lengthwise of the clamp and extending transversely thereof, clamp connection means on each said part for connecting a respective said clamp thereto, each said clamp connection means comprising a clamp holder, means for locking said holder in either a locked or unlocked condition, said clamp holder having a first axis of rotation spaced radially outwards of said outer part whereby said clamp holder when in an unlocked condition, along with its associated said clamp can bodily rotate about said first axis, said clamp holder being adjustably supported for slidable movement lengthwise along its said first axis whereby the spatial position of its associated said clamp can be varied by varying the radial distance measured along said first axis between said clamp and the telescoping unit, and wherein each said clamp is rotatably supported by said clamp holder so as to permit the clamp to bodily rotate about a second axis of rotation extending lengthwise thereof and at right angles to said first axis.
9. An improved telescopic external fixation device according to claim 8 wherein each said clamp connection means comprises a connector slidably supported on its associated said telescoping part, means for releasably securing said connector to its associated said telescoping part, which when released, permits the connector along with its associated said clamp to slide longitudinally of said telescoping unit.
10. An improved telescopic external fixation device according to either claim 8 or claim 9 wherein each said connector is rotatably supported on its said telescoping part whereby its associated said clamp connection means can be rotationally adjusted about an axis which coincides with the longitudinal axis of said telescoping unit, to assume different angular positions relative to the telescoping unit.
11. An improved telescopic external fixation device according to any one of claims 8, 9 or 10 wherein there are two said connectors, one of which is fast with the free end of the inner telescoping part, the other being slidably located along the length of the outer telescoping part.
12. An improved telescopic external fixation device according to any one of claims 8 to 11 wherein each said clamp connection means comprises a swivel block interconnected between its associated said connector and said clamp holder and being rotatable, when in an unlocked condition, about a third axis which extends at right angles to both the axis of the telescoping unit and said first axis.
13. An improved telescopic external fixation device according to any one of claims 8 to 12 wherein each said connector comprises a pair of halves which surround its associated telescoping part, and locking means for clampingly engaging said halves against the periphery of said part to thereby lock same against both rotational and sliding movement relative to the telescoping unit.
WO ??/????? PCT/AU91/00036
WO ??/????? PCT/AU91/00036
14. An improved telescopic external fixation device according to claim 13 wherein said halves are hingedly joined together along an axis parallel to the axis of said telescoping unit, and said locking means comprises a clamping or locking screw clamping together the adjacent ends of said halves on the side opposite to said hinge axis.
15. An improved telescopic external fixation device according to any one of the preceding claims wherein each said clamp holder comprises a transversely extending short length pin or shaft journalled for rotation about said first axis and fixedly carrying at its distal end a pair of semi-circular fingers or jaw members, the inner peripheral walls of which together define a through opening in which is rotatably received a respective said clamp to enable said clamp to be rotated through 360°, to in turn permit the orientation of the fixator pins held therein to be similarly varied.
16. An improved telescopic external fixation device according to claim 15 wherein each said pin clamp is a three-piece assembly comprising a pair of separate identical axially aligned spaced apart half plates each having a plurality of transverse grooves spaced lengthwise thereof and extending across an inner face thereof, and a unitary member comprising a central circular bearing portion which makes bearing contact with said inner peripheral walls of said fingers or jaw members, and a pair of plate portions projecting from opposite sides of said bearing portion and which co-operate with said half plates to form transversely extending through openings for clampingly receiving said fixator retainer pins, there being clamping screws for clamping together each said pair of plates.
17. An improved telescopic external fixation device according to any one of the preceding claims further comprising releaseable locking means for releasably locking said inner and outer parts against relative axial movement.
18. An improved telescopic external fixation device according to claim 17 wherein limit means are provided for limiting the range of axial movement of said inner telescoping part relative to said outer part, when said locking means is released.
19. An improved telescopic external fixation device according to claim 18 wherein said limit means comprises an abutment surface at the inner or distal end of said inner part which co-operates with a radial wall on the outer part.
20. An improved telescopic external fixation device according to any one of claims 17 to 19 wherein said releasable locking means comprises a locking collar having an internal thread which threadably engages an external thread at the proximal end of said outer part, said locking collar being moveable between a locked or tightened condition which locks said parts against relative axial movement, and a loosened or release condition which allows said parts to undergo relative axial movement.
21. An improved telescopic external fixation device according to any one of the preceding claims further comprising an axial loading device which comprises an adjustable spring mechanism attachable to the distal end of said housing and co-operable with said inner part to provide an adjustable axial loading force to resist motion of said inner part and to prevent relative axial movement of the telescoping parts until a set or pre-determined load is exceeded.
22. An improved telescopic external fixation device according to any one of claims 1 to 20 further comprising an adjustable axial distraction device attachable to said housing at its distal end and comprising a longitudinally extending threaded rod arranged co-axially with said unit for effecting axial separation of the telescoping parts and in turn distraction of the bone parts, so as to allow bone lengthening procedures.
23. A telescopic external fixator, comprising;
an elongate telescoping unit comprising telescopically engaging inner and outer parts arranged for limited axial reciprocal movement relative to one another along the longitudinal axis of the unit, the outer one of said parts constituting a housing having a central bore extending the whole length thereof, the inner one of said parts constituting a rod which engages with a sliding fit in the bore and extending the full length thereof, said rod being non-rotatable about said axis, wherein said rod is formed of metal, and the surface of said bore comprises hard polymeric material, co-operable limit means and limit engaging means between the rod and the housing for limiting movement of the rod relative to the housing within predetermined limits, arranged so that during said limited reciprocal movement, the rod maintains sliding contact with the bore approximately along the whole length thereof.
an elongate telescoping unit comprising telescopically engaging inner and outer parts arranged for limited axial reciprocal movement relative to one another along the longitudinal axis of the unit, the outer one of said parts constituting a housing having a central bore extending the whole length thereof, the inner one of said parts constituting a rod which engages with a sliding fit in the bore and extending the full length thereof, said rod being non-rotatable about said axis, wherein said rod is formed of metal, and the surface of said bore comprises hard polymeric material, co-operable limit means and limit engaging means between the rod and the housing for limiting movement of the rod relative to the housing within predetermined limits, arranged so that during said limited reciprocal movement, the rod maintains sliding contact with the bore approximately along the whole length thereof.
24. An improved telescopic external fixation device according to claim 23 comprising locking means for releasably locking the rod and housing against said axial movement.
25. An improved telescopic external fixation device according to either claim 23 or claim 24 wherein said limit means comprises a limit block carried at the distal end of said rod co-axial therewith, and said limit engaging means comprises a radially inwardly directed wall at the distal end of the housing.
26. An improved telescopic external fixation device according to any one of claims 23 to 25 comprising a pair of orthopaedic pin clamp assemblies, one of which is carried by the rod adjacent its proximal end, the other being adjustably carried on the housing for positioning along the length thereof, each assembly comprising pin clamps for removably securing one or more pins therein.
27. An improved telescopic external fixation device substantially as hereinbefore described and with reference to and as illustrated in FIGS. 1 to 6 of the accompanying drawings, or as modified as shown in any one of FIGS. 7 to 9 of the drawings herein.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPJ8440 | 1990-02-05 | ||
| AUPJ844090 | 1990-02-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2050596A1 true CA2050596A1 (en) | 1991-08-06 |
Family
ID=3774483
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002050596A Abandoned CA2050596A1 (en) | 1990-02-05 | 1991-02-05 | External fixation device |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR920700591A (en) |
| CA (1) | CA2050596A1 (en) |
| DE (1) | DE69111931T2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109907811A (en) * | 2019-04-29 | 2019-06-21 | 大博医疗科技股份有限公司 | Fixed frame and reset system |
| CN111714792A (en) * | 2020-06-30 | 2020-09-29 | 中国人民解放军陆军军医大学第一附属医院 | Shank fixed knot constructs for radiotherapy |
-
1991
- 1991-02-05 DE DE69111931T patent/DE69111931T2/en not_active Expired - Fee Related
- 1991-02-05 KR KR1019910701277A patent/KR920700591A/en not_active Application Discontinuation
- 1991-02-05 CA CA002050596A patent/CA2050596A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109907811A (en) * | 2019-04-29 | 2019-06-21 | 大博医疗科技股份有限公司 | Fixed frame and reset system |
| CN109907811B (en) * | 2019-04-29 | 2023-09-26 | 大博医疗科技股份有限公司 | Fixing frame and resetting system |
| CN111714792A (en) * | 2020-06-30 | 2020-09-29 | 中国人民解放军陆军军医大学第一附属医院 | Shank fixed knot constructs for radiotherapy |
| CN111714792B (en) * | 2020-06-30 | 2022-03-08 | 中国人民解放军陆军军医大学第一附属医院 | Shank fixed knot constructs for radiotherapy |
Also Published As
| Publication number | Publication date |
|---|---|
| DE69111931T2 (en) | 1996-04-11 |
| KR920700591A (en) | 1992-08-10 |
| DE69111931D1 (en) | 1995-09-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |