Note: Descriptions are shown in the official language in which they were submitted.
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
.
.. .... ~.~..._.
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~
, ; . . . . . .
.. . : ., : , . : . .: . .
. -... . . . . ., .. ` . : . ... . .. .
WO 91/1 1 149
PCI ~A ~191/00036
Z3
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,
--6--
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 .
,~ .. .... . , . .; . . . ... ,. . . . ~ , . . .
` ;, ' ' . ' ' `'. : , ,. " ` ' '' " , ' ` ' ~ ' '
o 9~
PCT/AU91/00036
~ 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
8--
~ -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~_ .
.
. ; ., . - .,: . . .
: - . . .
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.
~,....
.. , . . ........ ~: . , . . -
, , . . . .. : ; , . ~ ,- ., .. . ; ., . : .:, .. . : .. : . . :: . ,.; .,:: - .: ., ,. ::: - . : .. : . :.
WO91/11.J49 PCT/AU91/00036
~r! J ~ c ~ Y
- 1 0
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~
.`,, . : , . ` , ` `
`, ,, . ` . .
` ` . ~ `` . . - , . ..
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
. .
--12--
:
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~ ~,. ,); ;, . . , -
-13-
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
-14-
~ 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
.. - ..... . . . .. .
.. . , . ..... ~ . . .. . . . . . .
.. - ~ . ~ .. - ; . `. .. . -. ~ .
~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
''
:'',,.. ,.'',''' ,;'' ' ,`' ~. :'
