CA2189677C - Expandable fabric implant for stabilizing the spinal motion segment - Google Patents

Abstract

An expandable, porous fabric implant for insertion into the interior of a reamed out disc which is packed with material to stabilize the spinal segment. The fabric pores allows for tissue ingrowth the implant.

Description

~ WO95/31948 218g677 r~l/u~ ~.r~79 EXPANDABLE FABRIC IMPLANT FOR STABILIZING
THE SPINAL MOTION SEGMENT
n .. 1~ ~. ou,,d of tllc InYcntion 1. Ficld Or th.. IIIYr~ntinn S Tilis invention relales to n method nnd deviee for stabilizin~ a ~1. I ;~,,,li,,~ spinnl motion segmen~ eomposed of two vertebrne adjaeent n dise.

2. Deseription of the Rel ited Art . t Lo Y baek pain is n medieal eondilion nffeeting millions of humans. It is the most eommon eause of disability for tlle middle aged working populntion. In 10 addition to the diseomfort nnd pnin c~ ;cl~ccd by the individual, substantial eosts are borne by soeiety, ineluding eosts for tile dingnosis nnd treatment. nnd tlle eost of payments for diisability benerlts. Lost pro~iuctivi~y is more difFcult to qunntify, but we know that it is substanti;il. Any new i;no~vledge thnt lends to a ~greater u l ~,.,..li.~ or the eauses, prevention, or trentment of the low back p iin is n worthwhile and important ~5 ~ i..,, tO the welfare of individuals and society in general. Any i~ lLio.l that reduees or eliminates symptoms woul~i eonstitute a si~nirleant iJ~ uul 1~. That diseovery would improve the quality of life for eountless individuals and reduee the expenditure Or searee soeietal finaneial resources.
ReeeM medieal evidence indicates that tlle symptoms of low back pain 20 are most eommonly cnused by patl1ologic changes occurring in wllat is called the ~spinal motion se~ment." The spinnl motion segment consists of n unit of spinal anatomy bounded by two vertebMI bodies, containing those bodies and the interposed i.. i~.i.i,.,.l disc, ;Is well ns tlle :Ittaclled li~aments, muscles, ;Ind the faeet joints.
The disc eonsists of the eartilaginous end plates nt the top nnd bottom of 25 the YertebMI bones, tile nnnulus ~ïbrosis running eireumferentinlly around the nueleus, and the nucleus itself. In normnl dises. the nucleus acts ~s a dnmper to cushion applied loads, thus proteeting the other elements of the-motion segment. The nueleus contains hydrophilic (wnter nttMeting) ~u~uiloly~ ridc~ and a sma'il nmount of f~brous stMnds. Tlle nueleus is ;ll~oll~ )lc. It responds to CO~ u~a~;ùll rorces (ns in 30 sitting, stnnding wnlkin~ nnd lifting) by bulgin~ outwnrd ngainst the vertebral end plates and tlle annulus Flbrosis. Meeh:mieal forees aeting on the dise are substantial, i.e.
.I,U~JlU~ 1000 Ibs/in' when n lleavy load is lifted.
Tile annulus consists Or a woven r;lbric of colla~en rlbers and n smnller WO 95/31948 P~,lll 'C 179 nmount of elnstic fibers, botll of which r,re e~tremely strong in resisting tension forces.
Ul~ru-Lull~ ly tlle nnnulus is not very strong when it,ls required to withstnnd cu~ aa;ull nnd sl~enr forces. Tl~e verteb~l end;p!nte cnn deform slightly by bulging inlo Ihe verlebrnl bodies, ns long ns Ille npplied forces nre nol grent, nnd n long ns Ihe S force is dnmpened by II~e bulging of Ihe nnnulus.
Disc Dc~,."...~ r.
The primnry cnuse of low bnck pnin is u~ Liol~ of Ihe lumbnr discs.
For rensons lI~nt nre nol perfectly cle:lr, mnny if not most humnns develop pnLhologic 10 ch~n~es in the nucleus ns tl~ey nppronch middle nge. In about one tllird of individunls, the process is pninless. In tlle olher Iwo-lhirds, Ihe disense cnuses pnin vnrying from mild nnd iMermittent to severe nnd constnnt. As tlle nucleus begins to dry up, so to spenk, il frngmenls, nnd looses its' :Ibility to nct ns n cushion. This process is usunlly slow, but mny be r~pid if tlle disc is injured by tl~e npplicnlion of n very grent load; ns5 mny occur during nn nccident or by tl~e lifling of n grenl weighl, or ns n resull of Ihe ;.. \ of forces while slooping, bending, Iwisting or lifting.
Tllis condition of disc ici..r~ tio.~ is sometimes cnlled "isolnted disc resorption." Dehydrntion of Ille nucleus reduces ils' nbility to nct ns n cushion. As a result, londs nre trnnsferred to tlle nnnulus of the ~iisc nnd to the fncet joints. These 20 Imer SlrUCtUres are nol cnpnble of wiLll~L,I~ the npplied cù~ "~aaion nnd torsionnl loads, nnd they grndunlly deteriorntc. Effecls of Illis process includè nnrrowing of Ihe interspnce, bony spur formntion, f,.. ~,.. I .~i.. ,. of the nnnulus, frncture nnd d.,hl;u..,Liu,. of Ihe cnrlilnginous end plnles, nnd d.;~;u~ti~n of Ihe cnrtilnge of Ihe fncel joinls. Tl~e :Innulus nnd fncct joints loosc tlleir structurnl st:~bility wllile subtle but 25 pathologic motions occur between the spinnl bones - n condition known ns "segmentnl instnbility" occurs. Tile process is sometimes referred lo ns the rdc~,~",.""Li~"
cnscnde.~ Brenkdown producls Or Ille ciisc nnd fncet joinl, including Ill.l..luacu~J;c ellunks, I.,;c.U~.u,u;c pnrlicles, nnd noxious chemicnl subslnnces build up. These brenkdown prod~lcls stimulnle sensitive nerve endings in nnd nround Ihe disc, producing 30 low bnck pnin nnd somelimes, sciriticn. Affecled individunls experience muscle spnsms, reduced fiexibility of II~e low bnck, nnd pnin when ordinnry movemenls of t'ne ruck nre mlempled; e.g. stooping, bending, lifling, sLnnding, wnlking, or even rolling over in bed. Simpie nnd efrective cures do nol exisl. The process is irreversible.

2l8g677 WO 9'il31948 P.~ b t79

-3 -Fortunately, in some if not most cases, '~s the disease continues to run its' course, the body eventually re-stabilizes ti~e disc by stiffening the joints of the motion segment.
Then the pain may decrease or cense nltogether. u~lrO-Lu~ t~ly, in n signific;mt number of individuals (10-15%) the rP~hili7~tir~n process does not take place. EYen in the 5 group where rP~hili7~tir.~ occurs, tlle process requires several yenrs or even decndes to complete. During that time the pntients often experience recurrent bouts of disabling pain.
Dircct OiJ.~Iv.lliul.~ by otller ill~C~ ula iiurin~ e perrormnnce of lumbnr procedures have conf~rmed Ihe sensitiYity of certain lumbar tissues. In ~0 addition, the most extensive direct OiJa.. v..~iù..s of these phenomenn to determine the exact source of lumbar pain llave been performed and published by the inventor, Clinic~lly si~nirlcnnt low bnck pnin is derived, in the m~in, from p~tholo~ic stimulation of these, and only these structures: 1) the vertebMl end pl~te, 2) the outer layers Or the ~nnulus fibrosis, nnd to a lesser extent, 3) tlle c~lpsule of the 15 facet joint. J~ll of these structures produce typical low back pain when they are rubjected to mechanical forces that exceed ~ certain threshold. In addition, it is likely, based on recent ;-~v~Li~ iu~-~ into the bir~rhPmir~l milieu of the motion segment, that eertnin loeal cllemieal nhnrrm~litiP~ may play a role in lowering the threshold for the stimulation orpain ~,..,.~.":;li"~ fibers.
Surgeons have ~ievised seveMI methods to stabilize tlle motion segment.
These methods fall into the followin~ genernl cntegories:
I) Dccu.."u-.,s;ù., of tlle spinal canDI by removal of part or all Or the remaining nucleus, sometimes cnlled "partial discectomy" or "discec~omy."
~) D~u.nl".as;o.. ol tl~c spi~ l c;ln:ll by rcmoY;ll Or non-nuclcar tissues., e.~.
li~mrnt,lm finvum rcmov;~l or bone rcmov;ll, sometimes calle~ u~u~y"
or " ll~ ullly . "
3) Spinal fusion by a great Ynriety of teehniques.
rusion consists of the preparation of tile existing bone surfaces by dccù.tic.iliù.. (scrapin~ the surface Or the bone) nnd the deposition of additionnl bone 30 onto the prepnred surface. The fusion mny be posterior (from the back side of the pntient) or nnterior (from tlle front side of the pntient). Tllc bone mny be cortical (hard bone) or c;mcellous (soft bone) or n r~""l.:., :il~jl of the two (cortico-eancellous). Great .ullLIuv.,~y exists reg~rding tlle prcferred metllo~i Or pcrforming these fusions for ~oss/3l948 2~8~677 ;1 ir r~ 5179 ~
vnrious conditions of the spine. Sometimes non biolo~icnl mnterinl are used to augment and support the bone graft (rlxation systems). Sometimes the fixation isperformed from the posterior route (posterior fixation), or from the nnterior route ~anterior fix ttion), or eYen both si~ies (,tnterior posterior f x ttions or cil~u-., 5 fusion).
Bagby w~s the firsl to describe n method of stabilizing tl~e spine by irtterbody fusion using a rigid, I~ollow llousing cont~tining bone graft, wherein the bone ft is contained entirely within tlle housing or impl;tnt. My mn~lirir~!inn of that method of spinnl ~usion (U.S. Patent 5,015,255) ~ttempts to accomplish a fusion with 10 less damage to aulluul~di~ tissue and earlier 5~hili7~inn of the motion segment, and using special tools for safe insertion. Even th,tt method ~nd many others similar to it require the pl~cement of devices from both sides of the spine and the installation of a ftirly large implant thnt will not fit throu~l1 small portals. Examples include the implants described by Br;tntigtln in U.S. Patent 5,192,327; 4,878,915: 4,834,757 and 15 4,743,256. Two types or PYrqn~ h~ bone containing implants have been described.
One is that of Kuslicl~, U.S. Patent 5,059,193 consisting of a cyiindric,tl device that expands to from a reinforccd ;Irch when it is expanded in the interbody space. Kuslich 5,059,193 uses a netting to prevent its ribs from sinking into soft vertebMI bone. The other uses a memory metal (nickel-tit;mium alloy) that expands in the interspace when 20 the t..~ Lu.~ cl~:mges. Turn buckle type implants of Razian, U.S. Patent 4,401,112 and O~ilvie, U.S. P ttent 4,63G,217 cxpand, b~lt do not contain gMrt witl~in a housing.
Artilur Steffee describes an ~rtificial disc with an elastomeric core between fi;tt rigid pl~tes in U.S. Patent 5,071,437. An ~rtificial disc using a spring is described in Kostuik et nl, U.S. P:ltent 4,759,769. C;lsey Lec et ;1l, in U.S. Pntents 25 5,171.281 ;Ind 4.911,718 dcscribe ;..t.,~.,t~l.,.ll disc spacers. Rty et nl in U.S. P;ltent

4,904,260 describes ~ disc c;lpsule wi~icll must block passnge or llumLln eells. Bao et al in U.S. P ttent 5,192,326 describes t l.~ L for the nucleus filled with hydrogeibeads. None Or these encourage or tllow through-growth of living eells.
Tlle art described in tllis seetion is not intended to eonstitute an 30 ~dmission thnt any patent, publication or otller inrormation referred to herein is "prior artr ~vitl1 respect to this invention, unless specifically designated as such. In addition, this section should not be construed tG meDn tllat n se trch has been m tde or that no other pertinent inrormttion ns defned in 37 C.F.R. 1.56(a) exists.

~ W095/:~1948 ~96~77 P~ 79 ~ummnrv Or t!-e Invention The invention provides n flexible fnbric implnnt thnt may be inserted into n cnvity formed in n ~ disc. Tlle flexibility Or the bag nllows it to be inserted througll n relntivcly smnll opening in n disc. Tlle baf, is ~hen positioned so its

5 fill opening mny receive biolo~ic~l fill mnterial. Tllis mnterial is pncked into the nexible bn~, c~usin~ the b:l~ to expnnd ;md conform to the clvity formed in Ihe disc.
Fill material is ndded until enough mnterinl is present to "inflnte" tlle disc to the desircd position. At this time, the bng fill opening is closed to prevent egress of the fill material.
The relatively open wenve of the bng allows the normal movement of body !luids througll the bng. It also allows the ingrowth of bony tMbecul~e and fibrous elements into and through tlle fexible bng. It does not allow the egress of the non-liquid fll materi~
In preferred rorms Or the invention, the llexible bng includes an 15 equatorinl band which is substimtially less ilexible thnn the remainder of the bag. This controls the shape of the bag and pressures within the bag by means of applying tension on the band and thereby restricting equntorinl expnnsion while ~ polar expansion along the long axis of the spine.
20 ~3rief DescriDtion of tllc Drn~vines A dctniled description of the invention is llerenfter described witl specific reference being mlde to the drnwings in wllich:
FIG. 1 is n top plnn view Or the device of the invention;
FIG. 2 is a side elevalion;ll view ~llereor ~lle invenlive device;
FIG. 3 i5 n fMgmentnry view Or n spinnl column unopeMted spine showing normnl nnd pnthologic discs;
FIG. 4 is n fMgmentnry view of n spinal motion segment after disc rlf~ l..,....1 is used, reamed out with parts cutnwny;
FIG. S is a fr.. ~;.. ll~lly view tllereof with insertion of the device of the30 invention;
FIG. 6 is n r,~-~;-,----l.-ly view thereof showing infntion of the device being innated with fill material;
FIG. ~n is n rrn~mentnry view tllereof showing n pnrtinl henling spinnl wo ss/3ls48 ~1~ 9 ~ 7 7 PCTIUS95/06179 motion segment nfter the method is complete:
FIG. ~b is n tMnsverse seclion showing insertion of the bng from ~nother direction;
FIG. 8 is nn Pmho~lim~ nt includin~ nn eq~mtori:ll bnnd;
FIG. 9 is ~ side elev~tionnl Yiew thereof of the ~ " ~,n~ 1 of FIG. 8;
FIG. 10 is ~ r~ ,.. ",y view thereof sllowing the device of FIG. 8 in position:
FIG. Il is ~ tr:msverse section showing nlternntive use of the inventive f~bric b~gs for po~...u~ fusion;
~0 FIG. 12 is n Ifln~it~ in~l view of nn nl!ernmive use ns in FIG. 11 thereof;
FIG. 13 is n sectional view of nn equntorinl bnnd Or FIG. 8;
FIG. 14 is nn nlternnte tû FIG. 13 in ~vhich the equntorinl bnnd is simply multiple f~bric Inyers;
FIG. 15 is n section~l view similnr to FIG. 13 in whicll the equ~tûrial bnnd is hollow;
FIG. 16 is n frngmentnry view of ~n nltern~tive closure device method thereof;
FIG. 17 is n frngmentnry view of nn nltermltive closure device method thereof;
FIG. 18 is n frngmentnry view of nn nlternative closure device thereof;
FIG. 19 is ~ ~r~gmentnry vicw of nn nlternntive closure device;
FIG. 20 is n rMgmentnry view of nn nltermtive closure device;
FIG. 21 sl~ows n t~evicc lor coupling tû n r~ll openin~ Or tlle device in order to inject in rll materinl;
FIG. æ SIIOWS thc b:lg inllntinS ns tlle rll mnteri~l is injected rrom the device ûf FIG. 21;
FIG. 23 shows closure Or the rlll opening with n cnp in the rll device of FIGS. 21 ~nd 22;
FIG. 24 shows n disensed disc nnd the rnnges of motion;
FIG. 25 shows n rr~mentnry, pnrti~lly cut-nwny spinnl motion segment r~stored wilh tlle invention;
FIG. 2G sllows tllc motion segment of FIG. 25 with biolo~icnl fluids ~l~g~77.
~ W0 95131948 , P~ .. ,.,.r~~79 ., ~
moving in nnd out of ~lle b~g;
rIG. 27 shows a c3rtridge loaded with fill m3terinl ror use in injecting material into the bng 3s in rIG. 21;
rlG. 28 is 3 cross-section31 Yiew ti~rougll lines 28-28 of rIG. 27;
rIG. 29 shows 3 press with the cnrtridge of rIGS. 27, 28 being loaded with material;
rIG. 30 shows a device ror accepting a cnrtridge of rIG. 27 to inject material:
rIG. 31 shows Ihe device of rIG. 30 wi!h plunger witlldrawn;
rIG. 32 is a pnrtial enl3rged vicw of rlG. 31 showing insertion of n cartridge;
rIG. 33 shows injection of m3terial through the device;
rIG. 34 shows filling of the b3g;
rIG. 35 shows 3 cross-section of tlle end Or the device of rIG. 34 filling of the bag;
rIG. 36 shows tlle b3g infi3ting;
rIG. 37 shows tlle bag nenrly fully innnted with the closure plug about to engage;
rIG. 38 shows rotntion of the insertion tool plunger to rotate the closure 20 plug;
rIG. 39 sllows the ciosure plug sccure~i;
rIG. 40 shows a rlll opening CO.I~LlUL,Liu~., rIG. 41 shows the rlll opening of rIG. 40 exploded;
rIG. 42 sllows 3 cross-section31 view tllrou~ll line 42-42 Or rIG. 40:
rIG. 43 sllows an 3nnulus witl~ nn opening to close;
rIG. 44 shows n puncll removing d;lmnged annulus m3terial down to raw bleeding bone;
rIG. 45 shows tlle nnnulus rendy to accept n pntch;
rIG. 46 shows a pntch stnpied in plnce;
rIG. 47 is a cross-sectionnl view of rlG. 46 showing tlle staples and pntch;
rIG. 48 is n view Or n spinnl segment showing nn opening to seal;
rIG. 49 shows thc spin31 segmeD~ Or rlG. 48 witll :I rep3ir pntch in WO95/31948 2189S77 ,~ P~ C5179 place:
FIG. 50 sllows an nlternative method to form the bag of the invention showing nn exploded bng;
rIG. 51 shows tlle bng of rIG. 50 nssembled;
rIG. 52 is a sectionnl view tnken nlong line 52-52 of rIG. 51;
rIG. 53 shows rllling, of the bng by an insertion tool;
FIG. 54 shows filling Or the ba~ by an insertion tool with the tool enîering the bag;
FIG. 55 shows the bng inflating, with the bng expanding to self-seal; and rIG. 56 sllows the insertion tool removed with internal pressure in the bag closing the insertion opening.
~escrir)tion Or tl~e rreferred F...l.n.l ....1~
With reference to the I:igures, l~ig. 3 shows typical spinal motion 15 segments, with lumbar vertebrae 10, 12, 14 and 16 shown, separnted by three discs 18, 20 and 22. As depicted, disc 20 is d.t..;~ g. E~ch disc includes n nucleus 24, top and bottom end plntes 26, 2g and nn annulus ribrosis 30.
The implants of the invention offer n third method of expansion by means of injection o~ mnterial into n tcnsion-resisting ~nbric bng that expands to 20 IJLr~ l 1 dimensions when rllled to ~ull cnpacity. In nddition, the invention may consist of materinls tlmt arc eventunlly resorbed by the body, leaving no trace of forei~n substances.
Most of tlle factors that are known to produce or potenti~te pain production c,ln bc explnincd by tllc pntl~ologic disc dc~j."...~lion and tl~c se~mental 25 instability tl~nt rOllows its arrp:lran~P. Most Or the previously described methods of spinnl ~t~hili7a~inn have been developed with the expressed purpose of treating the condition o~ disc dc~..,...,~iu.. only arter irreversible clmnges have tnken place in the otller tissues of the motion segment.
Methods tl~nt will ncce~ernte tlle normnl rP~ahili7~inn process ought to 30 be i".l,l...,..,~. ~l during tlle early plmscs of disc ~if~;,, ...li~l" berore severe pathologic ch~nges occur in the aulluul~d;ll~ tissues, and be~ore the patient develops the physical and ~ay.llolOgi..ll dis~bilities nssociated with the normnl course of the condition. For instmce, the metllods described here may be used during routine removnl of disc W095/31948 21896'77 r~ l79 hernintions in order to preempt tlle furtller ~lr~ , "lin,~ and resultinf, back pain and irlstability that frequently results from these types of procedures. Sprangford et al reported 31.5% railure rates in terms of continued low back pain in spite of good results for scia~ic~ relief ~vilen disc herniations were treated by l ,;",, ~ ,Y. Acta.
5 Ortl!op. Scanda, 1972, 142 (Suppl.), 1-95.
The most of~en performed spinal fusions are classified as postero-lateral or interbody in order to specify tlle are~ of d~ulLi~ iuil and bone grnft ~rrlir~tirln Postero-lnteMI grarting is often effective but its fusion rate is low when more th~n one leYel is fused and the operation requires a lnrge exposure with resultant high blood 10 loss, long recovery time, long operation times nnd frequent episodes of lingering pain in spite of ;Ipparently solid fusion.
The mctilods nnd spinal implnnts of the invention nre designed to re-stabilize the spin~l motion seQvment in ~ Mpid and efrective manner. Tiley should lerd to relier of the low back pain nnd a .u". r..r.~ ;IIIIJIUY.l~ in the quality of life ror the patient. In addition, one might rensonably expect that these methods andimplants will nlso decrease the cost of medic~l c;lre :md a reduce the disability-associ~ted expenses to society.
Dr~scription of thc Dcviccs Tile inventive implant 40 consists Or a smnll (npprox. one to four cm diameter) fabric bag, rougllly spherical in shape, although elliptical shapes :md other geometric shapes may be used.(See I:igs. l, 2). One additional shape ~,l,l~; l. ,.,~;r would be the provision for an enl3r~ed or constricted and~or less compliant equ~torial band 42 th~lt would conrme tlle illtcrnal cavity morc securely at the center or equntor of the implnnt 40, at tlle point where tlle implnnt 40 is opposed to the :mnular wall, which is less rigid tllan tile cnncellous bone ~Ynll Or tl~e carved out cavity 44 of the vertebral bodies. The bag is pliable and maileable before its interior space is filled with the contents to be described. Wllile in tllis initial condition, the bag mny be passed, uninfiated, through a relatively small tube or portal, perhaps one cm or smaller in - 30 dinmeter. (See Figs. 5, 21). Tllis reature is importnnt because nccess to the iJ~.II disc is limited by anatomy nnd tl~ererore snfety rn"~ direct us to use the smallest possible portal of entry.
The bag 40 is constructed in a special 2nd noYel way. The ba~ fnbric WO 95/~il941 2 1 8 9 6 ~ 7 P~llu~ ~.r '179 may be ~Yoven or form-moidcd to ~ density thnt will nllow in~ress nnd egress of fiuids and solutions nnd will nllo~v the ingrowth and through-growth of blood vessels nnd fibrous tissue And bony tMbeculne, but ti~e wenve is tigllt enou~h to ret~in smnll particles of enclosed materinl, sucll ns ~round up bone ~Mft, olher tissues or solid 5 pieces of bone inducing mnterinl such ns ;,~ u.~ Lilc or other binff~mr~ihlf materinls known to promote bone formntion. CeneMlly, the pores of tlle fnbric will have n diameter of nbout 0.25 mm to about 5.0 mm. The size is selccted to allow tissue ingrowtll while contnining the mnterial packed into the bng.
The fabric is light, ~ u~ fexible nnd easiiy hnndled, but its 10 fabric is very strong in terms of resisting tension, ~nd thus uniikely to rip or tear during insertion and infiation. Wllen the device is infinted, the device expands to a L'l''i' `~ ,"",,~.1 shape, nnd in ~ioing so, it fills n previously excavnted spnce 44 between the vertebral bodies. Tilis fillin~ results in tlle separntion of tlle vertebral bodies along tbe crnnial-caudnl nxis, lPnf~thf-ninf~ nnci tightening the rlbers of the nnnulus fibrosis 3û, 15 and in the process, as we know from the teacllinf~s of Cloward and Bagby, results in the c~hili7~tinn of tlle spinnl motion segment. (See l~igs. 6, 7a).
The use of tlle term "rnbric" llerein is me:mt to include the usual definition of that term and to include any mnterial thnt functions like a fabric. that is, the "f~lbric" of the invention must hnve n plurality of pores through which materinl and 20 fluid fow is nllowed under the terms ns described, nnd the "fnbric" must be fexible enougll to allow it to be collapsed nnd inserted into nn openin~ smnller thnn tlle infi~ted bag size.
Accordin~ly, tlle "rnbric~ bng or implnnt 40 m~y be rormed from a polymeric b~lloon to wllicll n plurnlity Or perror:ltions nrc rormcd or ndded. It need not 25 be woven and mny be molded or otilerwise rormeci ns is well Icnown in tlle art. The prererred mnterinl may provicie tllc abilily to tailor bio..i,~ull,.,,l.. Mtes. Any suture-type mnterinl used medicnlly mny be useci to rorm tlle implnnt 40. The implant may be formed Or plnstic or even metnl. Tlle rill openinr~ mny be ~ bushin~ 72 tllat could be i,lf )~ sucll ns lly i~u7~ lJ.l~itr, or it could be n plnstic or metnl. The bag 40 30 could be formed rrom a solid mnterinl to whicll perfoMtions nre added. Tlle implant 40 mny be pnrtially or totnlly nbsorbable, metnl, plnstic, woven, solid, rilm or nn extruded balloon.

~ WO95/31948 21 89677 ~ u~ 79 The use of e.xtemnl elec~ricnl fileds to stimulnte bone ~rowth and repnir is well known. It is also possible to include metnl or other conductive fibers 50 in the wnlls Or the bng 40 sucll thnt an externnl electricnl rleld could nmpliry nnd stimulnte bone union nt the situs of the bng.
As will be described, it is nnticipnled thnt ~he bng 40 will be prefer~bly used in surgery in spines of humans ns well ns other nnimals.
Accordingly, the mnterinl of bng 40 should be l,;,,~ ..ti SURGIG~L METIIOD
10 1. Formrltion of Entrnncc Bore As indicn~ed, the bng 40 is prefernbly used in spinnl ~-~hili7~iAn surgery. FrG. 3 of the drawings shows vertebrne 12 nnd 14 sepnrated by disc mn~erial 20 thnt is pnthologic nnd in need of repnir.
The cnYity 44 in tl~e disc 20 mny be formed in nccordnnce with the 15 methods and deYices of U.S. Patent 5,059,1g3, tlle disclosure of which is illl,Ul~JUI ' ' herein by reference. Genernlly, after identifying a disensed disc 20, the surgeon forms n bore 46 through the nnnulus 30. The bore 46 is formed througll any Cullv...l~iu,u~l menns. The bore is sized such thnt the diameter of the bore 46 is .~ u~i..l~t~ly sizd to be the external dinmeter of tile implnnt body 40 when in tlle relnxed or first state ns 2û si~own in FIG. 5. The depth Or tlle bore 46 is controlled so thnt the nxinl length of the body 40 may be fully inserted within the bore, with the body 40 rully locnted between opposing vertebrne 12, 14.
Wllile the dinmeter of bûdy 40 nnd bore 46 will vnry from pntient to paticnt, ~here is zl prnctic.ll mnximum si7c Or Illc di;lme~cr Or borc 46 for nny givcn 25 pntient. This mnximum is nttributcd to tlle fnct thnt too Inrgc of n drill bit cDnnot be passed tllrougll tlle pntient's body :Ind pl;lce~i n~ninst disc tissue. If too Inrge n drill bit is used, the si_e of the bit will interfere nnd possibly dnmage other nnatomicnl pnrts.
ruch ns importnnt blood vessels, nerves, etc.
A typicnl selected di~meter Or body 40 (when in the first stnte) nnd bore 30 46 is prefernbly nbout 12 mm. Tllis dinmeter is selected for bore 46 to cut tllrough disc mnterial sep~rnting tlle fourtil nnd rlrtil lumbnr vertebrae in n humnn spine in n typicnl ndult lluman mnle. Tlle ~ieptll of the i";.. ~ l spacc between the fourth and rlfth lumbnr vertebrne in nn ,Idult llumnn mnle (mensured ns tlle nnterior-posterior wos~/3l948 ~18g677' r~ .~I79 dimension of Ihe vertebrae) is commonly about 35 mm. As a result, n preferred length of body 40 will be nbout 25 mm so that the body 40 mny be fully received within and between opposing vertebrne.
It wiil be npprecinted tlmt tlle foregoing dimensions and d~ have been given with respect to n particulnr vertebrne locntion in the spine of nn ndult human mtlle. It is tmticip~ted the present implnnt nnd method could be used on nny nnimal spine. Accordingly, the dimensions of the bng 40 nnd entrnnce bore 46 will vnry ~lU~ Li~ ly with increnses or decrGlses in spinnl anntomy between dirferent nnimal types. Also, in humnns, the dimension will vnry with numerous fnctors, includinganatomic region of the spine, age nnd sex. i or exnmple, the implant nnd surgical method is not limited to the lumbnr region, and mny be utilized in other regions of the spine where vertebrne dimensions mny be dirferent than those described. Therefore, several ~iifferent sizes of the bn~ 40 nre nnticipnted so n surgeon can select the optimum btlg 40 for ~ given pntient.
2. Formation of Enlarged Cl13mbcr With the entrance bore 46 formed ns describe~i, tlle surgeon then cuts tl hollow chamber 44 between the opposing vertebrae 12 nnd 14. The chnmber 44 is sr~ed to be cr~ .y to tlle exterior dimensions of the implnnt 40 in the enlargedstate.
Since the chnmber 44 lms grenter volume tllan n bore 46, tlle cutting of chamber 44 removes grenter nmounts o~ disc mnterial and exposes a grenter surface area of tile opposing vertebrne bone mnterinl. T!le exposure of the n~i~iitional surfnce nren increases tile probnbility of successful grnfting between the opposing vertebrne 12, 14.
Tile form~tion of tlle enlnrged spilericnl chnmber 44 cnn be forrned througll any suitnble teclmique. Prer~rllbly, lile cllambcr 44 is rorme~i tllrougll tlle use of ~n illL.~ t.i~l.,l reamer such ns tlmt shown and described in U.S. Pat. No.
5,015,255 and copendin~ U.S. P~t. applicntion Ser. No. 071350,050, filed on May 10, 19~9, which nnmes myself and Jnmes D. Corin ns joint inventors.
The diameter of tile clmmber 44 (nnd hence, the mnximum allowable diameter of the expnnded bng 40) is selected to provide n clearance so that the ch~mber 44 is not cut through the sides Or the vertebrne. Tilis dinmeter will vnry from patient to pntient, nn~i between locntions in the spinc. Mowever, to provide n clear~nce of W0 9~i131948 t 896 7.7, ., I r~"~ 79 about 5 to about 11 mm of the sides of ~lle vertebrae, the chnmber is preferably held to a mzximum dirmeter of about 20 to about 30 mm.
3. Insertion tnd Expansion Or Implnnt With the enlarged chamber 44 so formed. the surgeon pl~ces bag 40 in the collapsed, .~ ".,..l. .l state into bore 46 and into cavity 44. (See Fig. 5). The fill opening 48 of tlle bag 40 is positioned in bore 46.
In FIG. 5, Dn ~ (l bag 40 is shown inserted within an enlarged chamber 44. In the position shown in l;IG. 5, the bDg 40 is not urging vertebra 12, 14 10 apzrt. Accordingly, the nnnulus 30 (tlle flbrous outer c;~ul~lr~c~ portion of disc 20) connecting the vertebra 12, 14 is sllown in a relnxed or unstretclled state.With the bag 40 so inserted, tlle surgeon then fills the bag or implant 40 until inflated to the desired exten~ to cause tlle annulus îo stretch out and re-establish the proper distance between the vertebrae 12, 14.
Tlle surgeon continues to insert material until the b~g 40 is expanded to the fully expanded stnte. As it expands. tlle outer surfaces Or the bag 40 abut against the opposing surf:lces of the vertebMe 12, 14. Continued expansion of the bag 40causes tlle vertebrDe 12, 14 to stretc~l np~rt slightly. This stRtching acts to tighten the annulus 30 of disc 20, whicll lms not been removed through the formation of bore 46 20 and cllamber 44. Those skilled in the nrt will recognize tlle annulus 30 as being the fibrous outer cll~,ulllrtlc~l~iDl portion or the disc 20. Tlle stretching and tightening of the annulus provides initial ~ between the opposing Yertebrae. So that stretching will occur, the external dimensions of cllamber 44 are preferably sized to be about 3 mm less tl~an the cxternnl dimensions Or tlle ba~ 40 measured in the fully 25 expanded state. With the bDg 40 fully expnnded, the surgeon must close the bag opening 48 to prevent egress of tlle fll material.
In FIGS. 11 Dnd 12, a bag of tlle invention is depicted as a s~usage shaped container 146 whicll is not implanted into a disc cavity. Rather, one or more of tlle bag containers 146, prefilled witll fll materi~l 52, are positioned against the bone 30 of ndjacent vertebr~le. Tlle bone may be rougllened to a bleeding surface to hasten bone gro~vtll into the cont:liners 146. As time goes by, the contniners will become very rigid and will be nttnclled via bone in~rowth to both vertebrae where they contact native bone. Tllis will providc ;I SD~'C. simplc fusion. Tlle bags providc l .. ~ ;,.,.. l of Wo 9~/31948 - ' r~-,u.. 179 }i-tile bone-growth mmerial to ensure ti~nt tlle fusion ~akes place wilere inLiicated.
4. Use Or a Graft Medium Ti~e chnmber 44 is flled ~vitll n grnft medium 52 to fncilitnte fusion or 5 fibrous union between the opposing vertebrne 12, 14. The preferred grnft medium or fll mnterial 52 would be finely cllopped corticll or cnncellous bone chips ror fusion or comnective tissue when a fibrous union is desired.
In the forms of the inYention sllown in Figs. 8-10 and 16-29, tlle bng 40 may be filled by pncking the grnft medium 52 through a guide tube 54. Af~er the b~g 10 40 is flled as needed, the bag fill opening 48 is closed. Fig. 17 shows a simple staple 60 closure of opening 48. Figure 18 shows the fll opening 48 closed by tying a knot in the enti. Figure 19 SIIOWS n closure using a purse-string ~2 closure.
In the forms in which an equntorinl band 42 is employed a different fill opening and closure is possible. l:igures 13-15 show tiifferent ways in which the 15 equatorinl band 42 may be formed. As shown, tlle band 42 may be a molded plastic ~.;L,,IllllLlcllii.d band that is stiffer than tlle bag fabric to which i~ is attached. In the form of Fig. 15, the band 42 may be hollowed to form a cavity 64 into which boneeement or other material m.ly be ad~ied before or after insertion to increase the rigidity of the band. Fig. 14 shows thnt the bnnd 42 mny simply be multiple Inyers of the20 fnbric which forms the bng.
Figure 16 shows tlmt the simple band 42 of Fig. 15 may include a fill opening 66 and a slot G4 into wllich a free end 70 of band 42 may be inserted to close off tlle opening 66. In n more elnbornte closure, bnnd 42 as sllown in Fig. 20 may inclutie :I moltic~ re:l(ie~i busl~ing 72 Illrougll wllicll ~lle bn~ mny bc fille~i. Such a 25 tllrended buslling 72 is rea~iily closeti l~y n tllrende~i screw 74.
FIGS. 21-23, 30-39 sllow :l mc~llod ~or 3~imi~ling ~he graft medium 52 into cilamber 44. As shown, the bng 40 includes n threaded fill port 80 which has internnl threads 82 to receive n tllreaded screw 84. Preferably, a device 90 is used to nttach to the f~ll port ns shown. Device 90 is prefilled with tlle grnft medium 52 as 30 shown in Figs. 21-23. In Fi~s. 30-39, devicc 90 may accept a cnrtridge 92 which mny be packed with n press 102. Tlle cartritige 92 would typically include a plurality of side openings ~4 to allow nuid nn~i smnll particles to exit during filling.
The cnrtridge 92 is inserted inlo cicvice 90 in an opening 88. Tlle device ~ W095131948 ~1~!167? P1/~,",~,,1`-,79 90 is tllreaded or otherwise attached to fill port 80. A plunger 96 pushes the screw 84 toward the internal threads 82, pus~ling tlle graf~ medium 52 into the bag. As the stroke is completed, the plunger 96 is rotnted to turn the screw 84 in nnd se~l the implant 40. The plunger m~y contact tlle screw Yia a pair of studs 98 that project into 5 screw recesses 100. The deYice 90 is tllen withdrawn.
With the gMft medium in place, the surgeon can then close the patient through :my suitable technique. Tl~e gMfting of bone chips rcsults in Lt fusion between the YertebMe bodies 12, 14. Wllile tlle rusion process is tnking place, the surgeon may monitor tlle patient's progress if some portion Or tlle implant is radiopaque such as a 10 small wire frame on the leading and tMiling edges of the bag. Also, during the fusion process, the bng 40 is self-ret tining in a rigid, geneMlly spherical shape due to the fill rLmterial therewithin. The rigidity Or the enlarged, rllled bag 40, together with the stretching of the nnnulus, proYides stnbilization between Yertebrrle 12, 14 during the fusion process.
With reference to Figures 40-42, the b~g 40 is shown witll a formed fill opening 48 in which the fabric or other m tteriLIl of tlle bag is trapped between an iMer ring 106 and an outer ring 108 to provi~ie a thrended opening as shown. Outer ring 108 is thre~ded so it may be closed with a mating cnp. The coMection between thep~rts of FIGS. 40-42 mL~y be through tlle applic3tion of seiectiYe henting and cooling, 20 such th~t each ring is taken to ~ set t~ C-.-iulc ~t which expansion or contMction from its normal stnte occurs. At tllat time, ~l~e l~bric of the bng is ~.l..~.v;.I.~d ll,~.cl,.i~
and tile parts nre allowed to rebound to their normal shapes, causing t tight rlt as shown.
Witll rererencc to FiGS. 43-47, it will bc seen tllat an opening or hole in 25 the annulus 30 may be repnired. In FIC. 46, tlle opening in the aMulus may be closed off with a repair p:ltch lZ0. FIG. 44 shows a punch 122 wllich cuts out a pre-defined opening exposing bleeding bone 124. A biologic~l graft of connective tissue 120 such as bovine ~ diu~l or llumnn f~sci;l which may be ~L...I~;LI.~,.,Cd witll polymer layers is fashioned nnd placed oYer the derlned opening. S~aples 126 may be used to coMect - 30 the patch 120 in place. Tile pLltch 120 may be formed from multiple l~yers, with n first porous layer 128 through wllicll blood and other products mny pass, a second layer 130 defilLing strips to form ch~nnels and a third oYer-layer 132. The channels tvould allow ingrowth of corLnectiYe tissue to complete tlle repair. Before the patch 120 is WO 95/31948 2 ~ X ~ 6 7 7 r~ 0~l79 ~
-16- ~ `
positioned, dura ;s covered with fat. Tllis provides a bârrier to excessive scarformation. Sucll a pntcil may prevent recurrent disc hernia after routine disc excision.
FIGS. 48 nnd 49 show that an opening 140 cut into the distnl surface of vertebra 12 may be closed in a manner similar to that shown in FiGS. 43-47. The 5 opening may be closed by cutting into bone to provide n surface for a patch 142 which may then be secured by staples 126. Underlayers of fnt ns n cushion may be ndded ns indicated.
FiGS. 50-5G show a bag 10 construction in wllich the bag 40 is rormed from two l....li~yll..~ 160, 162 and a central band 164 . As shown in Figure 52, the 10 l~ayers of l...";~ .es 160, 162 and band 164 overlap to provide n three-ply equatorial band region which will be stiffer than otller nrens of the bng 40. The bag is completed by sealing, as by sutures 166 througll each Inyer. An unsealed region is used tointroduce ;m insertion tool 90.
Tllis unique design of Ille b~ag ns shown in Figs. 50-56 allows easy rllling 15 ;md self-sealing due to the internnl pressure in the filled bag 40. As shown in Fig. 53, the insertion tool 90 is simply pushed tllrough the triple f~bric layers of II~Illi >,Uil~lC~
160, 162 and bnnd 164. By compnring Figs. 54, 55 and 56, it will be readily seen that internal pressure generated as the bag fills with fill material 52 causes fabric edges 160, 162 to bow back and when the tool 90 is withdrnwn, the edges reseal as shown in Fig.
20 56. This fll port is very simple, and only involves passing the insertion tool 90 through an unsealed area (or wllere seal is opened). The .u.~ LLion will normally try to self-seal when pressure is appTied from tlle bag interior, as by filling.
iRE SULTS
E~pcriments in my l;lboratory llave conrlrmed tlle ~act tllat inllation Or 25 the prototype ~ievicc ~sing morscli7.cd hone grart r~repared in ;I bonc mill, undcr proper pressure Or inllation, rcsults in ;I rcm;lrk;lblc cll;lnge in thc mecllanical properties Or tlle implant. Namely, tlle device bccomes extremely rigid nnd relatively ;.,cu...~ ii,lc.
This C~ Or tlle innated condition explains the remarkable stability thnt is produced in the motion segment. Bnsed on tlle tenchings of several surgeons, we know 30 tlmt densely compacted bone grart, inserted into the properly prepared vertebral interspace, will result in the growth Or certain tissues into and through the graft materi~l, eventunlly resulting in n fbrous or bony rusion, effectively cementing the vertebral bones into a stable union that is known to be dcsirable in terms of reducing ~ WO9!j/31948 2~8g~ P~ 9 spin41 p4in 4nd improYin~ function.
The f4bric deYice of the inYention vould 41so produce this strbilizing fusion. rulLI~ lulc, the fnbric enc4sed gMft impl4n~ would have cert4in 4dY~mtages over the mere injection of gMft m4teri41 into tl~e i..;., ~ILcblLIl sp~lce without the 5 ~ncasing fnbric. N~lmely, the f4bric encased gr4ft would hnve less tendency to flow out of the i..t~.~.li.l,.41 c~vity, since its contents would be ret4ined by the walls of the f4bric b4~ dditionally, tl~e enc4sed gMft vould ret21in its mech~nic41 function for 4 mucll longer time, providing st~bility to tlle motion segment 4nd thus providing ~n ide~l milieu for tissue bondin~ bet~veen the vertebral bodies, ~û
Steps in thc Process of Spin41 IC/~ ;, /; . Usin~ this Method S~ep ,Y1. Expose 4nd remove tlle dise~sed nucleus nnd/or iMer 4nnulus by one of sever41 menns, including tlle use of the Kuslicll l~rnnr~nhlP Re4mer, U.S.
P~tent 5,015,255, tl~e disclosure of whicl~ is inco.l,u...;.d herein by reference.
Step iY2. Insert the ~ rrl device (I~ .lr F4bric B4g Device) ~D) into Ille c4vity between the Yertebr41 bones.
Step #3. Prep4re m4teri41 to be inserted (or injected into the EFBD).
This m lteri:~l might be one or more of the following, or ~ny oth~r b;v~ ;I .lr m~teri:ll judged to h:lYe the desired pl~ h)~;c response:
A) Morselized bone ~Mft, cortic:ll, c4ncellous, or cortico-c4ncellous, including4utogr4ft, 4110gMrt, or xenogMft.
B) Any bone graft substitute or rn...l.;, 'i~., of bone gMrt substitutes, or ~r,...l.: :;....c of bone grllft nnd bone gMft substitutes, or bone inducing substLmces, includin~ but not lin~itcd to:
~Iydlu~ .llit-Bone ~u~ o~ protcin C~lcirled or dec;llcifie~ bone dcriY4tiYe Step #4. Inject or insert the ~r4ft m4teri41 into the deYice using sufficient pressure to fill tlle intern:ll c4vity Or t~-e deYice, thus producing rigidily ~md tension on the w:lll of the deYice.
Step #5. Closure of the fill opening to preYent egress of inflation materi~l.
The deYices :md methods of the invention m:ly be used 4nytime in which Wo 95131948 2 ~ ~ 9 ~7 7 ~ 6179 a disc is being rep~ired or replnced. The deYice m~y be ndd~d ~o ~ cavity formedwllen the nucleus of the disc is excised, thereby restoring the proper height 2nd cushionin~. If the disc is to be replaced, portions of the disc may be left to confine the inventive device wllicll allo~vs rlbrous growth ~nd runctions as :I repnired disc, While 5 the disclosure has primnrily sllown ~enerally spherical bngs, it is cr~ tllat any shape, including figurc 8 sll~ped b:lgs, donut sh:lped b~gs :md the like are usable l~erein.
In ~ddition, the device of tlle invention may be used in "~ with other devices. For example, tlle device of my U.S. Paten~ 5,059,193 may be 10;~I~ulL~ L~d inside of the inventiYe b~g of this invention if the ~dvant~ges of th;lt invention are desired in ~ddition to those of the present invention.
While tllis invention m~y be embodied in many different forms, tllere nre shown in the dMwings :md described in detail herein specific preferred r~ o~ of the invention. The present disclosure is an exempliricntion of the principles of the 15 invention and is not intended to limit the invention to the p~rticular ~ .o~li.....
illustMted.
This completes the description of the prererred ~nd altern~te ",I.r.,l".. t~ of the invention. Those skilled in the art may recognize other equivalents to the speciric ~mho~lim~nl described llerein which equiv~lents ~re intended to be 20 ~ I by the cl~ims ntt;lched hereto.
.

2~8~677 ~ WO 95/31948 I ~l/u,. ~'~~179 R22.2-4~78 E:~PANDABLE FA.BRIC IMrLANT FOR STABILIZING THE SPINAL
MOTrON SEGMENT
Dr. S~ephen D. Kuslich RE~ERENCE NUMERAL LIST
10 lumbar Yertebrae 64 cavity in equatorial band 12 lumbar vertebMe 66 openin~ fig. 16 14 lumbar vertebrae 68 16 lumbnr vertebrae 70 end, ban~i 18 disc 72 bushing 20 disc (diseased) 74 threaded screw 22 disc 76 24 nucleus (disc) 78 26 top end plate (disc) 80 rlll port (fig. 21) 28 bottom end pla~e (disc) 82 internal threads 30 annulus fibrosis (disc) 84 threaded screw 34 88 opening 36 90 device- filler 38 92 cnrtridge 40 bag, implant 94 c~rtridge side openings 42 equatorial band 96 plunger 44 excav~ted space in disc (cavity) 98 studs 4G bore in :mnulus 100 screw recesses 48 fll opening 102 press 50 metal fibers 104 52 fill material 106 .inner ring 54 guide tube 108 outer ring 58 I;not 112 60 staple fiil opening closure 114 62 purse-string closure 116 ... ..

Woss/319~8 2189677 PCT/USg5/06179 K22.2~G78 E~rANDABLE FABRIC lI\IrL~NT FOR STA13ILIZING THE SPINAL
MOTION SEGMENT
REFERENCE I~UMERAL LIST

120 patch, fig 46 176 122 punch 178 124 bleeding bone 180 126 staples 182 128 1st layer patch 184 130 2d layer patch 186 13~ 3rd, outer layer patch 188 140 opening, distal, fig 48 142 patch, fig 49 146 container, fig. 11 160 hemisphere, upper 162 hemisphere, lower 164 band (Fig. 50) 166 sutures (rig. 51) vl< ~ r ~ 517

Claims (2)

Claims:

1. A device for use in stabilizing a spinal motion segment comprising:
a generally hollow, flexible bag adapted for expansion solely by the introduction of graft material, said bag being further characterized by the absence of any other expansion means, said bag including at least one fill opening into which biological fill material for promoting bony or fibrous union may be inserted, said bag being filled with biological fill material to a rigid state, said flexible bag including a plurality of pores, said pores being sized to allow ingress and egress of liquids, solutions, small particle suspensions and ingrowth of bony trabeculae or fibrous elements into and through said device when said device is positioned in a hollowed region of an intervertebral space, said pores being sized to retain said fill material within said bag; said bag further including closure means for closing said fill opening to prevent egress of said fill material from said bag, wherein said bag is generally spherical in shape, having an equator defined by a line extending circumferentially around a periphery of the spherical shape, an axis and an equatorial band, said equatorial band having greater rigidity than the remainder of said bag causing a force to be directed in a predefined direction, e.g. normal to the axis of the equator of the device.

2. The device of claim 2 wherein said band has a height that approximates a height of normal interdiscal interval at or near a margin of the disc, and wherein said band is formed of a material with substantially less resilience that material forming the remainder of said bag.