CA2205107A1 - Implant material and process for producing it - Google Patents

Abstract

The invention provides a nanotechnology process for implant surface treatment for producing an implant article. The nanotechnology process comprises subjecting a non-porous material to a mechanical or chemical surface treatment until a surface roughness with an average peak distance (Ra value) between 10 and 1,000 nm is obtained. The roughened surface can subsequently be subjected to precipitation of calcium phosphate from a solution containing calcium and phosphate ions.

Description

BO ~91 CA 02205107 1997-05-12 Impl~nt matenial ~od proce~s fo~ producing it The present i~ .Aio~ relates to an implantable dcvice, to a pIocess of ~-~)duci~ a device and to the l, ~ Ji~l usc of such ~ device.
US Patent 5,456,7~ 5 an implant havi~g a pOrOUS mrplli~ surfac~
5 which has been t eated by sandbla ~ d rcductive acid etching IeSlllti~ in a surface mi~o-roug}rPCc havi~g a m~simllm pcak-to-va~ley height of about 20 to 30 ~Im anda ~u~slmes.. spa~ing of abollt 1-5 ~. Thc G~t~Cly sharp, oomb-like ~ uClul~ iS
n~ in order to a~hieve ylffinPnt ad~si~I~ bet~een the implant aDd tilc coating mate~ ua~dydtite) foImed on it by ~ e the h~l~u,~atilc in the implallt.
loA !~ .bad~ 0~ mo6t L~Lo.~yo~dtitc-cootGd impl~ntS is that the ,~l~r.l,n.j"~ of~l~OAyap~ t; onto the ~mplant lequires high ~ ~r~ S, ~hich lim~t the choice of sub~ Pn~lc and rcsult in hi~her ~oe~ costs. ~e ~Gviullsly ;r~J~ for coating implant m~trr1~lc ~v~th ~ uAyd~dlite is plasma ~posilioll (for a review, see P. Scrckian, ;D I~ylapatite Coahngs zn Or~or~
15Sur,~e y, Ed. Geesink and ~mlcy, ~ave~ Press NY, 1993, p. 81--87). A~other dis--advantage of the pl~ a depositic.n ~ cl -;qlJ~, ~n addieion tû the high h~
involved, rcsidcs in the ~elatively ~ge particle 6ize, in the order Of 30-70 ,um.
'rbe aim Of thc plescnt in~ention is to p~ovidc an i--pl~nt~le device that can bc used in a wide vanety of biomedical ~p~ innc (surgery, bo~e-rel~1~e.n~, 20 prosth-~lontirc etc.), and rcsults in an ~f~ i bonc r.,.~ iOll and can be pluccs~d at ambient ~ erdt~
The aim is ac~ieved by a s~aped article sultable ~ an implant of a 601id, i.e.
non-fluid, po~ous or non-porous ~nOterial havirlg a wrface na~o~ou~nfisc with anaYelage pcak dist~cc (~a value) bct~Yecn 10 l~m and 1,000 mn, giving risc to the;2s f~ nP.tinn of a c~ coaffllg when placcd in s~ t1nnc of boIle-foIming Ihe suIface ro~nP~ is a ~ntical factor of t~c artide ~.g to the inve~ltion. The surface r~ehJl~c is defined bercin by the a~er~gc peak dir~nr~, i e the avaage spacing bctwcen prOtrUSiOns ûn the urface (Ra vable). I~his average peak 30 distance can be d~t~ Pd e.g. by means of Sc~nni~~ l~lcctron Mic~ (SEM:). I~
general, the avcrage peak distance sllould bc 1,000 nm ol less. Ihe most suitable ~o~ghnP~c depends on ~e ~e of ~e ~naterial of the ~rticle. ~or article~ msde of !;t.~ ., the avcrage peak dist~nce can bc C.K. fraln 10 to 200 nm, for polymer~cn~ thc p.~ .d peak distance is ~om ~0 to 500 , l,vh~l~ for s~inless steel ~e pealc ~li~aDr~ i~ adva~tageously between 50 alld 1,000 nm. Ill genaal, the yl~r,.~d 5 averagc pe~lc distance Ia~ge is bet~eeII 2 and ~0~ nm.
Ihe depth of 1:he surface ro~ ;s of t1~e ar~clc i6 le66 cr~tieal th~ t~e peak n~ However, a ~ depdl ~ des~rable, in pa~ticular a peak height - w~th respccs to tllc de~epest sitcs on the 6u~facc - of at least 20 , ~Ip to about 2,000 ~m.
The psefared average depth is of the same o~dcr of lf~;h.~l~ as the aveaagc peakdi~nr~ and is i~ particular fro~ S0 nm to 1,000 nm. The averagc dcpth can also be d~ tf, ~ cd b5~ mcans of Sca~llin~ ElectIoD l!~ic~
I~e s~bstr~ts of the implant article can bc of various nlaterials. These includcmetals, in particula~ pa~iblr metals s~ch a~ -...., t ~lt~llml~ r~iQbi~lm ~ i~ and alloys thereof, as wcll as ~ stcel. Anotller uscful class of bio-15 "~ b~e m~trn~lC co-np.~cs a~ganic nah~ and~synt~ l;c poly~ .s such as poly-cthylene, ~l~lu~,lene, yolyl~luo~ ylcnc CIeflon~), which may also be bio-lc polymc~s such as POIYZ~ O1;C acid, polylactic acid or c~tain poly-s,lc~l ~idcs C~nir matcrials such as calcium ~h~CI~ , alumiDa or hir~ c, as wdl as .:o...~ite materials, can also be used as an implant s ~h~tr The mate~ial may be 20 porous or non-pornus. Whe~e it is porous, the po~s are ~ I;n~ c~ om the valleys of the su~f~ce ron~n~.eC by thcir depth: i.e. tbc pores have depths ~ i .11y ~eatcr than 2 ~un, and the s~rface roug~n~-cc may be ~ os~d on thc pore walls.
The sub~atc having the sllrfacc ~ou~nr-ss a6 d~fined above can vcry ,~1;. ;. ..,lly be coated with a layer of ~ calc~um ~h~ h~ cithcr in vitro, or in vivo. If the calcium 25 ph~ e coat~ng is applied ~ vitro, the c~lcilun rb~crh~te layer caII bc rclatively thirl, the order of ~m a e.~ 50 ~m to 200 ,~un, Pc~i~l1y ~om 1 to 50 llm. Ihe calcium c~p~~ preferably ~orms small crystals, ~ e an ~l~o.tphuub-like Shu~lu~. Thc calcium rhns~.h -~ can be any u~nhin~hr " of calcium and p} .~ ions, ~ptjnn~lly together witb e.g. L~ AidC, chlonde, ~lrb~tr nitrate etc. anions or h~hoO_~, sodium, 30 ~l~ssi-~ , m~Psium etc, eations. F~c~al)ly~ e calaum p~o's~ b iS not a hydlOAy-apatite, sirlce thc latter tends to havc too large particles.
The ~alci~un coating can be ~pplicd from a solution co~t~ in~ calcium and ~0~0391 CA 0220~l07 l997-0~-l2 ~.h~,h~t~ iOnS. The solution may be ~ tt ~1 nr even supcr-~dtuldtc~, but it may also bc relatively diluted. This is an '~ advanta~e of ebe prcsen~ i.. ~e. ltio~ since it allows the ~-~Atlnl- of a calci~ ph~ coaein~ ~om ppr~ir~lly any solutiou c~uPl and ~h~h t~ ions. Ihe p~ e of the calcium l~h~l~h~te con-s eaining snlytion may be behveen 4 and 10, ~fefer~ lly ~h._ ~ and 8.
~io.. also providcs B process of producing a shaped article as descr~be~l abovc, c~r~ .e ~u~);ectil~g a solid m~ter~l tO a ".~ i~l or rh~.mir~l suIface t e~ until a s~ce rou~nPcc with ~c ~qui~ed averagc pealc ~ nc~ (~a value) is o~tained.
0 ~e nlc~l~a~ surfac~ 1seatl~clt may e.g. be a ~anding or sco~ng treatment USiDg coll~,. ,lti~al 5~0~ emery paper OI ~lass papeI having an approyriate fiIIe-~c~, e.g. glade 4000, ~~pti~lly in the p~ , of water or other fluids. Dialnond paste c~n aJso bc used in t~e "~r~ ;c~l surface ~lf ~,r~t The s~ ace ron~ninE~ can further bc obt~ by powder bl, ~inE using suitab~c f~nc pO..~lS. Ihe cJ~r.";~,~l surface ~ Cllt may e.g. be a tIcatment with a s~ g, prefcrably mine~al, acid sQ~ n, suchas h,~ 3~ hydro~h1~ llrhllnc~ nitIic, perchloric acid or ~ ln,~ nc thereof, optio~ally followed by o~ ci~ agents such as nitric acid, pc..,.- :.lc, L~o~ ides or I~L~ ." ~lU"i~C, opt~ n:ll1y followed by neutra~isiIIg steps. It is iu,~o~"Jt that ~e surface rough~rlin~ is perf~ r~ under wntrolle~ c4~;1ir.n~c to ensl re a unifûrm r,esult.
~o The ~ulr~cl, lo~ fd imrl~nt~ deviccs accu~ g to the inv ~tion are inte~ed for l~ m~'~ ~l use, i.e. ~ a bonc ~ ;, a joint p~C-th~ ~ic, a dental impl,ant ~rqsth~ s)~a~n~si1lof~r;q~implant,avcltebralsur3~eryaid,atl~s~ nF.~ device (stoma and the lilcc) and other medical or COS3~ devices. Such imr1sntC can serve as a bone ~ Or bone l~ei~.n~,ll.,.ll, but also as a means of fi~cirlg a device to a~srti~.1~ bone.
Ihe imr~ h1~ devtces can be plovided as such, i.e. withûllt calciuln rh~l.h ~le coating. Bone f~ st;orl can then be induccd in ~vo due to the presence of thc specific sn~face lu~d. .;.,~,, whicb can ~esult in the form~tior~ of a calcium ph~s~..k~; coatirlg in situ. The articles caIl also bc pre coated ~ntb calci~ )hosp1~t~, 30 thc p~ecoat servi~ then to acccleldtc and enha~nee bonc fnrm ~inn a~d fix~tion of the implaïlt ~ the target olg~isnl.

B0~0391 CA 02205107 1997-05-12 EXAMPLE 1.
~cri~ls and Mdhods Ti 6AI-4V a~d l~-AI-25Fe s~ 6, 9.15 mm and 5 mm ~n ~ t~ ~L~ely and 15 n~m t~ck, werc uscd. They werc ~und flat in SiC paper6, 1~00, 4000 grit aud s J'~ ~ r~ down to 1 ,u~. 316L 5~;nlP~ tccl samples, ca. 80 mm2, were aEso ground in SiC papcss, 1200 and 4000 grit. ALI samplcs ~ere UlllA~ y de~e,d in 90% cthaIlol ~or 20 minutes followed by a 20-minute double ~i~l6C with distilled water and dried under ~ flow of hot air. Ibe 611rface rou~)~AF-,-~C wcre ~l~e~vl~d with a laser profilomcter (Perki~ Flmer). Table 1 shows the results of the followi~lg roug~
0 pa~-~--P~u~ Ra ~ .elic mean of the roughness hcight, Rz - mean pcalc-t~vallcy heig~t aIld Rma,~ n ~ul-gh~ . depth.
After surface p- lichil~ aDd clr~n;T~ all sample6 wcre ~,s~d in Ha~ks' P~ cd Salt Soh~ n (HI~SS) ~t 3~~C for 14 days in sepa~atc pol~,lhylcLI~ eo..~ . To allo~
a U~ AI~ supply of sol~tion this was changed cve~y 48 ho~ls. ~npty pol~Ah~lenc 5 ro~ were used as reference. A sample of each ~etli~ t solution was stored iD 2 pPnti~ rfTM at 4~C Ca and P ~ t~tjonc in these sol-,tlon~ ~cre later n~ 1 by atomic d~ul~liull s~l.o...l,~y ~anan SpectAA 300) and s~c~hol,holo-metry (Vitalab 21, Vitalab ~iPntifie), lc~ ly. All the results are the averagc of at least tbree mc~u.c...e..ls.
20 All surfaoes were o~ by sc~A~nni~e elect~on ~ u ~o~r (Philip~ SEM 525M) before aDd after ~mmersioD a~ alyscd by ~MA (Voyager ~MA, ~ORAI~ I~hu~e.~
X~ (Philips Ihin-f~lm XRD) was used to c~ .",i"r the shucture of ~c ~lC lJII-Ic la~er, alld AFM was used to obsc~vc its molphology oP polished tit~uulll alloys. ~esults and d;~
2s Flg. 1 shc~ws ~e Ca CO~ t;ul.~ as a fU~n of time. A l~ OtO ;C d.,G~L5C of theCa c~n~.,h~ was clP,~e~Pd in thc sol1lti~n~ that were in contact w~th the alloys. The ~ne ~h~ ~----r~ -- waS obse.~,~ for the l~.rc,cuce HBSS. Until day 5 all curves we~e s~milar but aftcr day 5 the Ti-6AI-4V 1 ,unl samples e~ibited a highcr ~c~s~, which rcaches 123+1.5 ppm. For both Ti-6AI-4V 4000 and 1~ .5~e 1 ~ samples the 30 C~a ~4~e ~"t~ation dc~l~ more rapidly afte~ day 7 ~ similar fi~al Ca uptake c .~ .ations, ~1+2.3 and 63~1.5 ppm, l.s~ ,ly. All ot~er s~u~r~c - h;bi~
uptake valucs between S and 20 ppm.
Fig. 2 shows thc P ~ ~ ~ io~ as a fanction of timc. The P uptake cunes, likc the Ca .t. ".;,r 1;ol.~, also sbowcd a d~ as a f~ction of time. Thc Ti-6AI-4V 400~ d 1 ~ and the ~ 25~e 1 ~m sho~ved tbc highest P uptake; 29~.1, 34~1.5 and 58 ~ I ? ~ ppDI, ,~cLi~ . Ihcse filldings suggest that a Ca and P rich prectpitatc is formcd on all tltc surfaces ~om HBSS. ~n fact, a ~vhite fil~ d~;t~,d on tbe poly-~jl~c that ~o,.~ r~A with HBSS could bc see~. Ti-Al-25Fe 40(10 and 1200 sho~ved 5 thc hwest C~ and P upt~kc. Ihc decrease m both Ca and P was attributed to the growth of ~ nudei OII the surfaces ~Om tl~ S 501~ nn Simil_r b~vio~ was found by Li et a~ [~1 ~ter ;II~UJ~ of silica-gcl alld gel-dcrived titania in ~;im-~lAt~d ~ody Fl~ud; Radin et ul. [2] also ~po~ted a ~ in Ca and P
c~ n~ o~l in .Cim~ te~ y.cihln~ Soll~inn after the h ~ ;o~ of ceramic 0 pa~ticles.
~lg. 3 shows SEM ~h ~ o~ ~aphs of the md~l sur~aocs aftcT imm~rsioJl iI] HBSS.
t'l .. ~p - ~ . ¢ the p~ ~t- V AI~h~ aIl Fig. 3 it can bc secn that thc ylc~ layeI has a platc k~lQgr on which "globules" and/or ~y~tals graw. ~A revealed 8 high~
q~antity of Ca aDd P on these E~cutidcs than in the pl~te p~c~ . It was possiblc to ls obsene that the plates Ji~lu~cd on some of the ~f ~s, na~cly l~ 6AI-4V 1200 a~d 1 ~un, rl-AI-25Fe 1 ,uln and st~inless steel 1200. Ihe o~ ~t~tio~ of the L~ es does not seem to dcpend on the ori~nt~t;tm of thc eJin~j~ fiaws as it is p~ssible to observe a random ~ackil~g of thc plates. The ~ r;p;l;~lr fo~med on ~l-~Al~V 4000 s~ows aconti~~ te~ture at the samc ma~ifirat ~. as thc other ol)s~;.v~tions. It was only 20 possiblc to detect ha~ cs on these s~ Ps, on the Ca and P rich layer, at mq~ific~tjcmc l~ hcr tban 2400 x.
Ii et ~ [6] p~lîol,l,ed a series of e pl .;~,....~t~ vhich silica-~el was iJ ~-J- ~
SBP. T~cy SUggESt that thc regulation of apatitc g~wth is ~latcd to the (~atP mol~r rstio of the fluids. Fu~ishiro ~ a~ [11 obt~ncd .li~ s by ;~ c;~.e Fe 25 and l~ Ca(edta)2--~aH2PO~ s~ ti~n ~arious ~n~.nlr~ of C:a(edta)~~ had a direct effect Oll the - ,~ of the llyd~ atite film.
Ihe SE~ Obsei~vdtiOllS wggcst that the mo~phology of the p.~ic;~ t~ layer sccms to be . ~It both o~ nlat~:rial and surfaoe finichir~ as the i...,..~ C:O.. flllid was the same ;.. .cllt~.
30 Fig. 4 shows an AFM Fh~olnif~ognd~h from a 'ri-AI-25Fc 1 ~m samplc. rt is alJl a~ t that the calcium ~ho~ t~ rich coating is cv~ A by thc a~ln...~ of s~ he.i~l particlcs. Similar Iesults were ol~k~h-cd foI the Ti-~Al-4V 1 ,4n 6urf~ It fiecms that thc ~olmatioII of the coat~ng staIts with h~,t~,~0~ 1S preriri~tinn of nuclci whiCh gather wit4 timc until all the surface is covercd.

It was _~;c:.~lr that the r~ 2.5Fe alloy s~faccs 4000 and 1200 did not e~ibit plate ~ t s. It was only possible to obseIvc small scatt~rcd depos~ts whicb had a similar "los~-logy to c~ ;l;o~ on the flat ~ou.ld ~ ,owed thc presesne of no C~ or P. T~c same aC~icitinn on tbe c ystals showcd the ~.~s~ -~e 5 of the alloy clr .r ~1C~ Ca and P, ~60ri~'l,d wit-h Si. Si seems to act as a nucleus fo~ the p~ 1;n-- and grawth of thc c~stals. This il-lyu~ily is l,loL.dl)l~ due to t~c SiC~ emery paper used dunng Ulc surface pl~ Eithcr the dcg ~g and ~ ";.~e of thc surface was not suff;t ie~t~ on these .n~ s, to ~ o~c the SiC or somc SiC particles might bc ~Lud~olcl in thc alloy's su~facc as n~ 2.5Fe is a 60~tcr m~tPri~l tha~ ~e 10 oth~ alloy6.
Fig. S e~hibits ~IA spcctra acquL~e~ in a T~-6AI-4Y 4000 sarnple bcfoIc and after n , ~ in HBSS. Onc can observe thc pl~ce of thc alloy ele~ t~ as wdl as ve~y well defined Ca and P pcaks on the after-i-~ ;n,~ spectra. The C~ t~d CalP ratiois 1 ~0 0~ whicl~ ;c~ s t~at the ~-~ci~ probably co~sists ~nly of ~ir~1r;l-m 15 phos~hatc ~ig. 6 shows XR~ spectra ~quir~d On non-i~JJ~ d (A) and i~ d (B) Ti~
4V 1 ~ rf~<fC On the i.~ cd samples one can obser~e t~c app~ce of a well defincd ~002] pc~k and a broade~ vhich seems to be ~ d by the junction Of p~s [211~ a~d [ll:Z] in(~ ti~ thc amorphous ~h~- t~ irs of t~c calcium 2u Fho~h~ts. These results suggest that the l,~r ~r ;~ layel ~as an - . .ol ykO~ apatite-l~ce ~ rc. S~lar res~lts were oln~ed for the Ti-Al-25Fc 1 ~rn r ' S
The l~ of this laye~ was plc~;ously t~ .";. ~d by S~iM obscrvations and is ca S ~. Ii et a~ [6] mo~ d the d~ ,lo~ ,t ~!t of ~ o"ydpdite dcposits on gel-derived titania, as a ~ . of time, after iU~ cl~;on in ~5iFn~ t~d Body Pluid. I~ tbc initial 2~ ~itages they dete~d ~It~rc~ Ciyildt~,s all ovcr the surface which ~ - e d in ~un:lbcr and size until, cvcntually, all thc sur~cc was covered by a 10 ~ m coating. Duchc~ne et a~ [5~ ~po~hd the fn~n~tinn of small dcposits on titas~iunl discs after 1~ay CAY~JSU~j to a Simulated Physiological Solutiou. ~ro weeks of ~ clclnial ;.. ,n~ ~ ? jnr~ we~c needcd to produce a~ apatite layer w-ith a ~h~ cc of 1~0 Han~wa et a~ [3] also ~polhd that apatite is naturally formed on Ll~iu~l~ wbe iul~l is h~el~d in a solution whose pH is similar to tbat of thc bioliquid. Theyt~,d a tl .~C~; of 7 mn of the apatite film grown on Ti~ 4V which malce6 it imros6itll~ for this layer to cxhibit ~ny l,.o~.tics of calcium l,h..~ te in this e.l~ilu~c.,l The prcscnt re6ults indicate t~at a calcium r~ with aII apatite-like structure is Daturally fonned on thc surfaces of polLchcd titaT.uuln ~lloys. I~e ll.:~L .~r sc of this layer malces it a sL~itablc surface for bonc ;---h-- l;~ ,r~5 of at least 1 llm are needed for thc calawn l-hr~ h- ~ to sho~ up~ll;cs and cause bone ;...1~..i;~..
~, The nto~rhn'~y of calcium phosphate yle~p;~ depeIlds o~ thc mcta1 s~t~tr- and its surface c~ s It is possible to p~oduce a ~aturally formcd calciuun ~kos~h-~
coa~g by ;."...r,,~ , mctals such ~s titan~um alloys and s~ir-lecc stcel in HBSS.
Ti~ 4V 4000 sce~ls to be the surface that is most favouIable to produce a 0 cnntinl-ous a~d more adhe.~ t ~ te-like coating ~;apable of bone in~luchon LE 2. Dete~nina~on orcalcium p' -sp' ~te depth di~ tio~ on a tita~i~m alloy bul~l~ate using ~-my photoel~hon ~pect~
d~tcs the .~ ~~ r - - of the depth Cli~t~ t~ of sct~d cl~ s in a ~11m, p~;os~ho,u~ d oxygen - ~-4--1~ g coating on a tit~nillm alloy Sa~SlplC
g dcpth ~.~,r,L,.g X-ray Pbot~-1~rt~on Sp.,cl~oscop~, (XPS or ESCA).
'~J~
The samples we~ titanium aUoy plates that h~d bee~ surfacc trcated acco~d~ to the c~eA~ of E~cample 1 to prodl~cc a calcium ~h~s~ coat~ ~hcn ;.. ~ ,~cd m ~jfir~ ulio..S Or s;~ trd body nuids. The salnples were mn-l~tcd dire~y tO
20 a Sl~l~ XPS ~iamplc holder using a sp~g clip ~..;.. ~,. - ....~, with no pre-treahnent.
Thc outer coat~Dg sur~acc was ~ ~~r;. ;r"~ lly ~hJ~ e that no clccllosla~ic ~dl~ problems v.rere ~ tl cd during ~-ray ~rladiation or ion beam etching. All a~alysis v"ere carried out usmg a Su~faoe Scicnce L~lu~ s (SSI) M-probc opc,rating at a base p~e~ul~ of 3~10-9 tO~r.
25 A~
sulvey ~;tlUIU was ~ ûm the "as rc~;~,~3~ surface, to d(t ~ r t~e sulrface co.llposition of thc coating and therefore d~ the Pl~n~nt~ to be .llollilol~d for thc dcpth profile. The XPS de~th profile was o~ h~r~ by ~ t;~ argon ion ~t~e ;nt (ovcr ~n area of approx. 2 x 2 mm) and data ~ icit;~n (from a~l area of30 approx. 300 llm di~eter centre~ in the etched crater). F,~Pntc analysed were carbo~, oxygen, ~~ m~ rh~horusl magnesium and tiPnil~n- Etc~ timc per stcp wa~ variable ~o~ 15 to 120 seconds per cycle and the etc~ ~ate was 3 nm/min using a total sputter time of 4470 s~o~lc ~SJ~
~hc surf~oe rh-~mi~l C~ (il2 atomic percent) of the 'tas ~ dn ooatm~
carbon 44.9%, o~cygen 33.8%, cal~iu~ 10.5%, ~ k~,o~s 8.8%, ~ t~ ll 2.0%
aI~d tit~nil~m 09~o (figur~ 7). Ihe depdl profile o~ the coating rcvcaled a gradual 5 t~n~hnn of c:~c~um and yl.n5r~ om thc coati~g to the su~~ tr;~ ; the ~ nld1 j~l.. of these ~Tem~ntc in thc ~ur~ce toxide la~er), and thus a chpmi~l bonding between coa~ng a~d subs~r~t~ (fi~ure 8). The calcium - o~ygen ~ o~l~h~ uu:~ laye~
(ca~ ml llh~ k ~) i6 tdlm ted aS belllg l~r C ~ -Iy 90 nm, ~lminC a sputter ~ateof 3 nm per mimlte ~ TiT~d on ~ t nt~ F- ~On ;fT~ film On ~ ' and that ~L
10 ~t;u1. . ~ is dcfmed .~ the poi~ wh~c the titauium rcaches approx. ~0% of its inal valuc. A thiJ~ layer of lit~ ,", oxide 5~"~rAt-.~ the calcium 1-~-05~T~t~ layer from the alloy snhStrtqtr- The i~ betwee~ the calciu~ phrS~ TI; aDd t.l i.....
shows ~ges in the oxygcn, ~h~h~oùs~ calcium .~d tit~ tJ~ 5 Thc XPS
pe~ birK~ing ~n~I~ of calcium and ~ )hn~u~ d~e;~ at the I f~~: with the 15 ti~ whcre a ~jt~njlnn û~ide layer is foumd. A~ tL~ egion is lLkely to occur at the bo~ and oxygen has been ~ep' t ~ f~n the calcium E,hosph-~r- to form tih~ u dio~cide at the int~ ~. Metallic titanium is pre6cnt below tbe L~tc~hase Fegion. Mv~ ~ ci ~ ~ is dctect~d a~ 2 - 4 atomic percent thrû~ghout the cal~ .h ~
l~ycr and i..c~eases slightly in co~r ~ation ~ith dcpth towardc the interface with thc iu~ll (oxide). Grbon is found in the b~ of the ti~n;u~n Thc cal~ tc layer t~at ~s fonncd ûn thc titanium alloy c~ ;~t~o iS chf~ y bound to the su~ ta its surface o~ude layer.
EXAMP~E 3. P~epara~on of b~omhnetIc caIci~m phosphate c(iali~gs OD ~etallic 2s Implant~
Ihis e~mrlc illustr~tes a DCW t~o-step rb~i~t l.Gd~lt for prcpar~Dg aII implant w~th a ~fic surfacG ro~ghn~cc., rr.s..l~ [ in a me~allic su~facc that allows f~ct p~ ;n~ of bin~ lci~ phn~rh~te (Ca-P) coatings ~om in vi~o super--saturated r '~fir -i~!n sol~ (SCS). The specific surfa~e lo~ esults in the 30 following advantages: (i) the l,;u..~ coatings directly induccd f~om SCS are ~b~ IIy bouDd t~ mctallic subs~ and show higher bone-bondin~ sbility, (ii) the ro~tin~ can be produced onto c~npleY-sh~pcd and/or maclo-porolls i~nrlq~tc, and (iii) it is ~ controllable and cost-effective way to aC4ulr~ Ca-P ~o~tin~

BO ~91 CA 02205107 1997-05-12 Mmniab a~d A~ethods A nc~ly dcveloped two step rbpmir~l h~ .lcltwaS ~"F,, r~ -~ on thc m~tallic i~plant ~"~t~ lc, i.e. c~c.wally pu~e tita~ium (rp.Ti), ~ 116A14V aDd po~ous t~nt~ n CIa), to produce a ~fic surface 5~ zh-n~ss~ ~ur~g this treannent, two selies s of ~h~mi.~ol r~ae. ~ W~ ~d for titanium (cp.r~ d Ti6~1~V) ~d p-lt~l~m implant m~t~l5~ ~ ,cli~ , that resulted ~n the p~ i of t~c speciS~
~c ~ for the pl~dtil)ll of the coating. For the fo~met, tbc samples were treatbdwi~ a ~e of HCI and H2SO4, followed by j"""r,~ n in a NaOH s~iutinn The pOlOUs t~nt~ samples were t~bated with a mixture of HCI, H~S04 and HF, followed 10 by i,~~ - s,oJ~ m ~2~2 Two ki~ds of SCSs with di~ t ~a and P c4~r~ alions, f~st r~ fioatinn solution (FCS) and coln~erc;al Ha~}~s' b~ salt solution,ffIBSS), were used for ~~
p c~ti~ rO prolhote thc C~--P t~ m OD the metallic s~ ~s, a pqr~l~ ;f;r".l;"" (~re-Ca) ~lu~dulb ~a6 p~ r~ o~ half the t~eated samples before 15 ;---- .." Fi~ ~ ~ the SCS. The Pre-Ca was carried out by ;. ~f ~-h~ ~;~ the samples in 05N
Na~HPO4 ovc~night and then t.~ r~ e them into saturated Ca(OH)~ fo~ S h The ~CS
solution volume used for imm~on was 15 ml per cm2 of sample 6urface arca. I~e samples vvele ,a~u~l ed in sealed poly~ly~buc v~als at 37CC in a calibrated water-bath.
~nniT~e elcctroD mic~03copy (S~M) togcther ~vith cnc~gy dispe~se X-ray ~
20 analyses, ~-ray di~ ion (XR~ ared (D?.) s~ Lo~o~lletry werc used to t~ the ob~ P c~
~esults T~e l~ cli~ Ca-P coatings were fast l)r~ d on the treated ~p.ri and Ti6A14 samples by ~ ~sio.~ iQ both FCS and HBSS no matter whcthcr the Pre-Ca p~ucc~h 25 wa~ ~.fo~ cd or llot. But the P~c-Ca ~ o.~t~ 0uld /lr~m~t~ y ~peed-up tbe t~t~ ate of the Ca-P coatings as listed in table 2.
Figure 9 show6 that a h:~mim~ Ca-P coating, ~,~ "ntely 16~ thick, was formed o~ treated ~:p.Ti after 16 hours of ~ iO~ vi~ Prc~a. ~e coating got thicker with ~ n~ time asiT~irato~d by ~D~ (~Igure 10) and XRI) (figurc 11) 30 ~sults. Tbc p.~, -;yitatiOn ~ate of thc Ca-P coating irl ~IBSS is slower than tbat in FCS.
But thc coati~g ~om HBSS (figure 12) ~vas mu~ denser than that ~m F~:S. The coating from HBSS ma~nly ~ ;ct~l of apatite (~Igure 13). Riomi~Pt;r Ca-P c~

~40391 CA 02205107 1997-05-12 could ~o be precipitated on pO~ S Ta samples (f;gure 14) after the Lc~t.. ~ nt. Ihe sur~ce ~o~tent ~hangc of t~e sample was Art~rteA by E~X as show~ L~ fi~ure 15. lt is ~ h, that no ~ pi~ftiO~ was o~ ,d on aIIy untIeated s~nples after 2 wceks of ;~ r..~ CS or TIBSS, eve~ with Pre-Ca. The for~nation of a spe~fic ht~jllm s alld t~nt~l~lm o~de laye~ their llc7tm~nt~ is pr~bably the ma~n r~son for the i~lu~ p~cipitation of Ca-P c~ ~i~ by means of in vitro ;---- ~ s in~l in SCS. Tbe p~u~i of thc h~ ~ for titanium impl~ and tf~ h~ could not be c - ~.1. ~er.~, o~ no Ca-P ooating was acquihcd.
Co. ~
10 This bi'~ tt;r calcium I~hosF~h~te coating study has show~ tha~:-. Ihe neuvly du~,lopcd tw~step trcatment is an cffective mcthod to prepare ~ ;oc,~
- mctallic implaIIt s~lrfaccs allo~ing f~st yle~ip~ of adherent b;QY~ PI;r Ca-P
C4 ~ y in v~o in.~ .. iu SCS. The rh~nie~l Ieagents nccded for thc treatme~t of tit~n~ n ~pl~nt . ~ and t~nt~h~n a~e di~ t from eac~ oth~.
15 . The p~ of Ca-P coat~gs could be r1-~ n~tiC~IIy accele~ated by means of pre-calcify~ the treated samples befo~c thc ;~ n--~.
. Ihe ~ ;nn ~ate and ~ -l-4Sjtinn of tbe Ca-P coati~gs can be ~ t~d by controlli~g ~c c~ -Q-~J~I~ of the SCSs (EiCS o~ ~BSS) for ;~ r~;on Table 1- Surface rou~Dess me~ure~ents results zo Surface fiuisb R8 (~Im) Rz ~1~) ~ (l~m) ~-6AI-4V 1200 grit 0,47 0.01 3.74~0.04 5.13~0.08 rl-~Al~V4000grit 0.~~0.03 1.91~0.31 2.46~0~4 ~ 4V 1 llm 0.03+0.00 o ~s~o.ns 0.48~0.03 n-Al-2~Fe 1200 g~it 0.4~0.03 2.g7_0~5 3.47_0.48 2s 15~ 25~e 4000 gr~t 0.23-0.01 1.97~0.18 2.46~034 Ti-AI-2.5Fc ~ ~un 0.04~0.01 0.28+0.11 0.36+019 316 L 1200 gnt 0.3+0.06 2.32-0.47 2.96+0.03 316 L 4000 grlt 0.04+û.01 0.35+0.1 0.46 ~ 0.1 ~040391 CA 02205107 1997-05-12 11 , Table 2 - Iist Of Ca2~ d HPo42- c~ t;~,c, precipihtion rate aod ~f Ca-P coa~neS OII cp.n ~d T~ 4V.

C~t~io.~ ~mM) Ca2~ 3.0 1 26 Hpo42 1.87 0.78 ~" rate of ~o Pre-C~ 0.5 ~ mlwk S cûa~ Prc~ ~r 3 ~wk ('~ s;tic~ of coating apatitc, OCPapa~dtc ~ ptions Figur~ 1 - Ca ~- ~.~.dLiul~ as a functiQn of time Figure 2 - P CO~ LiOI- as a fi~nction of time 0 F~gure 3 - SEM ph~l -;~ ~ographs of the metal s~facc~ after imme~sio~ IBSS. A: -6AI-4V 1200; B: Ti 6Al-4V 4000, C: Ti~ 4V 1 ~m; D~ 1-25Fe 1 llm, E: Ti-AI-25Fe 4000; F - st~jnl~cc cteel 1200 Fgure 4 - AFl~ ~l-ot~ og~aph of a r~ 5Fe 1 ,~n sample aftcr I ~,.sio~ in ~BSS. In~,l~g J~ .;ri~o~j9~ ~om field n to 3. S~ nin~ le~gth ~m field 3:
15 ~Im.
F~gun; S - ~MA spec~a ~c4uhc~ on a Ti-6Al-4V 41)00 sample bcfore (A) and after Figure ~ - XRD ~ acquired on a non-h .,.scd (A) ~nd ;~ 3) li-6~1-4V 1 ~m ~e ~o Fgure 7. Sur~ace chP~nieAl cr. ~ (in atomic perccnt) of the "as ~ ,1 coating. Tc 8. Dept~ profile of the coating, ~om coating to ~ t~.
Figure ~ nni~ electrorl rnicrograph of the Ca-P coatinK (CP) pr~ ~ o~ cp.Ti ~i) afte~ lfi hou~s ûf i~ r ~ -~.. in E~CS with Pre-Ca ~ure 10. ED~ spectra of the cp.Ti 6~1rfaces Don-trea~ed, treated and ;",. -r"~'~1 ill FCS
with Pre-Ca for ~lifrG~c~ hou~s. Thc ~h~ APr of O kQ pea~ is cle~rll~ seen afterthe l.e~t~ c .-. ~e Ca and P co~tPDts i. ~ d with the i~lGIc--- of ;~
time.
re 11. XRD pattP~s of the cp.Ti suIfaces after dlrrc~ t hûuss of i~T~m~hr~ iD. FCS
with Pre-Ca. The counts of apatitc peaks get higher with incl~ascd ;...~ ,.6io t~mes. Octa calcium ph~;rh~t~ (OCP) starts to be formcd at around 8 hours.

CA 02205l07 l997-05-l2 Figurc 1~ nr:~ dectro~ h of a de~sc Ca-P ~oatmg (CP~ on c~.Ti from ~SS a~ 1 weck Of inlmr ~ with Pre-Ca The laycr betwec:u coating aDd ~.uL~ r~ the til~;ul~l ~dc layer (OL), ~smed as a Iesult of the s ~lgure 13 Ihi~-film XRD patte~ of a densc Ca-P coating ~ il. d by j~mPrcinn in~iS with Pre-(::a fa~ 1 week.
~gu~ 14. S~-~s-nni~ elect~ ph of porous i ~ Tn CTa) after 2 day6 ;...~ ~ ~ cioJ~
S with Pre-Ca. I~e coating is fosmed ~ol.gLwl t~e porous Tng~P~gl Figu~ 15. EDX spec~a of (a) noII-trcated, (b) tIeated, and (c) Pre-Ca treated, 2 day 0 FCS ;.. ~c.~ed po~ous ~ n~ ~ra) sa~plc.

Litera~u~e rc~e. ~
1. Y. Fujishiro, T. Sato and A. Oku~i, rco~tjng of h~d~u~y~alitL on metal platcs using thc~ iccor~7~ioD of calaum -EDTA c}lelste in l,~h~c ~ ~ sol-~jnn~ under hydrothennal c~ t1OD~", J. Ma~er. ~ ter in Med, 6, pp. 172-176, 1995 2. S.R. Radin and P. DUC~ C~ 1. BianL Ua~er. Res." 27, pp. 35, 1993 3. T Hanaw~, "T~tanium ~d its o~de film: a ~~!bch~qt~- for fo~g apatite", in Proc.
of the ~one Riow~t~ql T~lt~.lf~ W(!rlrshnp Toronto, Dec. 19~Q, J.E. Davie6 ed.J
Uni~r. Toronto Press, pp. 49-61, 1991 4. ~. Leit~o, M.A. Barbosa and K. dc Groot, "In vitr~ rRI~;ri~ali~f~ of 0~ ~3~1ic z0 i~plant m~t~ql~n~ J. M~ter. Sc: ~ate~ in Med, 6, pp. 84~852, 1995 5. P D~ c, S. Radin and K. lshilcawa, "~e ~te of dciuIn rh~
- ;~ ioL. o~ metal and Q~nR~~ and the ~ t~r~n~hip to l);o~ivily", in Bo~c ~on~ g Rjomqt~iRI~, P. Pucheyne, r. Kokubo ~ CA. Ya~ Blitters~ill~ (eds), Reed ~tb~re C~ vu~ic~tio~Ns~ pp. 213-218, 1~g2 zS 6. Ii, P, P~D Thesis, Leiden I~ ity (1993)

Claims (11)

1. An implantable device of a material having a surface roughness with an average peak distance (Ra value) between 10 and 1,000 nm.

2. An implantable device according to claim 1 having a surface roughness with anaverage peak distance between 20 and 500 nm.

3. An implantable device according to claim 1 or 2 having a surface roughness with an average depth between 20 and 1,000 nm.

4. An implantable device according to any one of claims 1-3, wherein the surfaceis coated with a layer of a calcium phosphate having a thickness of 50 nm - 100 µm, in particular of between 1000 nm and 50 µm.

5. An implantable device according to any one of claims 1-4, wherein said material is a metal, a metal alloy, a ceramic material, a natural or synthetic polymer, or a composite of any of these materials.

6. A process for producing an implantable device, comprising subjecting a porous or non-porous material to a surface treatment until a surface roughness with an average peak distance (Ra value) between 10 and 1,000 nm is obtained.

7. A process according to claim 6, wherein said surface treatment comprises a mechanical treatment such as a sanding or scouring step, e.g. using a diamond paste.

8. A process according to claim 6, wherein said surface treatment comprises a chemical treatment involving subjecting the surface to acidic, alkaline and/or oxidising solutions.

9. A process according to any one of claims 6-8, wherein the roughened surface is subsequently subjected to precipitation of calcium phosphate from a solution containing calcium and phosphate ions.

10. A process according to claim 9, wherein said solution has a pH of 4-10, preferably 6-8.

11. Use of a device according to any one of claims 1-5, or produced according to any one of claims 6-8, as a bone substitute, a joint prosthesis, a dental implant, amaxillofacial implant, a vertebral surgery aid, a transcutaneous device or any other hard-tissue-related device.