Effect of Surface Texturing on Friction and Lubrication of Ti6Al4V Biomaterials for Joint Implants

Vol.:(0123456789) T ibology Le e s (2025) 73:15 h ps://doi.o g/10.1007/s11249-024-01950-5 ORIGINAL PAPER E ec o Su ace Tex u ing onF ic ion andLub ica ion o Ti6Al4V Bioma e ials o Join Implan s Ma úšRanuša1· LukášOdehnal1· OndřejKuče a1· Da idNečas1· Ma inHa l1· I anKřupka1· Ma inV bka1 Recei ed: 6 Augus 2024 / Accep ed: 4 Decembe 2024 / Published online: 19 Decembe 2024 © The Au ho (s) 2024 Abs ac The numbe o endop os he ic implan s o bo h la ge and small join s is inc easing a a s eady a e, he eby c ea ing a g owing demand o du able p oduc s ha closely eplica e he unc ionali y o human join s. No wi hs anding he a o emen ioned ad ancemen s, challenges pe aining o implan ixa ion and ibological su aces pe sis . The ad en o p og essi e echnolo- gies, such as h ee-dimensional p in ing, o e s a p omising a enue o add essing hese challenges in implan design and su ace enginee ing. The Ti6Al4V and CoC Mo alloys, enowned o hei biocompa ibili y and osseoin eg a ion p ope ies, ep esen p omising p in able ma e ials, al hough hey a e suscep ible o wea on a icula ing su aces. In o de o mi iga e he e ec s o ab asion, i is essen ial o implemen su ace ea men s o acili a e he o ma ion o a obus lub ica ing ilm. This esea ch in es iga es he po en ial o ex u ing and elec ochemical polishing o enhance p o ein agg ega ion in he con ac a ea. The s udy employs a ecip oca ing simula o and colo ime ic in e e ome y o obse e he con ac a ea and measu e he coe icien o ic ion (CoF) o modi ied su aces. The indings demons a e ha ex u ed su aces and he combina ion o elec ochemical polishing esul in an inc ease in he hickness o he p o ein lub ica ion ilm, which may po en ially educe wea . These ou comes sugges he po en ial o he u iliza ion o Ti6Al4V alloy implan s wi h ewe ele- men s manu ac u ed by addi i e echnology. * Ma úš Ranuša [email p o ec ed] 1 Bio ibology Resea ch G oup, Facul y o Mechanical Enginee ing, B no Uni e si y o Technology, Technická 2896/2, 61669B no, CzechRepublic T ibology Le e s (2025) 73:1515 Page 2 o 18 G aphical Abs ac Glass pla e Ligh sou ce Ti6Al4V alloy & CoC Mo alloy Ma e ials and Me hods Film hickness &Coe icien o ic ion Keywo ds Ti6Al4V· Mic o- ex u e· Implan · Op ical in e e ome y· F ic ion· Film hickness 1 In oduc ion Join a h oplas y is a common su ge y wi h an inc easing incidence. The ma e ials used in a h oplas y ha e a high s anda d, wi h a good biocompa ibili y, and osseoin eg a ion abili y. The opic o join wea emains a signi ican a ea o esea ch, wi h he de elopmen o new ma e ials leading o a educ ion in he amoun o loose ma e ial. [1]. Addi i e Manu ac u ing (AM) ha e ad anced his ield by cus om- izing he implan s o be e com o and a longe se ice li e [2]. Ne e heless, he ad en o addi i e echnologies has also in oduced a numbe o new challenges. One such challenge is he iden i ica ion o he op imal manu ac u ing pa ame e s o he p oduc ion o s uc u es sui able o osse- oin eg a ion o he imp o emen o he ibological p ope - ies o a icula ing su aces [3]. The longe i y o implan s is a ec ed by he ibological beha io o he a icula ing su aces, and in e ac ion wi h he coun e body su ace. A numbe o s udies in his ield demons a e he in e play be ween indi idual su ace ma e- ials and he complexi y o he molecula componen s o he syno ial luid, which change wi h pa ien age [4]. The basic ma e ials ha combine he ad an ages o biocompa - ibili y and esis ance, while allowing he use o 3D p in - ing by selec i e lase mel ing (SLM), a e ep esen ed by he CoC Mo and Ti6Al4V alloys [5]. The possibili y o 3D p in ing o bo h ma e ials o e s he ad an ages o cus omiza ion and os eoin eg a ion, bu b ings new challenges a he same ime. One o he challenges is he beha io o he p in ed a icula ing su ace compa ed o con en ional p oduc ion. One o he di e ences is he ensile s eng h. The SLM-p oduced CoC Mo alloys exhibi a highe ul ima e ensile s eng h and ha dness compa ed o hose made ia in es men cas ing. Fo ins ance, he SLM samples can achie e yield s eng hs a ound 1.4 GPa, bu a he same ime, hey end o ha e a highe wea a e compa ed o he cas samples, which exhibi lowe wea a es due o hei dense mic os uc u e [6, 7]. Howe e , in bo h cases, he wea esis ance is ela i ely high, and bo h p oduc ion echnologies exhibi su icien mechanical p ope ies and co osion esis ance [8]. Fu he mo e, he o ma ion o a passi e oxide ilm on he me al su ace in he human body also con ibu es o a be e wea esis ance o he CoC Mo implan s [9]. This oxide laye is mainly composed o cobal , T ibology Le e s (2025) 73:15 Page 3 o 18 15 ch omium, and molybdenum oxides. Among hese, C 2O3 inhibi s bo h he anodic and ca hodic eac ions. I ac s as a physical ba ie , limi ing he anspo o ca ions and anions o he me al su ace, and se es as an elec onic ba ie o elec ons [10, 11]. In he case o he Ti6Al4V alloys, he con en ional me hods p oduce coa se g ains, which can hinde disloca ion mo emen , leading o a lowe s eng h compa ed o he 3D-p in ed su aces. The 3D-p in ed Ti6Al4V alloys can achie e s eng hs up o 1492.89MPa, al hough wi h a educed elonga ion (5.76%) due o mic o- s uc u al de ec s [12]. Ti6Al4V is equen ly used in onco- logical implan s due o i s mechanical p ope ies, which a e simila o hose o a human bone. This minimizes he s ess shielding and p omo es he osseoin eg a ion [13]. Howe e , he alloy is suscep ible o a high ab asion on he a icula ing su aces. This issue can be po en ially esol ed by a ious su ace modi ica ions, such as a coa ing o mic o- ex u ing. Bo h coa ing and mic o- ex u ing can enhance he mechani- cal p ope ies and he du abili y o he implan s. Howe e , he coa ing echniques may su e om an ins abili y o he coa ing laye . I is, he e o e, a challenging ask o de e mine he mos app op ia e manu ac u ing echnique o su ace ea men and, a he same ime, o design he op imal ex u e geome y o mul i-le el ex u e wi h espec o he kinema - ics o he selec ed join . Mic o- ex u ing has he po en ial o modi y he beha io o he lub ica ion laye , he eby enhanc- ing he sus ainabili y o he pe o mance, while allowing he use o di e en ma e ials [14, 15]. Modi ied ma e ials equen ly exhibi no only enhanced du abili y bu also he p esence o highly c oss-linked polye hylenes, which a e o en doped wi h a ange o subs ances, including he E i amin. This doping p ocess augmen s he ma e ial's ic- ional esis ance while simul aneously s abilizing he ee adicals wi hin he s uc u al ma ix. This dual e ec esul s in a no able enhancemen in he ma e ial's esis ance o he oxida ion and delamina ion a he su ace [16, 17]. The ex u ing o su aces has been demons a ed o exe a bene icial in luence on he ibological p ope ies, esul - ing in an augmen ed hyd odynamic p essu e and diminished su ace wea . Howe e , he e icacy o his app oach emains a opic o con en ion, pa icula ly in he con ex o non-con- o mal con ac s [18]. In con as , o he con o mal con ac s, i esul s in he sepa a ion o he con ac su aces by a hicke laye o p o ein-con aining lub ican , which al e s he lub i- ca ion egime and educes he wea . Simul aneously, he ex- u es se e as lub ican ese oi s, acili a ing he desi ed sepa a ion o he a icula ing su aces [19, 20]. Addi ion- ally, he ex u es can cap u e and emo e wea pa icles om he con ac a ea. Asep ic wea pa icles a e p oduced as a esul o he ab asi e wea o he ma e ials, p ima ily in he bounda y and mixed lub ica ion egimes. Ca e ully chosen ex u es can e icien ly emo e he pa icles om he con ac a ea o e ain hem wi hin he ex u e, he eby enabling he a icula ing su aces o main ain a smoo h su ace opog a- phy o longe pe iods in i o [21, 22]. Se e al s udies ha e in es iga ed he e ec o he mic o- ex u ing on he coe icien o ic ion [23–25]. Some o hese s udies sugges an inc ease in ic ion, which is mainly caused by he beha io o he p o ein componen s o he syn- o ial luid as i passes h ough he con ac . This beha io is due o he shea s ess o he agg ega ed p o eins adhe ing o he su ace (γ-globulin) o o he u he laye ing o he albu- min wi h al eady a lowe shea . Ne e heless, i is impo an o supplemen he gi en conclusions wi h kinema ic condi- ions, which ha e a signi ican in luence on he beha io o he lub ica ing laye and he design o he ex u e [26–28]. The po en ial applica ions o mic o- ex u ing ex end o a ange o implan s, wi h he possibili y o i becoming a s anda d ea men o all a icula ing su aces in he u u e. Howe e , he cu en ocus is mainly on small join eplace- men s, whe e he numbe o su ge ies is s eadily inc easing yea on yea [29]. De elopmen s in his ield o en p o ide solu ions ha do no e lec cu en ends in endop os he ics and eplace hem wi h p o en p ocedu es ha a e o en a he expense o pa ien com o . A clea example is he me a a - sophalangeal join , which is o en a ec ed by hallux algus and hallux igidus. In such cases, wo ea men op ions a e simul aneously o e ed o he pa ien . One is a h odesis, which esul s in he loss o join unc ionali y. The o he op ion is a mobile eplacemen o he a ec ed join . Despi e a numbe o disad an ages, a h odesis is he mos common solu ion due o i s simplici y and eliabili y. This is because i does no con ain in e locking mo ing pa s [30]. These s a is ics also indica e he necessi y o u he de elopmen in he ield o unc ional MTP eplacemen s in o de o make hem he su geons' p e e ed solu ion due o hei eliabili y. Mic o- ex u ing is la gely dependen on he load and he a e o mo emen o he in e ac ing su aces. As o load- ing, he con ac con o mi y, con ac p essu e and ma e ial a e impo an . Mic o- ex u ing on ha d ma e ials such as he CoC Mo o Ti6Al4V is especially p omising o he small join implan s, whe e he a icula ing su aces a e less exposed o con ac p essu e and anges o mo ion. A s udy by She e e al. [31] desc ibed he kinema ics o he me a a sophalangeal join o pa ien s wi h a join disabil- i y. The a e age o al ange o mo ion in he sagi al plane was 111°, wi h app oxima ely 76° o do sal lexion and 34° o plan a lexion. The implan a emp s o main ain a ull ange o mo ion, which has a signi ican impac on a pe - son's s abili y and p ope oo unc ion. Zhang e al. [32] conduc ed a nume ical s udy on he p essu e dis ibu ion. They ound ha inc ease in he con ac p essu e o pa ien s a ec ed by he hallux algus disease, which also led o a highe isk o he join damage. The p essu e o he no mal join is 1.53MPa and a ec ed join 2.21MPa. In he case o he Mo gan e al. esea ch [33], he con ac p essu es we e T ibology Le e s (2025) 73:1515 Page 4 o 18 highe . In he case o he cada e es s, he alues we e in excess o 30MPa, wi h nume ical simula ions showing al- ues as low as 10MPa in he 200–230MPa load ange. The alues we e signi ican ly highe o join implan s, depend- ing on he ma e ial used. The p essu e on he implan was ecalcula ed in ela ion o he geome y o he pai , based on he p edic ions om he heal hy join [25, 34]. The CoC Mo alloy shows a good ab asion esis ance. Howe e , since i s mechanical p ope ies di e signi ican ly om hose o a human bone, i is suscep ible o iboco o- sion and asep ic loosening. Wang e al. [35] compa ed he CoC Mo alloys wi h he Ti alloys, speci ically in e ms o he iboco osion. The s udy concluded ha he Ti alloy was be e al e na i e o he CoC Mo alloy, due o i s lowe wea and po en ial o he heal h haza dous ions, such as Co(III) and C (VI). The Ti6Al4V exhibi s a high wea a e [36, 37], which can be esol ed by su ace modi ica ions o modi ica ions ha c ea e a lub ica ing ilm o sepa a e he join su aces. 1.1 P oduc ion andImpac o  heMic o‑ ex u es Mic o- ex u es a e equen ly used in he a h oplas y o la ge join s as hey o e a be e su ace wea esis ance and lub ica ion compa ed o he smoo h su aces [36, 38–40]. Fo small eplacemen s, he ex u ing has an e en g ea e po en ial due o lowe con ac p essu es. The mos used ex u e shape is a ci cula o ounded dimple o ien ed in he slip di ec ion. Con e sely, al e na- i e ex u e shapes ha e been iden i ied ha demons a e he po en ial o educe he coe icien o ic ion (CoF) e en u - he . Howe e , he ques ion o he e iciency o he p oduc- ion o hese shapes and hei applicabili y in he con ex o mo e complex kinema ics and in combina ion wi h di e en ma e ials emains unanswe ed [41]. The basic ex u e pa ame e is he a io o dep h (hp) o diame e (dp), which is c i ical o he wea pe o mance. Co ec adjus men o his a io (ε) can esul in a educ- ion in he CoF o up o 30% due o locally a ying hyd o- dynamic p essu es [42]. In gene al, small dep h ex u es (a ound 1μm) can inc ease he CoF and wea a low loads due o insu icien hyd odynamic p essu e gene a ion. How- e e , his s a emen does no apply o he use o a p o ein lub ica ing ilm due o he o ma ion o p o ein clus e s du - ing he con ac passage, and he e o e, an inc ease in he CoF does no necessa ily imply wo se esul s in e ms o he long- e m wea . In he syno ial join en i onmen , deepe ex u es (1–15μm) appea op imal as hey bo h inc ease he hyd odynamic p essu e and ac as lub ican ese oi s [43]. Despi e he posi i e e ec o he ex u e on he lub ic- i y, a nega i e e ec is possible as well, especially i he load exceeds op imum h esholds and he lub ica ion limi is eached [44]. Ano he c i ical pa ame e is he combina ion o he ε a io wi h he ex u e, su ace co e age densi y (Sp), and shape, which de e mine he e ec i eness in he di e en lub ica ion egimes du ing he implan cycle [45, 46]. I is expec ed ha he ic ion educ ion will be mo e p onounced o shallow dimples (3–10μm) ha ing smalle diame e s (100–200μm) [47]. The e ec o su ace ex u es on ic ion will be u he d i en mainly by he pa ame e s o he ex u es. Depending on he aspec a io ε, he ex- u es will ei he p o ide an enhanced hyd odynamic e ec (ε < 0.1) o se e as a lub ican ese oi (ε > 0.1). Se e al s udies sugges ha an op imal a io alue is 0.1 o lowe , depending on he ma e ial used [48]. Howe e , he conclu- sions ega ding he co e age densi y a e no clea . Some s udies p o ed ha ibological p ope ies can imp o e wi h an inc easing ex u e densi y, while o he s showed he oppo- si e end, wi h imp o emen occu ing wi h a dec easing densi y [49]. Qiu e al. [50] conduc ed expe imen s on he con o mal con ac sys em unde he bounda y lub ica ion condi ions. They in es iga ed h ee ex u e densi ies o 26%, 41%, and 58% a an ε a io o 0.1. The esul s showed ha he lowes ic ion coe icien was achie ed a 58%. Li e al. [51] in es iga ed he e ec o h ee di e en densi ies o hemisphe ical pi s (5%, 13%, and 35%) a he ε a io o 0.01. They ound ha he lowes ic ion coe icien was achie ed wi h a densi y o 13%. Simila ly, Raeymaeke s e al. [52] ound ha densi ies o app oxima ely 15% and ε a ios in he ange o 0.1 o 0.3 p oduced he bes esul s. Zhang e al. [53] p oposed a pa elloid ex u e p oduced by a pulsed lase abla ion. Pin-on-pla e es s demons a ed a long- e m dec ease in he coe icien o ic ion, esul ing in a educ ion o he wea a e in he hyd odynamic lub ica ion egime. The lub ica ion p ope ies a e in luenced no only by he densi y o he mic o- ex u e co e age bu also by he a angemen o he ex u e. The ex u es a e a anged acco ding o he di ec ion o mo emen , wi h longi udinal, ans e se, o oblique o ien a ion. The ex u es a e a anged mainly in a squa e, iangula (hexagonal), o a andom pa - e n. Choudhu y e al. [54] in es iga ed he dis ibu ion o he mic o- ex u es in squa e, ci cula , and iangula a ays on he hip eplacemen s. They concluded ha he squa e a angemen p o ided he bes ibological p ope ies. Acco ding o B aun e al. [55], he use o he ci cula ex- u es o a sui able size in a iangula a angemen can lead o a educ ion in he ic ion o up o 80%. Schneide e al. [48] concluded ha a pi ing aspec a io o 10% esul s in a educ ion in ic ion o 0.1. A iangula pa e n is supe io o a squa e a angemen , p o ided ha he ex u e design is o high quali y. The ex u ing echnology has a majo in luence on he o e all unc ion o he ex u e. Among mic o-machining illing me hod [56], lase machining is he mos common echnique. Howe e , i has a d awback: i o ms sha p co - ne s ha ac as s ess concen a o s. This leads o wo-body T ibology Le e s (2025) 73:15 Page 5 o 18 15 ab asi e wea , whe e he sha p ims cause mic o-sc a ches on he coun e -su ace, inc easing he coe icien o ic ion. To mi iga e his issue, e o s a e made o ound he ims and educe hei nega i e impac . This ex discusses di e en me hods o he su ace modi ica ion o ough su ace p epa- a ion in i anium implan s. The me hods a e based on he mechanical, he mal, chemical, elec ochemical, and lase echniques. I should be no ed ha hese me hods do no only emo e he ims caused by he lase machining bu also modi y he o e all su ace [57, 58]. O e he pas decade, he pa en ed DLy e echnology has ga ne ed a signi ican a en ion. Unlike he con en ional echnologies, he DLy e only smoo hs he peaks o he oughness, no he alleys, h ough a selec i e su ace smoo hing. The DLy e ope a es on he p inciple o an ion anspo by ee solids, which is a combina ion o an elec ical low and a pa icle mo emen h ough an elec oly ic medium [59–61]. 1.2 Aim o  heS udy Addi i e me hods oge he wi h he mic o- ex u ing and he DLy e echnology ha e he po en ial o in oduce a cus om- ized, on-o de manu ac u ing o he implan s. Howe e , i is c ucial o in es iga e close he beha io o he speci ic alloys ha a e sui able o addi i e p oduc ion, such as he CoC Mo and Ti6Al4V alloys, in join implan simula ions. This s udy in es iga es he beha io o syno ial luid in he con ac egion o ex u ed specimens made o Ti6Al4V alloy using colo ime ic in e e ome y and ic ion coe - icien . Colo ime ic in e e ome y was p o en o b ing an essen ial insigh in o assessing lub ica ion mechanisms in hip eplacemen s be o e [62]. Subsequen ly, he esul s a e compa ed wi h hose o a con en ional CoC Mo alloy. In addi ion, a en ion is paid o he DLy e me hod, which has he po en ial o modi y he inal su ace in e ms o local i egula i ies. 2 Ma e ials andMe hods 2.1 Appa a us The analysis o he lub ica ion ilm o ma ion and he ic- ion was conduc ed using a ecip oca ing mo ion simu- la o wi h a pin-on-pla e con igu a ion. This allowed o simul aneous obse a ion o he con ac and insi u ic ion measu emen s. Figu e1 displays he design o he de ice, which was modi ied om he one used by Čípek e al. o ca ilage analysis [63, 64]. The de ice was equipped wi h a Fig. 1 Schema ic o he measu ing appa a us in a pin-on-pla e con igu a ion T ibology Le e s (2025) 73:1515 Page 6 o 18 colo ime ic in e e ome y appa a us o obse e he hick- ness o he lub ican ilm. The simula o ba h was hea ed o a empe a u e o 37°C o simula e he human body en i onmen . A glass pla e was moun ed on a mo able ca iage, which pe o med a ecip oca ing mo ion, while he specimen emained s a iona y. The o ma ion o he lub ica ion ilm was obse ed using an op ical imaging sys em ha included a mic oscope, a halogen ligh sou ce, a CMOS digi al high-speed came a (Phan om 710), and a PC. When he me al pin and he glass pla e came in o a con ac and we e illumina ed, he colo New on ings we e obse ed. Ha l e al. used a hin ilm colo ime ic in e - e ome y o e alua e he ilm hickness [65]. In ou s udy, he con ac su ace o he glass pla e was coa ed wi h a semi- e lec i e ch omium laye o inc ease he con as o he in e e ence inges. The ilm hickness e alua ion was based on h ee s eps: (1) The calib a ion cu es we e ob ained om an in e - e og am o a ligh ly loaded s a ic con ac , which was hen ma ched wi h he measu ed con ac p o ile. This p o ided in o ma ion abou he ela ionship be ween he colo and he ilm hickness. (2) In e e og ams o a ully loaded con ac du ing he ansla ion o he ca iage we e cap u ed using a high- speed came a (Phan om V710, Vision Resea ch, USA). (3) The hickness a any a bi a y loca ion o he con ac could be de e mined by ma ching he cap u ed in e - e og ams wi h he calib a ion cu es. 2.2 Samples A sample o an op ical glass BK270 wi h dimensions o 155 × 44 × 4mm was used as a pla e. One side o he glass was coa ed wi h a semi- e lec i e ch omium laye and he o he wi h an an i- e lec i e laye . The expe imen al pins we e made o wo main ma e ials used in he implan ology: he medical g ade cas CoC Mo alloy (ASTM-F75) and he Ti6Al4V alloy (ISO 5832-3). The CoC Mo pin was manu ac u ed om a cold-d awn ba , cu and u ned unde he same cu ing condi ions as he con en ional join eplacemen implan s. The adius o he head o he pin was R100 and he diame e o he pin was 9.7mm. The ball su ace was u he polished o he equi ed minimum oughness Rq o 0.012 ± 0.005μm. The Ti6Al4V pin was manu ac u ed om a 10-mm-diame e cold-d awn ba and hen machined and polished o achie e he same geome y and su ace inish as he CoC Mo pin. The su ace geome y o he samples was e alua ed be o e he expe imen s. An op ical p o ilome e based on phase-shi ing in e e ome y (B uke , Con ou GT-X8) was used o analyze he su ace oughness (Rq) in he con ac a ea wi h dimensions o 1 × 1.2mm co e ing a heo e ically calcula ed ci cula con ac a ea wi h adii o 0.06mm. The dis ibu ion o he mic o- ex u es was chosen o be iangula , wi h he basic elemen o his la ice being an equila e al iangle o side leng h 42.7µm. The shape o he mic o- ex u e i sel was ci cula , while he bo om o he ex u e was la as a as possible (Fig.2). This ex u e shape Fig. 2 Dis ibu ion and geome y o he ex u es on he su ace o he samples T ibology Le e s (2025) 73:15 Page 7 o 18 15 was chosen because i is easy o ab ica e wi h a picosecond lase while main aining he geome ic epea abili y a each pi . The ci cula shape also gi es us he ad an age o he consis ency o he ilm beha io e en wi h changes in he di ec ion o he mo ion, which is expec ed due o i s use in an a icula ing implan . A schema ic o he a angemen and shape o he ex u e is shown in Fig.2. Based on he esul s o he li e a u e sea ch, he mos e ec i e co e age densi y Sp o 15% was chosen in e ms o he lub ican ilm o ma- ion, conside ing he numbe o ex u es in con ac wi h he ma e ials a ull load. The condi ion was he pa icipa ion o a leas 5 ex u es in he con ac a ea, which is ensu ed in he gi en con igu a ion. The chosen a iable pa ame e is he a io ε. In o de o a y he alue in he ange o 0.01–0.2, which is gi en in he li e a u e as he mos e ec i e alue o he gi en co e age, he only a iable pa ame e le is he ex u e dep h dp. Fo his eason, 5 ex u e pa ame e s we e chosen (dp 0.4–6μm). The dis ance be ween he cen - e s o he dimples was 74μm, and he adii o he dimples we e 15μm. The ex u es we e c ea ed using a lase mic omachining wi h a picosecond lase [Pe la 100 (Hilase)] o minimize he he mal impac on he su ace. The lase ope a ed a a wa eleng h o 1030nm, a pulse leng h o 1ps, a epe i ion a e o 60kHz, and a maximum pulse ene gy o 1mJ. The lase beam was guided h ough a ha monic equency a enu- a o and an op ical combine . The lase beam was guided h ough a sys em o mi o s o an In elliscan 14 (Scanlab) scanning head, which was placed on a sliding z-axis s age. The ex u es we e ab ica ed a an a e age powe o 72 mW, mo ing he lase beam along a spi al ajec o y a speeds up o 400mm/s. Ten samples we e c ea ed o each ma e ial, wi h each ex u e (0.4–6 dep hs). The DLy e me hod was used o emo e he sha p ims ha we e p oduced du ing he p ocess on he ex u e. The CoC Mo pins we e polished using CoC DLy e MIX MSA-S H FOR S100 elec oly e, while Ti DLy e MIX MSA PLUS-S elec oly e was used o polishing i anium samples. 2.3 Lub ican The model solu ion comp ised bo ine se um albumin (BSA, Sigma Ald ich A7030, Da ms ad , Ge many), bo ine se um y-globulin (BSG, Sigma Ald ich G5009, Da ms ad , Ge - many), hyalu onic acid wi h a molecula weigh o 1000kDa (HA), and phospholipids. The cons i uen s we e added o a phospha e-bu e ed saline (PBS). Concen a ions co e- sponded o he composi ion o he syno ial luid o pa ien s a e a o al join a h oplas y (albumin 26.3mg/ml, y-glob- ulin 8.2mg/ml, Phospholipids 0.35mg/ml, Hyalu onic acid 0.82mg/ml) [66]. The lub ican s we e hawed p io o he es ing and s o ed in a e ige a o o ensu e a comple e p o- ein dissolu ion in he PBS. Each expe imen used a o al olume o 14ml o lub ican and was conduc ed unde ully looded condi ions o a oid con ac s a a ion. 2.4 Expe imen al Design The kinema ic condi ions o he expe imen we e de i ed om he kinema ics o he i s me a a sophalangeal (MTP) join . Acco ding o Du an e al.'s s udy [67], he MTP join unde goes a 65° o a ion. The angula alues o he ini ial and he inal declina ion di e acco ding o he physiology, gai ype, and join damage o each pe son. Howe e , an angle o 65° ep esen s he mean alue o an a e age pe son [39, 40]. Fo he MTP join implan s, a head and a socke wi h a adius o R100 we e used. The a c pa h leng h was calcula ed as he p oduc o he adius and angle in adians, esul ing in an app oxima e leng h o 11.3mm. Howe e , due o he ibome e condi ions, he leng h was inc eased o 20mm. Each cycle in ol ed a back-and- o h mo ion, esul - ing in a o al cycle leng h o 40mm. The equency o he mo emen was 0.5Hz, esul ing in a speed o 20mm/s o a 40mm pa h. The kinema ic condi ions o he expe imen a e summa ized in Table1. The load o 0.5 N was applied o bo h mic o- ex u es. Fo he CoC Mo compa ed o glass, he con ac a ea diame e was 180μm and he con ac p es- su e was 29.6MPa. Fo he Ti6Al4V compa ed o glass, he con ac a ea diame e was 191μm and he con ac p essu e was 26.3MPa. The con ac a ea diame e and p essu e we e calcula ed using he con ac He z heo y. The o e all design o he expe imen was de ised wi h he objec i e o obse ing phenomena in he con ac egion, o gain some undamen al insigh s and compa isons. In his con ex , se e al simpli ica ions we e made o he in i o condi ions in compa ison o he eal in i o condi ions in he MTP join . The p ima y limi a ion is he non-con o mal su ace and he associa ed inc ease in con ac p essu e o a highe ange o alues ha occu a he join s. Concu en ly, he al e a ion in con ac p essu e esul s in he eplacemen o he a icula ing pai wi h a anspa en glass wi h a lowe Young's modulus han he Ti6Al4V alloy. These di e ences can a ec he hickness o he lub ica ing ilm, which can ul ima ely ha e a nega i e e ec on he o e all wea . The e- o e, hese limi a ions mus be conside ed in any wea e alu- a ion and long- e m wea es s [68, 69]. Fo each ex u e, including he e e ence wi hou ex u e (six samples), a single measu emen was conduc ed, com- p ising h ee consecu i e cycles. A schema ic o he expe i- men is p esen ed in Fig.3. 2.5 Da a P ocessing The ibological beha io o he lub ican and he implan ma e ials was e alua ed based on wo main pa ame e s: he coe icien o ic ion (CoF) and he ilm hickness. T ibology Le e s (2025) 73:1515 Page 8 o 18 The coe icien o ic ion was measu ed in h ee con- secu i e cycles, which we e hen combined in o a single g aph. The discon inui y o he measu emen s in o indi- idual cycles was necessa y due o he memo y capaci y o he high-speed came a. The sampling equency was 50Hz, esul ing in he ic ion coe icien alues ob ained o ime pe iods o 0.02s. Fil e ing and da a p ocessing we e conduc ed using MATLAB so wa e. The da a we e il e ed based on a 5% de ia ion om he mean eloc- i y o emo e he ou lie s and he da a om he mo ion change sec ions whe e he null eloci y was eached. The ilm hickness was quan i ied using he colo ime ic in e - e ome y. The undamen al p inciple o his me hod is he op ical eco ding o he con ac a ea, cap u ed a a a e o 100 ames/s. The ames we e ex ac ed om he scanned da a a egula in e als. The glass pa o he simula o was mo ed a a cons an speed along he pin. This esul ed in 20 ames o e alua ion a 20 cycles. The in e e og ams we e e alua ed using a cus om so wa e [65]. In each o he 20 ames, h ee e e ence loca ions in he con ac a ea we e selec ed, and he a e age hickness o he lub ica ing ilm was de e mined. The inal alue o one cycle was calcula ed as an a i hme ic mean o hese h ee alues. Fo each measu emen , a o al o 20 a e age hicknesses we e ob ained, esul ing in 60 alues in h ee cycles o each ma e ial pai es ed. 3 Resul s andDiscussion The esul s p esen ed conce n he mic o- ex u ed su ace and i s in luence on he coe icien o ic ion, wi h he objec i e o desc ibing he lub ica ion egime using he obse ed ilm hickness in he con ac a ea. The main con ibu ion is he use o Ti6Al4V alloy, which has he po en ial o u u e use in he ab ica ion o indi idualized implan s using addi i e manu ac u ing. The esea ch is mainly conce ned wi h he desc ip ion o he ibologi- cal p ocesses in he con ac egion, wi h he objec i e o p epa ing he basis o u he necessa y su ace ea - men s imp o ing wea esis ance. The CoC Mo alloy was employed as a e e ence, enabling esul s compa ison. The a icula ing su ace was hen augmen ed wi h a ange o mic o- ex u es, which we e subsequen ly modi ied by elec ochemical machining. This allowed o he in es iga- ion o he impac o hese modi ica ions on he lub ica- ion p ocesses in he con ac a ea. The a ionale behind modi ying he su ace in his manne is o iden i y op imal condi ions o he o ma ion o a ilm capable o sepa a ing he a icula ing su aces, he eby educing he quan i y o loose ab asi e pa icles. Table 1 Expe imen al condi ions (A) sample cha ac e is ics, (B) kinema ic condi ions (A) Samples Ma e ial Semi- inished p oduc Young’s modulus (GPa) Poisson’s a ios Con ac p essu e pin on pla e (MPa) Pin ( adii 100mm) Ti6Al4V alloy Ba 114 0.34 26.3 CoC Mo alloy Ba 230 0.28 29.6 Pla e Bo osilica e glass B270 62 0.22 – Albumin γ-Globulin Phospholipids Hyalu onic acid 26.3 8.2 0.35 0.82 (B) Load (N) Veloci y (mm/s) S oke (mm) To al dis ance (mm) Numbe o cycles Du a ion (s) Tempe a u e (°C) 0.5 20 20 2400 60 120 37 Fig. 3 Expe imen al se -up T ibology Le e s (2025) 73:15 Page 9 o 18 15 3.1 Su ace Topog aphy In he ini ial s age o he s udy, he a icula ing su aces o he samples we e e alua ed wi hou ex u e, and subse- quen ly, a e ex u e p oduc ion and elec ochemical ea - men wi h DLy e. The ini ial su ace was polished o achie e a oughness alue below 10nm (wi hou ex u e), which mee s he ISO 7206-2 s anda d o a icula ing su aces o me allic implan s [70]. The su ace i sel was also e alua ed in e ms o i s o e all geome y, wi h espec o he pos- sible in luence on he con ac a ea and, hus he con ac p essu e o be induced [71]. O e all, a de ia ion o up o 10% o he equi ed nominal adius R100 was accep ed. This de ia ion was based on he accu acy o he measu emen s hemsel es and he manu ac u ing capabili ies. I was also conside ed ha he specimens we e manu ac u ed using he same me hod as commonly used implan s, which gua an- eed he same manu ac u ing de ia ions and su ace quali y achie ed in endop os he ics. Howe e , an issue a ose in he e alua ion o he o e all su ace wa iness, whe e i egula i- ies we e mo e equen , which in luenced he shape o he con ac a ea. Based on hese condi ions, he specimens ha demons a ed he mos a o able esul s in he analysis o he con ac a ea we e selec ed. The samples we e hen ex u ed wi h i e di e en ex u e dep hs o he same dis ibu ion and diame e using a picosecond lase . Lase su ace ex u ing p ocess has a he mal abla ion p ocess, due o hese high empe a u es a e encoun e ed a ound he dimple and cause mic os uc u al changes, esidual he mal s esses, im o - ma ion in he lase -i adia ed zone and subs a e [72]. As he dep h o he ex u e inc eased, he im o dimples ela i e o he e e ence su ace also inc eased. This was caused by he g ea e ma e ial emo al and ma e ial mel ing a he im o he ex u e. Some la ge ims (270–380nm) a ound he dim- ples (2–6µm) we e obse ed o he Ti6Al4V alloy (Fig.4C, D). Fo he CoC Mo, he ims we e signi ican ly lowe , he maximum im heigh s we e up o 270nm. To elimina e hese inequali ies, he elec ochemical me hod DLy e has p o en and led o a ela i e dec ease in he ims o bo h ma e ials. Howe e , despi e he emo al o he ims, his me hod p o ed o be unsui able o he CoC Mo alloy. E en a sho exposu e wi h he DLy e me hod (0.4s) esul ed in he emo al o ims, a he same ime i led o damage o he es o he su ace, se e ely damaging he obse ed a ea and making u he e alua ion o he esul s impos- sible. This phenomenon can be obse ed in he plo o o al oughness (Fig.4A, B), whe e no able disc epancies we e obse ed in he CoC Mo alloy. Se e al s udies ound ha Co–C –Mo alloys ha e a dend i ic su ace s uc u e wi h a 1 o 4nm hick oxide laye , p o iding a co osion ba ie in he human body. Co osion ba ie can a ec p ocesses du ing elec ochemical machining, which p e en s us om c ea ing an ideal geome y wi h a uni o m con ac su ace. Fo his eason, he esul s om colo ime ic in e e ome y Fig. 4 A e age su ace ough- ness wi h masked ex u e: A Ti6Al4V, B CoC Mo, im heigh o ex u es o Ti6Al4V: C be o e DLy e, D a e DLy e T ibology Le e s (2025) 73:1515 Page 16 o 18 and analyzed he expe imen s and w o e he o iginal d a o he man- usc ip . D. Nečas, M. Ha l and I. Křupka supe ised he s udy. M. V bka supe ised and inanced he s udy. Funding This esea ch was ca ied ou unde he P ojec “F ic- ion and lub ica ion o small join implan s p oduced by 3D me al p in ing addi i e echnology” unded by he Czech Science Foun- da ion, No. 22-02154S and by he P ojec “Mechanical Enginee - ing o Biological and Bio-inspi ed Sys ems,” unded as P ojec No. CZ.02.01.01/00/22_008/0004634 by P og amme Johannes Amos Commenius, Call Excellen Resea ch, adminis e ed by he Minis y o Educa ion, Spo s and You h. Also, hanks o P oSpon, spol. s . o. company o he p epa a ion o he samples. Da a A ailabili y The da a ha suppo he indings o his s udy a e openly a ailable in eposi o y Zenodo a h p:// doi. o g/h ps:// doi. o g/ 10. 5281/ zenodo. 13235 495. Decla a ions Con lic o in e es The au ho s decla e no con lic o in e es . Open Access This a icle is licensed unde a C ea i e Commons A i- bu ion 4.0 In e na ional License, which pe mi s use, sha ing, adap a- ion, dis ibu ion and ep oduc ion in any medium o o ma , as long as you gi e app op ia e c edi o he o iginal au ho (s) and he sou ce, p o ide a link o he C ea i e Commons licence, and indica e i changes we e made. The images o o he hi d pa y ma e ial in his a icle a e included in he a icle’s C ea i e Commons licence, unless indica ed o he wise in a c edi line o he ma e ial. I ma e ial is no included in he a icle’s C ea i e Commons licence and you in ended use is no pe mi ed by s a u o y egula ion o exceeds he pe mi ed use, you will need o ob ain pe mission di ec ly om he copy igh holde . To iew a copy o his licence, isi h p://c ea i ecommons.o g/licenses/by/4.0/. Re e ences 1. Siddiqi, A., Le ine, B.R., Sp inge , B.D.: Highligh s o he 2021 Ame ican Join Replacemen Regis y Annual Repo . A h o- plas y Today 13, 205–207 (2022) 2. C oes, M., Akha an, B., Sha i ahmadian, O., Fan, H., Me ens, R., Tan, R.P., e al.: A mul i ace ed biomime ic in e ace o imp o e he longe i y o o hopedic implan s. Ac a Bioma e . 110, 266– 279 (2020) 3. Fashanu, F.F., Ma cellin-Li le, D.J., Linke, B.S.: Re iew o su ace inishing o addi i ely manu ac u ed me al implan s. In: P oceedings o he ASME 2020 15 h In e na ional Manu ac u ing Science and Enginee ing Con e ence MSEC2020, 2020 (2020) 4. Ma ian, M., Shah, R., Gashi, B., Zhang, S., Bha nani, K., Wa - zack, S., e al.: Explo ing he lub ica ion mechanisms o syno ial luids o join longe i y—a pe spec i e. Colloids Su . B 206, 111926 (2021) 5. Sing, S.L., Tey, C.F., Tan, J.H.K., Huang, S., Yeong, W.Y.: Chap 2: 3D p in ing o me als in apid p o o yping o bioma e ials: echniques in addi i e manu ac u ing. In: Na ayan, R. (ed.) Rapid P o o yping o Bioma e ials, 2nd edn., pp. 17–40. Woodhead Pub- lishing, Saws on (2020) 6. Khimich, M.A., Ib agimo , E.A., Chebodae a, V.V., P osolo , K.A., Tolmache , A.I., Glukho , I.A., e al.: F om aw elemen s o 3D samples: an economical ou e o Co–C –Mo alloy ab ica- ion. J. Alloys Compd. 978, 173460 (2024) 7. S amenko ić, D., Popo ić, M., Rudol , R., Z ilić, M., Raić, K., Đu ičić, K.O., e al.: Compa a i e s udy o he mic os uc u e and p ope ies o cas - ab ica ed and 3D-p in ed lase -sin e ed Co–C alloys o emo able pa ial den u e amewo ks. Ma e ials 16(8), 3267 (2023) 8. Oc an, E.K., Guen he , L.E., B and , J.-M., Wyss, U., Ojo, O.A.: Co osion and e ing co osion s udies o medical g ade CoC Mo alloy in a clinically ele an simula ed body luid en i- onmen . Me all. Ma e . T ans. A 46, 2696–2709 (2015) 9. Me ikoš-Huko ić, M., Babić, R.: Passi a ion and co osion beha - iou s o cobal and cobal –ch omium–molybdenum alloy. Co os. Sci. 49, 3570–3579 (2007) 10. Chen, Y., Li, Y., Ku osu, S., Meng, Q., Tang, N., Koizumi, Y., e al.: Analysis o in i o wea beha io and con ac mechanisms o me al-on-me al hip join bea ings wi h di e en adial clea - ances. Ma e . T ans. (2015). h ps:// doi. o g/ 10. 2320/ ma e ans. M2014 440 11. de Cas o Gi ão, D., Bé eš, M., Ja dini, A.L., Filho, R.M., Sil a, C.C., de Sie o, A., e al.: An assessmen o biomedical CoC Mo alloy ab ica ed by di ec me al lase sin e ing echnique o implan applica ions. Ma e . Sci. Eng. C 107, 110305 (2020) 12. Dawei, L., Lihai, C., Yuqiang, M., Yandong, W., Xinghua, W., Pengcheng, R., e al.: The imp o ed s eng h and ac u e mecha- nism o addi i e manu ac u ed Ti–6Al–4V alloys compa ed wi h co esponding as- olled alloys. J. Ma e . Res. 39, 891–902 (2024) 13. Nagha i, S.A., Tamaddon, M., Ga cia-Sou o, P., Moazen, M., Taylo , S., Hua, J., e al.: A no el hyb id design and modelling o a cus omised g aded Ti–6Al–4V po ous hip implan o educe s ess-shielding: an expe imen al and nume ical analysis. F on . Bioeng. Bio echnol. (2023). h ps:// doi. o g/ 10. 3389/ bioe. 2023. 10923 61 14. G ü zmache , P.G., P o i o, F.J., Rosenk anz, A.: Mul i-scale su - ace ex u ing in ibology—cu en knowledge and u u e pe - spec i es. Lub ican s 7(11), 95 (2019) 15. Ma ian, M., Almq is , A., Rosenk anz, A., Fillon, M.: Nume i- cal mic o- ex u e op imiza ion o lub ica ed con ac s—a c i ical discussion. F ic ion 10, 1772–1809 (2022) 16. Sagbas, B., Du akbasa, N.: Su ace ex u ing o i amin E blended UHMWPE o educ ion o wea . Ac a Phys. Pol. A 125, 481–483 (2014) 17. I o, H., Kaneda, K., Yuh a, T., Nishimu a, I., Yasuda, K., Ma - suno, T.: Reduc ion o polye hylene wea by conca e dimples on he ic ional su ace in a i icial hip join s. J. A h oplas y 15, 332–338 (2000) 18. Gacho , C., Rosenk anz, A., Hsu, S.M., Cos a, H.L.: A c i ical assessmen o su ace ex u ing o ic ion and wea imp o e- men . Wea 372–373, 21–41 (2017) 19. Lu, X., Khonsa i, M.M.: An expe imen al in es iga ion o dimple e ec on he S ibeck cu e o jou nal bea ings. T ibol. Le . 27, 169–176 (2007) 20. Ko alchenko, A., Ajayi, O., E demi , A., Fenske, G., E sion, I.: The e ec o lase ex u ing o s eel su aces and speed-load pa ame e s on he ansi ion o lub ica ion egime om bounda y o hyd odynamic. T ibol. T ans. 47, 299–307 (2004) 21. Shen, G., Fang, F., Kang, C.: T ibological pe o mance o bio- implan s: a comp ehensi e e iew. Nano echnol. P ecis. Eng. 1, 107–122 (2018) 22. Wei, X., Li, W., Liang, B., Li, B., Zhang, J., Zhang, L., e al.: Su ace modi ica ion o Co–C –Mo implan alloy by lase in e e - ence li hog aphy. T ibol. In . 97, 212–217 (2016) 23. Pe e sson, U., Jacobson, S.: F ic ion and wea p ope ies o mic o ex u ed DLC coa ed su aces in bounda y lub ica ed sliding. T i- bol. Le . 17, 553–559 (2004) 24. Nakano, M., Ko enaga, A., Ko enaga, A., Miyake, K., Mu akami, T., Ando, Y., e al.: Applying mic o- ex u e o cas i on su aces o educe he ic ion coe icien unde lub ica ed condi ions. T ibol. Le . 28, 131–137 (2007) T ibology Le e s (2025) 73:15 Page 17 o 18 15 25. Odehnal, L., Ranuša, M., V bka, M., Křupka, I., Ha l, M.: T ibo- logical beha iou o Ti6Al4V alloy: an applica ion in small join implan s. T ibol. Le . 71, 125 (2023) 26. Nečas, D., V bka, M., Křupka, I., Ha l, M.: The e ec o kin- ema ic condi ions and syno ial luid composi ion on he ic ional beha iou o ma e ials o a i icial join s. Ma e ials 11(5), 767 (2018) 27. Wang, F.C., B ocke , C., Williams, S., Udo ia, I., Fishe , J., Jin, Z.M.: Lub ica ion and ic ion p edic ion in me al-on-me al hip implan s. Phys. Med. Biol. 53, 1277 (2008) 28. Whi by, R.D.: Coe icien o ic ion in a i icial join s. T ibol. Lub . Technol. 74, 84–84 (2018) 29. Mils ey, A., Domnick, C., Ga cia, P., Raschke, M., E e s, J., Ochman, S.: T ends in a h odeses and o al join eplacemen s in oo and ankle su ge y in Ge many du ing he pas decade—back o he usion? Foo Ankle Su g. 27(3), 301–304 (2020) 30. B ews e , M.: Does o al join eplacemen o a h odesis o he i s me a a sophalangeal join yield be e unc ional esul s? A sys ema ic e iew o he li e a u e. J. Foo Ankle Su g. 49, 546– 552 (2010) 31. She e , M.J., Bejjani, F.J., Kumme , F.J.: Kinema ics o he i s me a a sophalangeal join . J. Bone J Su g. 68(3), 392–398 (1986) 32. Zhang, Y., Aw ejcewicz, J., Szymanowska, O., Shen, S., Zhao, X., Bake , J.S., e al.: E ec s o se e e hallux algus on me a a sal s ess and he me a a sophalangeal loading du ing balanced s and- ing: a ini e elemen analysis. Compu . Biol. Med. 97, 1–7 (2018) 33. Mo gan, O.J., Hills om, H.J., Bi a , R., S u nick, D., Ko , M.F., Ellis, S.J., e al.: Fini e elemen modeling o planus and ec us oo ypes o he s udy o i s me a a sophalangeal and i s me a a - socunei o m join con ac mechanics. J. Biomech. Eng. 144(8), 081005 (2022) 34. Ranuša, M., Čípek, P., V bka, M., Paloušek, D., Křupka, I., Ha l, M.: T ibological beha iou o 3D p in ed ma e ials o small join implan s: a pilo s udy. J. Mech. Beha . Biomed. Ma e . 132, 105274 (2022) 35. Wang, H., Zheng, J., Sun, X., Luo, Y.: T ibo-co osion mecha- nisms and elec omechanical beha iou s o me al implan s ma e- ials o CoC Mo, Ti6Al4V and Ti15Mo alloys. Biosu . Bio ibol. 8, 44–51 (2022) 36. P a ap, T., Pa a, K.: T ibological pe o mances o symme ically mic o- ex u ed Ti–6Al–4V alloy o hip join . In . J. Mech. Sci. 182, 105736 (2020) 37. C eme , L., No je, B.D., an de Me we, J., Becke , T.H.: Wea o con en ional UHMWPE a icula ing agains addi i ely manu- ac u ed Ti–6Al–4V and Co–C –Mo. Bio ibology 33–34, 100231 (2023) 38. Sulli an, S.J.L., Topoleski, L.D.T.: Su ace modi ica ions o imp o ed wea pe o mance in a i icial join s: a e iew. JOM 67, 2502–2517 (2015) 39. Niemczewska-Wójcik, M., Piekoszewski, W.: The su ace ex u e and i s in luence on he ibological cha ac e is ics o a ic ion pai : me al–polyme . A ch. Ci . Mech. Eng. 17, 344–353 (2017) 40. Allen, Q., Raeymaeke s, B.: Su ace ex u ing o p os he ic hip implan bea ing su aces: a e iew. J. T ibol. 143, 040801 (2021) 41. Sol ani-Ko dshuli, F., Choudhu y, D., Goss, J.A., Campbell, M., Smi h, E., Sonn ag, S., e al.: Ca ilage-inspi ed su ace ex u es o imp o ed ibological pe o mance o o hopedic implan s. J. Mech. Beha . Biomed. Ma e . 138, 105572 (2023) 42. Long, R., Li, M., Jin, Z., Zhang, Y., Han, H.: T ibological beha io o pi s ex u ed mul i- olle s sliding– olling ibo-pai unde pe iodic a ied load and d y wea . Ad . Mech. Eng. 14, 16878132221092520 (2022) 43. A ulkuma , M., P ashanna Rangan, R., P em Anan h, M., S i - idhyasak hi, V., Aadi ya, R.: Expe imen al e i ica ion on he in luence o su ace ex u ing on bioma e ials and s udy o i s ibological cha ac e is ics. Ma e . Today P oc. (2023). h ps:// doi. o g/ 10. 1016/j. ma p . 2023. 01. 172 44. Al a ez-Ve a, M., O ega-Saenz, J.A., He nandez-Rod íguez, M.A.L.: A s udy o he wea pe o mance in a hip simula o o a me al–me al Co–C alloy wi h di e en bo on addi ions. Wea 301, 175–181 (2013) 45. Vishnoi, M., Kuma , P., Mu aza, Q.: Su ace ex u ing echniques o enhance ibological pe o mance: a e iew. Su . In e aces 27, 101463 (2021) 46. Yu, H., Deng, H., Huang, W., Wang, X.: The e ec o dimple shapes on ic ion o pa allel su aces. P oc. Ins . Mech. Eng. J 225, 693–703 (2011) 47. Allen, Q., Raeymaeke s, B.: Su ace ex u ing o p os he ic hip implan bea ing su aces: a e iew. J. T ibol. 143(4), 040801 (2020) 48. Schneide , J., B aun, D., G eine , C.: Lase ex u ed su aces o mixed lub ica ion: in luence o aspec a io, ex u ed a ea and dimple a angemen . Lub ican s 5(3), 32 (2017) 49. Wang, X., Ka o, K., Adachi, K., Aizawa, K.: The e ec o lase ex u ing o SiC su ace on he c i ical load o he ansi ion o wa e lub ica ion mode om hyd odynamic o mixed. T ibol. In . 34, 703–711 (2001) 50. Qiu, M., Delic, A., Raeymaeke s, B.: The e ec o ex u e shape on he load-ca ying capaci y o gas-lub ica ed pa allel slide bea ings. T ibol. Le . 48, 315–327 (2012) 51. Li, K., Yao, Z., Hu, Y., Gu, W.: F ic ion and wea pe o mance o lase peen ex u ed su ace unde s a ed lub ica ion. T ibol. In . 77, 97–105 (2014) 52. Raeymaeke s, B., E sion, I., Talke, F.E.: A model o magne ic ape/guide ic ion educ ion by lase su ace ex u ing. T ibol. Le . 28, 9–17 (2007) 53. Zhang, H., Qin, L., Hua, M., Dong, G., Chin, K.-S.: A ibologi- cal s udy o he pe aloid su ace ex u ing o Co–C –Mo alloy a i icial join s. Appl. Su . Sci. 332, 557–564 (2015) 54. Choudhu y, D., V bka, M., Mama , A.B., S a ness, I., Roy, C.K., Moo anah, R., e al.: The impac o su ace and geome y on coe icien o ic ion o a i icial hip join s. J. Mech. Beha . Biomed. Ma e . 72, 192–199 (2017) 55. B aun, D., G eine , C., Schneide , J., Gumbsch, P.: E iciency o lase su ace ex u ing in he educ ion o ic ion unde mixed lub ica ion. T ibol. In . 77, 142–147 (2014) 56. Nečas, D., Usami, H., Niimi, T., Sawae, Y., Křupka, I., Ha l, M.: Running-in ic ion o hip join eplacemen s can be sig- ni ican ly educed: he e ec o su ace- ex u ed ace abula cup. F ic ion 8, 1137–1152 (2020) 57. Alla, R.K., Ginjupalli, K., Upadhya, N., Shammas, M., Ra i, R.K., Sekha , R.: Su ace oughness o implan s: a e iew. T ends Bioma e . A i . O gans 25, 112–118 (2011) 58. Hashmi, A.W., Mali, H.S., Meena, A., Saxena, K.K., Ahmad, S., Ag awal, M.K., e al.: A comp ehensi e e iew on su ace pos - ea men s o ee o m su aces o bio-implan s. J. Ma e . Res. Technol. 23, 4866–4908 (2023) 59. Kalman, L., Kalman, B.: P elimina y assessmen o d y elec- opolishing echnology on a no el addi i e manu ac u ed Ti–6Al–4V implan abu men . Jpn J. Res. 2, 1–4 (2021) 60. Guioma Riu, P., Joan Josep Roa, R.: Chap e 7: can he D y- Ly e® echnology polish 3D p in ed ce amic/me al samples and in pa icula WC-Co? In: Ashu osh, S. (ed.) Ad ances in 3D P in ing. In echOpen, London (2023) 61. Jä enpää, A., Kim, D.B., Män yjä i, K.: Chap e 14: me al addi i e manu ac u ing. In: Khoshnaw, F. (ed.) Welding o Me allic Ma e ials, pp. 493–536. Else ie , Ams e dam (2023) 62. Nečas, D., V bka, M., Gallo, J., Křupka, I., Ha l, M.: On he obse a ion o lub ica ion mechanisms wi hin hip join eplace- men s. Pa II: ha d-on-ha d bea ing pai s. J. Mech. Beha . Biomed. Ma e . 89, 249–259 (2019) T ibology Le e s (2025) 73:1515 Page 18 o 18 63. Čípek, P., Rebenda, D., Nečas, D., V bka, M., K upka, I., Ha l, M.: Visualiza ion o lub ica ion ilm in model o syno ial join . T ibol. Ind. 41, 387–393 (2019) 64. Čípek, P., V bka, M., Rebenda, D., Nečas, D., Křupka, I.: Bio i- bology o syno ial ca ilage: a new me hod o isualiza ion o lub ica ing ilm and simul aneous measu emen o he ic ion coe icien . Ma e ials 13, 2075 (2020) 65. Ha l, M., K upka, I., Poliscuk, R., Liska, M., Molima d, J., Que y, M., e al.: Thin ilm colo ime ic in e e ome y. T ibol. T ans. 44, 270–276 (2001) 66. Galandako a, A., Ul icho a, J., Lango a, K., Hanako a, A., V bka, M., Ha l, M., e al.: Cha ac e is ics o syno ial luid equi ed o op imiza ion o lub ica ion luid o bio ibological expe imen s. J. Biomed. Ma e . Res. B 105, 1422–1431 (2017) 67. Du an , M., Du an , L., McEl oy, T.: Es ablishing a common ins an aneous cen e o o a ion o he me a a so-phalangeal and me a a so-sesamoid join s: a heo e ical geome ic model based on speci ic mo phome ics. J. O hop. Su g. Res. 14, 107 (2019) 68. Myan , C., Unde wood, R., Fan, J., Cann, P.M.: Lub ica ion o me al-on-me al hip join s: he e ec o p o ein con en and load on ilm o ma ion and wea . J. Mech. Beha . Biomed. Ma e . 6, 30–40 (2012) 69. Myan , C.W., Cann, P.: The e ec o ansien condi ions on syno ial luid p o ein agg ega ion lub ica ion. J. Mech. Beha . Biomed. Ma e . 34, 349–357 (2014) 70. ISO: ISO 7206–2 I: Implan s o Su ge y—Pa ial and To al Hip Join P os heses Pa 2: A icula ing Su aces Made o Me allic, Ce amic and Plas ics Ma e ials, p. 5. ISO, Gene a (2011) 71. Cubillos, P.O., Dos San os, V.O., Pizzola i, A.L.A., Mo é, A.D.O., Roesle , C.R.M.: Su ace inish o o al hip a h oplas y implan s: a e we e alua ing and manu ac u ing hem app op i- a ely? J. Tes . E al. 49, 4550–4559 (2021) 72. P asad, N., Syed, I., Subbu, S.: Lase dimple ex u ing—appli- ca ions, p ocess, challenges, and ecen de elopmen s: a e iew. Aus . J. Mech. Eng. 20, 1–16 (2019) 73. Ţălu, Ş, S ach, S., Klaić, B., Čelebić, A.: e alua ion o opog aphi- cal Co–C –Mo alloy su ace changes a e a ious inishing ea - men s. Ac a S oma ol. C oa . 53, 264–273 (2019) 74. Celebic, A., S e licic, V., Malina, J., Klaic, B.: Co–C –Mo alloy su ace ea u es and composi ion p io and a e mechanical polishing and co osion in luids simula ing o al condi ions. In: Bioma e ials De elopmen s and Applica ions, pp. 415–433. No a Science Publishe s, Hauppauge (2009). 75. Zhang, Y., Li, J., Che, S., Tian, Y.: Elec ochemical polishing o addi i ely manu ac u ed Ti–6Al–4V Alloy. Me . Ma e . In . 26, 783–792 (2020) 76. Odehnal, L., Ranuša, M., Wimme , M.A., V bka, M., Křupka, I.: De elopmen o lub ica ion ilm and in luence on ic ion in a o al knee eplacemen du ing a gai cycle. T ibol. In . 178, 108073 (2023) 77. Talha, M., Ma, Y., Kuma , P., Lin, Y., Singh, A.: Role o p o ein adso p ion in he bio co osion o me allic implan s—a e iew. Colloids Su . B 176, 494–506 (2019) 78. Ghosh, S., Choudhu y, D., Das, N.S., Pingguan-Mu phy, B.: T i- bological ole o syno ial luid composi ions on a i icial join s—a sys ema ic e iew o he las 10 yea s. Lub . Sci. 26, 387–410 (2014) 79. Woźniak, A., Bialas, O., Adamiak, M., Hadzima, B., Szewczenko, J.: The in luence o lase ex u ing on he ibological beha io o i anium alloy Ti6Al4V in medical applica ions. A ch. Ci . Mech. Eng. 24, 146 (2024) 80. Soneka , M.M., Ra hod, W.S.: An expe imen al in es iga ion on ibological beha io o bio-implan ma e ial (SS-316 l and Ti6Al4V) o o hopaedic applica ions. Ma e . Today P oc. 19, 444–447 (2019) 81. Lin, N., Li, D., Zou, J., Xie, R., Wang, Z., Tang, B.: Su ace ex u e-based su ace ea men s on Ti6Al4V i anium alloys o ibological and biological applica ions: a mini e iew. Ma e ials 11(4), 487 (2018) 82. P a ap, T., Pa a, K.: Mechanical mic o- ex u ing o Ti–6Al–4V su aces o imp o ed we abili y and bio- ibological pe o - mances. Su . Coa . Technol. 349, 71–81 (2018) 83. Choudhu y, D., Ghosh, S., Ali, F., V bka, M., Ha l, M., K upka, I.: The in luence o su ace modi ica ion on ic ion and lub ica- ion mechanism unde a bo ine se um lub ica ed condi ion. T i- bol. T ans. (2015). h ps:// doi. o g/ 10. 1080/ 10402 004. 2015. 10774 09 84. Yang, D., Sun, H., Ji, G., Xiang, Y., Wang, J.: E ec o elec oly ic plasma polishing on su ace p ope ies o i anium alloy. Coa ings 14(5), 615 (2024) 85. Inogamo , N.A., Zhakho sky, V.V., Ilni sky, D.K., Khokhlo , V.A.: Lase shock peening. J. Phys. Con . Se . 1787, 012024 (2021) Publishe 's No e Sp inge Na u e emains neu al wi h ega d o ju isdic ional claims in published maps and ins i u ional a ilia ions.