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Knee
knowledge
23. July 2026

Cus­tom, Tail­o­red Knee Prosthesis

Mo­dern Knee Re­pla­ce­ments – Why Cus­to­miza­tion Is So Im­portant Today

Mo­dern knee re­pla­ce­ment sur­gery has ad­van­ced si­gni­fi­cantly in re­cent ye­ars. Whe­reas in the past the same stan­dard ali­gnment was used for ne­arly all pa­ti­ents, to­day the fo­cus is in­cre­asingly on in­di­vi­dua­li­zed tre­at­ment plans.

To­day, state-of-the-art na­vi­ga­tion sys­tems, com­pu­ter-as­sis­ted pre­cis­ion tech­no­lo­gies, and mo­dern sur­gi­cal ro­bots make it pos­si­ble to tailor pro­ce­du­res much more pre­cis­ely to each individual’s uni­que ana­tomy. The goal is to res­tore the knee joint as na­tu­rally as pos­si­ble and achieve a har­mo­nious sense of movement.

Dr. Ma­xi­mi­lian Kas­pa­rek has been con­duc­ting ex­ten­sive re­se­arch on per­so­na­li­zed knee re­pla­ce­ments for many ye­ars and, tog­e­ther with Prim. Univ.-Doz. Dr. Tho­mas Müll­ner and his re­se­arch team, pu­blished re­cent cli­ni­cal data in the Jour­nal of Cli­ni­cal Me­di­cine (JCM). In the fol­lo­wing in­ter­view, he ex­plains in layman’s terms the ad­van­ta­ges mo­dern tech­no­lo­gies of­fer, for whom they are suitable—and where their li­mi­ta­ti­ons lie.

An in­ter­view with Priv.-Doz. DDr. Ma­xi­mi­lian Kas­pa­rek, MSc

Cus­tom Knee Re­pla­ce­ments Ex­plai­ned in Simple Terms

“Every knee is different—and tha­t’s exactly what we’re ta­king into ac­count today”
Dr. Kas­pa­rek, what exactly is meant by a “cus­tom knee replacement”?

In the past, knee re­pla­ce­ments were usually per­for­med ac­cor­ding to a highly stan­dar­di­zed pro­ce­dure. The goal was al­most al­ways a per­fectly straight leg—regardless of whe­ther the pa­ti­ent ori­gi­nally had bow­legs or knock-knees.

To­day, ho­we­ver, we know that every per­son has a uni­que knee ana­tomy. The leg axis, joint line, and li­ga­ment ten­sion of­ten vary si­gni­fi­cantly from per­son to person.

A mo­dern, cus­to­mi­zed knee re­pla­ce­ment the­r­e­fore me­ans, above all, a per­so­na­li­zed tre­at­ment plan. Our goal is to res­tore the knee as clo­sely as pos­si­ble to the con­di­tion it was in be­fore os­teo­ar­thri­tis set in.

Mo­dern na­vi­ga­tion sys­tems, com­pu­ter-as­sis­ted pre­cis­ion tech­no­lo­gies, state-of-the-art sur­gi­cal ro­bots, and pre­cise plan­ning sys­tems help us achieve this.

Is this a cus­tom-made prosthesis?

Not ne­ces­s­a­rily. We usually use tried-and-true stan­dard im­plants, which are, ho­we­ver, very pre­cis­ely ad­apted to the pa­ti­en­t’s in­di­vi­dual anatomy.

What mat­ters most is not so much the pro­sthe­sis its­elf, but ra­ther the in­di­vi­dua­li­zed plan­ning and pre­cise positioning.

Thanks to mo­dern na­vi­ga­tion sys­tems, com­pu­ter-as­sis­ted pre­cis­ion tech­no­lo­gies, and state-of-the-art sur­gi­cal ro­bots, we can now re­con­s­truct the na­tu­ral leg axis, joint line, and li­ga­ment ten­sion with much grea­ter ac­cu­racy than in the past.

Dif­fe­rence from a tra­di­tio­nal knee replacement

What is the most im­portant dif­fe­rence com­pared to the tra­di­tio­nal knee re­pla­ce­ment?

The big­gest dif­fe­rence lies in the philosophy.

In the past, at­tempts were made to align every knee ac­cor­ding to the same pat­tern. To­day, we fo­cus more on the pa­ti­en­t’s ori­gi­nal anatomy.

The goal isn’t sim­ply a “straight leg,” but a knee that feels as na­tu­ral as possible.
Many pa­ti­ents say af­ter surgery:
“I hardly ever think about my ar­ti­fi­cial knee in my daily life.”

That is exactly what the so-cal­led “For­got­ten Joint Score” describes—a sci­en­ti­fic me­a­sure of how na­tu­ral an ar­ti­fi­cial joint feels.

Does the dif­fe­rence re­late more to the plan­ning or to the sur­gery itself?

Both.

Mo­dern knee re­pla­ce­ment be­g­ins even be­fore sur­gery with a very de­tailed ana­ly­sis of the pa­ti­en­t’s in­di­vi­dual anatomy.

Du­ring the sur­gery, state-of-the-art na­vi­ga­tion sys­tems and sur­gi­cal ro­bots help us achieve the plan­ned po­si­tion with ex­treme precision.

As a re­sult, we of­ten need to make si­gni­fi­cantly fe­wer ad­jus­t­ments to the li­ga­ments than in the past, when the leg was fre­quently po­si­tio­ned in an un­na­tu­rally straight ali­gnment. This makes the pro­ce­dure less in­va­sive in many cases.

Does this also ch­ange the im­plan­ta­tion pro­ce­dure itself?

Yes.

With the tra­di­tio­nal tech­ni­que, stan­dar­di­zed bone cuts were fre­quently performed.

In mo­dern ki­ne­ma­tic or func­tional ali­gnment, we fo­cus more on the pa­ti­en­t’s na­tu­ral ana­tomy. The bone cuts are cus­to­mi­zed for each patient.

This helps pre­serve the na­tu­ral ten­sion of the li­ga­ments, the axes of mo­ve­ment, and of­ten the sen­sa­tion of mo­ve­ment as well.

What are the be­ne­fits of mo­dern na­vi­ga­tion and sur­gi­cal robots?

What prac­ti­cal be­ne­fits do you see?

In my opi­nion, the most im­portant be­ne­fit is the more na­tu­ral fee­ling in the knee.

Many pa­ti­ents re­port that their knee feels more sta­ble, more ba­lan­ced, and less “ar­ti­fi­cial.”

In ad­di­tion, we of­ten observe:

  • fas­ter mobilization
  • less stress on the soft tissues
  • fe­wer pro­ce­du­res on the ligaments
  • grea­ter mobility
  • more con­fi­dence in the knee
  • grea­ter sa­tis­fac­tion in ever­y­day life

Sci­en­ti­fic stu­dies also show im­pro­ve­ments in func­tion, ac­ti­vity, and pa­ti­ent satisfaction.

Is the main con­cern here ac­cu­racy, fit, or pro­tec­ting the soft tissues?

Ac­tually, it’s about everything.

As we found in our study, mo­dern na­vi­ga­tion and com­pu­ter-as­sis­ted pre­cis­ion tech­no­lo­gies now enable a very high de­gree of ac­cu­racy du­ring implantation.

For pa­ti­ents, this of­ten means:

  • pre­cise positioning
  • less un­neces­sary strain
  • fe­wer pro­ce­du­res in­vol­ving li­ga­ments and soft tissues
  • of­ten a fas­ter recovery
Do pa­ti­ents re­ally no­tice a difference?

A lot of them, yes.

Peo­ple who are par­ti­cu­larly ac­tive or pa­ti­ents with high func­tional de­mands of­ten re­port a more na­tu­ral fee­ling of movement.

Many peo­ple are once again able to walk lon­ger di­stances in their daily li­ves, climb stairs more ea­sily, or even re­sume exercising.

Of course, every knee re­pla­ce­ment is still an ar­ti­fi­cial joint. Our goal, ho­we­ver, is to make it feel as little like one as possible.

Who is a good can­di­date for a cus­tom knee replacement?

Are there also si­tua­tions in which tra­di­tio­nal care is appropriate?

Yes.

In ca­ses of se­vere li­ga­ment in­sta­bi­lity, com­plex prior sur­ge­ries, or cer­tain mis­a­lignments, a de­cis­ion must be made on a case-by-case ba­sis as to which tech­ni­que is most appropriate.

It’s im­portant to note that not every mo­dern tech­no­logy is au­to­ma­ti­cally the best so­lu­tion for every patient.

Ex­pe­ri­ence, careful plan­ning, and choo­sing the right me­thod re­main crucial.

Tre­at­ment Process

What exactly does the tre­at­ment involve?

First, a tho­rough ex­ami­na­tion is con­duc­ted using ra­dio­lo­gi­cal imaging.

In do­ing so, we ana­lyze, among other things:

  • Leg axis
  • Joint Line
  • Belt Ten­sion
  • in­di­vi­dual anatomy

This is fol­lo­wed by pre­cise sur­gi­cal planning.

Du­ring sur­gery, we use state-of-the-art na­vi­ga­tion sys­tems and sur­gi­cal ro­bots to achieve the plan­ned po­si­tio­ning as pre­cis­ely as possible—much like a GPS sys­tem for the surgeon.

Is the pro­ce­dure for pa­ti­ents dif­fe­rent from that of a stan­dard surgery?

For pa­ti­ents, usually very little.

The dif­fe­ren­ces mainly con­cern plan­ning and pre­cis­ion du­ring the operation.

The goal al­ways re­mains the same:
a safe sur­gery, as little pain as pos­si­ble, and a quick re­turn to mobility.

Sci­en­ti­fic Fin­dings and Experience

What has been your own ex­pe­ri­ence with this technique?

Very po­si­tive.

We of­ten see high le­vels of sa­tis­fac­tion and a very na­tu­ral fee­ling of movement.

It is par­ti­cu­larly in­te­res­t­ing that many pa­ti­ents are much less aware of their ar­ti­fi­cial knee in ever­y­day life.

Our sci­en­ti­fic data also show im­pro­ve­ments in:

  • Pain
  • Func­tion
  • Ac­ti­vity
  • Qua­lity of Life
  • Pa­ti­ent Satisfaction
What were the fin­dings of the pu­blished study?

The re­sults af­ter about a year were very promising:

  • Si­gni­fi­cant im­pro­ve­ment in the For­got­ten Joint Score
  • si­gni­fi­cantly hig­her ac­ti­vity le­vels in daily life
  • ex­cep­tio­nally high sur­gi­cal precision

The com­bi­na­tion of high pre­cis­ion and high pa­ti­ent sa­tis­fac­tion was par­ti­cu­larly im­portant to us.

An Ho­nest As­sess­ment from a Me­di­cal Perspective

Is the term “cus­tom knee re­pla­ce­ment” me­di­cally accurate?

Par­ti­ally.

The term is of­ten used in a sim­pli­fied way.

Ac­tually, it’s less about a “spe­cial pro­sthe­sis” and more about a cus­to­mi­zed re­con­s­truc­tion of the knee joint.

To­day, mo­dern tech­no­logy al­lows us to tailor our ap­proach much more pre­cis­ely to a pa­ti­en­t’s in­di­vi­dual anatomy.

How do you ex­plain the dif­fe­rence to patients?

I al­ways tell my pa­ti­ents quite frankly:

A mo­dern knee re­pla­ce­ment can im­prove many things—but it does not fully re­place a na­tu­ral knee.

The ma­jor ad­vance is that we can now work in a more per­so­na­li­zed, pre­cise, and gentle man­ner than we could in the past.

As a re­sult, many mo­dern knee re­pla­ce­ments feel more na­tu­ral and of­ten func­tion bet­ter in ever­y­day life.

But even mo­dern me­thods have their limits.

What are some com­mon misunderstandings?

Many peo­ple be­lieve that a mo­dern knee re­pla­ce­ment is au­to­ma­ti­cally fully customized.

In rea­lity, pre­cise, in­di­vi­dua­li­zed plan­ning is of­ten more im­portant than the pro­sthe­sis itself.

An­o­ther mis­con­cep­tion is that mo­dern sur­gi­cal ro­bots or na­vi­ga­tion sys­tems re­place surgeons.

Tha­t’s not true.

Tech­no­logy is an im­portant tool—but ex­pe­ri­ence, ex­per­tise, and careful plan­ning re­main crucial.

Con­clu­sion: Mo­dern knee re­pla­ce­ments mean grea­ter customization

Cus­to­mi­zed knee re­pla­ce­ments, which uti­lize ad­van­ced na­vi­ga­tion sys­tems, com­pu­ter-as­sis­ted pre­cis­ion tech­no­lo­gies, and mo­dern sur­gi­cal ro­bots, re­pre­sent a ma­jor ad­vance in knee re­pla­ce­ment surgery.

The fo­cus is no lon­ger on a one-size-fits-all so­lu­tion for all pa­ti­ents, but ra­ther on res­to­ring each patient’s in­di­vi­dual ana­tomy as na­tu­rally as possible.

Re­cent sci­en­ti­fic data show:

  • high pre­cis­ion
  • high pa­ti­ent satisfaction
  • more phy­si­cal ac­ti­vity in daily life
  • a more na­tu­ral fee­ling in the knee

At the same time, the fol­lo­wing applies: “
” Even mo­dern tech­no­lo­gies must be eva­lua­ted cri­ti­cally. Long-term data will show in the co­ming ye­ars which be­ne­fits will en­dure over the long term.

Ho­we­ver, there are al­re­ady many in­di­ca­ti­ons that per­so­na­li­zed knee re­pla­ce­ment is an im­portant step toward more na­tu­ral and pa­ti­ent-fri­endly knee surgeries.

Cus­tom Knee Re­pla­ce­ment in Vienna
The de­cis­ion to un­dergo knee re­pla­ce­ment sur­gery should al­ways be made on an in­di­vi­dual ba­sis. At my pri­vate prac­tice in Vi­enna, I take the time to con­duct a tho­rough eva­lua­tion and pro­vide per­so­na­li­zed tre­at­ment re­com­men­da­ti­ons. Mo­dern, per­so­na­li­zed knee re­pla­ce­ment sur­gery makes it pos­si­ble to tailor the pro­ce­dure as pre­cis­ely as pos­si­ble to your ana­tomy, your sym­ptoms, and your mo­bi­lity goals. 

Sche­dule your ap­point­ment now for a per­so­nal consultation.

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Priv.Doz. DDr.
Maximilian Kasparek, MSc
haelsi Gesundheitszentrum im Achtzehnten Theresiengasse 46/2 1180 Vienna

+43 1 399 08 63
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