Can s anda d implan s ep oduce he na i e
kinema ics o a TKA pa ien ?
Ma ia Paz Quilez1, Hend ik Delpo 2, Roel Wi ix-Spee jens1, Ma iska
Wesseling1, Ma ia Angeles Pe ez Anson3, Ilse Jonke s2, Jos Vande Slo en2
1 Ma e ialise NV, Leu en, Belgium
2 Ka holieke Uni e si e Leu en, Belgium
3 Uni e si y o Za agoza, Spain
[email p o ec ed]
Abs ac
To al knee a h oplas y (TKA) is a eliable su gical p ocedu e, ye up o a i h o
p ima y implan pa ien s emains unsa is ied. Musculoskele al modeling (MSM) has he
po en ial o explo e he ela ionship be ween implan alignmen and unc ional ou come
[3]. Consequen ly, implan alignmen can be quan i a i ely op imized o es o e he p e-
TKA join beha io and, he e o e, achie e he mos a o able unc ional ou come o he
speci ic pa ien . Fo his eason, we de eloped a me hod o op imize he implan
alignmen , wi h he aim o es o ing he na i e kinema ics and ligamen elonga ions o
he pa ien be o e unde going TKA. Subjec -speci ic op imiza ion owa ds ligamen
elonga ions demons a ed o accu a ely emula e he p e-TKA ligamen beha io , in
con as o he mechanically aligned app oach. Howe e , he alues o he op imized
implan posi ions esul ing om he p e-TKA kinema ic op imiza ion we e ex eme in
some cases. The p esen ed modelling app oach is a p omising s a ing poin o allowing
su geons o e alua e he pa ien -speci ic implan alignmen and es o e he pa ien -
speci ic biomechanics.
1 In oduc ion
To al knee a h oplas y (TKA) is a eliable su gical p ocedu e, ye up o a i h o p ima y implan
pa ien s emains unsa is ied. One o he mos common p ocedu es in TKA ocuses on achie ing good
alignmen o he mechanical axes, which no always esul s in he desi ed unc ional ou come o he
pa ien . The e o e, new app oaches as so - issue balancing [1] and kinema ics alignmen [2] ha e been
eme ging. Al hough p e-ope a i e planning ools we e ecen ly in oduced o suppo he su geon in
ob aining mechanical alignmen , hese planning ools do no suppo so - issue balancing and kinema ic
alignmen app oaches ye .
Heal h
Sciences
EPiC Se ies in Heal h Sciences
Volume 3, 2019, Pages 311–314
CAOS 2019. The 19 h Annual Mee ing o he In e na ional
Socie y o Compu e Assis ed O hopaedic Su ge y
P. Mee e and F. Rod iguez Y Baena (eds.), CAOS 2019 (EPiC Se ies in Heal h Sciences, ol. 3), pp. 311–314
Musculoskele al modeling (MSM) has he po en ial o explo e he ela ionship be ween implan
alignmen and unc ional ou come [3]. Consequen ly, implan alignmen can be quan i a i ely
op imized o es o e he p e-TKA join beha io and, he e o e, achie e he mos a o able unc ional
ou come o he speci ic pa ien . Fo his eason, we de eloped a me hod o op imize he implan
alignmen , wi h he aim o es o ing he na i e kinema ics and ligamen elonga ions o he pa ien be o e
unde going TKA.
2 Me hod
A pa ien -speci ic musculoskele al model (MSM) was p e iously de eloped and alida ed by
Vanheule e al [3]. This model p edic s kinema ics and ligamen leng h elonga ions when squa ing, o
bo h p e-TKA and pos -TKA knees. In his s udy, we used he model and he ou cada e ic expe imen s
pe o med in ha wo k.
P e-TKA ibio- emo al kinema ics and medial and la e al colla e al ligamen (MCL and LCL)
elonga ions we e compu ed o he ou specimens using he p e-TKA knee model. Nex , he pos -TKA
model using a pos e io -s abilized (PS) implan sys em was used o calcula e he kinema ics and
ligamen elonga ions o a combina ion o di e en emo al and ibial implan posi ions. Implan
posi ions we e de e mined by he ollowing pa ame e s: a us- algus (VV), p oximal-dis al (PD), slope
(Sl), in e nal-ex e nal (IE) o bo h emo al and ibial componen , and also an e io -pos e io (AP) o
he emo al componen . 130 simula ions we e un based on a design o expe imen s (DOE), a ying
each a iable om -5 mm o -5º o +5 mm o +5º.
The esul s o he kinema ics and ligamen elonga ions ob ained om he simula ions we e used o
de e mine he op imal implan posi ion using a esponse su ace me hod (RSM). The op imal implan
posi ions we e de ined as he posi ions wi h he smalles e o be ween he p e-TKA and he pos -TKA
ibio- emo al kinema ics and ligamen elonga ions. Then, hose esul s we e compa ed wi h he esul s
o he mechanical alignmen echnique.
3 Resul s
The op imal se o implan posi ion pa ame e s ha p oduced p e-TKA ligamen elonga ions we e
calcula ed o he ou specimens (Figu e 1a). The ob ained op imized posi ions we e used o compu e
he ligamen elonga ions o each specimen, and compa ed o he mechanically aligned app oach. This
compa ison e ealed a meaning ul di e ence be ween he op imized and mechanically aligned
posi ions (Figu e 2).
Can s anda d implan s ep oduce he na i e kinema ics o a TKA pa ien ? M. P. Quilez e al.
312
The implan posi ion was also op imized owa ds he p e-TKA kinema ics (Figu e 1b). In e es ingly,
hese op imal solu ions we e associa ed wi h high alues o ibial slopes o specimen 1 (15.2º), 3 (8.9º)
and 4 (9.2º)
Can s anda d implan s ep oduce he na i e kinema ics o a TKA pa ien ? M. P. Quilez e al.
313
4 Discussion
Asseln e al. [4] e alua ed he kinema ics o he knee join and i s ele ance o TKA implan design.
Simila ly, Twiggs e al. [5] epo ed co ela ions be ween kinema ics and pa ien sa is ac ion. Howe e ,
o ou knowledge he e is no s udy abou he use o MSM o di ec ly suppo ing he su geon decision-
aking.
As shown in igu e 2, subjec -speci ic op imiza ion owa ds ligamen elonga ions demons a ed o
accu a ely emula e he p e-TKA ligamen beha io , in con as o he mechanically aligned app oach.
The alues o he op imized implan posi ions esul ing om he p e-TKA kinema ic op imiza ion
we e ex eme in some cases. We a ibu e his o he PS mechanism ha es ic s mainly he mo ion in
he an e io -pos e io and in e nal-ex e nal di ec ions. Assigning lowe weigh o hose pa ame e s in
he op imiza ion p ocess would be mo e ep esen a i e o he PS sys em and, he e o e, i could likely
gi e mo e ealis ic esul s. Addi ionally as u u e wo k, a less cons ained implan sys em as a c ucia e-
e aining (CR) implan will be e alua ed, as i could p o ide mo e eedom o he op imiza ion p ocess
and would allow app oxima ing mo e closely he na i e knee beha io .
An impo an limi a ion o his s udy is ha he expe imen al da a is limi ed o ou cada e ic
specimens and esul s need o be con i med in a la ge da ase .
We conclude ha he p esen ed modelling app oach is a p omising candida e o allowing su geons
o e alua e he pa ien -speci ic implan alignmen and es o e he pa ien -speci ic biomechanics. The
cu en me hod p o ides a solid s a ing poin o enhance he in eg a ion o compu a ional models in o
clinical p ac ice and e ol e owa ds a pa ien -speci ic op imized app oach.
Re e ences
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[2] Y. S. Lee e al., “Kinema ic alignmen is a possible al e na i e o mechanical alignmen in o al
knee a h oplas y,” Knee Su ge y, Spo . T auma ol. A h osc., ol. 25, no. 11, pp. 3467–3479, 2017.
[3] V. Vanheule e al., “E alua ion o p edic ed knee unc ion o componen mal o a ion in o al
knee a h oplas y,” Med. Eng. Phys., ol. 40, pp. 56–64, 2017.
[4] M. Asseln, L. Be ge , M. Ve jans, and K. Rade mache , “E ec s o he medial and la e al
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[5] P. Joshua Twiggs, BE, Edga Wakelin, PhD, Jus in Roe, MD, Da id Dickison, MD, B e
F i sch, MD, B ad Miles, PhD, And ew Ruys, “Pa ien Speci ic Simula ed Dynamics ollowing TKA
Co ela e wi h Pa ien Repo ed Ou comes,” J. A h oplas y, ol. 33, no. 9, pp. 2843–2850, 2018.
Can s anda d implan s ep oduce he na i e kinema ics o a TKA pa ien ? M. P. Quilez e al.
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