Ci a ion: Wegne , M.; Kuwe , S.;
K a zens ein, S.; Simon, M.J.K.;
Mo adi, B. Femo al T ansla ion in
Pa ien s wi h Unicompa men al
Os eoa h i is—A Coho S udy.
Biomechanics 2024,4, 428–438.
h ps://doi.o g/10.3390/
biomechanics4030029
Academic Edi o : A kady Voloshin
Recei ed: 20 May 2024
Re ised: 30 June 2024
Accep ed: 10 July 2024
Published: 12 July 2024
Copy igh : © 2024 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
condi ions o he C ea i e Commons
A ibu ion (CC BY) license (h ps://
c ea i ecommons.o g/licenses/by/
4.0/).
A icle
Femo al T ansla ion in Pa ien s wi h Unicompa men al
Os eoa h i is—A Coho S udy
Ma his Wegne 1,* , Simon Kuwe 1, S e an K a zens ein 2, Maciej J. K. Simon 1and Babak Mo adi 1
1Depa men o O hopedics and T auma Su ge y, Medical Uni e si y Cen e Schleswig-Hols ein—Campus
Kiel, A nold-Helle -S asse 3, 24105 Kiel, Ge many; [email p o ec ed] (S.K.);
[email p o ec ed] (M.J.K.S.); [email p o ec ed] (B.M.)
2CAU Mo ion Labo a o y, Kiel Uni e si y, Olshausens aße 74, 24098 Kiel, Ge many;
[email p o ec ed]
*Co espondence: [email p o ec ed]; Tel.: +49-431-500-24501
Abs ac : The use o h ee-dimensional (3D) gai analysis o image emo o ibial ansla ion can
aid in he diagnosis o pa hology and p o ide addi ional insigh in o he se e i y o KOA (knee
os eoa h i is). Femo o ibial ansla ion is o pa icula impo ance in pa ien s unde going UKA
(unicompa men al knee a h oplas y), as he absence o elonga ion o ligamen ous s uc u es esul s
in changes in he kinema ic alignmen . The aim o he s udy was o e alua e he pa ame e s o
emo o ibial ansla ion in pa ien s wi h MOA (medial unicompa men al OA). An a i icial model
was employed o de elop a me hod o calcula ing emo o ibial ansla ion
in i o
. In a p ospec-
i e coho s udy, gai da a using h ee-dimensional gai analysis we e collec ed om 11 pa ien s
(
68.73 ±9.22 yea s
) wi h se e e OA scheduled o UKA and 29 unma ched heal hy pa icipan s
(
22.07 ±2.23 yea s
). The disc e e a iables cha ac e ising emo o ibial ansla ion we e compa ed o
s a is ical signi icance (p< 0.05) using he S uden ’s - es and he Mann–Whi ney U- es . The esul s
o he s udy alida ed an a i icial model o mimic emo o ibial ansla ion. The compa ison o pa-
ien s scheduled o UKA and a heal hy unma ched con ol g oup showed no s a is ically signi ican
di e ences conce ning emo o ibial ansla ion in all h ee planes (p> 0.05). Howe e , he PROMs
(pa ien - epo ed ou come measu es), spa io empo al, and kinema ic pa ame e s showed s a is ically
signi ican di e ences be ween he g oups (p< 0.001). The da a p esen ed he e demons a e ypical
changes in PROMs as well as spa io empo al and kinema ic ou comes o MOA as seen in knee OA.
The esul s o he clinical gai analyses demons a e indi idualised emo o ibial ansla ion. The
ex en o indi idual emo o ibial ansla ion may p o e o be an impo an pa ame e o al e ed join
kinema ics in pa ien s wi h MOA, especially p io o UKA implan a ion.
Keywo ds: emo o ibial ansla ion; 3D gai analysis; knee os eoa h i is
1. In oduc ion
Knee os eoa h i is (KOA) is he mos p e alen o m o os eoa h i is (OA) in he
Wes e n wo ld. I is cha ac e ised by pain, swelling, s i ness and slow wea . KOA can
esul in a loss o join unc ion and a signi ican educ ion in he quali y o li e o he
a ec ed indi idual [
1
]. Among he h ee compa men s o he knees, KOA is mos com-
monly obse ed in he medial compa men [
2
–
5
]. The cu en imaging p ocedu es o
he diagnosis o KOA ( adiog aphy, compu ed omog aphy, magne esonance imaging)
a e exclusi ely s a ic imaging echniques. Func ional changes associa ed wi h he disease
canno be e alua ed [
2
,
3
]. The use o dynamic gai analysis has been es ablished as a
diagnos ic ool o he iden i ica ion o kinema ic changes associa ed wi h KOA [
3
,
4
,
6
,
7
].
Reduced knee lexion a heel s ike, educed knee abduc ion angle a 50% o s ance phase
and educed knee lexion ange du ing gai ha e been epo ed in pa ien s wi h KOA [
8
].
The emo al condyles’ ansla ion ela i e o he ibia has been he subjec o a limi ed
Biomechanics 2024,4, 428–438. h ps://doi.o g/10.3390/biomechanics4030029 h ps://www.mdpi.com/jou nal/biomechanics
Biomechanics 2024,4429
numbe o s udies, which ha e yielded he e ogeneous esul s [
6
,
7
,
9
–
12
]. Consequen ly, he
ibio- emo al mo emen pa e ns emain a subjec o con en ion.
Femo o ibial ansla ion is o c i ical impo ance in pa ien s wi h medial unicompa -
men al knee os eoa h i is (MOA), as i is a key pa ame e e lec ing he abno mal loading
and wea pa e ns o he a ec ed compa men o he knee join [
3
]. The inc eased shea
o ces ha ac du ing his phase o he gai cycle esul in inc eased wea and ea , leading
o g ea e ca ilage loss. This esul s in a change in he kinema ics o he knee join and a
u he inc ease in emo o ibial ansla ion, which ep esen s a sign o ea ly os eoa h i is
(OA) [6–8].
In ea ly MOA, mobile-bea ing UKA (unicompa men al knee a h oplas y) ep e-
sen s a alid he apeu ic op ion wi h g ea ad an ages o pa ien s. The bea ing pe ec ly
con o ms wi h emo al and ibial componen s and mo es comple ely passi ely be ween
he emo al and ibial implan [
13
]. This esul s in almos physiologic knee kinema ics
compa ed wi h o al knee a h oplas y (TKA) [
14
,
15
]. UKA in ol es eplacing only he
damaged compa men o he knee, hus p ese ing he heal hy bone, ca ilage, and lig-
amen s. This leads o a mo e na u al knee unc ion pos -su ge y. Many pa ien s epo
high le els o sa is ac ion wi h he ou comes o UKA, including imp o ed unc ion and
quali y o li e. The UKA’s knee-spa ing app oach has led o an inc ease in he numbe
o implan ed unicondyla endop os heses, which, in u n, has necessi a ed high-quali y
su gical indica ions [
13
,
16
–
19
]. The kinema ic alignmen and, hus, he unc ion o he
ligamen s uc u es in he knee join is o pa icula impo ance when de e mining he
indica ion o su ge y and implan a ion o a UKA. A de iciency in he an e io c ucia e
ligamen ha becomes appa en du ing su ge y has signi ican consequences o he pa ien ,
as he implan composi ion mus be al e ed o a o al knee a h oplas y (TKA) mus be
employed [2,7,15].
I he indica ion is co ec , he kinema ically aligned UKA ep esen s an al e na i e
knee p os hesis ha is mo e indi idualised, physiological and ana omical [
17
]. The abili y
o adequa ely isualise emo o ibial ansla ion in a p eope a i e h ee-dimensional gai
analysis would signi ican ly con ibu e o an e en mo e p ecise indica ion o he implan a-
ion o a UKA. Consequen ly, he de elopmen o indi idualised implan s in a h oplas y
would be u he ad anced.
Gi en he g owing numbe o kinema ically aligned UKAs, i becomes e iden ha a
unc ional assessmen o he MOA is necessa y. The objec i e o ou s udy was o in es iga e
he di e ences in emo o ibial ansla ion in pa ien s unde going planned UKA.
2. Ma e ials and Me hods
The da a used in his s udy we e collec ed in an
in i o
se ing and a clinical case-
con ol s udy. In he i s pa , an a i icial model was used o de elop a me hod o
calcula ing emo o ibial ansla ion
in i o
using 3D gai analysis. In he second pa o he
s udy, he e icacy o a me hod o isualising emo o ibial ansla ion using 3D kinema ic
mo ion analysis was e alua ed. This was pe o med h ough a p ospec i e coho s udy
ha pe o med an in aindi idual compa ison o a g oup wi h MOA in which UKA is
indica ed. This was ollowed by a compa ison wi h a heal hy con ol g oup.
Emphasis was placed on he loading esponse in he s ance phase o he gai cycle [
8
].
In ou se ing, he loading esponse was de ined as he i s 12% o he gai cycle. Ini ial
con ac was iden i ied using kinema ic-based e en de ec ion.
2.1. Model Analysis
Fo calcula ing emo o ibial ansla ion
in i o
, a i ual ma ke wi hin he ibial
pla eau was c ea ed by using he analogue ma ke placemen s on he medial and la e al
edges o he ibia and se ing he i ual ma ke o hal he dis ance be ween hem, whe e
emo o ibial ansla ion was expec ed o be he la ges . An ana omical a i icial bone
model wi h an implan ed medial mobile-bea ing UKA wi h a emo able inlay was used.
A coo dina e sys em was compiled a he dis al end o he emu . The i ual ma ke is
Biomechanics 2024,4430
illus a ed in Figu e 1. To assess emo o ibial ansla ion, he mo emen o he i ual ibial
ma ke was eco ded in he local emo al coo dina e sys em and calcula ed as ROM in he
loading esponse o he an e io –pos e io , medio–la e al, and c anio–caudal axes o he
a e aged mo emen .
Biomechanics 2024, 5, FOR PEER REVIEW 3
A coo dina e sys em was compiled a he dis al end o he emu . The i ual ma ke is
illus a ed in Figu e 1. To assess emo o ibial ansla ion, he mo emen o he i ual ib-
ial ma ke was eco ded in he local emo al coo dina e sys em and calcula ed as ROM in
he loading esponse o he an e io –pos e io , medio–la e al, and c anio–caudal axes o
he a e aged mo emen .
Figu e 1. Ma ke sys em wi h he i ual ibial ma ke (blue).
In he in i o model, he diffe ences be ween a physiological and a pa hological
mo emen wi h inc eased emo o ibial ansla ion we e eco ded using an ana omic
model o he knee wi h he implan ed mobile-bea ing UKA, a emo able inlay and sp ings
applied o mimic ligamen ension [20].
2.2. Clinical S udy
F om 2021 un il 2022, pa ien s wi h an indica ion o a medial UKA a a uni e si y
medical cen e we e included in he p ospec i e coho s udy. Pa icipan s comple ed he
ollowing ques ionnai es, including pa ien - epo ed ou come measu es (PROMs): he
Ox o d Knee Sco e (OKS) [21], he Knee Socie y Sco e (KSS) [22], he Uni e si y o Cali-
o nia a Los Angeles (UCLA) Ac i i y Scale, he Nume ic Ra ing Scale (NRS) o pain [23]
and he Sho Fo m 12 Ques ionnai e (SF-12) [24].
2.3. Rec ui men and Inclusion C i e ia
Inclusion c i e ia o he MOA g oup consis ed o se e e unila e al os eoa h i is o
he medial compa men classi ied using he Kellg en–Law ence classi ica ion [25] o he
Ahlbäck classi ica ion [26] wi h ull- hickness a icula ca ilage loss (‘bone on bone’). In
all pa ien s in he p eope a i e examina ion, he an e io c ucia e ligamen and he medial
and la e al colla e al ligamen s we e unc ionally in ac , he algus de o mi y was manu-
ally co ec able and he e was no e idence o OA in he la e al knee compa men . Rheu-
ma oid a h i is, ixed algus de o mi y (e.g., >15°), lexion de o mi y > 15°, o he inabili y
o walk 6 min wi hou an assis i e de ice was conside ed a con aindica ion. The con ol
Figu e 1. Ma ke sys em wi h he i ual ibial ma ke (blue).
In he
in i o
model, he di e ences be ween a physiological and a pa hological
mo emen wi h inc eased emo o ibial ansla ion we e eco ded using an ana omic model
o he knee wi h he implan ed mobile-bea ing UKA, a emo able inlay and sp ings applied
o mimic ligamen ension [20].
2.2. Clinical S udy
F om 2021 un il 2022, pa ien s wi h an indica ion o a medial UKA a a uni e si y
medical cen e we e included in he p ospec i e coho s udy. Pa icipan s comple ed
he ollowing ques ionnai es, including pa ien - epo ed ou come measu es (PROMs):
he Ox o d Knee Sco e (OKS) [
21
], he Knee Socie y Sco e (KSS) [
22
], he Uni e si y o
Cali o nia a Los Angeles (UCLA) Ac i i y Scale, he Nume ic Ra ing Scale (NRS) o
pain [23] and he Sho Fo m 12 Ques ionnai e (SF-12) [24].
2.3. Rec ui men and Inclusion C i e ia
Inclusion c i e ia o he MOA g oup consis ed o se e e unila e al os eoa h i is o
he medial compa men classi ied using he Kellg en–Law ence classi ica ion [
25
] o he
Ahlbäck classi ica ion [
26
] wi h ull- hickness a icula ca ilage loss (‘bone on bone’). In all
pa ien s in he p eope a i e examina ion, he an e io c ucia e ligamen and he medial and
la e al colla e al ligamen s we e unc ionally in ac , he algus de o mi y was manually
co ec able and he e was no e idence o OA in he la e al knee compa men . Rheuma oid
a h i is, ixed algus de o mi y (e.g., >15
◦
), lexion de o mi y > 15
◦
, o he inabili y o
walk 6 min wi hou an assis i e de ice was conside ed a con aindica ion. The con ol
Biomechanics 2024,4431
g oup consis ed o young and heal hy subjec s. Excluded we e pa icipan s wi h p io knee
su ge y and unc ional limi a ions in he knee.
2.4. Mo ion Analysis
To e alua e kinema ic join pa ame e s, spa io empo al pa ame e s we e collec ed,
and emo o ibial ansla ion and gai analysis we e pe o med using he Op iT ack 3D
mo ion analysis sys em (Na u alPoin Inc., Co allis, OR, USA) wi h a eco ding equency
o 100 Hz and he “705 CST P o o m” eadmill. Thi een e lec i e ma ke s we e a ached
wi h adhesi e ape o ana omical landma ks on each leg [
27
] (Figu e 2). The eco dings
we e managed using ‘Cap u e2D™’ ( 1.0.0.194, C-Mo ion Inc., Boyds, MD, USA) [
20
]. A
lowpass Bu e wo h il e wi h a h eshold o 6 Hz o he i s o de was applied o p ocess
and analyse he eco ded da a, and missing da a we e in e pola ed up o 10 ames using
Visual 3D P o essional™ ( 1.0.0.194, C-Mo ion Inc., Boyds, MD, USA). All pa icipan s
walked o wa d and we e eco ded o 30 s.
Biomechanics 2024, 5, FOR PEER REVIEW 4
g oup consis ed o young and heal hy subjec s. Excluded we e pa icipan s wi h p io
knee su ge y and unc ional limi a ions in he knee.
2.4. Mo ion Analysis
To e alua e kinema ic join pa ame e s, spa io empo al pa ame e s we e collec ed,
and emo o ibial ansla ion and gai analysis we e pe o med using he Op iT ack 3D
mo ion analysis sys em (Na u alPoin Inc., Co allis, OR, USA) wi h a eco ding e-
quency o 100 Hz and he “705 CST P o o m” eadmill. Thi een e lec i e ma ke s we e
a ached wi h adhesi e ape o ana omical landma ks on each leg [27] (Figu e 2). The e-
co dings we e managed using ‘Cap u e2D™’ ( 1.0.0.194, C-Mo ion Inc., Boyds, MD, USA)
[20]. A lowpass Bu e wo h il e wi h a h eshold o 6 Hz o he i s o de was applied
o p ocess and analyse he eco ded da a, and missing da a we e in e pola ed up o 10
ames using Visual 3D P o essional™ ( 1.0.0.194, C-Mo ion Inc., Boyds, MD, USA). All
pa icipan s walked o wa d and we e eco ded o 30 s.
(a) (b)
Figu e 2. Re lec ing ma ke s used o gai analysis: (a) on al iew; (b) sagi al iew.
2.5. Mo ion Assessmen
P io o eco ding gai and unning analyses, an accele a ion-based unc ional cali-
b a ion p ocedu e was pe o med each ime. Pa icipan s began walking on he eadmill
a a sel -selec ed speed. Pa icipan s had a six-minu e pe iod o habi ua ion o walking on
he eadmill o ule ou bias due o al e ed gai pa e n [28].
A e a com o able walking speed was es ablished, he in es iga o eco ded a leas
23 walking cycles on he eadmill a e signalling he pa icipan . Spa io empo al mo ion
pa ame e s, as well as he ROM in all h ee axes, we e eco ded pe pa icipan . In all
eco dings, he used ma ke sys em had a esidual o 1.2 mm.
2.6. S a is ical Analysis
S a is ical analysis was pe o med by using Jamo i o Windows (The Jamo i p ojec
(2022), Ve sion 2.2.5, www.jamo i.o g accessed on 7 May 2023). Fo no mal dis ibu ion,
Figu e 2. Re lec ing ma ke s used o gai analysis: (a) on al iew; (b) sagi al iew.
2.5. Mo ion Assessmen
P io o eco ding gai and unning analyses, an accele a ion-based unc ional calib a-
ion p ocedu e was pe o med each ime. Pa icipan s began walking on he eadmill a a
sel -selec ed speed. Pa icipan s had a six-minu e pe iod o habi ua ion o walking on he
eadmill o ule ou bias due o al e ed gai pa e n [28].
A e a com o able walking speed was es ablished, he in es iga o eco ded a leas
23 walking cycles on he eadmill a e signalling he pa icipan . Spa io empo al mo ion
pa ame e s, as well as he ROM in all h ee axes, we e eco ded pe pa icipan . In all
eco dings, he used ma ke sys em had a esidual o 1.2 mm.
Biomechanics 2024,4432
2.6. S a is ical Analysis
S a is ical analysis was pe o med by using Jamo i o Windows (The Jamo i p ojec
(2022), Ve sion 2.2.5, www.jamo i.o g accessed on 7 May 2023). Fo no mal dis ibu ion,
he Shapi o–Wilk es was pe o med. The S uden ’s - es and he Mann–Whi ney U- es
we e used o es o s a is ical signi icance. The signi icance le el was de ined as p< 0.05.
Fo mul iple es ing, he Bon e oni co ec ion was applied [29].
3. Resul s
3.1. In Vi o Analysis
The ROM o he ibial ma ke in he loading esponse phase o he gai cycle is shown
in Table 1. The collec ed esul s a y when a i icial ligamen ension is applied o he inlay
is emo ed.
Table 1. Range o he emo o ibial ansla ion in he a i icial model o a knee. Values a e gi en as
mean ±s anda d de ia ion (SD).
Range o Mo ion Medio–La e al An e io –Pos e io C anio–Caudal
mean ±SD [mm] 2.05 ±1.05 2.25 ±0.55 2.18 ±0.57
inlay−/s ings+ 1.11 1.58 1.34
inlay−/s ings−3.14 2.31 2.43
inlay+/s ings+ 1.21 2.92 2.47
inlay+/s ings−2.75 2.21 2.50
3.2. Case–Con ol S udy
A o al o 40 pa icipan s we e included in he s udy. The MOA g oup consis ed o
11 pa ien s (3 women, 8 men) wi h se e e MOA scheduled o unicompa men al knee
eplacemen su ge y. The con ol g oup con ained 29 heal hy pa icipan s (16 women,
13 men). Demog aphic da a a e shown in Table 2.
Table 2. Demog aphics o he pa icipan s. Values as mean ±s anda d de ia ion (SD).
Pa ame e s Con ol G oup MOA G oup
age [yea s] 22.07 ±2.23 68.73 ±9.22
heigh [cm] 175.76 ±7.79 179.27 ±7.96
weigh [kg] 69.91 ±12.43 88.27 ±17.75
BMI 1[kg/m2]22.5 ±2.83 27.52 ±5.59
1Body mass index.
The MOA g oup showed signi ican di e ences in he KSS (p< 0.001), OKS (p< 0.001),
UCLA Ac i i y Scale (p< 0.001), NRS o pain (p< 0.001) and SF-12 Physical Componen
Summa y (PCS) (p< 0.001) o he con ols. The SF-12 Men al Componen Summa y (MCS)
showed no signi ican di e ences (p= 0.785). The absolu e alues a e shown in Table 3.
Table 3. Sco es o he pa icipan s in he case–con ol s udy. Values a e gi en as mean ±SD.
Sco es [Range] Con ol G oup MOA G oup p-Value
KSS 1[0–200] 195.5 ±8.38 126.73 ±42.54 <0.001
OKS 2[12–60] 12.20 ±0.95 31.40 ±4.92 <0.001
UCLAAS 3[1–10] 9.66 ±1.04 6.36 ±1.03 <0.001
NRS 4[0–10] 0.35 ±0.90 5.36 ±1.86 <0.001
SF-12 PCS 556.80 ±2.37 38.6 ±8.48 <0.001
SF-12 MCS 654.20 ±6.94 54.10 ±10.40 0.785
1
Knee Socie y Sco e.
2
Ox o d Knee Sco e.
3
UCLA Ac i i y Scale.
4
Nume ic Ra ing Scale.
5
Sho Fo m 12-I em
Heal h Su ey Physical Componen Summa y.
6
Sho Fo m 12-I em Heal h Su ey Men al Componen Summa y.

Biomechanics 2024,4433
The spa io empo al pa ame e s o he MOA g oup showed a signi ican educ ion
in speed (1.23
±
0.16 m/s s. 0.86
±
0.31 m/s, p< 0.001) and s ide leng h (1.4
±
0.16 m
s. 1.0
±
0.28 m, p< 0.001) compa ed o he con ol g oup (Table 4). S ide equency was
no signi ican ly di e en (105.0
±
6.5 s eps/min s. 99.0
±
15.9 s eps/min, p= 0.074).
The ROM o lexion signi ican ly dec eased h oughou he gai cycle o bo h legs
(
p< 0.001
). Loading esponse changes in lexion di e ences we e no s a is ically signi i-
can (
p= 0.074
le , p= 0.096 igh ). The di e ences in ROM o abduc ion/adduc ion
we e no signi ican .
Table 4. Spa io empo al and kinema ic pa ame e s in he case–con ol s udy.
Pa ame e s Side Con ol G oup MOA G oup p-Value
eloci y [m/s] 1.23 ±0.16 0.86 ±0.31 <0.01 *,1
cadence [1/min] 105.00 ±6.50 99.00 ±15.9 0.07 1
s ide leng h [m] 1.40 ±0.16 1.02 ±0.28 <0.01 *,1
ROM lexion [◦] ull gai cycle le 62.57 ±6.99 50.00 ±7.61 <0.01 *,1
igh 62.58 ±6.32 52.40 ±6.58 <0.01 *,1
ROM lexion [◦] loading esponse le 9.34 ±3.81 7.10 ±7 6.59 0.07 2
igh 12.35 ±4.43 10.50 ±8.95 0.09 2
ROM ab-/adduc ion [◦] ull gai cycle le 12.03 ±3.97 9.16 ±2.90 0.04 1
igh 11.74 ±4.03 8.24 ±2.99 0.01 1
ROM ab-/adduc ion [◦] loading esponse le 3.78 ±1.89 2.59 ±1.50 0.07 2
igh 3.57 ±1.46 3.00 ±1.82 0.18 2
Mean
±
s anda d de ia ion, ROM = ange o mo ion, * s a is ical signi icance,
1
S uden ’s - es ,
2
Mann–Whi ney
U- es .
Femo o ibial ansla ion in he loading phase was no signi ican ly di e en be ween
he MOA g oup and he con ol g oup (Table 5). The 4% gai cycle ime shi was applied
o he da a p io o analysis.
Table 5. Femo o ibial ansla ion in he loading esponse.
Axis Side
Con ol G oup
MOA G oup p-Value
medio–la e al
[mm]
le 5.2 ±2.9 4.1 ±2.6 0.27 1
igh 6.6 ±4.5 4.6 ±3.6 0.18 2
an e io –pos e io
[mm]
le 8.6 ±4.4 7.4 ±5.0 0.46 1
igh 8.6 ±5.3 9.7 ±7.5 0.79 2
c anio–caudal
[mm]
le 2.6 ±1.5 3.5 ±2.8 0.16 1
igh 4.5 ±2.4 5.1 ±3.6 0.56 1
Mean ±SD, 1S uden ’s - es , 2Mann–Whi ney U- es .
Di e ences be ween he pa ien s’ legs we e conside ed. In he medio–la e al axis,
ansla ion was 3.2
±
2.0 mm in he diseased limb and 5.5
±
3.6 mm in he heal hy
limb (
p= 0.065
). An e io –pos e io ansla ion was 8.2
±
3.6 mm (diseased limb)
and
9.0 ±8.4 mm
(heal hy limb) (p= 0.562). Fo supe io –in e io , ansla ion was
3.5 ±2.3 mm
(diseased limb) and 5.2
±
3.9 mm (heal hy limb) (p= 0.401). The in aindi-
idual compa ison showed no s a is ically signi ican di e ences. A la ge in aindi idual
a ia ion o emo o ibial ansla ion in he an e io –pos e io plane is exempla ily shown
in Figu e 3.
Biomechanics 2024,4434
Biomechanics 2024, 5, FOR PEER REVIEW 7
(a) (b)
Figu e 3. Femo o ibial ansla ion in he loading esponse phase ( i s 12% o he gai cycle) in he
an e io –pos e io plane o he case–con ol s udy: (a) con ol g oup; (b) MOA g oup.
4. Discussion
OA is one o he mos common causes o pain ul loss o mobili y in many popula ions
[30,31]. Biological, mechanical and s uc u al componen s a e associa ed wi h OA as a dis-
ease o he whole join [2]. An in e play o me abolic and mechanical changes and changes
in he le els o in lamma o y cy okines [6] leads o an o e all change in he kinema ics o
he join as an exp ession o he clinical p og ession o OA. As he se e i y o OA co e-
sponds wi h he exp ession o kinema ic changes [14], he iming o diagnosis and in e -
en ion is essen ial o pa ien s’ ou comes [2].
Gai analysis can be used o iden i y unc ional changes in knee kinema ics in pa ien s
wi h KOA. Dec eased knee lexion and p olonged heel s ike du ing he loading esponse
phase o he gai cycle a e signs o ea ly OA [8]. The me hodical app oach ca ied ou in
his s udy demons a es ha small dec eases in ligamen ension esul in a highe em-
o o ibial ansla ion du ing he loading esponse phase as a possible indica o and ea ly
sign o changed knee kinema ics in OA esul ing in mechanical changes (Figu e 3).
To p o e ha inc eased emo o ibial ansla ion is p esen in pa ien s wi h se ious
KOA and can be subs an ia ed by 3D gai analysis and demons a ed among o he ypical
KOA changes, we ca ied ou a ield ial using a eadmill algo i hm and a ma ke -based
analy ic sys em [32]. Ou expe imen al design was con i med by mul iple eco dings, e-
sul ing in a low a iance o da a. In ecen yea s, ma ke less mo ion analysis me hods and
in e ac i e measu emen sys ems ha e been gaining g ound. The in eg a ion o a i icial
in elligence in o mo ion analysis opens up he possibili y o pe o ming mo ion analysis
wi h less da a acquisi ion and p ocessing ime compa ed o ma ke -based me hods [33].
Ne e heless, we chose o eco d he gai o pa ien s wi h KOA using a ma ke -based sys-
em because he de e mina ion o join cen es and join angles wi h a ma ke less sys em
is no ye accu a e enough o clinical applica ions.
The esul s o his s udy demons a e and con i m os eoa h i ic changes in se e e
unicompa men al medial OA gai [15]. Signi ican changes in spa io empo al and kine-
ma ic pa ame e s ypical o pa ien s wi h MOA we e ound. These included educed
speed, educed s ide leng h and educed ROM o knee lexion [8–13]. Diffe ences in ca-
dence and s ide leng h and ROM o abduc ion/adduc ion we e no s a is ically signi i-
can . Recen s udies ha e demons a ed gai abno mali ies in os eoa h i ic join s using
ma ke less 3D gai analysis and wea able senso s [34,35]. Boekes eijn (e al.) (2022)
showed spa io empo al changes and compensa o y mechanisms ypical o OA and we e
able o objec i ely assess he gai pa e n using an ine ial measu emen sys em in a clini-
cal se ing. Wang (e al.) (2024) ound he amoun o knee lexion du ing inline lunging o
be ano he po en ial indica o o knee os eoa h i is using a ma ke less mo ion cap u e
sys em [35].
Figu e 3. Femo o ibial ansla ion in he loading esponse phase ( i s 12% o he gai cycle) in he
an e io –pos e io plane o he case–con ol s udy: (a) con ol g oup; (b) MOA g oup.
4. Discussion
OA is one o he mos common causes o pain ul loss o mobili y in many
popula ions [30,31]
. Biological, mechanical and s uc u al componen s a e associa ed wi h
OA as a disease o he whole join [
2
]. An in e play o me abolic and mechanical changes
and changes in he le els o in lamma o y cy okines [
6
] leads o an o e all change in he
kinema ics o he join as an exp ession o he clinical p og ession o OA. As he se e i y o
OA co esponds wi h he exp ession o kinema ic changes [
14
], he iming o diagnosis and
in e en ion is essen ial o pa ien s’ ou comes [2].
Gai analysis can be used o iden i y unc ional changes in knee kinema ics in pa ien s
wi h KOA. Dec eased knee lexion and p olonged heel s ike du ing he loading esponse
phase o he gai cycle a e signs o ea ly OA [
8
]. The me hodical app oach ca ied ou in his
s udy demons a es ha small dec eases in ligamen ension esul in a highe emo o ibial
ansla ion du ing he loading esponse phase as a possible indica o and ea ly sign o
changed knee kinema ics in OA esul ing in mechanical changes (Figu e 3).
To p o e ha inc eased emo o ibial ansla ion is p esen in pa ien s wi h se ious KOA
and can be subs an ia ed by 3D gai analysis and demons a ed among o he ypical KOA
changes, we ca ied ou a ield ial using a eadmill algo i hm and a ma ke -based analy ic
sys em [
32
]. Ou expe imen al design was con i med by mul iple eco dings, esul ing in a
low a iance o da a. In ecen yea s, ma ke less mo ion analysis me hods and in e ac i e
measu emen sys ems ha e been gaining g ound. The in eg a ion o a i icial in elligence
in o mo ion analysis opens up he possibili y o pe o ming mo ion analysis wi h less da a
acquisi ion and p ocessing ime compa ed o ma ke -based me hods [
33
]. Ne e heless,
we chose o eco d he gai o pa ien s wi h KOA using a ma ke -based sys em because he
de e mina ion o join cen es and join angles wi h a ma ke less sys em is no ye accu a e
enough o clinical applica ions.
The esul s o his s udy demons a e and con i m os eoa h i ic changes in se e e
unicompa men al medial OA gai [
15
]. Signi ican changes in spa io empo al and kine-
ma ic pa ame e s ypical o pa ien s wi h MOA we e ound. These included educed speed,
educed s ide leng h and educed ROM o knee lexion [
8
–
13
]. Di e ences in cadence and
s ide leng h and ROM o abduc ion/adduc ion we e no s a is ically signi ican . Recen
s udies ha e demons a ed gai abno mali ies in os eoa h i ic join s using ma ke less 3D
gai analysis and wea able senso s [
34
,
35
]. Boekes eijn (e al.) (2022) showed spa io em-
po al changes and compensa o y mechanisms ypical o OA and we e able o objec i ely
assess he gai pa e n using an ine ial measu emen sys em in a clinical se ing. Wang (e
al.) (2024) ound he amoun o knee lexion du ing inline lunging o be ano he po en ial
indica o o knee os eoa h i is using a ma ke less mo ion cap u e sys em [35].
Biomechanics 2024,4435
When looking a PROMs, ou coho displays di e ences om he con ol g oup in
all sco es speci ic o knee unc ion, con i ming ha ou MOA coho had signi ican ly
wo se knee unc ion and physical heal h. MOA pa ien s did no show any impai men s
ega ding hei men al heal h despi e hei ad anced KOA. O e all, ou MOA coho was
ep esen a i e o pa ien s wi h KOA [36].
The hypo hesis ha an os eoa h i ic knee would ha e a g ea e emo o ibial ans-
la ion han an una ec ed knee was no con i med. Ou s udy design may ha e led o
g oup e ec s due o signi ican di e ences in demog aphics (age, weigh , BMI). Inc easing
age in luences he spa io empo al pa ame e s o gai , as ageing leads o educed join
mobili y and a dec ease in muscle mass. Inc eased weigh , and consequen ly inc eased
BMI, inc eases join loading and g ound eac ion o ces, which can lead o al e ed gai
pa e ns in people wi h highe BMI. When high BMI and olde age a e combined, hei
e ec s on gai may be exace ba ed and esul in a unc ional decline [37–39].
The e we e no s a is ically signi ican di e ences in emo o ibial ansla ion be ween
he con ol and MOA g oups. This is consis en wi h he da a om Fa e (e al.) (2014), who
we e unable o de ec an e io displacemen o he emu in pa ien s wi h se e e OA. [
40
].
In hei s udy on he ela ionship be ween he Kellg en–Law ence sco e and 3D kinema ic
gai analysis, Zeng (e al.) (2017) obse ed ha in a Chinese popula ion su e ing om KOA,
he e was inc eased emo al ansla ion an e io ly and dis ally a heel s ike. In a ecen
s udy by Pos olka (e al.) (2020), he au ho s demons a e ha he ansla ion be ween he
wo emo al condyles and he ibia is highly ask-dependen and indi idualised. They
also s a e ha u he esea ch is needed o cla i y he ole o limb alignmen on knee join
kinema ics, which is consis en wi h ou indings. The s udy indica es ha he selec ion o
implan s o a h oplas y should be indi idualised, aking in o accoun he ecogni ion o
knee join kinema ics p io o su ge y. This app oach may acili a e u he imp o emen s
in a h oplas y ou comes.
In he cu en s udy, no ele an di e ences be ween he le and igh sides we e iden-
i ied (Table 5). I is no iceable ha he sca e o he da a is la ge in ou s udy popula ion.
This means ha he e is a la ge in e indi idual a ia ion in emo o ibial ansla ion as well,
wi hou a speci ic pa e n being ecognisable o KOA (Figu e 3). Fu he mo e, he e is no
ele an di e ence in emo o ibial ansla ion be ween he heal hy and diseased limbs in
he MOA g oup. This is in con as o a s udy by Zeng (e al.) (2024), which demons a ed
inc eased emo o ibial ansla ion in ACL-de icien knees wi h ca ilage lesions compa ed
o ACL-de icien knees wi hou ca ilage lesions in pa ien s wi h pos - auma ic os eoa h i-
is (PTOA). These esul s could ha e signi ican implica ions o u u e indica ions o UKA
o TKA and suppo he need o p eope a i e kinema ic analysis in pa ien s wi h MOA,
especially in PTOA [7].
KOA is no limi ed o one limb, as p e iously desc ibed by Pe y (1992) and Good-
ellow (e al.) (2015). KOA al e s mechanical and kinema ic pa e ns in mo emen as a
sys emic disease; hus, he impai ed unc ion o one leg leads o an al e ed gai pa e n in
bo h legs [2,8,15].
The indings o his s udy mus be in e p e ed in he con ex o i s limi a ions. T eadmill
walking p o ides con olled and epea able condi ions, ye i can al e na u al gai pa e ns
and esul in slowe gai speed and sho e s ide leng h [
41
]. This is a bias in ou s udy
ha mus be aken in o accoun when in e p e ing he esul s. Skin ma ke s we e used o
eco d he mo emen s; howe e , ma ke placemen is known o be able o bias da a. In ou
eco dings, he used ma ke sys em had a esidual o 1.2 mm, which led o unce ain y. This
p oblem is p esen in any ma ke -based mo ion cap u e sys em and canno be excluded.
The e o e, his inaccu acy o 1.2 mm o he emo o ibial ansla ion could ha e caused bias
and de aul ed in o no signi ican a iances be ween heal hy and unheal hy join s. Thi dly,
he numbe o pa icipan s was limi ed o n = 40, and he g oups we e no age-ma ched.
We unde s and ha he g oups a e di icul o compa e, bu he goal was o eco d a heal hy
knee and compa e i wi h se e e OA o he knee; he e o e, we decided o include young
and heal hy pa icipan s in he con ol g oup despi e he age di e ences and possible bias.
Biomechanics 2024,4436
5. Conclusions
The cu en esul s co obo a e he ypical changes obse ed in PROMs, as well as
he spa io empo al and kinema ic esul s associa ed wi h MOA, as e idenced by he gai
changes ypically obse ed in pa ien s wi h KOA. Howe e , clinical gai analyses e ealed
no signi ican di e ence in emo o ibial ansla ion du ing he loading esponse phase o
s ance. The ex en o indi idual emo o ibial ansla ion may p o e o be an impo an
pa ame e o al e ed join kinema ics in pa ien s wi h MOA, especially p io o UKA
implan a ion. In he u u e, he ex en o emo o ibial ansla ion may p o ide aluable
in o ma ion o he diagnosis, ea men and moni o ing o MOA.
Au ho Con ibu ions: Concep ualisa ion, S.K. (Simon Kuwe ), M.W., S.K. (S e an K a zens ein) and
B.M.; me hodology, S.K. (Simon Kuwe ) and S.K. (S e an K a zens ein); so wa e, S.K. (Simon Kuwe )
and S.K. (S e an K a zens ein); alida ion, S.K. (Simon Kuwe ), S.K. (S e an K a zens ein), M.W.
and B.M.; o mal analysis, S.K. (Simon Kuwe ); in es iga ion, S.K. (Simon Kuwe ); esou ces, S.K.
(S e an K a zens ein); da a cu a ion, S.K. (Simon Kuwe ); w i ing—o iginal d a p epa a ion, S.K.
(Simon Kuwe ); w i ing— e iew and edi ing, S.K. (Simon Kuwe ), M.W., S.K. (S e an K a zens ein),
M.J.K.S. and B.M.; isualisa ion, S.K. (Simon Kuwe ); supe ision, B.M.; p ojec adminis a ion,
S.K. (S e an K a zens ein) and B.M. All au ho s ha e ead and ag eed o he published e sion o
he manusc ip .
Funding: This esea ch ecei ed no ex e nal unding.
Ins i u ional Re iew Boa d S a emen : The s udy was conduc ed in acco dance wi h he Decla a ion
o Helsinki and app o ed by he Ins i u ional E hics Commi ee o Kiel Uni e si y (D536/21).
In o med Consen S a emen : In o med consen was ob ained om all subjec s in ol ed in
he s udy.
Da a A ailabili y S a emen : Da a a e con ained wi hin he a icle.
Con lic s o In e es : The au ho s decla e no con lic s o in e es .
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