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168
N. R. Patel et al.
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. Table 15.1 (continued)
15
Authors Year #
Swank etal.
1993)
(
Lewold etal.
(
1995)
Tabor Jr. and
Tabor (
1998)
Ohdera etal.
2001)
(
Ashraf etal.
(
2002)
Keblish and
2004)
Briard (
Saxler etal.
(
2004)
O'Rourke etal.
2005)
(
Carlsson etal.
(
2006)
Cartier etal.
(2007)
Forster etal.
2007)
(
Sah and Scott
(
2007)
Argenson etal.
2008)
(
Bertani etal.
(2008)
Lustig etal.
2009)
(
John etal.
(2011)
Pandit etal.
(2010)
Lustig etal.
2011)
(
Berend etal.
(2012)
Heyse etal.
2012)
(
Lustig etal.
(2012)
1993 7 5 Fibermesh (Zimmer); 2 Microloc (DePuy);
1995 36 Oxford (Biomet), cemented, mobile bearing 6 (1–10) 86.1% at 6years (5)
1998 6 Marmor-style, cemented, all-poly tibia 9.7 (5–20) 66.7% at 9.7years (2)
2001 18 Four different designs 8.25 (5–15.75) NA (2)
2002 83 St. Georg Sled (Link), cemented all-poly tibia 9 (2–21) 74% at 15years (15)
2004 19 LCS (DePuy), cemented, mobile bearing 11 (5–19) 84.2% at 11years (3)
2004 46 AMC Uniglide (Corin), 72% cemented, 25%
2005 14 Marmor (Smith & Nephew), cemented all-poly
2006 29 Miller-Galante (Zimmer), cemented, metal-
2007 30 < age 60, Genesis (Smith & Nephew); 20%
2007 30 Preservation (DePuy), cemented, 13 mobile
2007 49 Four different designs 5.2 (2–14) 100% at 5.4years (0)
2008 38 Four different designs 12.6 (3–23) 84% at 16years (5)
2008 35 Four different designs 9 (2–22) 85.7% at 9years (5)
2009 60 HLS Evolution (Tornier), cemented, all-poly
2010 9 Miller-Galante (Zimmer), cemented, metal-
2010 53 Oxford I&II (Biomet) 5.2 82% at 4years (11)
2011 54 HLS Evolution, all-poly tibia 8.4 (5–16) 98.1% (1)
2012 132 Vanguard M (Biomet), cemented, metal-backed 2.4 (1–5.8) 100% at 2years (0)
2012 50 Genesis (now Accuris; Smith & Nephew), 20
2012 13 All post-traumatic; 6 HLS Evolution all-poly; 2
Type of implant (manufacturer) Follow-up
Knees
cementless & cemented
cementless, 3% hybrid, mobile bearing
tibia
backed (75%); all-poly tibia (25%)
cementless; 43% all-poly
bearing; 17 all-poly xed
tibia
backed, xed bearing
65 Oxford III at tibia 4.7 (3–9) 91% at 4years (9)
101 Oxford III domed tibia 2.3 (1–4) 98% at 4years (1)
uncemented, 23 all-poly
Marmor II (Richards) metal-backed; 5
Miller-Galante metal-backed
(years)
5.5 (4–8) 87.8% at 5.5years (na)
5.5 (2.3–12.5) 89% at 5.5years (5)
24 (17–28) 72% at 25years (2)
12.4
(3.1–15.6)
(5–14) 94% at 10years; 92% at
2 Mobile-77% at 2years
5.2 (2.1–13.3) 98.3% at 5years; 98.3% at
10.8 (2–16) 97% at 5years; 41% at
10.8 (5–16) 94.0% (3)
10.2 (3–22) 92.3% (1)
Survivorship (# Revisions)
100% at 12.4years (0)
11years; 88% at 12years
(3); xed-100% at 2years
(0)
10years (11/144)
8years
Lateral Unicompartmental Knee Arthroplasty
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. Table 15.1 (continued)
169
15
Authors Year #
Panni etal.
2012)
(
Schelfaut etal.
(
2013)
Streit etal.
(
2012)
Xing etal.
2012)
(
Altuntas etal.
(
2013)
Sebilo etal.
2013)
(
Thompson etal.
(
2013)
Marson etal.
(2014)
Smith etal.
(
2014)
Walker etal.
2014)
(
Weston-Simons
etal. (
2014)
Berend etal.
2015)
(
Demange etal.
(2015)
Newman etal.
(
2017)
Fornell etal.
(2018)
Edmiston etal.
2018)
(
Walker etal.
(2020)
Zambianchi
2020)
etal. (
Gill and Nicolai
(2019)
Greco etal.
2019)
(
2012 9 Zimmer High Flex (Zimmer) 4.5 (3–6) 100% (0)
2013 25 Oxford III domed mobile bearing Min 1 96% (1)
2012 50 Oxford III domed mobile bearing 3 (2–4) 94% (3)
2012 31 Preservation (DePuy) 4.5 (2–6) 100% (0)
2013 64 Oxford III domed mobile bearing 3.2 (2–5) 96.9% (2)
2013 82 Implants from 30 companies 5.2 (<1–23) 84% at 10years
2013 30 Miller-Galante, Zimmer ZUK, Smith &
2014 15 Oxford domed mobile bearing 2.9 (1–4) 93.3% (1)
2014 101 AMC Uniglide xed bearing (Corin) 3.9 98.7% at 2years
2014 22 Oxford III domed mobile bearing 1.8 96% at 2years (1)
2014 265 Oxford III domed mobile bearing 4 (0.5–8.3) 92.1% at 8years (4)
2015 104 Vanguard M xed bearing 2.3 (<1–6.2) 98.1% (2)
2015 33 iUni G1 (ConforMIS) 2–4.4 97% at 3.1years (2)
2017 61 Oxford III domed mobile bearing 7 87% at 7years
2018 41 Oxford III domed mobile bearing Min 2 97.6% at 2years (1)
2018 67 Zimmer Unicompartmental knee system or the
2019 52 Oxford xed lateral prosthesis 2 100% at 2years
2019 67 Robotic assisted Stryker Restoris MCK Min 2 100% at 2years
2019 14 Physica Zuk 1.5 100% at 1.5years
2019 56 Oxford xed lateral prosthesis 2.7 96% at min 2years
Type of implant (manufacturer) Follow-up
Knees
Nephew Journey, Mako
12 Zimmer High-ex xed bearing 2.7 (1–6) 100% (0)
19 Miller-Galante 6.3 (2–9) 85% at 2.8years (3)
Zimmer Miller-Galante Unicompartmental
knee before 2004
(years)
2 96.4%
Min 2years;
mean: 7years
Survivorship (# Revisions)
95.5% at 5years
13% reoperation
94% at min 2years
170
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N. R. Patel et al.
15
Take-Home Messages
5 Isolated lateral compartment knee osteoar-
thritis occurs in 5–10% of individuals with
knee osteoarthritis.
5 Varus stress and exed posteroanterior radio-
graphs are critical to identifying patients with
isolated lateral compartment arthritis.
5 Lateral parapatellar approach limits incision
size, but care must be taken to preserve the
inferior fat pad with thin lateral retinacular
tissue to provide adequate closure.
5 Care must be taken during the vertical tibial
saw cut to ensure proper rotation and limit
any violation of the posterior cortex.
5 The normal knee kinematics and exion/
extension ligamentous laxity should be taken
into consideration when balancing the knee.
The lateral compartment has greater laxity in
exion than extension and should be reproduced when performing lateral UKA.
5 Cementation techniques include drilling holes
to increase surface area, limiting posterior
extrusion of the cement, and using a 90-degree
Woodson curette to remove any additional
cement.
5 Lateral UKA has excellent results and early
survivorship with proper patient selection,
implant selection, and proper surgical technique.
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Lateral Unicompartmental
https://t.me/medicina_free
Knee Arthroplasty: AFrench
Perspective
AxelSchmidt, ChristopheJacquet, MatthieuOllivier,
andJean- NoëlArgenson
Contents
16.1 Introduction – 174
16.2 Case Example – 174
16.3 Anatomy – 175
173
16
16.4 Indications andPreoperative Investigations – 176
16.5 Kinematics ofaNative Knee andAfterUKA – 177
16.6 Surgical Technique – 177
16.6.1 Tibial Cut – 178
16.6.2 Femoral Cuts – 179
16.6.3 Implant Positioning – 180
16.6.4 Common Mistakes andOperating Diculties – 183
16.7 Results andRevision – 184
References – 185
© The Author(s), under exclusive license to Springer-Verlag GmbH, DE, part of Springer Nature 2022
E. Hansen, K.-D. Kühn (eds.), Essentials of Cemented Knee Arthroplasty,
https://doi.org/10.1007/978-3-662-63113-3_16
16
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174
A. Schmidt et al.
16.1 Introduction
Lateral unicompartmental knee arthroplasty (UKA)
represents a minority, around 10% (Scott 2005), of all
UKA performed for osteoarthritis (OA) (Parratte etal.
2015; Berend etal. 2015). Lateral UKA is a challenging
surgical procedure, more than medial UKA due to its
rarity (low incidence of genu valgum in the population
(Ranawat etal. 2005; Rossi etal. 2014) and better tolerance in the long term of lateral compartment osteoarthritis), to the specicity of the indications, and the
characteristics of the lateral knee compartment (anatomy and kinematics).
The surgical procedure is performed through a lateral parapatellar approach. An orthogonal tibial cut to
the mechanical axis is performed which has to be as
minimal as possible. The lateral tibial slope is less
important than in the medial compartment and should
be reproduced. The sagittal tibial cut is realized close to
the tibial spines and in the internal rotation due to the
constitutional external rotation of the lateral tibial plateau (screw-home mechanism). The distal femoral cut
should be as conservative as possible allowing to “distalize” the femoral implant and compensate for the congenital hypoplasia and the wear. In genu valgum, OA
affects preferentially the posterior part of the femoral
condyle explaining why there may be intact cartilage on
the distal part of the condyle which has to be removed
before positioning the distal femoral cutting guide. Due
to the divergence of the lateral condyle, it is crucial to
avoid excessive internal rotation in exion, which will
create an impingement in extension with the tibial
spines.
The tibial implant should be close to the tibial spines
with 15°–20° of internal rotation. The femoral implant
is placed on a exed knee with external rotation and as
lateral as possible, sometimes it may rest on lateral condyle osteophytes.
Clinical and radiological results of lateral UKA are
similar to medial UKA with 90% survival at medium term
and 80% at long term. The main cause of failure for lateral
UKA is OA progression (87.5%), especially in the medial
compartment, followed by aseptic loosening (12.5%).
16.2 Case Example
A 64-year-old woman suffered from isolated lateral knee
pain for 2years. The clinical examination found a valgus
morphotype completely reducible with no sagittal laxity,
no stiffness, and no medial tibiofemoral or patellofemoral pain. Standard radiographic investigations
(. Fig.16.1) showed isolated joint space narrowing of
the lateral tibiofemoral joint with condensation of the
. Fig. 16.1 Standard X-ray. Lateral OA stage 2 with lateral tibial
osteophytes
lateral sub-chondral tibial plateau and osteophytes. The
OA was conrmed with the Rosenberg view (
Fig.16.2)
.
showing complete joint space loss (stage 3 of Ahlback’s
classication) indicating that cartilage wear is predominately posterior. Complete X-ray investigations were
realized with varus/valgus stress and leg-length views
Fig.16.3). They conrmed the complete reducibility
(.
of the knee (varus stress), no medial collateral ligament
laxity (valgus stress), and quantied the importance of
the valgus deformity and the origin of the deformation
(leg-length view): valgus deformation of 10° (HKA
angle = 190°) with hypoplasia of the lateral condyle
(mechanical femoral angle=98°) (Moreland etal. 1987).
A lateral UKA was performed (. Fig.16.4). Varus
femoral osteotomy was not recommended for this case
because of the advanced OA stage. A UKA was preferred over TKA because the pain was limited to lateral
knee compartment with preserved medial and patello-
Lateral Unicompartmental Knee Arthroplasty: AFrench Perspective
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. Fig. 16.2 Narrowing of the lateral joint line with lateral OA
stage 3in Rosenberg view
175
femoral joint spaces. A tibial implant was positioned as
close as possible to the tibial spines with internal rotation. The femoral implant was positioned very lateral
and vertical to have optimal contact with the tibial
implant during all range of motion and avoid any
impingement with the patella and the tibial spines.
Attention should be paid to avoid any overhanging and
altering of the tibial slope.
16.3 Anatomy
Asymmetries between the medial and the lateral tibiofemoral spaces are explained by their proper anatomical
characteristics (Miyatake etal. 2016).
The lateral tibial plateau has four characteristics
(Weinberg etal. 2017):
5 The cartilage surface is convex.
5 The articular surface is smaller than the medial tibial
plateau (anteroposterior and mediolateral axis).
16
. Fig. 16.3 Complete X-ray investigation with varus/valgus stress and leg-length X-ray. A good reduction of the deformity with varus stress
can be observed
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176
A. Schmidt et al.
. Fig. 16.4 Postoperative X-ray after lateral cemented UKA
5 The anteroposterior axis has an internal rotational
axis of 10–15°.
5 The posterior tibial slope is reduced on the lateral
side compared to the medial side (4° vs. 7°) (Karimi
etal. 2017).
Regarding the lateral femoral condyle, it is mostly
hypoplastic in genu valgum with a divergent axis from
the anteromedial to the posterolateral side.
The congruency between the femoral condyle and
the tibial plateau is closely related to the lateral meniscus: its shape and its mobility. In the case of prior lateral
meniscectomy, the stability of the lateral compartment
is altered leading to degenerative tears explaining the
high rate of lateral OA in young patients after meniscectomy (Longo etal. 2019).
All these anatomical characteristics of the lateral tibiofemoral compartment will impact the surgical technique, implant positioning, and the choice of prosthesis
(Demange etal. 2015; Greco etal. 2019).
> While in the medial compartment, the cartilage wear
is preferentially developing in the anterior part of the
joint, in the lateral compartment, OA starts in the
posterior part of the joint (Gulati etal. 2009).
This is particularly important and will inuence the
radiological investigations, especially with the Rosenberg posteroanterior view required to see the posterior
wear and appreciate the stage of OA.
16.4 Indications andPreoperative
Investigations
Indications and Contraindications of Lateral UKA
Indications:
5 Primary lateral OA secondary to a constitutional
genu valgum
5 Avascular osteonecrosis of the femoral condyle or
tibial plateau
5 Post-traumatic OA secondary to tibial plateau
fracture or a femoral condyle fracture
5 Post-meniscectomy OA
Contraindications:
5 OA in other compartments are as follows:
– Medial tibiofemoral compartment
– Patellofemoral compartment (especially on the
lateral facet)
5 Chronic anterior laxity
5 Medial or lateral laxity due to collateral ligament
insufciency
5 Valgus deformity >15° or non-reducible valgus
deformity (Kozinn and Scott
5 Preoperative exion contracture >15°
5 Stiffness with exion limited to 100°
5 Previous history of distal femoral osteotomy or
high tibial osteotomy
5 Inammatory disease
The clinical exam has to demonstrate concordanceregarding the location of the pain which has to be limited to the lateral compartment and eliminate other
contraindications. Testing of the collateral ligaments
and the cruciate ligament is crucial to estimate their
integrity. Conrmation with radiographic stress exams
varus/valgus and anteroposterior plane may be helpful.
The ACL evaluation may be difcult to interpret due to
the pain and the effusion.
The standard preoperative radiological investigations will conrm the localization in the lateral compartment of the OA, without medial tibiofemoral or
patellofemoral degeneration and can be graded according to Ahlback’s classication. The stress X-rays in
varus/valgus will evaluate the reducibility of the deformity and the thickness of the cartilage in the contralateral compartment. The full leg-length X-rays are
necessary to appreciate the global deformity of the lower
limbs and analyze the origin of the valgus deformity.
1989)
Lateral Unicompartmental Knee Arthroplasty: AFrench Perspective
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Origins of Valgus Knee Deformity
5 Lateral femoral condyle dysplasia (Feldman etal.
2016)
5 Post-traumatic valgus secondary to a tibial plateau
or lateral condyle fracture (Lustig etal.
5 OA after lateral meniscectomy (Pengas etal. 2017)
5 Avascular osteonecrosis of the femoral condyle or
lateral tibial plateau
5 Valgus secondary to a hip pathology (Barrios etal.
2016)
5 Congenital tibial deformity (van Lieshout et al.
2019)
2012)
Hypoplasia of the lateral femoral condyle is the most
frequent cause of valgus deformity (Rossi etal. 2014). In
this case, the position of the femoral component has to
be adapted to the severity of the dysplasia: distally and
posteriorly to restore a normal intra-articular joint
space in sagittal and coronal planes.
In cases of post-traumatic OA (Lustig et al. 2012),
the challenge is not due to bone dysplasia but rather
poor bone quality or a malunion which has to be anticipated and addressed with one option being bone graft
with screw xation. Although this indication is rare, lateral UKA is an efcient procedure with good results on
knee pain and a good survival rate in the long term
(Lustig etal. 2012).
177
> Appropriate understanding of this tibial external
rotation during extension explains why the femoral
implant has to be placed as lateral as possible and the
tibial implant has to be positioned in internal rotation
to avoid any impingement with the tibial spines in
extension.
16.6 Surgical Technique
Classically, a lateral parapatellar approach is preferentially used for this procedure even if some authors publish on the possibility of performing it through a medial
approach (Berend etal. 2012; Sah and Scott 2008).
The skin incision starts from the superior border of
the patella and nishes 2cm distally to the lateral border
of the ATT (. Fig.16.5). After a lateral arthrotomy, an
articular exploration conrms ACL integrity and conrms the limitation of OA in the lateral compartment.
Sometimes, to improve the exposure a lateral vertical
facet osteotomy of the patella is required.
> To maintain appropriate ligament tension, it is impor-
tant to respect the peripheral structures around the
lateral tibial plateau (lateral collateral ligament and
16
16.5 Kinematics ofaNative Knee
andAfterUKA
Kinematics of a native knee consists of external femoral
rotation on the tibia during knee exion associated with
posterior femoral roll-back, more important for the lateral condyle (10 mm) than for the medial condyle
(2 mm). This is the concept of “medial pivot of the
knee”: the medial compartment is the compartment of
knee stability, while the lateral compartment is the compartment of mobility (Argenson etal. 2002). The translation of the medial femoral condyle seems to be
correlated to ACL integrity (Du et al. 2018) while the
mobility of the lateral condyle on the lateral tibial plateau seems to be independent of the osteoarthritis and
ACL status. The femur will progressively pass from its
neutral position at 0° of rotation in full extension to 7°
of external rotation during exion. At the end of the
extension, between 0° and 20° of exion, both cruciate
ligaments exert tension on the tibia, putting it in external rotation and locking the knee. The tibia is then in the
position of maximal stability with the femur. This mechanism, called “the screw-home mechanism” is the key to
knee stability in terminal extension (Kim etal. 2015).
. Fig. 16.5 Skin incision and cutaneous landmarks
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A. Schmidt et al.
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. Fig. 16.6 Tibial cut with an extra-medullary guide placed
orthogonal to the mechanical tibial axis
fascia lata), while keeping a nal undercorrection of
coronal alignment (Ollivier etal. 2014).
To avoid any impingement with ACL, osteophytes of
the intercondylar notch are removed while osteophytes
of the lateral condyle are initially preserved. They will
be useful for helping the positioning of the femoral
implant (Argenson et al. 2008). The anterior contact
point in extension between femur and tibia has to be
noticed and will be a landmark for implant positioning
(size and orientation).
16.6.1 Tibial Cut
With an extra-medullary guide, an orthogonal tibial cut
to the mechanical axis is performed which has to be as
minimal as possible (Scott 2005) (. Figs.16.6, 16.7 and
. Fig. 16.7 Tibial cut with an extra-medullary guide. Preview of
the cut with the palpator
16.8). An economic bone resection will insure a bigger
bone surface area for the component and a better cortical support.
In the lateral compartment, the tibial slope is less
important than in the medial compartment (Weinberg
etal. 2017), and should be reproduced with the prosthesis to avoid any exion laxity or stiffness (Lustig etal.
2014; Randall etal. 2019). An excessive posterior tibial
slope will increase the anterior tibial translation and the
tension on the ACL (Dejour and Bonnin
1994).
The sagittal tibial cut is realized close to the tibial
spines and will determine the rotation of the tibial
implant. The two landmarks of this anteroposterior cut
are as follows:
5 In extension: the medial point of the anterior lateral
tibial plateau, in front of ACL insertion.
5 In exion: the medial point of the lateral tibial pla-
teau, behind the ACL insertion.
Due to the constitutional external rotation of the lateral
tibial plateau (screw-home mechanism (Kim etal. 2015)),
this line will cross the patellar ligament which has to be
carefully retracted to perform the bone cut (.
Fig.16.9).
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