Technique
UKA
Lee Beom Koo
Gachon university Gil Hospital
Pre-op measurement of
tibia resection line & slope
Lateral joint line을 기준으로 joint에 parallel 하게 선을 긋고
그선에서 7mm하방으로 선을 그은 후 그선 과tibia medial plateau
와의 거리를 측정한 다 ( 대개 2-4 mm이다)
Lateral 사진을 보고sagittal slope측정하여 7 도 이하이면 natural
slope로 ,cutting line을 정하고
7도이상이면
slope를 7도 정도에 맞추어 자른 다
horizontal Tibial resection;depth
•
the depth of the tibial cut as
conservative as possible to take
advantage of the strength of the
tibial cortex and the increased area
of contact proximally
• 2 to 4 mm off the deepest
portion of the medial tibial
plateau.
• , 2-3 mm; oxford
• .
Scott
Insall 4th edit
Argenson, Jean-Noel A MD; Parratte,
corr 464 Nov 2007 P32
Important techn in UKA
• Our results seem to reflect those seen in registries
confirming an earlier higher revision rate and
highlight the technical issues of overstuffing the
compartment,
• The main issues in technique were overstuffing the
medial compartment usually as a result of under
resection of tibial bone and/or MCL attenuation
• The desire for maximal bone preservation cannot
supercede the need for adequte bone
resection and varus resection on the tibial side
aggravated this situation and must be avoided
Initial Experience With the Oxford Unicompartmental Knee Arthroplasty
Geoffrey F. Dervin MD, FRCSC, a, Chris Carruthers MD, FRCSCa, Robert J. Feibel MD,
FRCSCa, Alan A. Giachino MD, FRCSCa, Paul R. Kim MD, FRCSCa and Peter R. Thurston
MD, FR
JA February 2011, Pages 192-197
Approach
AM arthrotomy후 proximal tibia의medial
soft tissue 를 elevation하는 데 deep
MCL과 MCL tibia insertion중 proximal
insertion은 elevate 한다
그후 The anterior part of medial
meniscus 을 자르고 The medial spur도
rongeur and osteotome 으로 자른 다
MCL retractor 가 쉽게 들어갈 정도
Evaluation of joint
While the patella is retracted.
Resistance of ACL and state
of cartilage of lateral &
patellofemoral joint is
inspected
Exposure of medial compartment
patella를 retraction후
MCL 을 MCL retractor로 retract하고 다
리를 slight external rotation of leg 하면
전체적으로 좋은 시야가 나온 다
Adjustment and fixation of tibia guide
Guide의 shaft를 tibia crest에 맞추어coronal alignment결정후 하나의
screw를 박아서 coronal alignment를 정한다
Guide의 center를 술전 tibia axis 만나는 곳에 둔다
balancing
After removal of the
osteophytes, the varus deformity
can be corrected.
Scott
Insall 4th edit
Adjustment and fixation of tibia guide
Sagittal slope 를 재고 distal 에서 guide를 올려서slope 를
정한다
. The natural slope is preferred But slope greater than
7 is not recommended
수술 전 계획 대로
Slope of tibia
• usually between 5° and 7° of posterior
slope
Argenson, Jean-Noel A MD; Parratte,
corr 464 Nov 2007 P32
• The natural slope is restored, but a
posterior slope greater than 7 degrees
is not recommended
Scott
Insall 4th edit
Posterior Slope of the Tibial Implant and the
Outcome of Unicompartmental Knee
Arthroplasty
Philippe Hernigou and Gerard Deschamps
J Bone Joint Surg Am. 2004;86:506-511
Horizontal cut
MCL retractor 로 MCL protection요하며.
• 역시 너무 깊이 들어가 N_V 손상주지 않도록 조심 해야한다
The sagittal tibial cut
위치 ;
The sagittal cutting line is marked at the medial edge
of ACL
Rotation;
Sagittal cut line point toward the Femoral head in
flexion
,akaki line
medial femoral condyle wall방향
깊이;
너무 깊지 않게 , 깊으면 후에 tibia fx올수
있다
the direction of the sagittal cut
R
i
c
h
a
r
d
D
.
S
c
o
t
t
• determined by the condyle
itself
• parallel to the wear pattern of
the tibia
• toward Femoral head in
flexion (임홍철)
• Having the patella not
dislocated from the patellar
groove is necessary for an
appropriate tracking of
component congruity.
Bobby로marking하면 좋다
이범구
Scott
Insall 4th edit
Balance in extension
After placement of sliding
spacer block, the medial
joint space should open
up 1 or 2 mm when
valgus stress is applied
with the knee in full
extension.
It is very important to
avoid overstuff &
overcorrection
Balance in flexion
,
2 to 3 mm laxity is suggested.in medial
UKA after placing block
For the balance in flexion,
the thigh should be lifted
with one arm to balance
the flexion gap
Ideal balance
med
lat
extension
2mm
2mm
flexion
3mm
4mm
ICL AAOS 2010 Richard A Berger P47
flexion gap balancing
• performed by sliding a
spacer block representing
the thickness of the tibial
component
• To balance the flexion gap,
the thigh should be lifted
with one arm.
• The block should slide
backward with mild
resistance.
• 1 to 2 mm laxity is
suggested.in medial UKA
Scott
Insall 4th edit
the proper thickness of the tibial component
• . After medial compartment replacement,
the medial joint space should open up 1
or 2 mm when valgus stress is applied
with the knee in full extension.
• . The deformity should not be
overcorrected
insall 4th edit Wolfgang FitzRichard D. Scott
Important techn in UKA
• Our results seem to reflect those seen in registries
confirming an earlier higher revision rate and
highlight the technical issues of overstuffing the
compartment,
• The main issues in technique were overstuffing the
medial compartment usually as a result of under
resection of tibial bone and/or MCL attenuation
• The desire for maximal bone preservation cannot
supercede the need for adequte bone resection
and varus resection on the tibial side aggravated
this situation and must be avoided
Initial Experience With the Oxford Unicompartmental Knee Arthroplasty
Geoffrey F. Dervin MD, FRCSC, a, Chris Carruthers MD, FRCSCa, Robert J. Feibel MD,
FRCSCa, Alan A. Giachino MD, FRCSCa, Paul R. Kim MD, FRCSCa and Peter R. Thurston
MD, FR
JA February 2011, Pages 192-197
If the flexion gap is too tight;
first step
종종 pre-op tibia slope가 7도 이상이나
tibia 를 slope를 7도로 주고 하면 flexion
gap이 tight해진 다
If the flexion gap is too tight , cartilage
or bone should be removed from the
posterior condyle of femur with rasp or
saw
or The slope should be slightly
increased
Marking of femoral rotation line
Next step for the Marking of
femoral rotation line
the center of the tibial spacer
block is marked with a Bovie on
the femoral condyle in different
positions
It should not be judged while the
patella is everted
or perpendicular line to the cut tibia bone
can be chosen
Distal femoral cut
the distal femoral
cutting guide is
slided in extension
and fixed with two
pin and resected .
The knee should
be flexed 5 if the
resected posterior
slope of tibia is 5
to avoid
hyperextension.
Distal cut가 flex해지면 flex gap이 tight해진다
Tilt안 되게 자른 다
자른 골의 두께 를 측 정, shim이 위로 안 가게 check
shim can be used
to manage the
bone defect.
Slope of distal femur cutting
• For example, for a 5-degree tibia slope
• the knee should be held in 5 degrees of
flexion to fix the distal femoral cutting
block.
• Because If the distal femoral cutting
block is pinned in full extension, the
knee will hyperextend 5 degrees, as
determined by the tibial slope
Scott
Insall 4th edit
Distal cut가 flex해지면 flex gap이 tight해진다
The entrance hole of the distal femur
• centered above the roof of the
intercondylar notch.
• often requires bringing the knee to
lower degrees of flexion; otherwise, in
flexion, the unyielding patella might
induce incorrect alignment of the
intramedullary guide
Argenson, Jean-Noel A MD; Parratte,
corr 464 Nov 2007 P32
Distal femoral cut
Scuderi Insall 4th edit
The drilling of the femoral medullary canal
through a short incision often requires bringing the
knee to lower degrees of flexion; otherwise, in flexion, the
patella might induce incorrect alignment of the intramedullary
guide.
the distal femoral cut ;Angle
• calculated on the full weightbearing view
• the angle between the anatomic and
mechanical axis is chosen
• This angle is usually 4° to 6°
The amount of bone resected
The amount of bone resected ;
corresponds to the femoral prosthesis
thickness
Scuderi Insall 4th edit
the deeper resection (line A)
results in less valgus than line B (3
degrees versus 5 degrees).
This also allows for more space in
full extension
For valgus knees, it is often
necessary to use a more proximal
distal femoral cut
The Extramedullary Spacer Block
Technique
Figure 82-15 A, After tibial
resection the gap is checked
with a spacer block. B, The
appropriate spacer block is
inserted into the joint space. C,
The spacer block and distal
cutting guide assembly are
shown. D, The distal cutting
guide is secured to the distal
femur. E, Alignment is
confirmed with the appropriate
block and rod.
Scuderi Insall 4th edit
Finishing cutting guide placement
.
Femur finishing guide is
inserted in 90 degree
flexion
Finishing cut ;Size
If the size is proper,
1 to 2 mm of exposed bone . At the anterior edge
The anterior extent of the
weightbearing surface
• defined by the
junction between
the eburnated
bone of the
femoral condyle
and the intact
cartilage
remaining in the
trochlear groove.
Finishing cut ;Size
There should be 1 to 2 mm of
exposed bone along the anterior
edge of the guide.
The leading edge of the femoral
component must be countersunk
into this junction to prevent patellar
impingement during flexion of the
knee
If the finishing guide appears to be
between sizes, it is preferable to
pick the smaller size.
Scuderi Insall 4th edit
Mediolateral dimension
For the correct mediolateral position, The guide
should be placed in the center of the femoral
condyle,mediolaterally
Rotation
femoral rotation may follow
the previously Marked
rotation line or
This guide should also be
rotationally set so that the
posterior cutting surface of
femoral condyle is parallel to
the resected tibia
Finishing cut ;
To assess the amount of external rotation,
• the center of the tibial trial is
marked with a Bovie on the .
femoral condyle in different
positions (90, 60, 30, 0 degrees)..
• The femoral prosthesis should be
only slightly externally rotated
•
External rotation of more than 5
degrees is not recommended so
that the possibility of edge loading
is minimized.
Scott
Insall 4th edit
Finishing cut; rotation
.This guide should
also be
rotationally set so
that the posterior
surface is parallel
to the resected
tibia
Guide를 tibia spacer넣
고 그위에 finishing
guide넣으면 편할 듯
이범구
Scuderi Insall 4th edit
Fixation of finishing guide
Posterior & Champer cut
Finishing guide is fixed with two screw.
at the Anterior margin of guide, bone is gouged slightly to accept the
curved prosthesis
While the MCL is protected with MCL retractor placed at femoral side, the
posterior femur is resected and after anterior and posterior chamfer cut ,
two femoral peg hole is drilled
Posterior condyle resection
• . The posterior condylar bone should be
resected to at least the thickness of the
metallic implant.
• It is better to resect slightly too much
of the posterior condyle than too little to
avoid making the components too tight
in flexion
Scott
Insall 4th edit
removal of any posterior osteophytes
• Once the posterior cut has been made
and the cutting guide removed, removal
of any posterior osteophytes is
necessary using a curved osteotome to
increase the range of flexion and avoid
any posterior impingement with the
polyethylene in high flexion
Scott
Insall 4th edit
The femoral component should be
placed
• in the center of the mediolateral dimension of the femoral
condyle,. when the knee is extended
• . The femoral component should extend far enough anteriorly to
cover the weightbearing surface that comes in contact with the
tibia in full extension.
• the articulating surfaces of the two components are rotationally
congruent during weightbearing . in full extension.
• It should not be judged while the knee is flexed and the patella
is everted.
Scott
Insall 4th edit
1st alignment check
Post. Condyle trimming to
avoid impingement posteriorly
Post. Condyle trimming to avoid
impingement posteriorly
The final preparation of the tibia;
exposure
The leg is externally exposed, while the
MCL is retracted to expose the whole
medial compartment
The size of the tibial tray
Size는 AP 길이를 보고 결정해야한다
종종 ACL 보다 떨어져서 sagittal cut하는데 medial크기가 작아진 다
그후 coronal plane으로 크기 정하면 AP상 적은 크기가 들어가고
cortical support가 안 된다; tibia plate가 cancelleous bone에만 걸
치므로 조기collapse가 온 다
*Templating in estimating size of
unicondylar KA
• intra and inter observer reliability
가 poor
• accuracy of templating in TKA ;
50-57%
Heal and Blewitt JA 17;90,2002
(Bothra JOAr Sept'03P 780)
The size of the tibial tray
• best compromise between maximal
tibial coverage and overhang, which
might induce pain in the soft tissues.
•overhang, which might induce pain
in the soft tissues
Argenson, Jean-Noel A MD; Parratte,
corr 464 Nov 2007 P32
Tibia preparation;
tibia guide 넣고 일시적으로 tensor로 눌러서 고정후 the keel 을
특수한 osteotome을 써서 하며 peg hole
을 drilled
tibia의 posterior margin을 정확히 파악 후 하여야 하며
종종 tibia guide가 뒤로 가는 경우가 많으니 anterior cortical
shell에 guide의 margin을 맞 추는 것 이 좋다
Alignment check
Tibia cement
• Staged cementing
• Avoid tilt of tibia
plate especially
posterior ( which
result in tightness in
flexion.
• adequate exposure
of posteromedial
tibia
• adequate sizing
tilt of tibia plate especially posterior
• Easily happen when simultaneous
cementing because knee extension
cause pressure anteriorly
• which result in tightness in flexion
• Cement defect posteriorly.
Femoral cement
• Cement is applied
wholly to prosthesis
and femoral cut
surface except
posterior condyle &
prosthesis is
inserted & impacted
Argenson, Jean-Noel A MD; Parratte,
corr 464 Nov 2007 P32
cement
• Sequence;The tibial component
-will be cemented first with the knee
• Tibia cementing
-position; in full flexion and externally rotated for a
medial UKA.
-Cement should be removed posterioly
• Femoral cementing ;and posterior cement removal
cement is done in flexion but
Once the femoral implant has been cemented, bringing
the knee close to extension with the polyethylene
inserted last helps remove any posterior cement.
Argenson, Jean-Noel A MD; Parratte,
corr 464 Nov 2007 P32
Important techn in UKA
• inadequate cementation technique, and strict
adherence to patient selection.
issues of inappropriate patient selection and
technique did account for some early
failures
The other technical issue related to debonding of the
femoral component and care must be taken to
ensure the cement mantle is evenly pressurized at
45° flexion to avoid tilting in flexion or extension
while also ensuring adequate cement mantle on the
posterior undersurface and in the femoral hole for
the peg
Initial Experience With the Oxford Unicompartmental Knee Arthroplasty
Geoffrey F. Dervin MD, FRCSC, a, Chris Carruthers MD, FRCSCa, Robert J. Feibel MD,
FRCSCa, Alan A. Giachino MD, FRCSCa, Paul R. Kim MD, FRCSCa and Peter R. Thurston
MD, FR
JA February 2011, Pages 192-197
Liner insertion
• In flexion ,
the liner is
inserted with
hand
alignment
• The ideal correction as
measured on the
postoperative full
weightbearing view will
probably consist of a
tibiofemoral axis crossing the
knee between the tibial
spines and the medial third of
the tibial plateau for a medial
UKA
Argenson, Jean-Noel A MD;
Parratte,
corr 464 Nov 2007 P32
Kennedy WR, White RP. Unicompartmental
arthroplasty of the knee; post-operative alignment
and its influence on overall results. Clin Orthop Relat
Res. 1987;221:278-285
Lateral Unicompartmental
Replacement
Lateral Unicompartmental Knee Arthroplasty: Survivorship and
Technical Considerations at an Average Follow-Up of 12.4 Years
• unique tibial
component positioning
in 10° to 15° of internal
rotation to compensate
for the “screw-home”
mechanism
• Transpatella tendon
sagittal sawing or
medial approach is
helpful( AAOS 2012)
Pages 13-17 Jan'06 J arthroplasty
Donald W. Pennington, John J.
Swienckowski, William B. Lutes and
Gregory N. Drake
Trans patella
tendon sag
saw in lat
UKA to
achive IR in
tibia resection ,
trans tibial
axis rotation
Femur ; trans
tibia rotation
Keith R. Berend
Clin Orthop Relat Res (2012) 470:77–83
Flexion gap balancing
• Balancing is
similar to that
for a medial
UKA, but
looser; play of
2 to 3 mm
instead of 1 to
2 mm (medial
UKA) is
suggested.
Scott
Insall 4th edit P 1413
• When the lateral arthrotomy is performed, visualization of the
joint is often easier than on the medial side because of the
natural mobility of the lateral tibiofemoral joint.
• The tibial resection should stay minimal, because the disease is
more often on the femoral side..
• It is often necessary to mark the correct alignment in extension
rather than in flexion to avoid medial edge loading and
impingement between the femoral implant and the tibial spines.
• The polyethylene insert is often thicker than for the medial side,
• but the principle of undercorrecting the deformity for all cases
of lateral UKA remains the basis for successful long-term
results
Jean-Noel A
Insall 4th edit
• On the lateral condyle the patella is
more vulnerable to impingement on the
leading edge of the femoral component.
This problem can be avoided by
undersizing the femoral component
Insall
P 1416
lateral UKA
• The in vivo
kinematic evaluation
of patients with
lateral UKA found a
greater posterior
displacement of the
femor during
flexion-> dome
shaped implant is
advantageous
ESSKA 2008
Argenson JN, Komistek RD, Aubaniac JM, et al: In
vivo determination of knee kinematics for subjects
implanted with a unicompartmental arthroplasty. J
Arthroplasty 17:1049, 2002
Thank you for
your attention