Technique UKA

Lee Beom KooLee Beom Koo

Gachon university Gil HospitalGachon university Gil Hospital

Technique Technique UKAUKA

Pre-op measurement of tibia resection line & slope

Lateral joint line 을 기준으로 joint 에 parallel 하게 선을 긋고 그선에서 7mm 하방으로 선을 그은 후 그선 과 tibia medial plateau 와의 거리를 측정한 다 ( 대개 2-4 mm 이다 )

Lateral 사진을 보고 sagittal slope 측정하여 7 도 이하이면 natural slope 로 ,cutting line 을 정하고 7 도이상이면 slope 를 7 도 정도에 맞추어 자른 다

• 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

• .

horizontalhorizontal Tibial resection;depth Tibial resection;depth

Argenson, Jean-Noel A MD; Parratte, corr 464 Nov 2007 P32

Scott Insall 4th edit

• 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

ImportantImportant techn in UKAtechn in UKA

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

ApproachApproach

AM arthrotomy 후 proximal tibia 의medial soft tissue 를 elevation 하는 데 deep MCL 과 MCL tibia insertion 중 proximal insertion 은 elevate 한다그후 The anterior part of medial meniscus 을 자르고 The medial spur도 rongeur and osteotome 으로 자른 다MCL retractor 가 쉽게 들어갈 정도

Evaluation of jointEvaluation of joint

While the patella is retracted. Resistance of ACL and state of cartilage of lateral & patellofemoral joint is inspected

Exposure of medial compartment

patella 를 retraction 후 MCL 을 MCL retractor 로 retract 하고 다리를 slight external rotation of leg 하면 전체적으로 좋은 시야가 나온 다

Guide 의 shaft 를 tibia crest 에 맞추어 coronal alignment 결정후 하나의 screw 를 박아서 coronal alignment 를 정한다

Guide 의 center 를 술전 tibia axis 만나는 곳에 둔다

.

.

Adjustment and fixation of tibia guide

balancingbalancing

After removal of the osteophytes, the varus deformity can be corrected.


Adjustment and fixation of tibia guide

Sagittal slope 를 재고 distal 에서 guide 를 올려서slope 를 정한다

. The natural slope is preferred But slope greater than 7 is not recommended수술 전 계획 대로

• usually between 5° and 7° of posterior slope

• The natural slope is restored, but a posterior slope greater than 7 degrees is not recommended

Slope of tibiaSlope of tibia



Posterior Slope of the Tibial Implant Posterior Slope of the Tibial Implant and the Outcome of and the Outcome of

Unicompartmental Knee ArthroplastyUnicompartmental Knee Arthroplasty

Philippe Hernigou and Gerard Deschamps

J Bone Joint Surg Am. 2004;86:506-511

Horizontal cut

MCL retractor 로 MCL protection 요하며 .

• 역시 너무 깊이 들어가 N_V 손상주지 않도록 조심 해야한다

The sagittal tibial cut 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 wall 방향깊이 ;너무 깊지 않게 , 깊으면 후에 tibia fx올수 있다

• 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.

the direction of the sagittal the direction of the sagittal cutcut


Richard D. Scott

Bobby 로 marking 하면 좋다 이범구

Balance in extensionBalance in extensionAfter 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 flexionBalance 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 balanceIdeal balance

med lat

extension 2mm 2mm

flexion 3mm 4mm

ICL AAOS 2010 Richard A Berger P47

• 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

flexion gap balancingflexion gap balancing


• . 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

the proper thickness of the tibial componentthe proper thickness of the tibial component

insall 4th edit Wolfgang FitzRichard D. Scott

• 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




If the flexion gap is too tight;If the flexion gap is too tight;first step first step

종종 pre-op tibia slope 가 7 도 이상이나 tibia 를 slope 를 7 도로 주고 하면 flexion gap 이 tight 해진 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 lineMarking 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 cutDistal femoral cutthe 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.

shim can be used to manage the bone defect.

Distal cut 가 flex 해지면 flex gap 이 tight 해진다Tilt 안 되게 자른 다자른 골의 두께 를 측 정 , shim 이 위로 안 가게 check

• 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

Slope of distal femur cuttingSlope of distal femur cutting


Distal cut 가 flex 해지면 flex gap 이 tight 해진다

• 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

The entrance hole of the distal The entrance hole of the distal femurfemur


Distal femoral cutDistal femoral cut

Scuderi Insall 4th editThe drilling of the femoral medullary canalthrough a short incision often requires bringing theknee to lower degrees of flexion; otherwise, in flexion, thepatella might induce incorrect alignment of the intramedullaryguide.

• calculated on the full weightbearing view

• the angle between the anatomic and mechanical axis is chosen

• This angle is usually 4° to 6°

the distal femoral cut ;Angle the distal femoral cut ;Angle

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

Scuderi Insall 4th edit

For valgus knees, it is often necessary to use a more proximaldistal femoral cut

The amount of bone resected ; corresponds to the femoral prosthesis thickness

The amount of bone resected

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.


The Extramedullary Spacer Block Technique

Finishing cutting guide placement Finishing cutting guide placement

. Femur finishing guide is inserted in 90 degree flexion

Finishing cut ;SizeFinishing cut ;Size

If the size is proper,

1 to 2 mm of exposed bone . At the anterior edge

• defined by the junction between the eburnated bone of the femoral condyle and the intact cartilage remaining in the trochlear groove.

The anterior extent of the The anterior extent of the weightbearing surfaceweightbearing surface

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.

Finishing cut ;SizeFinishing cut ;Size


Mediolateral dimensionMediolateral dimension

For the correct mediolateral position, The guide should be placed in the center of the femoral condyle,mediolaterally

RotationRotation

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

• 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.

Finishing cut ;Finishing cut ;To assess the amount of external rotation,To assess the amount of external rotation,

..


.This guide should also be rotationally set so that the posterior surface is parallel to the resected tibia

Finishing cut; rotationFinishing cut; rotation


Guide 를 tibia spacer넣고 그위에 finishing guide 넣으면 편할 듯이범구

Fixation of finishing guide Fixation of finishing guide Posterior & Champer cutPosterior & Champer cut

Finishing guide is fixed with two screw. at the Anterior margin of guide, bone is gouged slightly to accept the curved prosthesisWhile 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

• . 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

Posterior condyle resectionPosterior condyle resection


• 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

removal of any posterior removal of any posterior osteophytesosteophytes


• 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.

The femoral component should be The femoral component should be placedplaced


11stst alignment check alignment check

Post. Condyle trimming to Post. Condyle trimming to avoid impingement avoid impingement

posteriorlyposteriorly

Post. Condyle trimming to avoid impingement posteriorly

The final preparation of the tibia;The final preparation of the tibia;exposureexposure

The leg is externally exposed, while the MCL is retracted to expose the whole medial compartment

The size of the tibial trayThe size of the tibial tray

Size 는 AP 길이를 보고 결정해야한다 종종 ACL 보다 떨어져서 sagittal cut 하는데 medial 크기가 작아진 다 그후 coronal plane 으로 크기 정하면 AP 상 적은 크기가 들어가고 cortical support 가 안 된다 ; tibia plate 가 cancelleous bone 에만 걸치므로 조기 collapse 가 온 다

• intra and inter observer reliability 가 poor

• accuracy of templating in TKA ; 50-57% Heal and Blewitt JA 17;90,2002

*Templating in estimating size of *Templating in estimating size of unicondylar KAunicondylar KA

(Bothra JOAr Sept'03P 780)

• best compromise between maximal tibial coverage and overhang, which might induce pain in the soft tissues.

The size of the tibial trayThe size of the tibial tray


•overhang, which might induce pain in the soft tissues

Tibia preparation; Tibia preparation;

tibia guide 넣고 일시적으로 tensor 로 눌러서 고정후 the keel 을특수한 osteotome 을 써서 하며 peg hole을 drilled

tibia 의 posterior margin 을 정확히 파악 후 하여야 하며종종 tibia guide 가 뒤로 가는 경우가 많으니 anterior cortical

shell 에 guide 의 margin 을 맞 추는 것 이 좋다

Alignment checkAlignment check

Tibia cementTibia 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 tilt of tibia plate especially posterior especially posterior

• Easily happen when simultaneous cementing because knee extension cause pressure anteriorly

• which result in tightness in flexion• Cement defect posteriorly.

• Cement is applied wholly to prosthesis and femoral cut surface except posterior condyle & prosthesis is inserted & impacted

Femoral cementFemoral 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.

cementcement


• 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




Liner insertionLiner insertion

• In flexion , the liner is inserted with hand

• 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

alignmentalignment

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 Lateral Unicompartmental Unicompartmental

Replacement Replacement

• 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)

Lateral Unicompartmental Knee Arthroplasty: Lateral Unicompartmental Knee Arthroplasty: Survivorship and Technical Considerations at an Survivorship and Technical Considerations at an

Average Follow-Up of 12.4 YearsAverage Follow-Up of 12.4 Years

Pages 13-17 Jan'06 J arthroplastyDonald 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. BerendClin Orthop Relat Res (2012) 470:77–83

• 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.

Flexion gap balancingFlexion gap balancing

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 AInsall 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

• 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

lateral UKAlateral UKA

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

ESSKA 2008

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