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

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 다

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 맞나는 곳에 둔다

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Adjustment and fixation of tibia guide

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 recommended

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

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

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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

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 해진다

Distal cut 가 flex 해지면 flex gap 이 tight 해진다

Distal femoral cutDistal femoral cut

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

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

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

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

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

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

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

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

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

Thank you for your Thank you for your attentionattention