total knee arthroplasty

Frank R. Ebert, MDFrank R. Ebert, MDUnion Memorial HospitalUnion Memorial Hospital

Baltimore, MarylandBaltimore, Maryland

TOTAL KNEE TOTAL KNEE ARTHROPLASTYARTHROPLASTY

Frank R. Ebert, MDUnion Memorial Hospital

Baltimore, Maryland

TOTAL KNEE ARTHROPLASTY

Total Knee Arthroplasty

Goal—Restore mechanical alignment—Restore joint line

Normal Knee Anatomy

Position in single leg stance Mechanical axis valgus 3º Femoral shaft axis valgus 6º Proximal tibia varus 3º


Radiographic Evaluation—Standing full length – AP—Standing AP—Extension/Flexion laterals—Tunnel view—Sunrise view


Radiographic EvaluationWeight Bearing X-rays

—Extent of joint space narrowing—Ligament stretch out—Subluxation of femus on tibia


Radiographic AnalysisAnatomic Axis – Femur

—Line that bisects the medullary canal of the femur

—Determines the entry point of the femoral medullary guide rod


Radiographic AnalysisMechanical Axis – Femur (MAF)

—A line from center of femoral head to center of distal femur


Radiographic AnalysisAnatomic Axis Tibia (AAT)

—A line that bisects the medullary canal of the tibia

—Determines the entry point of the guide rod


Radiographic EvaluationMechanical Axis – Tibia (MAT)

—Line from center of proximal tibia to center of ankle

—Proximal tibia is cut perpendicular to (MAT)

Issues with Surgical Techniques

Traditional Joint Line Orientation Tibial cut perpendicular to the MAT Femoral shaft at a valgus angle 5º to

8º valgus based off the ong standing x-ray

Surgical Technique

Incision — straight longitudinal incisionTissue handling keyAvoid flapsPreserve soft tissue flap about the patella

Surgical Technique

Remember 7cm Rule between incisions

Issues with Surgical Techniques Exposure options

— Subvastus / midvastus Routine knee replacements

Quicker rehab— Medial parapatellar / midline

Difficult total knee — obese patients

Revisions

MIS vs MINI TKA

Capsulotomy only?Mid vastus?Sub vastus?

MIS

MIS vs MINI TKA

Mid vastus?Sub vastus?Quad sparing? MIS

Area of Variation

Type I-High Insertion

Type II-Pole Insertion

Type III-Low Insertion

Anatomic Variations of VMO Insertion

Type I- High VMO Insertion

Retinacular Incision

Area of extended retinaculumMuscle

Insertion

Type II-Pole Insertion

Capsular or Retinacular Incision

Muscle Insertion

Type III-Low VMO Insertion

Area of Extended VMMuscle

Insertion


Alignment— Extramedullary vs Intramedullary

Accuracy vs increased PE riskFemur – Intramedullary Overdrill opening and

insert slowly IM guide Caution with bilateral Total

Knee ArthroplastyTibia – Extramedullary


Femoral Rotation— Landmarks

Posterior femoral condylesEpicondyles 5º external rotation

to the posterior condyles

Issues with Surgical Techniques Femur

— Measured resections: equal bone distally and posteriorly

— Tensioning devices & ligament releases

— Do not alter bone resection for ligament tightness


Tibial Component Rotation

— Transmalleolar axis

— Posterior tibial plateau

— Tibial tubercle — lies lateral

Malalignment

Tibial ComponentInternally Rotated

Tubercle Too Lateral

Management of Deformity

1. Release the tight side of the deformity

2. Tighten the loose side3. Accept some residual soft tissue

imbalance4. Combination

Surgical Techniques

Varus Knee1. Pes anserinus2. Joint Capsule3. Deep Tibial Collateral4. Semimembranosus5. Posterior Medial Capsule

Varus Knee

Varus KneeVarus Knee

Varus Knee

Surgical Techniques

Valgus Knee1. Iliotibial Band2. Popliteus Tendon3. Posterior Lateral Capsule4. Lateral Head of Gastroc5. Biceps Femoris

Surgical Techniques

Valgus Knee— Peroneal nerve palsy – valgus /

flexion deformity— Treatment

Release dressings or flex the knee

Surgical Techniques:

Flexion Contracture

1. Posterior capsule

2. Gastroc origins

3. Posterior cruciate

4. Distal femur

Fixed Flexion Deformity in TKA

Complex Combinations:

— musculotendinous contracture

— ligamentous contracture

— capsular contracture

— osteophytes of posterior condyle


Biomechanics— increased quadriceps force for

knee stabilization during weight bearing

— increased forces transmitted to the patellofemoral joint

Fixed Flexion Deformity in TKABiomechanics— increased forces are placed on

posterior tibial plateau— femoral condyles sink into the

tibial plateau— contact between intercondylar

notch and tibial eminence form a boney block


Associated deformity

— varus deformity 40% - > 5º range 5 to 30º varus

— valgus deformity 30% - > 5º range5 to 22º valgus

Firestone et alCOOR ‘92


Incidence of Problem – Review of 700 TKA & Revision TKA’s— 60% before primary TKA— 21% before revision TKA

Tew & ForsterJBJS (B) 87


Soft tissue release— Varies with angular deformity



Surgical Treatment Soft tissue release Additional bone resection Combination


Postoperative Correction

— the more severe the deformity must consider the pros and cons of additional bone resection and/or soft tissue release

Volz COOR ‘89


Additional bone resection – pros— joint line is positioned slightly more

proximal— functionally lengthens the collaterals and posterior capsule forward extension— doesn’t compromise flexion stability



Additional bone resection — cons (excessive)

• Collateral ligament laxity

• Quadriceps redundancy

• Hyperextension

• Bone quality can be compromisedMcPherson et al ‘94

Additional Femoral

Resection


Surgical Treatment for Deformity < 10º FFC Soft tissue release – only necessary

— posterior capsule— possibly PCL— posterior osteophytes


Surgical Treatment for Deformity 10-20º FFC— consider distal femoral resection 3 to 5 mm— Posterior capsule— PCL resection posterior

osteophytes

Firestone et al COOR ‘92


Surgical Treatment for Deformity 20-30º FFC— distal femoral resection 3 to 5 mm— posterior capsule— PCL resection posterior osteophytes

Firestone et al COOR ‘92


Surgical Treatment for Deformity > 30º FFC— consider pre-op casting ≠— distal femoral resection 5 mm— proximal tibial resection— PCL resection— posterior osteophytes

Firestone et al COOR ‘92et al J of Arthro ‘99


Peroneal Nerve Palsy Vascular Insufficiency Anterior Pressure Ulcers Manipulation


No formula is exact for treatment of the problem

Consider a balance between soft tissue release vs bone resection


Stiff Knee Remove osteophytes Insall Turn Down Osteotomize the tibial tubercle Rectus snip


Stiff Knee Epicondylar osteotomy for large

flexion / contracture Lateral release to evert the patella

Issues with Surgical Techniques Patellar resurfacing

— Recommended for all RA patients— Without resurfacing 4% to 6%

incidence of anterior knee pain— With resurfacing increased

incidence of fracture

Issues with Surgical Techniques Patellar resurfacing

— Thickness shouldn’t exceed 25 mm

— For every 1 mm thicker reduces flexion by 3º


Patellar Baja

• Proximal tibial osteotomy

• Tibial tubercle shift

• Prior fracture


Patellar Baja

• Don’t raise joint line

• Consider lowering joint line

— Distal femoral alignment

• Trim anterior tibial poly to avoid impingement of patella


Patellar Clunk Syndrome

— Seen at 35º-40º knee flexion

— Treatment is arthroscopic or open resection

Issues with Surgical Techniques Sagittal Plane Balancing

Situation Problem Solution

Cut Tight Symmetrical – cut morein extension gap proximal tibiaCut Tight in flexion

Cut Tight Asymmetrical – Release PCL;in extension gap Posterior capsule Cut Loose Consider PCL in flexion substituting prosthesis

– Resection distal femur AVOID recurvatum

Issues with Surgical Techniques Sagittal Plane Balancing

Situation Problem SolutionCut Good Asymmetrical – Resection additional in extension gap tibia Cut Tight in flexion – May need to release

PCL – Ensure posterior

slope of tibia

Cut Good Asymmetrical – Need femoral in extension gap augmentation Cut Loose – Adjust to larger in flexion femoral component

Complications in Total Knee Arthroplasty

Periprosthetic FracturesInfected Total Knee

Arthroplasty

SupracondylarFractures of the

Femur

After Total Knee Arthroplasty

Supracondylar Fractures After TKR

l Notching of the femoral cortex l Osteoporosisl Prolonged steroid usel Preexisting neurologic disorders


OSTEOPOROSIS

Bogoch, et al, CORR 1986


l Major trauma is not required to produce fractures in many TKA patients

l Alignment not correlated with fracture

l Weight not a significant factor

Fractures After TKANeer Classification of Supracondylar Fracturesl Type I - Minimal displacementl Type IIA - Medial displacement of

condylesl Type IIB - Lateral displacement of condylesl Type III - Supracondylar and shaft

fractures


TREATMENT

Type 1 – Nondisplaced


Type 1 fractures 83% success rate

Chen, et al, 1994



Chen, et al, 1994


l Castingl Traction followed by rest

Non Operative Method



Chen, et al, 1994


l Plates / Screw fixationl Intramedullary rodsl Rush pinsl External fixationl Primary arthrodesisl Revision arthroplasty

Operative Method


l Patients’ ability to tolerate tractionl Ability of bone to hold screwsl Ability of the surgeon

Type 2Considerations

Intercondylar Distances of Commonly Used Femoral Prostheses

Biomet, (Warsaw, IN) AGC 18 Universal 18

DePuy, (Warsaw, IN) AMK 20

Dow Corning Wright, (Arlington, TN) Whitesides modular 20Howmedica, (Rutherford, NJ) PCA 18.5Intermedics, (Austin, TX) Natural 14Johnson and Johnson, (New Brunswick, NJ) Press-fit condylar 20

Insall-Burstein* 15 (posterior stabilized)

Kirschner, (Timonium, MD) Performance 14Zimmer, (Warsaw, IN) Insall-Burstein I* 16

Insall-Burstein II 15 (posterior stabilized* or constrained condylar†) Miller-Galante I Small / small + ‡ 11 Regular / regular + 12.5 Large / large + 15 Large + + 18 Miller-Galante II 13

Manufacturer ModelModelIntercondylar Distance(Smallest Size) (mm))


No one form of treatment gives uniformly good

results

Infection in Total Knee Arthroplasty

Complications in Arthroplasty

Infection – Risk Factorsl Skin ulcerations / necrosisl Rheumatoid Arthritisl Previous hip/knee operationl Recurrent UTIl Oral corticosteroids


Infection – Risk Factorsl Chronic renal insufficiencyl Diabetes l Neoplasm requiring chemol Tooth extraction


Infection – Clinical Coursel Pain #1l Swellingl Feverl Wound breakdown drainage

Windsor et alJBJS; 1990

Early < 3 months

Lab Value

Mayo Series Mean 7,500

l Differential 67 PMN’s

l Sed rate 71 mm/hr

l Arthrocentesis

Infections About TKR

Late > 3 monthsSymptoms: 52 patients Pain 96% swelling 77% Debride 27% Active drainage 27% Sed rate 63 mm/hr WBC - 8300

Windsor et alJBJS; 1990



Infection – Surgical Techniquesl Avoid skin bridgesl Avoid creation of skin flapsl Hemostasisl Prolonged operating time


Infection – Work-Upl Wound Historyl Physical Examl Serial Radiographsl Lab/sed rate/CRPl Bone scan / Indium scan


InfectionArthrocentesis

l Cell countl Diff > 25,000 pmnl Protein – highl Glucose – low


Infectionl Host Response Glycocalyx

GristinaJBJS; 1983

Micro Organisms

Organisms Isolated from 71 Patients Organisms Isolated from 71 Patients With Infected Knee ReplacementWith Infected Knee Replacement

StaphylococcusStaphylococcus 6464 S. aureusS. aureus, penicillin sensitive , penicillin sensitive 1414 S. aureusS. aureus, penicillin resistant, penicillin resistant 2828 S. epidermisS. epidermis 2222Gram negativeGram negative 1212 PseudomonasPseudomonas 77 Escherichia coliEscherichia coli 55AnærobicAnærobic 66OtherOther 17 17

OrganismOrganism PercentPercent


Treatment Optionsl Antibiotic suppressionl Aggressive wound debridement


Treatment Optionsl Antibiotic suppression

Indicated in med compromisedOrganism - gram+ strep staphepi


Treatment Optionsl Resection arthroplastyl 2 Stage re-implantl Arthrodesisl Amputation

Complications in ArthroplastyTreatment Optionsl Debridement with antibiotic suppression

therapyStrep/staphepi -- bestAvoid repeated attemptsFrozen tissue sectionSuction drains


Two-Stage Reimplantationl Most successful treatmentl Procedure of choice

Complications in ArthroplastyTwo-Stage Reimplantation Procedure

l Remove components, cement, I&D

l Fabricate and place spacer

l 6 weeks of antibiotics

l Reimplantation


Two-Stage Reimplantation Stage Il create antibiotic spacer impregnated with antibioticsl wound closure

Complications in ArthroplastyTwo-Stage Reimplantation

l Spacer Antibiotic Regimen

Tobramycin 2.4 gm/3.6 gm per 40 gms of PMMA

Vancomycin > gm to 1 gm per gms of PMMA


Intra-operative Frozen Sectionl < 5 PMN’s per HPF – no

infectionl > 10 PMN’s per HPF – infection

Mirra; JBJS


Results — Gm positive

Windsor et al 92 % JBJS 1990

Insall et al 97% JBJS 1983


Resection Arthroplastyl Removal all componentsl Remove all cementl Effective in medically

compromised patient


Arthrodesis Indicationsl Extensor mechanism disruptionl Resistant bacterial Inadequate bonestockl Inadequate soft tissuesl Young patient

Advantages

Definitive treatment

Little chance of recurrence

Arthrodesis

Disadvantages

Difficulty with transfers / small spaces

Increase energy requirements

Arthrodesis

Algorithm

TKAClinical Sepsis

(GRAM + Organism)

< 3 wks > 3 wks

DebridementAntibiotics (6 wks)

2-StageReplant


AlgorithmDebridementAntibiotics

Success

2-stage Replant Arthrodesis


No Success

2-stage Replant

SuccessNo

Success

ResectionArthroplasty

Thank You

total knee arthroplasty

Healthcare