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 Evaluation

Weight 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 Analysis

Mechanical Axis – Femur (MAF)—A line from center of femoral

head to center of distal femur


Radiographic Analysis

Anatomic Axis Tibia (AAT)—A line that bisects the

medullary canal of the tibia—Determines the entry point of

the guide rod


Radiographic Evaluation

Mechanical 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 condyles

Epicondyles 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 Component

Internally Rotated

Tubercle Too Lateral

Management of Deformity

1. Release the tight side of the deformity

2. Tighten the loose side

3. Accept some residual soft tissue imbalance

4. Combination

Surgical Techniques

Varus Knee

1. Pes anserinus

2. Joint Capsule

3. Deep Tibial Collateral

4. Semimembranosus

5. Posterior Medial Capsule

Varus Knee

Varus KneeVarus Knee

Varus Knee

Surgical Techniques

Valgus Knee

1. Iliotibial Band

2. Popliteus Tendon

3. Posterior Lateral Capsule

4. Lateral Head of Gastroc

5. 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 osteophytesFirestone et al COOR ‘92

et 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


Patellar resurfacing

— Recommended for all RA patients

— Without resurfacing 4% to 6% incidence of anterior knee pain

— With resurfacing increased incidence of fracture


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 Solution

Cut 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 Osteoporosis

l Prolonged steroid use

l 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 Casting

l 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 traction

l 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 Factors

l Skin ulcerations / necrosis

l Rheumatoid Arthritis

l Previous hip/knee operation

l Recurrent UTI

l Oral corticosteroids


Infection – Risk Factors

l Chronic renal insufficiency

l Diabetes

l Neoplasm requiring chemo

l Tooth extraction


Infection – Clinical Course

l Pain #1

l Swelling

l Fever

l 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 Techniques

l Avoid skin bridges

l Avoid creation of skin flaps

l Hemostasis

l Prolonged operating time


Infection – Work-Up

l Wound History

l Physical Exam

l Serial Radiographs

l Lab/sed rate/CRP

l Bone scan / Indium scan


Infection

Arthrocentesis

l Cell count

l Diff > 25,000 pmn

l Protein – high

l Glucose – low


Infection

l 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 2222

Gram negativeGram negative 1212 PseudomonasPseudomonas 77 Escherichia coliEscherichia coli 55

AnærobicAnærobic 66

OtherOther 17 17

OrganismOrganism PercentPercent


Treatment Options

l Antibiotic suppression

l Aggressive wound debridement


Treatment Options

l Antibiotic suppression

Indicated in med compromised

Organism - gram+ strep staphepi


Treatment Options

l Resection arthroplasty

l 2 Stage re-implant

l Arthrodesisl Amputation


Treatment Optionsl Debridement with antibiotic

suppression therapyStrep/staphepi -- bestAvoid repeated attemptsFrozen tissue sectionSuction drains


Two-Stage Reimplantation

l Most successful treatment

l Procedure of choice


Two-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 I

l create antibiotic spacer impregnated with antibiotics

l wound closure


Two-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 Section

l < 5 PMN’s per HPF – no infection

l > 10 PMN’s per HPF – infection

Mirra; JBJS


Results — Gm positive

Windsor et al 92 % JBJS 1990

Insall et al 97% JBJS 1983


Resection Arthroplasty

l Removal all components

l Remove all cement

l Effective in medically compromised patient


Arthrodesis Indications

l Extensor mechanism disruption

l Resistant bacteria

l Inadequate bonestock

l Inadequate soft tissues

l 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


Algorithm

DebridementAntibiotics

Success

2-stage Replant Arthrodesis


No Success

2-stage Replant

SuccessNo

Success

ResectionArthroplasty

Thank You

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