Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland

Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland
TOTAL KNEE ARTHROPLASTY Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland

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 Analysis Anatomic 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 incision
Tissue handling key Avoid flaps Preserve soft tissue flap about the patella

Surgical Technique Remember 7cm Rule between incisions

Exposure options — Subvastus / midvastus u Routine knee replacements z Quicker rehab — Medial parapatellar / midline u Difficult total knee — obese patients u Revisions

MIS vs MINI TKA Capsulotomy only? Mid vastus? Sub vastus? MIS

MIS vs MINI TKA Mid vastus? Sub vastus? Quad sparing? MIS

Anatomic Variations of VMO Insertion
Type I-High Insertion Area of Variation Type II-Pole Insertion Type III-Low Insertion

Type I- High VMO Insertion
Area of extended retinaculum Muscle Insertion Retinacular Incision

Type II-Pole Insertion
Capsular or Retinacular Incision Muscle Insertion

Type III-Low VMO Insertion
Area of Extended VM Muscle Insertion

Alignment Extramedullary vs Intramedullary  Accuracy vs increased PE risk  Femur – Intramedullary z Overdrill opening and insert slowly IM guide z Caution with bilateral Total Knee Arthroplasty  Tibia – Extramedullary

Femoral Rotation Landmarks Posterior femoral condyles Epicondyles 5º external rotation to the posterior condyles

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

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

Biomechanics — 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 range 5 to 22º valgus Firestone et al COOR ‘92

Incidence of Problem – Review of 700 TKA & Revision TKA’s — 60% before primary TKA — 21% before revision TKA Tew & Forster JBJS (B) 87

Soft tissue release — Varies with angular deformity Firestone et al COOR ‘92

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 Firestone et al COOR ‘92

Additional bone resection — cons (excessive) Collateral ligament laxity Quadriceps redundancy Hyperextension Bone quality can be compromised McPherson 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 º FFC — consider distal femoral resection to 5 mm — Posterior capsule — PCL resection posterior osteophytes Firestone et al COOR ‘92

Surgical Treatment for Deformity º 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 ‘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 more in extension gap proximal tibia Cut 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 Fractures Infected Total Knee Arthroplasty

After Total Knee Arthroplasty
Supracondylar Fractures of the Femur After Total Knee Arthroplasty

Supracondylar Fractures After TKR
Notching of the femoral cortex Osteoporosis Prolonged steroid use Preexisting neurologic disorders

OSTEOPOROSIS Bogoch, et al, CORR 1986

Major trauma is not required to produce fractures in many TKA patients Alignment not correlated with fracture Weight not a significant factor

Fractures After TKA Neer Classification of Supracondylar Fractures
Type I - Minimal displacement Type IIA - Medial displacement of condyles Type IIB - Lateral displacement of condyles Type III - Supracondylar and shaft fractures

TREATMENT Type 1 – Nondisplaced

Type 1 fractures 83% success rate Chen, et al, 1994

Non Operative Method Casting Traction followed by rest

Operative Method Plates / Screw fixation Intramedullary rods Rush pins External fixation Primary arthrodesis Revision arthroplasty

Type 2 Considerations Patients’ ability to tolerate traction Ability of bone to hold screws Ability of the surgeon

Intercondylar Distances of Commonly Used Femoral Prostheses
Intercondylar Distance (Smallest Size) (mm) Manufacturer Model Biomet, (Warsaw, IN) AGC Universal 18 DePuy, (Warsaw, IN) AMK 20 Dow Corning Wright, (Arlington, TN) Whitesides modular 20 Howmedica, (Rutherford, NJ) PCA 18.5 Intermedics, (Austin, TX) Natural 14 Johnson and Johnson, (New Brunswick, NJ) Press-fit condylar 20 Insall-Burstein* (posterior stabilized) Kirschner, (Timonium, MD) Performance 14 Zimmer, (Warsaw, IN) Insall-Burstein I* 16 Insall-Burstein II (posterior stabilized* or constrained condylar†) Miller-Galante I Small / small + ‡ Regular / regular Large / large Large Miller-Galante II 13

No one form of treatment gives uniformly good results

Infection in Total Knee Arthroplasty

Complications in Arthroplasty
Infection – Risk Factors Skin ulcerations / necrosis Rheumatoid Arthritis Previous hip/knee operation Recurrent UTI Oral corticosteroids

Infection – Risk Factors Chronic renal insufficiency Diabetes Neoplasm requiring chemo Tooth extraction

Infection – Clinical Course Pain #1 Swelling Fever Wound breakdown drainage Windsor et al JBJS; 1990

Early < 3 months Lab Value Infections About TKR
 Mayo Series  Mean 7,500 Differential 67 PMN’s Sed rate 71 mm/hr Arthrocentesis

Late > 3 months Symptoms: 52 patients
Infections About TKR Late > 3 months Symptoms: 52 patients  Pain 96%  swelling 77%  Debride 27%  Active drainage 27%  Sed rate 63 mm/hr  WBC Windsor et al JBJS; 1990

Infection – Surgical Techniques Avoid skin bridges Avoid creation of skin flaps Hemostasis Prolonged operating time

Infection – Work-Up Wound History Physical Exam Serial Radiographs Lab/sed rate/CRP Bone scan / Indium scan

Infection Arthrocentesis Cell count Diff > 25,000 pmn Protein – high Glucose – low

Infection Host Response Glycocalyx Gristina JBJS; 1983

Micro Organisms

Organisms Isolated from 71 Patients With Infected Knee Replacement
Percent Staphylococcus 64 S. aureus, penicillin sensitive S. aureus, penicillin resistant 28 S. epidermis 22 Gram negative 12 Pseudomonas 7 Escherichia coli 5 Anærobic 6 Other 17

Treatment Options Antibiotic suppression Aggressive wound debridement

Treatment Options Antibiotic suppression Indicated in med compromised Organism - gram+ strep staphepi

Treatment Options Resection arthroplasty 2 Stage re-implant Arthrodesis Amputation

Treatment Options Debridement with antibiotic suppression therapy Strep/staphepi -- best Avoid repeated attempts Frozen tissue section Suction drains

Two-Stage Reimplantation Most successful treatment Procedure of choice

Two-Stage Reimplantation Procedure Remove components, cement, I&D Fabricate and place spacer 6 weeks of antibiotics Reimplantation

Two-Stage Reimplantation Stage I create antibiotic spacer impregnated with antibiotics wound closure

Two-Stage Reimplantation Spacer Antibiotic Regimen Tobramycin 2.4 gm/3.6 gm per gms of PMMA Vancomycin > gm to 1 gm per gms of PMMA

Intra-operative Frozen Section < 5 PMN’s per HPF – no infection > 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 Removal all components Remove all cement Effective in medically compromised patient

Arthrodesis Indications Extensor mechanism disruption Resistant bacteria Inadequate bonestock Inadequate soft tissues Young patient

Advantages  Definitive treatment  Little chance of recurrence
Arthrodesis Advantages  Definitive treatment  Little chance of recurrence

Disadvantages  Difficulty with transfers / small spaces
Arthrodesis Disadvantages  Difficulty with transfers / small spaces  Increase energy requirements

Algorithm TKA Clinical Sepsis (GRAM + Organism) < 3 wks > 3 wks
Infections About TKR Algorithm (GRAM + Organism) TKA Clinical Sepsis < 3 wks > 3 wks Debridement Antibiotics (6 wks) 2-Stage Replant

Debridement Antibiotics
Infections About TKR Algorithm Debridement Antibiotics 2-stage Replant No Success No Success Success Success Arthrodesis 2-stage Replant Resection Arthroplasty

Thank You

Frank R. Ebert, MD Union Memorial Hospital Baltimore, Maryland

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