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29 Cards in this Set
- Front
- Back
Why is a metal-backed tibial component used? What is the clinical significance?
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Decreases compressive force on tibial plateau
Minimizes osteolysis |
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What are the reported outcomes for tibial component with cement only under the metaphysis and a press fit stem?
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Increased risk of loosening relative to cementing entire component
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Is a metal-backed patellar component routinely used?
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No, as it has increased wear
All polyethylene patellar components are routinely used |
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What is the theoretical advantage of cruciate retaining total knee arthroplasty?
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Allows for physiologic rollback of femur on tibia
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Has this been borne out in radiographic studies?
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Fluoroscopic studies have found cruciate retaining knees do not exhibit physiologic rollback
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The most normal knee kinematics are actually seen with what knee design?
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Unicompartmental total knee arthroplasty
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What are the three symptoms of late cruciate failure after cruciate-retaining TKA?
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Effusion
Flexion instability Pain |
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In what four situations is a posterior stabilized knee indicated instead of cruciate retaining?
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Patellectomy
Inflammatory arthritis PCL absent or over-released Prior HTO |
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What are the two theoretical advantages of a PS knee?
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Improved flexion
Mechanical rollback achieved |
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Use of a PS knee requires careful attention to what to prevent what complications?
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Well-balanced knee required to prevent dislocation
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Hyperflexion of a PS knee may lead to what complications?
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Dislocation
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What are the two caused of cam impingement?
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Hyperextension
Femoral component flexion |
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Moving the joint line in what direction increases the chance of impingement?
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Joint line elevation may lead to patella baja and increased chance of impingement
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A patellar clunk is classically associated with PS knee in what position? What generally causes it?
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Extension
A superior nodule |
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How does mobile bearing articular conformity compare with standard TKA?
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Improved
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How do mobile bearing interface stresses compare with those in a standard knee?
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Decreased
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Have improved clinical outcomes been demonstrated with mobile bearing knees?
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No
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What two factors increase the risk of mobile bearing knee dislocation?
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Valgus alignment
Older patient |
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What are the four preoperative criteria for unicompartmental knee arthroplasty?
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Correctable valgus/varus deformity (not fixed deformity)
Flexion >90 degrees <10-degree flexion contracture No inflammatory arthritis |
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With medial unicompartmental replacement, what is the desired postoperative alignment?
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0 to 3 degrees valgus
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What is the reported advantage of a minimally invasive unicompartmental knee replacement?
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Faster rehabilitation
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How do failures from fixed bearing unicompartmental knees typically present?
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Component failure
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What is the presentation of failure after mobile bearing unicompartmental knee?
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Disease progression
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In general, in what situation should bilateral total knees be staged?
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If patient has many medical comorbidities
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What is the most common complication of simultaneous bilateral total knee arthroplasty?
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Deep venous thrombosis (DVT)
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What is the short-term benefit to a subvastus approach? Is there a long-term benefit?
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Improved early range of motion (ROM)
No long-term benefit |
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What is the observed clinical effect of patella baja in total knee arthroplasty?
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Decreased flexion
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In general, what are the four treatment options for patella baja?
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Lower the joint line
Use small superior paterllar dome Cut patellar polyethylene at impingement points Do not resurface the patella |
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In general, what are the outcomes of TKA in the setting of arthrofibrosis?
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Unpredictable
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