TKA

Question 1

How thick should a poly be?

Answer 1

> 8mm - less than this linked to catastrophic wear

Question 2

Would you rather have more contact or rollback for the knee poly?

Answer 2

Contact - aka more congruous joint
Note this is less anatomic because cut deeper
Sacrifice rollback aka less knee flexion

Question 3

What are 2 anatomic variables that contribute to poly wear?

Answer 3

Varus - can do a medial release to decrease varus
Excessive femoral rollback
- Increase slope of the tibia to prevent
- Or use a PCL substituting knee

Question 4

How do you want to sterilize poly?

Answer 4

Gamma radiation in an inert gas
In an O2 depleted environment - improves cross linking
(O2 increases free radicals)

Question 5

How should you mold poly to make it?

Answer 5

Direct compression - literally pour the powder into the component mold
No external molding or cutting
Shows lower wear rates

Question 6

CI for uni

Answer 6

Inflam arthritis
ACL out
Fixed varus or valgus (aka abnormal alignment)
Flexion contracture
Overweight, young active, heavy laborers
Tricompartmental arthritis

Question 7

Can you rely on a gram stain to dx knee PJI?

Answer 7

Nope. Cx > GS

Question 8

How to improve patellar tracking on the:
Femur
Tibia
Patella

Answer 8

ER femur + tibial
Laterally translate the femur
Med + sup place the patella

Goal = LOW Q angle

Question 9

What does synovasure (aka synovial alpha defensin) test for? What type of prosthesis gives false positive?

Answer 9

Intra-artic anti-microbial peptide defensin
Made by neutrophils + macrophages
FALSE POSITIVE w/ metal on metal implants