Chapter 50 - Revision Total Knee Arthropolasty

Question 1

what limb mal-alignment more commonly causes loosening?

Answer 1

varus

Question 2

loss of collateral support requires what in TKA setting?

Answer 2

revision to varus/valgus constrained implant

Question 3

patients with flexion instability complain of wht symptoms?

Answer 3

dull /vague pain and swelling after activity that gets better with rest

Question 4

patients with flexion instability demonstrate what on XR?

Answer 4

paradoxical motion - femur moving anterior on tibia during flexion rather than roll back

Question 5

a history of pain immediately post op (no symptom free interval) suggests what?

Answer 5

inflammatory or neurogenic source of pain

Question 6

what is the patholgy behind patellar clunk?

Answer 6

complication of PS knees (with a box)
- it is a wad of scar tissue at the inferior pole of the patella that engages in the trochlear groove with knee extension

Question 7

how to treat a large but contained defect

Answer 7

highly porous metal ingrowth cones

Question 8

do you need stems in PS and hinged knee implants?

Answer 8

yes - incresed torque on the components2/2 constraint

Question 9

what motion is MUA typically better at achieving?

Answer 9

flexion» extension

very hard to get extension back once you lose it

Question 10

in extensor allograft reconstruction wha does the literature support in terms of fixation methods?

Answer 10

tensioning the graft in full extension and NOT resurfacing the patella (increased risk of necrosis)

Question 11

how long to restrict ROM following extensor mechanism allograft reconstruction??

Answer 11

6 weeks at least

Question 12

what native anatomical source can you use to reconstruct the extensor mechanism?

Answer 12

medial head of the gastroc and its tendinous insertion