Leucht - Bone Graft Review

Question 1

what is the rationale for BMAC

Answer 1

[growth factor] within bone matrix and cell fraction in autograft is low
- idea to concentrate the growth factors

Question 2

possible new gold standard?

Answer 2

BMAC with HA scaffold

Question 3

disadvantages of RIA

Answer 3

• low number of MSCs due to the irrigation
• necrotic bone matrix from heat and mechanical disruption
• risk of fracture post-op if you create a stress riser by stopping the reamer halfway down the canal

Question 4

bone graft yield from RIA vs ICBG

Answer 4

• 20.7cc with anterior ICBG, 33 minutes
• 36.1cc with posterior ICBG, 40 minutes
• 37.7cc with RIA, in 29 minutes

Question 5

complication rates comparing anterior vs posterior crest harvesting?

Answer 5

anterior harvesting has higher complication rates

- there is also more pain with anterior harvests

Question 6

widest part of the iliac crest:

Answer 6

gluteus medius pillar

Question 7

how does allograft help bone formation?

Answer 7

osteoconductive

Question 8

what happens during allograft processing?

Answer 8

sterilization with gamma irradiation

• decreased mechanical properties
• deactivates proteins
• risk of HIV >1:1.6 million
• bacterial superinfection is more common

Question 9

which substitutes are osteoinductive?

Answer 9

DBM
DBM + BMA
autograft

Question 10

which substitutes are osteogenic

Answer 10

DBM + bMA
autograft
(only the things that contain osteoblasts)

Question 11

calcium phospohate cements vs calcium sulfate cements?

Answer 11

calcium phosphate cements have strongest compressive strength
- sulfate cements have rapid absorption

Question 12

what is an indication for calcium sulfate cements?

Answer 12

if you want them to elute antibiotics

- dissolves by 6 weeks as the antibiotics elute

Question 13

calcium phosphate cement for void filling in tibial plateaus?

Answer 13

better than all allografts or autografts

• excellent compressive strength
• should be used

Question 14

risk of using INFUSE

Answer 14

• increased cancer risk
• increased drainage
• really good at making bone

this is a huge supraphysiologic dose of BMP-2 and that is what causes the problem. new carriers are being produced that allow much lower concentrations

Question 15

what differentiation does BMP-2 induce?

Answer 15

depends on the cell that is exposed

• periosteal osteochondral progenitor cell will make cartilage
• endosteal osteochondral progenitor cell will make bone