Bone Graft Properties Flashcards
1
Q
What do bone grafts provide?
A
- mesenchymal stem cells, osteoblasts, growth factors, bone for scaffold dependent on the graft
2
Q
What is osteogenesis and what type of graft provides it?
A
- New bone development and support via osteoblasts
- Cancellous autograft
3
Q
What is osteoinduction and what type of graft provides it?
A
- Ability to induce migration and differentiation from mesenchymal stem cells into osteoblasts
- Example is demineralized bone matrix (bone morphogenic proteins)
4
Q
What is osteoconduction and what type of bone graft provides it?
A
- Ability of a material to provide a scaffold for host bone invasion
e. g. Cortical allograft
5
Q
What is osteointegration?
A
- Surface bonding between graft and host bone
6
Q
WHere do you get autogenous cancellous bone grafts from?
A
- Proximal humerus
- Proximal tibia
- Ilium
7
Q
How do you get autogenous cancellous bone?
A
- IM pin and curette
- He mixes bone marrow and the autogenous cancellous bone together
- Helps to speed it up and provides osteogenesis
8
Q
What does demineralized bone matrix provide?
A
- Osteoinductive with bone morphogenic proteins
- Osteoconductive with scaffolding
9
Q
How do you use demineralized bone matrix?
A
- Mix with blood
- Used a lot
10
Q
What does a cancellous autograft provide?
A
- Osteogenesis, osteoinduction, and osteoconduction
11
Q
What does a cortical autograft provide?
A
- Osteogenesis, osteoinduction, and osteoconduction (to a lesser degree)
- Also has strength
12
Q
What is radiographic union?
A
- Point at which healing has progressed that there is evidence of bone bridging of all fracture lines in all views
13
Q
What is clinical union?
A
- Point at which healing has progressed to the point in strength that the fixation can be removed
- You could let that patient go back to normal
- We are interested in this one
- DOn’t want to let them go back to completely unrestricted until radiographic union, but can let them go back to somewhat normal at clinical union
14
Q
Rate of union for clinical union using ESF and IM pins
Age:
- <3 months
- 3-6 months
- 6-12 months
- > 1 year
A
<3 months: 2-3 weeks
3-6 months: 4-6 weeks
6-12 months: 5-8 weeks
> 1 year: 7-12 weeks
15
Q
Rate of clinical union for direct healing
Age:
- <3 months
- 3-6 months
- 6-12 months
- > 1 year
A
- <3 months: 4 weeks
- 3-6 months: 2-3 months
- 6-12 months: 3-5 months
- > 1 year: 5 months to 1 year
16
Q
Delayed union
A
- Fractures that heal more slowly than anticipated
- Progressive signs of bone activity if visible on radiographs and bone union is anticipated by not ensured (e.g. around 8 weeks post casting don’t see union)
17
Q
What is #1 reason of delayed union, and what can you do to alleviate?
A
- # 1 reason is lack of stability
- Increase rigidity
18
Q
Reasons for delayed union in general
A
- Systemic status of the patient
- Nature of the trauma
- High energy fracture, soft tissue trauma, open?
- Poor decision making in fracture management (too rigid, unstable, large fracture gap, radiation therapy)
- Drugs (Steroids, NSAIDs
19
Q
What is nonunion?
A
- Arrested fracture repair process
20
Q
How do you correct a nonunion?
A
- Requires surgical intervention to achieve healing
21
Q
What is the general cause of a nonunion?
A
- Usually result of poor decision making and technical failure on the part of the surgeon
- Instability at the fracture site is the most common reason for a non-union
22
Q
Hypertrophic non-union
A
- Large amounts of non-bridging callus
23
Q
How to treat a hypertrophic non-union?
A
- Debridement, grafting, and stabilization
24
Q
Atrophic nonunion
A
- Biologically inactive pseudoarthrosis
- No evidence of bone reaction at the fracture site, and bone ends appear sclerotic
25
Malunion
- Healed fractures in which anatomic bone alignment is not achieved or maintained during healing
26
What is impact of malunion on function?
- Deleterious effect on function
- Severe malunions can cause arthritis of the affected joint due to the malalignment and joint incongruity
- Need a corrective osteotomy
- Likely need to be referred
27
Osteomyelitis definition
- Inflammatory condition of bone and medullary canal
28
Etiologies of osteomyelitis
- Bacterial or fungal (mostly bacterial; German Shepherds are at higher risk for fungal)
- Acute hematogenous vs post-traumatic (acute or chronic)
29
What is the etiology of most post-traumatic osteomyelitis?
- Bacterial infection
| - Biofilm
30
What is a biofilm?
- Biofilm is bacteria, glycocalyx, and implant surface
| - Protects the bacteria from antimicrobials and host defenses
31
Clinical signs of osteomyelitis
- Pain, tenderness, swelling, erythema (acutely)
| - Drainage (chronically
32
Lab findings of osteomyelitis
- No significant findings on bloodwork often
| - might see a left shift
33
Diagnostics for osteomyelitis
- Culture and sensitivity prior to antibiotics (best to aspirate down to the fracture site rather than swab the draining tract)
- Radiographs: varies with the stage of disease (Perisoteal reaction; sequestrum are possible findings)
34
Treatment for osteomyelitis
- Surgical debridement to healthy, bleeding bone
- Establish drainage (closed suction drains preferred)
- Re-stabilize
- Antibiotics for 4-6 weeks based on culture
35
Osteomyelitis and implants
- If implants are stable, leave in place until the fracture heals
- Infection will not clear until implants are removed
- If unstable, stabilize or remove and replace (you can add an external skeletal fixator)
36
Indications for implant removal
- Clinical union
- Radiographic union
- Growing animal/open physis
- Interference with function (if they seem bothered)
- Pain
- Unstable or loose implants
- Infection is not an indication for implant removal
- If infection is present once healing has occurred, the implant may need to be removed
37
Causes of pathologic fractures
- Neoplasia (often)
- Osteomyelitis
- Bone cyst
- Radiation therapy
38
Radiographic features of pathologic fracture
- Lytic/proliferative bone (classic for a tumor)
- Periosteal reaction
- Soft tissue mass
39
Quadriceps contracture
- Unstable fracture in a young dog
| - Leg remains extended
40
Sciatic nerve entrapment
- Not uncommon with pinning a femur
| - This is why you should try to place a pin in the femur normograde
41
Ankylosis of joint
- Can occur secondary to fracture repair
