Bone Grafting Flashcards
What is bone grafting and the point of it?
Bone grafting involves the transplantation or implantation of bone or bone substitute to enhance bone healing or replace missing bone.
Define autograft
From the same animal
Define allograft
From a different animal
Define xenograft
From different species
What are the types of autograft most commonly used? (3)
Cancellous
Cortical-cancellous
Cortical (vascularised, non-vascularised)
What are the types of allograft most commonly used? (3)
Cancellous bone chips
Cortical grafts
Demineralised bone matrix
What type of growth factor graft is commonly used?
Bone morphogenic proteins
What is the commonly used synthetic graft?
Hydroxyapatite
What are the 4 possible properties of a bone graft?
- Oestoconduction
- Osteoinduction
- Osteogenesis
- Osteopromotion
What is osteoconduction?
Provision of a scaffold matrix for mesenchymal stem cells and their progeny to migrate into and proliferate with.
Osteoconduction:
Materials may or may not impart A) characteristics during bone regeneration, may or may not be B) , and may be naturally occurring
A) load-bearing
B) absorbable
What is osteoinduction?
These materials recruit mesenchymal stem cells or their progeny to infiltrate the material or tissues (chemoattraction and migration), and then they induce multipotential cells to multiply and become cells that make up the regenerating bony callus (proliferation and differentiation).
What is osteogenesis
Formation of new bone by the graft; the graft must contain viable osteoblasts or stem cells that can differentiate into osteoblasts.
Osteopromotion can be achieved by
introduction of substances or materials that enhance bone regeneration or by physical or mechanical strategies that induce proliferation and differentiation of mesenchymal stem cells and their progeny.
Examples of osteopromotive (3)
platelet-rich plasma
hydrogels
biphasic calcium phosphate.
What bone grafts are considered the gold standard? Why? (3)
Autogenous cancellous bone graft
Properties: osteogenic, osteoconductive and osteoinductive
Disadvantages of autogenous calcellous bone graft? (6)
- 2nd surgical site
- increased surgical time
- increased cost
- increased morbidity
- pain
- risk of # at donor site
How to avoid # at donor site of autogenous cancellous bone graft? (2)
Small hole as poss
No levering
Properties of allografts? (2)
Osteoconduction
Osteoinductive
Advantages of allografts? (2)
- no 2nd surgical site
- Not volume limited
Why is osteogenesis impossible with allografts (3)
Frozen, demineralised or irradiated (eliminated living cells)
What is the property of growth factors?
osteoinductive
Synthetic graft example? (4)
Ceramics
Injectable Calcium Phosphate
Bioactive glass
Glass ionomer cements
True or False
Historically, synthetic grafts have suffered from poor clinical results, unpredictable resorption rates and inflammatory reactions
True
Indications for bone graft? (6)
- Complex fractures
- Fractures with poor healing potential
- Filling of bone defects
- Arthrodesis
- Intervertebral fusion
- Treatment of delayed or non-union.
Minimum time between collection of bone graft from same site?
3mo
Autogenous cancellous bone grafts (5)
Proximal lateral humerus (base of the greater tubercle)
Ilial wing (dorsal or lateral) (Cortico-cancellous bone graft)
Proximal lateral femur
Distal femoral condyle
Medial proximal tibia
What is the donor site of the proximal humerus?
Greater tubercle
Where is the level of surgical approach to the proximal humerus?
Greater tubercle - Level of the tendon of insertion of the infraspinatus muscle. (3cm incison cranial to deltoid m)
On the surgical approach to the proximal humerus:
How is the lateral cortex penetrated? (3)
Steinmann pin, hand chuck or drill by directing the tip of pin/drill away from the shoulder joint.
On the surgical approach to the proximal humerus: What is used to graft the bone?
Use a Spratt Volkmann type curette
How to store a bone graft once collected? (2) when to use?
Store the graft in the barrel of a 5- or 10-mL syringe by placing it along the plunger, to keep the graft material moist and protected.
Moist bloody swab
- USE ASAP
On the surgical approach to the proximal humerus:
Retractor type?
x 2 gelpi at orthogonal
How to close bone graft site?
-fascia and skin
What is the minimum time interval that should be allowed if repeating the harvesting bone graft from the proximal humerus?
8 weeks
Cortico-cancellous bone graft collection from the ilial wing
Where is it approached?
Elevate soft tissues from the cranial dorsal region of the iliac spine.
Cortico-cancellous bone graft collection from the ilial wing
- What is used in cats?
Ronguer;
Cortico-cancellous bone graft collection from the ilial wing
- What is used in dogs and what is removed?
Saw/osteome to remove v shaped; then harvested using curette
What is used to retract the gluteal muscle during cortico cancellous bone graft of ilieal wing?
Hohmann
When considering bone grafts and their substitutes what best describes osteogenesis?
Osteogenesis describes the formation of bone at the recipient site by supplying bone forming cells in a graft material.
You perform a pantarsal arthrodesis with a medially applied plate in a 2-year-old domestic shorthair cat to treat a chronic instability of the joint due to collateral ligament injury. You collect an autogenous cancellous bone graft, which you keep in a sterile syringe case.
How should it be placed? When to and not to flush?
Pack over the joint spaces cranial and caudal of, and around the plate.
Flush the surgical site before placing the graft.
Do not flush after graft placement.
