Physiology of fracture repair Flashcards
What types of load might be a problem during fracture repair?
Normal Loads
Why is it important to consider soft tissue trauma when dealing with a fracture?
Soft tissue provides a vascular supply to the callus during healing.
What happens when bone fractures?
Growth factors present in the ECM are released at the fracture line and bone is reabsorbed releasing further growth factors. These help to encourage growth and recruit stem cells.
Briefly describe the sequence of indirect fracture healing.
Heamatoma > medullary callus formation > angiogenesis of medullary blood supply into callus > activation of the perioseteum > callus completion and supplied by extraosseal blood.
From haematoma to callus, what is the relationship between cell type, oxygen tension and strain tolerance?
With progressing cell types greater oxygen tension is required and decreasing movement needed for proliferation.
What are the two types of direct fracture healing?
- Contact Healing
2. Gap healing
What is the difference between contact and gap healing?
- Contact = gap< 1mm Layered bone is deposited parrallel with the fracture so is very weak. Later osteones bridge the gap parallel to the bones long axis.
Both require absolute stability
Why is indirect union better if possible?
It reaches strength quicker and is more tolerant to movement.
Explain the terms:
- Non-union
- Malunion
- Bone fails/delays to unite
2. Bone unites but in the wrong position
What is meant by:
- Viable non-union
- Non-viable non-union
- Physiological process is working but has gone too far or too little
- Physiological healing not happening, intervention may be necessary.
What is the principle behind a bone graft?
Scraping away bone from one area releases growth factors which, when placed in the unhealthy tissue, may reactivate/promote normal fracture healing.
