Fracture Flashcards
What is the definition of a fracture?
A break in the continuity of bone
Describe the first stage of bone healing following a fracture.
A haematoma is formed. The fracture causes blood to leak out into the fracture site and this will then form a clot. This directs blood away from the surrounding cells which consequently die and attract macrophages and osteoclasts to clean up the debris. This causes local inflammation
Describe the second step of bone healing following a fracture.
The blood supply is reestablished with blood vessels growing into the haematoma.
Describe the reparative phase of bone healing following a fracture and the time taken for this stage to happen
A fibrocartilaginous callus is formed by fibroblasts from the periosteum laying down collagen. This creates a very soft callus in about three weeks
Describe the making of the bony callus in the process of bone healing following a fracture and the timescale in which this occurs
The osteogenic progenitor cells migrate to the border between healthy and dead bone cells and differentiate into osteoblasts and start to lay down a new bone matrix of spongy bone. This is called woven bone as the trabecullae are not arranged in an ordered way. This process can take up to three months to complete
Describe the final stage of the process of bone healing following a fracture.
Remodelling is the final phase. Woven bone is resorbed and a new bone matrix of both spongy and compact bone is laid down by osteoblasts in an orderly fashion.
How long does the formation of a haemotoma last during fracture healing?
6-8hours
How long does it take to reestablish blood supply after a fracture?
Several weeks
What is indirect fracture healing?
A method of fracture healing which occurs via a process of differential tissue formation until skeletal continuity is restored
What is direct fracture healing?
An artificial surgical situation where there is a direct formation of bone without the process of callus formation to restore skeletal comtinuity
Which fractures are particularly prone to problems with union or necrosis due to potential problems with blood supply?
Proximal pole of scaphoid
Talar neck
Intracapsular hip
Surgical neck of humerus
Which medications can inhibit fracture healing?
NSAIDs
Steroids
Bisphosponates
How to bisphosphonates affect fracture healing?
They inhibit osteoclastic activity to delay fracture healing
What patient factors affect fracture healing?
Increasing age Diabetes Anaemia Malnutrition Peripheral vascular disease Hypothyroidism Smoking Alcohol
When micro fractures occur, what factor is released from stromal cells to generate preosteoclasts?
Macrophage colony stimulating factor
