Physiology: Fracture Bone Healing

Question 1

What causes hypertrophic non-union?

Answer 1

Excessive movement at the fracture site - abundant hard callus formation, but there is too much movement give the fracture chance to bridge the gap

Question 2

Define secondary bone healing

Answer 2

There is a gap at the fracture site which needs to be filled temporarily by cartilage (soft callus) to act as a scaffold for new woven bone to be laid down (hard callus)

Question 3

Name the cells that let down the bone matrix in the fracture healing process

Answer 3

Osteoblasts

Question 4

Name the cells that remove fracture debris and resorb the newly exposed bone ends

Answer 4

Macrophages and osteoclasts

Question 5

Define primary bone healing

Answer 5

Occurs where there is minimal fracture gap (less than about 1mm) and the bone simply bridges the gap with new bone from osteoblasts

Question 6

Name 2 possible causes of atrophic non-union

Answer 6

Lack of blood supply, too big a fracture gap