Primary Bone Healing
In this kind of healing callus is not formed at all and requires rigid stabilization with or without compression of the bone ends.
Rigid stabilization suppresses the formation of a callus in either cancellous or cortical bone .
Because most fractures are managed in a way that results in some degree of motion, primary healing per se is rare.
Primary bone healing can be divided into gap healing and contact healing. Union occurs in both types.
Gap Healing
Gap healing occurs in two stages.
Firstly, the width of the gap is filled by direct bone formation. An initial scaffold of woven bone is laid down, followed by formation of lamellar bone as support. The orientation of the new bone formed in this first stage is transverse to that of the original lamellar bone orientation.
In the second stage, which happens after several weeks, longitudinal Haversian remodeling reconstructs the necrotic fracture ends and the newly formed bone to replace the woven bone with osteons of the original orientation. In the end, the normal bone structure results.
Contact Healing
Contact healing occurs where fragments are in direct apposition and osteons can grow across the fracture site, parallel to the long axis of the bone.
When fracture fragments are in contact, osteoclasts on one side of the fracture undergo a tunneling resorptive response, forming cutting cones that cross the fracture line.
This tunnelling allows the penetration of capillaries and eventually the formation of new haversian systems. These blood vessels are then accompanied by endothelial cells and osteoprogenitor cells for osteoblasts leading to the production of osteons across the fracture line eventually leading to regeneration of the normal bone architecture.
Secondary bone healing
It occurs when there is no rigid fixation of the fractured bone ends, which leads to the development of a fracture callus. It includes an inflammatory phase, a reparative phase, and a remodeling phase.
More about this type of healing can be found in following article
How Does Bone Fracture Healing Occur
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will a femoral shaft fracture heal when callous is formed between the left of the upper touching or joining the right of the lower thereby creating a mild displacement of the lingaments?
Dr Arun Pal Singh Reply:
December 21st, 2009 at 10:13 pm
@festus,
I am sorry. I did not get that.