How do bones Heal?
Bone healing means the treatment done for the broken bones Healing depends on the history of the AO. Bone healing can be of two types:
- Indirecting healing (or) secondary healing
- Direct healing (or) primary healing (or) remodeling
1.Indirect healing (or) secondary healing
Indirect healing is also known as secondary healing because historically this is how most fractures healed.
STEP 1: After your fracture, you have an inflammatory phase where hematoma forms around the fracture where you have to get Vasodilation of the surrounding tissues which allow blood and other helpful things like cytokines and macrophages to be recruited into that area.
STEP 2: After a week you have the formation of soft callus. Osteoblasts come in and create soft callus which essentially increases the stability of the area.
STEP 3: After that hard callus this is where the soft callus transitions to the woven bone and this happens from outside and this decreases the amount of strain in the area which helps you remodel bone.
STEP 4: This is the last and final phase of healing which is remodeling phase and this is where your transition from woven bone to lamellar bone and this is a long process that can take years. This happens a lot in kids so you might see huge callus formation and then take an extra couple of years later and the bone looks as if it was never broken.
The needs of this type of healing are different. Relative stability is what we need and can provide this with bridging or splinting constructs. The indirect or secondary healing does not need anatomic reduction so for certain areas at an anatomic reduction is not as important often shaft fractures and just need to have functional reduction. In this way, it is possible to decrease the amount of soft tissue destruction and it is also very good for comminuted fractures.
2. Direct healing (or) primary healing (or) Re-modelling
Primary healing is essentially your normal bone metabolic process this involves Osteoblasts, Osteoclasts and the cutting cones that happen in response to a sort of stress in your bone. This happens even without a fracture as your bone loads certain areas and it stimulates your body to lay down more bone in the stimulated areas and fewer bones where you do not need it.