To complete this series on broken bones, I will be going over how bones heal, and what can influence the healing process. The healing process of bone can take several weeks to months to completely remodel into normal bone tissue. The stages of bone healing involve an absolutely impressive and complex cellular reaction and responses, therefore I have done my best to simplify this in this explanation.
Stages of Healing:
Stage 1: Hematoma Formation (Days 1 to 5)
Immediately following the fracture, the blood vessels supplying the bone are ruptured, causing a hematoma (collection of blood clots) to form at the fracture site. The hematoma clots and forms a temporary framework for subsequent healing.
Stage 2: Fibrocartilaginous Callus Formation (Days 5 to 11)
Within the hematoma, granulation tissue begins to develop. An impressive response of the body is to send stem cells to the area, which begin to differentiate to become: fibroblasts (produce collagen formation), chondroblasts (Cartilage), and osteoblasts (produce bone cells). These cells create a collagen-rich fibrocartilaginous Callus which connects the fracture ends.
Stage 3: Bony Callus Formation (Days 11 to 28)
During this time the cartilaginous callus is reabsorbed by the body and is replaced by bone formation. At the end of this phase, a hard, calcified callus of immature bone forms.
Stage 4: Bone Remodelling (Day 18 onwards, lasting months to years)
This hard callus undergoes repeated remodeling. In a process known as ‘Coupled Remodeling’, the bony callus goes through a process of reabsorption and new bone formation – controlled by Osteoclasts (reabsorption) and Osteoblasts (creation of new bone cells). Substantial remodeling of the vasculature occurs alongside these changes. This process lasts for many months, resulting in the regeneration of the normal bone structure.
Things that influence healing bones:
- Fracture characteristics – excessive movement, misalignment, extensive damage
- Infection – can influence healing potential.
- Blood supply – reduced blood supply can lead to delayed healing or non-union.
- Endocrine conditions – eg. diabetes mellitus
- Steroid use/abuse
- Nutrition and Malnutrition
- Smoking and Alcohol Intake
Hopefully you have found this series on broken bones helpful and gives you a greater understanding of your injury. If you have sustained a bone injury, the most important thing is to listen to your healthcare provider and follow their advice so that you have a successful outcome and can get back to doing the things you love.