Bone healing occurs in four stages – Haematoma formation, cellular growth, callus formation, and ossification. When a fracture occurs there is bleeding from the vessels into the fracture site. Aseptic inflammatory response follows (except the skin is broken). The blood clots and forms a haematoma and inflammatory exudates around the damaged bone ends.
The blood clot is not absorbed; rather it becomes a part of the bone with time. Later, fibroblasts and capillaries from adjacent connective tissues and blood vessels spread into the haematoma and exudates, and form the granulation tissue.
This granulation tissue is referred to as provisional callus. Osteoblasts multiply from the inner surface of the periosteum and invade the granulation tissue to form the callus. In about 6-10 days, the granulation tissue is converted into a binding tissue called callus. The callus surrounds the bone at the site of fracture and increase the bone thickness.
The osteoblast ensures that the required mineral salts such as calcium and phosphate ions are deposited on the callus to strengthen it. The osteoclast remodels the new bone tissue ensuring its smoothness. In the adults the healing process takes about 2 to 3 months, whereas in children it is usually between 4-6 weeks.
Factors that promote bone healing:
1. Adequate rest: Adequate rest enables the body to mobilize all materials needed to fight stress and promote healing. Rest enables the body to produce granulation tissues as quickly as possible.
2. Good nutrition: Balanced diet rich especially in proteins and vitamin c is needed to promote bone healing. Vitamin c which is the healing vitamin should be gotten from fruits especially citrus. Calcium can be derived from sea foods, chicken bones, snails or from supplements e.g. calcium c300.
3. Good blood supply: Good blood supply ensures enough supply of oxygen and nutrients to the affected tissues, supply leucocytes that help to fight against bacteria, and also ensure removal of exudates or waste materials produced in the wound. Enough blood supply also helps in the proliferation of granulation tissues and capillaries that hasten the healing process.
4. Proper bone alignment: When there is good reduction or proper alignment of the ends of the broken bone or when the fragments are properly arranged healing is rapid. When there are no tissues in between the fragments and the initial haematoma is intact, it facilitates healing.
Causes of delay in fracture healing
Factors that can delay fracture healing include:
a. Poor blood supply: If the plaster of Paris or the splint applied to the limb is too tight it impairs blood supply to the limb. With poor blood supply healing is delayed.
b. Infection: Infection delays the growth of fibrous tissues and new blood vessels that should promote the healing of the bone cells. Infection also disrupts blood supply to the injured site and causes a delay in the healing of the fracture.
c. Loss of initial haematoma: The initial haematoma that forms around the fracture provides a foundation for the formation of granulation tissues and new blood capillaries. Whereby this initial haematoma is lost there would be a marked delay in the healing of the bone since the body would take a longer process to form these granulation tissues and capillaries without the haematoma.
d. Malnutrition: Malnutrition slows down the healing process since the essential nutrients – proteins, vitamins and minerals needed for rapid healing are in short supply.
e. Bone disease: Disease of the bone can also cause a delay in healing of the fracture. Malignant disease or cancer prevents the normal physiological process of healing from taking place hence a delay in the healing of the injury.
f. Wide gap between fragments: Where there is a wide separation between bone fragments healing takes a longer period to take place.