Even though the bones are strong, they are also
susceptible to fractures or breaks. Fractures may be classified based on the
(i) Positioning of the bone ends (ii) completeness
of the break (iii) orientation of the break relative to the long axis of the
bone and (iv) penetration through the skin. In addition to the above
classifications, all fractures can be described in terms of the location of the
fracture, the external appearance of the fracture or the nature of the break
The following are the common types of fractures,
1.Tranverse - A fracture that is at right angle to the bone's long axis.
2. Oblique non-displaced-A fracture that is
diagonal to the bone's long axis and the fractured bone is not displaced from
3. Oblique displaced A fracture that is diagonal to
the bone's long axis and the fractured bone is displaced from its position.
4. Spiral - Ragged break occurs when excessive
twisting forces are applied to a bone (common sports fracture).
5. Greenstick - Bone breaks incompletely, just like
a green twig breaks. It is common in children, because of the flexibility of
6 . Comminuted – Bone fragmented into three or more
pieces. Particularly common in the aged, whose bones are brittle (hard but
Bone is a cellular, living tissue capable of
growth, self-repair and remodeling in response to physical stresses. In the
adult skeleton, bone deposit and bone resorption occur. These two processes
together constitute in remodeling of bone. There are four major stages in
repairing a simple fracture (Figure 9.15).
When a bone breaks the blood vessels in the bone and surrounding tissues are torn and results in haemorrhage. Due to this a haematoma, a mass of clotted blood forms at the fracture site. The tissues at the site becomes swollen, painful and inflammed. The death of bone cells, occur due to lack of nutrition.
Within a few days several events lead to the
formation of soft granulation tissue called callus. Capillaries grow into the
haematoma and phagocytic cells invade the area and begin to clean up the
debris. Meanwhile the fibroblasts and osteoblasts invade from the nearby
periosteum and endosteum and begin reconstructing of the bone. The fibroblasts
produce fibres. The chondroblasts secrete the cartilage matrix. Within this
repair tissue, osteoblasts begin forming spongy bone. The cartilage matrix later
calcifies and forms the fibrocartilaginous callus.
New bone trabeculae begin to appear in the fibro
cartilaginous callus. Gradually that is converted into a bony (hard) callus of
spongy bone. Bony callus formation continues until a firm union is formed about
two months later to an year for complete woven bone formation.
Bony callus formation will be continued for several
months. After that the bony callus is remodelled. The excess material on the
diaphysis exterior and within the medullary cavity is removed and the compact
bone is laid down to reconstruct the shaft walls. The final structure of the
remodelled area resembles like the unbroken bony region.