Fracture Principles

What is a Fracture?

• A fracture is the loss in structural continuity of a bone.

What causes a Fracture?

A fracture may occur in:

1. A normal bone with abnormal force (e.g. falling off a ladder)
2. An abnormal bone with normal force (e.g. a pathological fracture)

Most fractures are caused by a sudden excessive force that may either be direct (bone breaks at point of impact) or indirect (bone breaks some distance away from the point at which force is applied).

Bones can fracture by a number of different mechanisms:

Direct violence

• Direct blow to the bone e.g. road traffic accident.

Figure 1 - Example of how direct violence may occur

Indirect violence

• No actual violence or contact is applied to the site of the fracture
• Such a fracture most commonly occurs as a result of a twisting injury.

Pathological fractures

• Fractures occur in bone which have been weakened already due to a pathological process.
• Causes of pathological fractures can be classified into generalised bone conditions or local benign causes
• General bone conditions
• Osteogenesis imperfecta
• Post-menopausal osteoporosis
• Metabolic bone disease
• Paget's disease
• Local benign causes
• Chronic infection of bone
• Solitary bone cysts
• Aneurysmal bone cysts
• Chondromas

Primary bone tumours such as chondrosarcomas, osteosarcomas and Ewing's sarcoma are all causes of pathological fractures and may metastasise to the breast, kidney, lung, prostate and thyroid.

Figure 2 - Pathological fracture (Metastatic lesion proximal femur)

Fatigue (stress fracture)

• Occur as a result of repetitive stress.

Figure 3 - Stress fracture third metarsal in a runner

Classification of Fractures