Atlas of pathophysiology, 2 Edition

Part II - Disorders

Musculoskeletal disorders

Fractures

When a force exceeds the compressive or tensile strength of the bone, a fracture will occur. An estimated 25% of the population has traumatic musculoskeletal injury each year, and a significant number of these involve fractures. The prognosis varies with the extent of disability or deformity, amount of tissue and vascular damage, adequacy of reduction and immobilization, and patient's age, health, and nutritional status.

Age Alert

Children's bones usually heal rapidly and without deformity. However, epiphyseal plate fractures in children are likely to cause deformity because they interfere with normal bone growth. In elderly people, underlying systemic illness, impaired circulation, or poor nutrition may cause slow or poor healing.

Causes

·   Falls, motor vehicle accidents, sports

·   Drugs that impair judgment or mobility

·   Young age (immaturity of bone)

·   Bone tumors

·   Metabolic illnesses (such as hypoparathyroidism or hyperparathyroidism)

·   Medications that cause iatrogenic osteoporosis such as corticosteroids

Age Alert

The highest incidence of fractures occurs in young males between ages 15 and 24 (tibia, clavicle, and distal humerus); these fractures are usually the result of trauma. In elderly people, fractures of proximal femur, proximal humerus, vertebrae, distal radius, or pelvis are often associated with osteoporosis.

Pathophysiology

A fracture disrupts the periosteum and blood vessels in the cortex, marrow, and surrounding soft tissue. A hematoma forms between the broken ends of the bone and beneath the periosteum, and granulation tissue eventually replaces the hematoma.

Damage to bone tissue triggers an intense inflammatory response in which cells from surrounding soft tissue and the marrow cavity invade the fracture area, and blood flow to the entire bone increases. Osteoblasts in the periosteum, endosteum, and marrow produce osteoid (collagenous, young bone that hasn't yet calcified, also called callus). The osteoid hardens along the outer surface of the shaft and over the broken ends of the bone. Osteoclasts reabsorb material from previously formed bones and osteoblasts to rebuild bone. Osteoblasts then transform into osteocytes (mature bone cells).

Signs and symptoms

·   Pain

·   Broken skin with bone protruding (open fracture)

·   Deformity

·   Swelling, muscle spasm, tenderness

·   Ecchymosis

·   Impaired sensation distal to fracture site

·   Limited range of motion

·   Crepitus or clicking sounds on movement

Diagnostic test results

·   X-rays confirm the diagnosis and, after treatment, confirm alignment.

Treatment

Emergency treatment for arm or leg fractures

·   Splinting the limb above and below the suspected fracture

·   Applying a cold pack and elevating the limb

For severe fractures that cause blood loss

·   Direct pressure to control bleeding

·   Fluid replacement as soon as possible

Closed reduction

·   Local anesthetic, analgesic, muscle relaxant, or a sedative

·   Manual manipulation

Open reduction (if closed reduction is impossible or unsuccessful)

·   Prophylactic tetanus immunization and antibiotics

·   Surgery

§  Thorough wound debridement

§  Immobilization by rods, plates, screws, or external fixation device

P.221

FRACTURES OF THE ELBOW

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FRACTURES OF THE HAND AND WRIST

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FRACTURES OF THE HIP

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FRACTURES OF THE FOOT AND ANKLE

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