Osteoporosis

Photomicrograph of osteoporotic bone– A generalized, progressive reduction of bone mass as bone resorption outstrips bone formation, causing skeletal weakness and fractures.

Causes and Incidence

The causes of primary osteoporosis are unknown, but contributing factors include an inadequate calcium intake, early menopause, thin body habitus, sedentary life-style, and a familial history of the disease. Secondary osteoporosis may be caused by endocrine disorders such as hypogonadism, hyperthyroidism, hyperparathyroidism, and diabetes mellitus; prolonged use of substances (corticosteroids, tobacco, barbiturates, or heparin); underlying disease (renal or liver disease, malabsorption syndrome, chronic obstructive pulmonary disease, rheumatoid arthritis, or sarcoidosis); and prolonged weightlessness or immobility. Postmenopausal women are the most susceptible to primary osteoporosis; an estimated 33% of these women develop the disease.

Disease Process

As bone resorption outstrips bone formation, bone tissue mass progressively declines but the bone is morphologically normal. Cortical thickness also declines, as do the number and size of trabeculae with normal osteoid seams.

Symptoms

Individuals are typically asymptomatic early in the disease. The first symptom is usually a dull, aching, constant pain in the bones, particularly the back and chest. The pain may radiate down the leg, and muscle spasms may be present. As the spinal column mass diminishes, dorsal kyphosis and cervical lordosis increase, leading to multiple compression fractures of the spine and a reduction in height. Other fractures occur with minimal or no trauma.

Potential Complications

Immobility from increased fractures and deformity from spinal crushing are common complications.

Diagnostic Tests

Clinical evaluation revealing bone pain, x-ray studies showing decreased radiodensity, photon absorptiometry, and quantitative computed tomography showing decreased bone density of the spine aid in diagnosis.

Treatments

Surgery
Open reduction internal fixation of fractures of femur.

Drugs
Calcium supplements and vitamin D for prevention and treatment; estrogen-progesterone combinations for postmenopausal women; nonsteroidal antiinflammatory drugs for pain; biphosphonates and growth factors are under clinical evaluation.

General
Consistent exercise regimen, including weight-bearing hyperextension and resistance exercises to slow calcium loss and strengthen musculature; heat and massage for muscle spasm; orthopedic supports for back and neck to prevent stress fractures; cane to aid in walking; high-protein diet; monitoring of calcium levels.