Osteoporosis—Extent and Cause of the Disease

Abstract

Osteoporosis is a common disorder producing an estimated 1.3 million fractures a year in the United States (1). It is characterized by low bone mass and fractures of the hip, spine, distal radius, pelvis, and proximal humerus (2). Fractures of the vertebrae are probably the most common of this group (3), but may be relatively asymptomatic in many cases. However, these vertebral fractures do produce deformity and cause pain for some individuals and in 1984 accounted for over 160,000 physician office visits and over 5 million days of restricted activity (4). Fractures of the hip are the most costly from a public health standpoint. It was estimated in 1984 that over 240,000 occurred in the United States (5). This number will increase as the population ages, doubling or tripling by the year 2050. The cost was estimated at 7.3 billion dollars in 1984 (6) and continues to rise. Hip fracture is associated with a 5–20% reduction in expected survival and half of the victims are unable to walk independently afterward (7). Much of this disability and the associated costs could be avoided if proper preventive measures were introduced earlier in life for those most at risk for future fractures.

It has previously been presumed that all osteoporotic fractures were of the same cause, but recently it has been suggested that some of these fractures may represent different syndromes (8, 9). Type 1 osteoporosis is associated with distal radial and vertebral fractures. It occurs primarily in women age 50–65 and is probably due to a decreased amount of cancellous bone at the fracture site. This deficit in cancellous bone may have resulted from an insufficient amount present at maturity or, alternatively, from an excessive loss after menopause.