Bone Mineral Density

Bone

is living tissue. It consists of crystals of minerals bound to protein. Mineral crystals - hydroxyapatite (calcium, phosphorus) Bound to an organic matrix - collagen Bone serves several functions: structural, mobility, protection, and a storehouse for essential minerals such as calcium and phosphorus

Adulthood/Aging: Bone "Remodeling"

is the removal and replacement of bone at the same site. Occurs throughout life so that most of the adult skeleton is replaced about every 10 years.

Problems with Vetebral fractures:

postural and height changes back pain trouble bending and reaching alter abdominal anatomy

Cortical

(dense outer layer) makes up 75% skeletal mass

Trabecular

(spongy, inner). Interior serves for mineral exchange. Present especially in spine and ends of long bones - sites that are under continuous stress from motion and weight bearing. Trabecular bone is more susceptible to fractures.

There are four steps, which together, can optimize bone health and help prevent osteoporosis. They are:

1. diet 2. exercise 3. minimize alcohol 4. no smoking

Problems with Hip fractures:

10-20% mortality within 1 year Chronic pain, disability May require long-term nursing home care.

Bone Mineral Content (BMC)

absolute amt of bone in grams

Bone Mineral Density (BMD)

An expression of bone density or grams bone per square cm or cubic cm depending on the technology. We use hip BMD to predict future fracture risk - bec it also predicts fractures at other sites.

Adulthood/Aging: Bone loss

As a consequence of aging, bone is broken down faster than it can be reformed. This process is accelerated in women for a few yrs after menopause when estrogen production declines.

Risk Factors You Cannot Change:

Being over age 50 Being female Low body weight/being small and thin Family History of osteoporosis Menopause (if female) Broken bones or height loss

Fractures may be the first visible sign of osteoporosis

It is the breakage of a bone either complete or incomplete. Especially in regions that have more trabecular bone and regions that bear force or weight such as the three sites below: Proximal femur (Hip) Lumbar Spine (L 1-4) Distal Forearm - Wrist (wrist fractures during falls)

What is osteoporosis?

It literally means "porous bones", but we diagnose it when a person's Bone Mineral Density (BMD) is low - 2.5 standard deviations or more below that of young healthy adults. It is the most common bone disease that usually does not manifest itself until later in life. There are two types of osteoporosis:

Risk Factors You Can Change:

Not getting enough calcium and vitamin D Not eating enough fruits and vegetables Getting too much protein, sodium, and caffeine Drinking too much alcohol Having an inactive lifestyle Smoking Be aware of certain medications that increase bone loss:

Childhood and Adolescence: Peak bone mass and Life Span

Peak bone mass is usually achieved by around age 30. Peak bone mass is the maximum bone mass accumulated during young adult life. The critical yrs for building bone mass are therefore between childhood and age 30. After that we try to minimize its loss.

Secondary osteoporosis-

caused by diseases and certain medications and toxic agents. eg. hyperthyroidism, renal disease, or certain drugs

Two types of bone:

cortical and trabecular

Primary osteoporosis

cumulative effects of bone loss as people age.

Quality of life:

depression, fear of falling lack of mobility

Bone Health is affected both by

genetics and environmental factors

Childhood and Adolescence: Bone "Modeling"

occurs during childhood and adolescence. This involves formation of new bone at one site (formation) and removal of old bone (resorption) at another site. This allows bone to grow in size and occupy more volume.

Z scores

person's BMD is compared to same age and sex

T scores

person's BMD is compared to young normal healthy same-sex adults (this one we use to diagnose osteoporosis)

Osteoporosis is a "____" disease

silent