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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
Bone density, or bone mineral density (BMD),[1] is the amount of bone mineral in bone tissue, measured as mass of mineral per volume of bone (relating to density). Clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging.[2] Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of a hospital or clinic. The measurement is painless and non-invasive with low radiation exposure. Measurements are usually made over the lumbar spine and the upper part of the hip.[3] The forearm may be scanned if the hip and lumbar spine are not accessible.
There is a statistical association between poor bone density and a higher probability of fracture. Fractures of the legs and pelvis due to falls are a significant public health problem, especially in elderly women, leading to substantial medical costs, inability to live independently, and even risk of death.[4] Bone density measurements are used to screen people for osteoporosis risk and to identify those who might benefit from measures to improve bone strength.
Volumetrically, women have greater bone density than men, as their bones are often not as long as men's bones.[5]
A bone density test may detect osteoporosis or osteopenia.[6] The usual response to either of these indications is consultation with a physician.[6] Bone density tests are not recommended for people without risk factors for weak bones,[7][6] which is more likely to result in unnecessary treatment rather than discovery of a weakness.[6]
The risk factors for low bone density and primary considerations for a bone density test include:
Other considerations that are related to the risk of low bone density and the need for a test include smoking habits, drinking habits, the long-term use of corticosteroid drugs, and a vitamin D deficiency.[6]
Results of the test are reported in three forms:
While there are many types of bone mineral density tests, all are non-invasive. The tests differ according to which bones are measured to determine the test result.
These tests include:
DXA is the most commonly used testing method as of 2016[update].[9] The DXA test works by measuring a specific bone or bones, usually the spine, hip, and wrist. The density of these bones is then compared with an average index based on age, sex, and size. The resulting comparison is used to determine the risk for fractures and the stage of osteoporosis (if any) in an individual.
Quantitative ultrasound (QUS) has been described as a more cost-effective approach for measuring bone density, as compared to DXA.[10]
Average bone mineral density = BMC / W [g/cm2]
Results are generally scored by two measures, the T-score and the Z-score. Scores indicate the amount one's bone mineral density varies from the mean. Negative scores indicate lower bone density, and positive scores indicate higher.
Less than 0.5% of patients who underwent DXA-scanning were found to have a T- or Z-score of more than +4.0, often the cause of an unusually high bone mass (HBM) and associated with mild skeletal dysplasia and the inability to float in water.[11]
The T-score is the relevant measure when screening for osteoporosis. It is the bone mineral density at the site when compared to the "young normal reference mean". It is a comparison of a patient's bone mineral density to that of a healthy 30-year-old.[12] The US standard is to use data for a 30-year-old of the same sex and ethnicity, but the WHO recommends using data for a 30-year-old white female for everyone.[13] Values for 30-year-olds are used in post-menopausal women and men over age 50 because they better predict the risk of future fracture.[14] The criteria of the World Health Organization are:[15]
| WHO category | Age 50–64 | Age > 64 | Overall |
|---|---|---|---|
| Normal | 5.3 | 9.4 | 6.6 |
| Osteopenia | 11.4 | 19.6 | 15.7 |
| Osteoporosis | 22.4 | 46.6 | 40.6 |
The Z-score for bone density is the comparison to the "age-matched normal" and is usually used in cases of severe osteoporosis. This is the standard score or number of standard deviations a patient's bone mineral density differs from the average for their age, sex, and ethnicity. This value is used in premenopausal women, men under the age of 50, and in children and adolescents.[14][18] It is most useful when the score is less than 2 standard deviations below this normal. In this setting, it is helpful to scrutinize for coexisting illnesses or treatments that may contribute to osteoporosis, such as glucocorticoid therapy, hyperparathyroidism, or alcoholism.
To prevent low bone density it is recommended to have sufficient calcium and vitamin D.[19][20] Sufficient calcium is defined as 1,000 mg per day, increasing to 1,200 mg for women above 50 and men above 70.[20] Sufficient vitamin D is defined as 600 IUs per day for adults 19 to 70, increasing to 800 IUs per day for those over 71.[20] Exercise, especially weight-bearing and resistance exercises are most effective for building bone. Weight-bearing exercise includes walking, jogging, dancing, and hiking. Resistance exercise is often accomplished through lifting weights.[21] Other therapies, such as estrogens (e.g., estradiol, conjugated estrogens), selective estrogen receptor modulators (e.g., raloxifene, bazedoxifene), and bisphosphonates (e.g., alendronic acid, risedronic acid), can also be used to improve or maintain bone density. Tobacco use and excessive alcohol consumption have detrimental effects on bone density.[22][20] Excessive alcohol consumption is defined as more than one standard-sized alcoholic beverage per day for women, and drinking two or more alcoholic beverages per day for men.[20]
Bone mineral density is highly variable between individuals. While there are many environmental factors that affect bone mineral density, genetic factors play the largest role.[9][23] Bone mineral density variation has been estimated to have 0.6–0.8 heritability factor, meaning that 60–80% of its variation is inherited from parents.[24] Because of the heritability of bone mineral density, family history of fractures is considered as a risk factor for osteoporosis.[25] Bone mineral density is polygenic and many of the genetic mechanisms remain poorly understood.[23]
There are several rare genetic diseases that have been associated with pathologic changes in bone mineral density. The table summarizes these diseases:[26][25]
| Disease | Gene affected | Inheritance | Source |
|---|---|---|---|
| Osteogenesis imperfecta | COLIA1 | Autosomal recessive | [26][25] |
| Osteogenesis imperfecta | COLIA2 | Autosomal recessive | [26][25] |
| Osteoporosis pseudoglioma syndrome | LRP5 | Autosomal recessive | [25] |
| Osteopetrosis | TCIRGI | Autosomal recessive | [25] |
| Camurati-Engelmann disease | TGFβ-1 | Autosomal recessive | [25] |
| Van Buchem disease | SOST | Autosomal recessive | [25] |
| Severe infantile osteopetrosis | CLCN7 | Autosomal recessive | [25] |
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Bone density, or bone mineral density (BMD), is the amount of bone mineral in bone tissue, measured as mass of mineral per volume of bone (relating to density). Clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of a hospital or clinic. The measurement is painless and non-invasive with low radiation exposure. Measurements are usually made over the lumbar spine and the upper part of the hip. The forearm may be scanned if the hip and lumbar spine are not accessible. There is a statistical association between poor bone density and a higher probability of fracture. Fractures of the legs and pelvis due to falls are a significant public health problem, especially in elderly women, leading to substantial medical costs, inability to live independently, and even risk of death. Bone density measurements are used to screen people for osteoporosis risk and to identify those who might benefit from measures to improve bone strength. Volumetrically, women have greater bone density than men, as their bones are often not as long as men's bones.
Bone erosion is the loss of bone from disease processes. Erosive arthritis is joint inflammation (arthritis) with bone destruction, and such conditions include rheumatoid arthritis. Bone erosion is the loss of bone in a certain area, rather than a change in bone density, which is found in osteoporosis. Surprisingly, bone erosion is not common in osteoarthritis, although there is a subtype of osteoarthritis (erosive osteoarthritis) that may result in bone erosion.
The trabecular bone score is a measure of bone texture correlated with bone microarchitecture and a marker for the risk of osteoporosis. Introduced in 2008, its main projected use is alongside measures of bone density in better predicting fracture risk in people with metabolic bone problems.
Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in fracture risk. Bones undergo continuous remodeling: osteoclasts resorb old bone, and osteoblasts synthesize new bone. With advancing age, the rate of resorption exceeds that of bone formation, causing bones to lose density and become more susceptible to fractures. The word "osteoporosis" is from the Greek terms for "porous bones". Osteoporosis is the most common reason for a broken bone among the elderly. Bones that commonly break include the vertebrae in the spine, the bones of the forearm, the wrist, and the hip. Until a broken bone occurs, there are typically no symptoms. Bones may weaken to such a degree that a break may occur with minor stress or spontaneously. After the broken bone heals, some people may have chronic pain and a decreased ability to carry out normal activities. Osteoporosis may be due to lower-than-normal maximum bone mass and greater-than-normal bone loss. Bone loss increases after menopause in women due to lower levels of estrogen, and after in older men due to lower levels of testosterone. Bone-density loss accelerates beginning about two years before menopause, and Dr. Jocelyn Wittstein says women could lose about 10% of their bone density during that relatively narrow period. Osteoporosis may also occur due to several diseases or treatments, including alcoholism, anorexia, hyperthyroidism, kidney disease, and after oophorectomy (surgical removal of the ovaries). Certain medications increase the rate of bone loss, including chemotherapy and glucocorticosteroids. Smoking and a sedentary lifestyle are also recognized as major risk factors. Osteoporosis is defined as a bone density of 2.5 standard deviations below that of a young adult. This is typically measured by a DXA (or DEXA) bone density scan. Prevention of osteoporosis includes a proper diet during childhood, hormone replacement therapy for menopausal women, and efforts to avoid medications that increase the rate of bone loss. Efforts to prevent broken bones in those with osteoporosis include a good diet, exercise, and fall prevention. Lifestyle changes such as stopping smoking and not drinking alcohol may help. Bisphosphonate medications are useful to decrease future broken bones in those with previous broken bones due to osteoporosis. In those with osteoporosis but no previous broken bones, they have been shown to be less effective. They do not appear to affect the risk of death. Osteoporosis becomes more common with age. About 15% of Caucasians in their 50s and 70% of those over 80 are affected. It is more common in women than men. In the developed world, depending on the method of diagnosis, 2% to 8% of males and 9% to 38% of females are affected. Rates of disease in the developing world are unclear. White and Asian people are at greater risk for low bone mineral density due to their lower serum vitamin D levels and less vitamin D synthesis at certain latitudes.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.