Osteoporosis
Osteoporosis is a skeletal disorder characterized by compromised bone strength, which predisposes to the development of fragility fractures. Bone strength is determined by both bone mass and bone quality. The diagnosis of osteoporosis is established by the presence of a true fragility or, in patients who have never sustained a fragility fracture, by measurement of bone mineral density (BMD).
2. What are fragility fractures?
Fragility fractures are fractures that occur spontaneously or following minimal trauma, defined as falling from a standing height or less. Fractures of the vertebrae, hips, and distal radius (Colles fracture) are the most characteristic fragility fractures, but patients with osteoporosis are prone to all types of fractures. Osteoporosis accounts for approximately 1.5 million fractures in the United States each year.
3. What are the complications of osteoporotic fractures?
Vertebral fractures cause loss of height, anterior kyphosis (dowager’s hump), reduced pulmonary function, and an increased mortality rate. Approximately one third of all vertebral fractures are painful, but two thirds are asymptomatic. Hip fractures are associated with permanent disability in nearly 50% of patients and with a 20% higher mortality rate than in the age-matched population without fractures.
4. What factors contribute most to the risk of an osteoporotic fracture?
Low BMD (twofold increased risk for every one standard deviation [SD] decrease of BMD)
Age (twofold increased risk for every decade of age above 60 years)
Previous fragility fracture (fivefold increased risk for a previous fracture)
5. What are the currently accepted indications for BMD measurement?
Estrogen deficiency plus one risk factor for osteoporosis
Vertebral deformity, fracture, or radiographic evidence of osteopenia
Glucocorticoid therapy, ≥ 5 mg/day of prednisone for ≥ 3 months
6. How is BMD currently measured?
Dual-energy x-ray absorptiometry (DXA) is the most accurate and widely used method in current practice. BMD can also be measured by computed tomography (CT) and ultrasound (US). Central densitometry measurements (spine and hip) are the best predictors of fracture risk and have the best precision for longitudinal monitoring. Peripheral densitometry measurements (heel, radius, hands) are more widely available and less expensive.
7. How do you read a bone densitometry report?
T-score: The number of SDs the patient’s value is below or above the mean value for young normal subjects (peak bone mass). The T-score is a good predictor of the fracture risk.
8. How is the diagnosis of osteoporosis made?
Osteoporosis should be diagnosed in any patient who sustains a fragility fracture. In a patient without fractures, the diagnosis can be made on the basis of the BMD T-score at the lowest skeletal site, using the following criteria:
9. What are the major risk factors for the development of osteoporosis?
| Non-modifiable risk factors | Age |
| Race (Caucasian, Asian) | |
| Female gender | |
| Early menopause | |
| Slender build | |
| Positive family history | |
| Modifiable risk factors | Low calcium intake |
| Low vitamin D intake | |
| Estrogen deficiency | |
| Sedentary lifestyle | |
| Cigarette smoking | |
| Alcohol excess (> 2 drinks/day) | |
| Caffeine excess (> 2 servings/day) |
10. What other conditions must be considered as causes of low BMD?
11. Outline a cost-effective evaluation to rule out other causes of low bone mass.
Creatinine (estimated glomerular filtration rate)
Thyroid-stimulating hormone (TSH)
Celiac disease antibody testing
Urine (24-hour) calcium, sodium, creatinine
In approximately one third of women and two thirds of men, an abnormality will be detected with this evaluation.
12. How do you determine whether a patient has had a previous vertebral fracture?
Back pain and tenderness are helpful clues but may be absent because two thirds of vertebral fractures are asymptomatic. Height loss of 2 inches or more and dorsal kyphosis are highly suggestive clinical findings. Lateral spine films and dual-energy x-ray absorptiometry vertebral fracture assessment (VFA) are the most accurate ways to detect existing vertebral fractures.
13. What are the most significant risk factors for frequent falls?
