OSTEOPOROSIS
Osteoporosis is extremely prevalent in the geriatric population, affecting one third of postmenopausal women and one half of the population older than 75 years.
The prevention and treatment of osteoporosis deserves more attention than it has received because the consequences of osteoporosis significantly affect patients in the rehabilitation setting.
Osteoporosis is defined as the increased resorption and the defective formation of bone during remodeling. Remodeling occurs more rapidly in trabecular bone, such as the vertebral bodies, pelvis, proximal femur, and distal radius, than in other bone. Low BMD results in bone fragility and, consequently, an increased risk of fracture.
The World Health Organization (WHO) defines osteoporosis as BMD >2.5 standard deviations (SDs) below the mean value in young adults; this measure is referred to as the T score.
In established osteoporosis, a fracture of any bone, usually the wrist, tibia, humerus, or hip or a low thoracic or lumbar vertebra, can occur with minimal trauma. Approximately 25% of women older than 50 years have 1 or more vertebral compression fractures related to osteoporosis.
Osteoporosis affects one half of the population older than the age of 75 years.
Determinants of osteoporosis late in life are peak bone mass and the rate of bone loss.
Bone mass peaks by the age of 35 years, and men have more bone mass than women.
Men have a 20-30% rate of lifetime bone loss, whereas women have a 45-50% rate of lifetime bone loss.
Bone loss begins earlier and progresses faster in women than in men.
Attention to the male, as well as the female, geriatric population is warranted in regard to the prevention and treatment of osteoporosis.
TYPES OF OSTEOPOROSIS
Different types of osteoporosis are described.
Localized osteoporosis is seen in primary disorders, such as complex regional pain syndrome (CRPS) (type I formerly known as reflex sympathetic dystrophy and type II formerly known as causalgia) and transient regional osteoporosis. It is also seen as a secondary disease due to a primary condition, such as immobilization, inflammation, tumor, or necrosis.
Generalized osteoporosis includes involutional osteoporosis. This most common type of osteoporosis is divided into type I "high turnover" postmenopausal osteoporosis and type II "low turnover" age-associated (senile) osteoporosis. General osteoporosis can also be secondary to a disease process; in this case, it is considered type III osteoporosis.
CRPS type I or II radiographic changes occur in the first 3-6 months after onset, and images show patchy, periarticular demineralization of the affected area (Sudeck osteopenia).
The triple-phase bone scan shows increased uptake in the involved extremity before radiographic changes occur. Treatment generally involves steroids. Tapering the dose is necessary to prevent further demineralization.
Transient regional osteoporosis is localized but migratory, and it predominantly involves the hip. This disease is usually self-limited, lasting 6-9 months. Transient regional osteoporosis is a rare cause of osteoporosis and is diagnosed with plain images, bone scans, and clinical suspicion.
Primary involutional type I postmenopausal osteoporosis affects only menopausal women. This disease is linked to estrogen deficiency. Estrogen inhibits secretion of IL-6, which recruits osteoclasts from the monocyte cell line.
Type I affect women aged 50-65 years and lasts 15-20 years after menopause. Rapid bone loss occurs at a rate of approximately 3-5% per year. Type I is predominantly characterized with trabecular bone loss in the axial skeleton, thus consequential vertebral compression fractures increase. Other associated fracture sites caused by moderate trauma occur at the hip and wrist. Wrist fractures tend to occur 20-25 years earlier than hip fractures. In men with low testosterone levels, osteoporosis may be included in this category, which may be renamed hormonal-deficient osteoporosis; men with hormonal deficiency are often overlooked in the management of osteoporosis.
Primary involutional type II age-associated osteoporosis can affect men with normal gonad function or women older than 70 years. It results from increased parathyroid hormone (PTH) levels, decreased vitamin D levels, decreased levels of growth hormone and insulin-like growth factors, decreased dietary intake of calcium, and decreased osteoblast function.
The annual bone loss is slower in type II than at type I at a rate of 0.5-3% per year. A proportional loss of trabecular and cortical bone occurs. Hip fractures characterize type II osteoporosis.
Type III osteoporosis is secondary to another disease process and usually reversible to some extent after treatment of the primary disease is established. The following conditions can contribute to secondary osteoporosis: bone marrow disorders; connective tissue disease; malnutrition; medication; cadmium poisoning; and endocrine, gastrointestinal, or lymphoproliferative disease.
To be complete, idiopathic juvenile osteoporosis affects children aged 8-14 years and is self-limited to duration of 2-4 years. Idiopathic young-adult osteoporosis can be mild to severe, and it is self-limited to a period of 5-10 years from its onset. However, the resolution of these forms of osteoporosis does not exclude the patient from having osteoporosis later in life.
HISTORY TAKING, PHYSICAL EXAMINATION, AND DIAGNOSTIC WORKUP FOR OSTEOPOROSIS
An assessment of the patient's history is extremely important for the prevention and treatment of osteoporosis. The history should focus on risk factors.
Screening and monitoring the geriatric population for osteoporosis is a certainty in the rehabilitation arena. At greatest risk are elderly white women.
Genetic risks include a family history of osteoporosis, early menopause (at <45 y), a small body frame, and white or Asian race.
Medical conditions that predispose a patient to osteoporosis include Cushing disease, hyperthyroidism, hypogonadism, liver disease, multiple myeloma, primary hyperparathyroidism, malabsorption, lactose intolerance, and renal disease.
Medications that can cause or exacerbate osteoporosis include steroids, high-dose inhaled corticosteroids, lithium, phenytoin, chronic high-dose heparin, and thyroxine. Lifestyle risks include low sun exposure, sedentary lifestyle, nulliparity, poor overall nutrition (including low calcium and vitamin D intake and high protein, sodium, and phosphate intake), smoking, and caffeine and alcohol consumption.
Other contributing factors in the geriatric population include dementia, poor general health, recurrent falls, impaired eyesight, weight less than 127 lb (as adipose tissue is the major source of extragonadal estrogen production after menopause), and bilateral oophorectomy.
Osteoporosis is diagnosed in patients with a BMD T score of more than 2.5 SDs below the mean. T scores are measured in comparison with values in young adults.
A T score above –1.0 is correlated with normal bone mass. A T score of –1 to –2 is considered low bone mass less than 10-20% of the normal range, and thus is associated with doubling of the risk of fracture.
A T-score below –2.0 (where bone mass is >20% below the normal value) quadruples the risk of fracture. Z scores, which are determined in comparison with values in persons of the patient's same age range, can also be measured.
Physical examination includes an evaluation of height, weight, strength, flexibility, and spinal deformities (eg, progressive dorsal kyphosis or Dowager hump).
Observation of the patient's balance and gait for a fall-risk assessment should be a standard part of the physical examination.
The patient's body habitus should be noted for signs of anorexia, Cushing disease, hypogonadism, goiter, gynecomastia, and barrel chest in chronic obstructive pulmonary disease (COPD). All of these medical conditions can contribute to changes in medical management.
Laboratory workup should include determinations of levels of the following: ionized calcium, 25-OH vitamin D, PTH, phosphorus, BUN, creatinine, albumin, total protein, thyroid-stimulating hormone (TSH)/T4, cortisol, alkaline phosphatase, and bioavailable testosterone in men and estrogen levels in women.
In addition, liver function tests (LFTs) should be performed and CBC counts obtained. Further testing is specific for clinical picture. The erythrocyte sedimentation rate (ESR) can rule out exacerbating inflammatory processes.
Urinalysis can be performed to look for proteinuria due to nephrotic syndrome. Erem and colleagues studied urine levels of cross-linked N -telopeptides of type I collagen (NTx), which are noted to be increased in patients who sustained osteoporotic hip fractures.
Plain images can indicate osteoporosis (25-30% loss of bone mass), but dual-energy radiographic absorptiometry (DRA) is the criterion standard for measuring and monitoring true bone density.
The National Osteoporosis Foundation recommends testing in these groups: all women older than 65 years, all postmenopausal women younger than 65 years if they have other risk factors, and postmenopausal women with fractures.
Quantitative CT can be used to measure true BMD; however, the radiation exposure and cost of quantitative CT are higher than those of DRA. Ultrasonography is an inexpensive method of screening asymptomatic women for osteoporosis, but it has not been proven to be equivalent to DRA as a diagnostic tool.
PREVENTION OF OSTEOPOROSIS
The prevention of osteoporosis includes medication, diet modification, and exercise.
A formal nutrition evaluation is recommended. A dose of 1500 mg of calcium daily is recommended for adults, and 800 mg/d is recommended for children.
A dose of 1000 mg of calcium daily is recommended if the patient is taking estrogen. An 8-oz glass of milk, an 8-oz cup of yogurt, and 1 oz of cheese each contain approximately 300 mg of calcium.
Calcium citrate is the recommended supplement because it has a higher rate of absorption than calcium carbonate supplements.
A dose of 800 IU of vitamin D is recommended in combination with calcium for optimal absorption. This amount of vitamin D can also be supplemented with 2 multivitamins per day.
Zinc and copper may also have a positive effect on osteoporosis when calcium supplementation is used because a subclinical deficiency and reduced dietary intake of these micronutrients may be concurrent conditions.
Diet modifications include lower caffeine, lower phosphorus, lower sodium, and higher calcium and vitamin D intake.
Smoking cessation and moderate alcohol intake are also lifestyle changes that should be implemented.
Weight-bearing exercise has a beneficial effect on BMD and helps to prevent osteoporosis. The Wolff law states that mechanical use results in increased cortical bone mass and strength along the line of force, whereas disuse leads to bone atrophy.
An exercise regimen of 45 minutes 4 times per week is recommended. Walking and stair climbing offers sufficient bone loading.
Extension-based exercises are warranted and have a positive correlation on BMD of the spine. Aerobic, weight-bearing, and resistance exercises are all effective in improving the BMD of the spine. Walking is effective for promoting BMD of the spine and hip. Aerobic exercise is effective in increasing BMD of the wrist.
Of note, tai chi chuan (tai chi quan) increases neuromuscular coordination with consequent reduction in the number of falls and fall-related fractures. It can also help in preventing osteoporosis.
A study by Qin et al found that the practice of tai chi for 4 years significantly increases BMD of the spine, proximal femur, and distal tibia. This effect may be explained by an exercise-induced deceleration of bone loss. The benefits of tai chi are promising, and in the future, it may become a recommended mainstream exercise for the geriatric population.
TREATMENT OF OSTEOPOROSIS
Treatment recommendations from the National Osteoporosis Foundation include the initiation of treatment in all women with T scores less than –2.0, in all women with T scores less than –1.5 if they have other risk factors, and all women older than 70 years if they have multiple risk factors.
In the elderly, calcium, vitamin D, regular exercise, postural stability, and fall prevention should be maintained in conjunction with other means of treatment for osteoporosis.
Women with hormonal deficiency can take 0.625 mg of estrogen daily for 3 of 4 weeks each month. If calcium is supplemented, 0.325 mg is sufficient.
Controversy persists in regard to an increased risk for breast cancer with estrogen use and the extent of the cardiovascular profile of estrogen. However, Raloxifene 60 mg qd, a selective estrogen receptor modulator (SERM) that inhibits osteoclastic activity, increases BMD in the spine and femoral neck by 2%, according to Ettinger and colleagues. It decreases the levels of low-density lipoprotein (LDL), increases high-density lipoprotein (HDL), and decreases the incidence of breast cancer.
Raloxifene has no negative effects on breast or endometrial tissue. Standardized regimens have not been studied in men with low testosterone levels, but they should be treated with supplementation and monitored on a regular basis.
Calcitonin 100 IU administered subcutaneously every 3 days inhibits osteoclastic activity and increases BMD in the spine by 3%.
This therapy is mainly used after a compression fracture of the spine has been documented. Salmon nasal spray in 1 nostril with a dose of 200 IU qd (alternating nostrils every other day) is also effective and has an analgesic affect with acute vertebral fractures.
Bisphosphonates, such as alendronate, etidronate, risedronate, and now once monthly ibandronate, may increase BMD in the spine and femoral neck by 5% or more.
Alendronate increases BMD in the lumbar spine by 9% and BMD in the femoral neck by 6%, and it also reduces vertebral compression fractures. Orwoll and colleagues noted a 2.6% increase in BMD of the hip and 5.3% increase in BMD of the spine in a study of men taking alendronate. Alendronate therapy is relatively contraindicated in those with gastroesophageal reflux disease (GERD).
PTH stimulates bone formation when given intermittently in low doses. It can increase BMD in the spine, but not the femoral neck.
Teriparatide is a biological PTH injectable (20 mcg qd) approved for men or women at high risk of fracture due to primary or hypogonadal osteoporosis or postmenopausal osteoporosis, respectively, taken for up to 24 months.
Growth factors may help in treating osteoporosis, but standard guidelines have not yet been established.
Sodium fluoride 25 mg twice daily with calcium citrate promotes osteoblasts by increasing BMD in the lumbar spine by 8% and by increasing BMD in the proximal femur by 4%.
CONSEQUENCES OF OSTEOPOROSIS
In the past decade, the incidence of hip fracture has increased at a faster pace than can be explained by our aging population.
About 1 in 3 women and 1 in 6 men will have a hip fracture by the age of 80 years. The primary risk factor in those older than 65 years is trabecular bone loss and diminished bone strength related to postmenopausal osteoporosis.
Approximately 90% of osteoporotic hip fractures are intertrochanteric and femoral neck fractures.
Fall prevention encompassing increased physical activity and postural stability in this group of geriatric patients cannot be emphasized enough.
Surgical repair of hip fractures usually entails a hemiarthroplasty or open reduction internal fixation (ORIF), depending on extent of the fracture. Surgical repair may be delayed as long as 7 days for medical stabilization without an adverse effect on outcome.
Postoperative rehabilitation addresses passive ROM (PROM) and active assistive ROM (AAROM). Isometric strengthening and the initiation of early ambulation with weight bearing depend on the components. Work simplification, energy conservation, joint protection, and hip precautions should be reinforced daily during rehabilitation.
The radiologic definition of a vertebral fracture is a 15-20% reduction of the total height of the bone in its anterior, posterior, or central aspect.
Anteroposterior (AP) and lateral views plus bone scans can be used to determine the acuity or chronicity of the fracture. The initial pain of a vertebral compression fracture resolves in 4-6 weeks.
For pain control, the following are appropriate measures: scheduled oral analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs), brief rest or activity modification, and a trial with a transcutaneous electrical nerve stimulation (TENS) unit. In addition, moist heat can be applied for 20 minutes every 2 hours to relieve muscle spasm, and ice massage for 7-10 minutes at a time can be used intermittently.
Occasionally, patients need bracing to prevent further fractures. Braces can also be used to improve postural alignment and pain relief.
Velcro-closure binders or corsets are used for lower lumbar spinal fractures, cruciform anterior sternal hyperextension (CASH) braces are used for lower thoracic fractures, and Jewett braces are used for thoracic fractures.
Thoracic lumbar spinal orthosis (TLSO) braces are also used for multiple fracture sites. The duration for which braces are used is undetermined but approximately 6-8 weeks.
Compression fractures can lead to postural deformity, more commonly from T8 to L3 than elsewhere; this deformity appears as kyphosis. Fractures of vertebral bodies at the T4 level or higher are rare and may suggest malignancy.
Respiratory impairment and pneumonia may ensue in a patient with kyphotic posture as a result of decreased space in the abdominal and thoracic cavity. Abdominal distention, early satiety, discomfort from ribs overlapping the iliac crests, sleep disturbances, and depression are also common sequelae.
CONCLUSION
Osteoporosis is an all-too-common disease in the elderly population, especially in women. A high rate of morbidity and mortality is related to osteoporosis.
Physicians should offer medication and therapy to prevent osteoporosis in all of their elderly patients. Once osteoporosis is diagnosed, formal treatment should be initiated.