Chapter ?? 23 Osteoporosis Nichols and Pavlovic C H A P T E R

Disease Definition Osteoporosis has classically been defined, for older women and men, as a pathological condition associated with increased loss of bone mass caused by increased bone resorption. Osteopenia is a less severe form of the disease in which bone mass has declined below normal levels, but not to the extent seen in osteoporosis.

Scope Fracture risk at the hip is 2.5 times higher for each standard deviation decrease in hip BMD. Osteoporosis now affects almost one out of every two women at some point in her life. Prevalence rates in men can be as high as 15%. Medical costs for osteoporosis are estimated at $19 billion per year. Estimate a fivefold increase in all-cause mortality in the 3 mo following a hip fracture in older adults.

Pathophysiology Changes in bone result from the continual process of bone resorption and bone formation—known as bone remodeling. –Bone remodeling does the following: Maintains the architecture and strength of the bone Regulates calcium levels Prevents fatigue damage (continued)

Figure 23.1

Pathophysiology (continued) Two most important factors in the development of osteoporosis: –Amount of peak bone mass attained –The rate of bone loss Peak bone density (or peak bone mass)— the highest amount of bone mass attained during life

Medical and Clinical Considerations Signs and symptoms Osteoporosis is asymptomatic Must consider possible risk factors:

Diagnostic Testing Primary means of assessing bone health is to measure bone mineral density. – Dual-energy X-ray absorptiometry (DXA) Bone mineral content per unit area (continued)

Diagnostic Testing (continued) A DXA image of a femoral neck scan, along with its accompanying printout. (continued)

Diagnostic Testing (continued) Exercise testing –Aims are to aid in the diagnosis of coronary artery disease and to determine an appropriate exercise prescription –Must be carefully evaluated to make certain that any potential benefits outweigh the risks Contraindications –Can lead to fractures –Osteoporosis and osteopenia: avoid exercise testing that involves high-impact skeletal loading such as jumping and stepping

Treatment Exercise can help increase or maintain bone mass Several nonpharmacologic and pharmacologic agents are available to increase bone mass or slow loss: –Calcium supplementation –Vitamin D supplementation –Estrogen (or hormone) replacement therapy –Selective estrogen receptor modulators (SERMs) –Bisphosphonates –Parathyroid hormone (PTH) –Denosumab –Calcitonin

Pharmacology See table 23.3 on pharmacology.

Exercise Prescription Several forms of exercise training have the potential to increase BMD as well as bone strength. Current experimental knowledge indicates that an osteogenic exercise regimen should include the following: –Load-bearing activities at high magnitude with few repetitions (continued)

Exercise Prescription (continued) –Create variable strain distributions throughout the bone structure (load the bone in directions to which it is unaccustomed). –Bone responds to loading in a site-specific manner (load joints that are at greatest risk for fracture such as hip, wrist, lower back). –Exercise should be long-term and progressive. –Added benefit may result from dispersing loading activities throughout the day rather than completing the exercise all at one time. (continued)

Exercise Prescription (continued) See table 23.4 on exercise prescription. Cardiovascular training: In older individuals, prolonged endurance training can increase fitness levels by 10% to 30%. Endurance training can decrease cardiovascular disease risk factors such as hypertension and cholesterol. Resistance training: Offers the most benefits for muscular strength and bone density Current recommendations listed in table 23.4 (continued)

Table 23.6

Exercise Prescription (continued) Balance and agility training: Neuromuscular training, which incorporates balance and agility, has been shown to be effective for preventing falls if performed two or three times per week. 1.Gradual reduction at the base of support through postural changes (e.g., progressing from a two-legged stand to a one- legged stand) 2.Dynamic movements that challenge the center of gravity (e.g., tandem walk) 3.Stressing stabilizing muscle groups (e.g., toe stands) 4.Reducing sensory input (e.g., standing with eyes closed)

Conclusion Cost and problems associated with osteoporosis will continue to increase. Osteoporosis or osteopenia can be diagnosed with the use of DXA technology. Bone density measurements should be seriously considered in anyone with existing risk factors for osteoporosis. Prevention should be the primary focus.