A 66-year-old female with a pack-a-day smoking habit is admitted to orthopedics with a hip fracture following a fall in her home. You are consulted to perform a pre-operative risk assessment and manage her heart failure. The following day, she undergoes an open reduction and internal fixation and does well following the surgery. She is scheduled to be discharged for rehabilitation in two days. She will continue taking her cardiac medications and the narcotics (as needed) for pain. What else can you recommend to reduce her chances of suffering another hip fracture?
Approximately 300,000 hip fractures occur each year in the United States.¹ The lifetime risk of sustaining a hip fracture is 18% for a woman and 6% for a man.2 One-year mortality after a hip fracture is 20% to 25%, and up to half of patients who live independently prior to their fracture cannot gain independence afterward.
In the late 1990s, inpatient care, nursing home care, and outpatient services associated with hip fractures totaled approximately $14 billion annually. These costs are predicted to reach $50 billion by the year 2040.3 Not surprisingly, second hip fractures are common, with up to 12% of patients suffering another fracture within one year of follow up.1 Risk of morbidity and mortality are even higher after a second hip fracture.
In most experts’ opinions, a fragility fracture indicates osteoporosis and warrants treatment—regardless of bone densitometry findings. Still, multiple studies have shown patients who sustain a hip fracture frequently are not diagnosed, evaluated, or treated for osteoporosis.4 This is analogous to treating an acute coronary syndrome without initiating treatment for a patient’s hypertension and hyperlipidemia prior to discharge. As such, providers clearly are missing an opportunity to begin effective measures at a critical stage in the disease.
Physiology of bone strength: Bone minerals—in particular calcium hydroxyapatite—contribute to bone strength by making bone a hard tissue. Collagen adds flexibility and gives bone the ability to absorb energy. The degree of bone mineralization and the number of collagen crosslinks help determine how much stress a bone can tolerate before it breaks. Further, in response to daily stressors, bone accumulates microcracks. Remodeling is then accomplished by bone resorption and formation.5
Estrogen plays an important role in normal remodeling by controlling osteoclast action. Thus, estrogen deficiency leads to prolonged osteoclast activity and increased rates of bone resorption. This explains why bone remodeling typically favors bone resorption later in life and why women are at greatest risk for fracture.5
Vitamin D and calcium: Vitamin D, produced by the skin or ingested, is transported in the circulation by a binding protein to the liver, where it is converted to 25-hydroxyvitamin D. This form is inactive and must be converted by the kidneys to the active form, 1,25-dihydroxyvitamin D. The active form is needed for absorption of renal and intestinal calcium.6
Without vitamin D only 10% to 15% of dietary calcium is absorbed. In one study, serum levels of 25-hydroxyvitamin D directly were related to bone mineral density. When the level was 30 ng/mL or less, there was a significant decrease in intestinal calcium absorption and bone mineral density.6