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Fig. 1 A, AP radiograph of 74-year-old female patient with left hip intertrochanteric fracture. B, Postoperative radiograph after intramedullary nail fixation. Courtesy Bradley R. Merk, MD / Northwestern Medicine

AAOS Now

Published 4/1/2016
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Andrew D. Bunta, MD; Joseph M. Lane, MD

Bone Health Lifetime Challenges: Accrue, Maintain, and Replenish

Part One: Nutrition, supplementation, and activity
With the orthopaedic surgery community now called upon to help assure the bone health of our patients as part of comprehensive musculoskeletal care, it is incumbent on us to understand more about the specifics of that care. This obligation is driven by the necessity of treating the osteoporosis in older adult fragility fracture patients to prevent future fractures. In addition, we have other obligations if we are to make our patients aware of their bone health as a quality-of-life issue at all ages.

Recently, the basic evaluation of a fragility fracture patient—an older adult of either sex (50 years and older) who sustains a low-trauma injury—was discussed in this publication. (See "Meeting the Bone Health Challenge," AAOS Now, December 2015.) In the article, we covered suggested laboratory tests and guidelines for the evaluation of patients' bone mass by Dual Energy Densitometry (DEXA), including the incorporation of a Vertebral Fracture Assessment (VFA) in that study.

Here we address the specifics of bone health nutritional issues and osteoporosis medications, including some indications for their use, adverse reactions that may occur, and the knowledge we have of their efficacy, along with the important role of activity and exercise in bone health.

The orthopaedist's role
Many orthopaedists may choose to have their patients' osteoporosis totally managed by primary care physicians or bone health specialists, affectionately known as "boneheads"— eg, endocrinologists, rheumatologists, or geriatricians. Nevertheless, as the coordinator of a patient's musculoskeletal care, the orthopaedist must have some understanding of these therapeutic issues. We have cited different models of care, some even including Advanced Practice Providers in an orthopaedic office, for coordinating patients' bone health care, which might include referring only the most complex cases to specialists.

In addressing the specifics of osteoporosis treatment, a mindset trained on a lifetime goal of bone health and fitness should prevail. We must support the pediatric community in clearly sending this message, whether as a pediatric orthopaedist, a general orthopaedist treating some pediatric patients, or other orthopaedic specialist discussing skeletal health issues with patients who may have children or grandchildren. As many in the bone health field have stated, the most effective treatment of osteoporosis is prevention. Therefore, we must emphasize the triad of goals for lifetime bone health—accrual, maintenance, and replenishment, or therapy—as needed. Peak bone mass is obtained by the end of the third decade in most young adults, so the early years are important in two major respects: nutrition and lifestyle choices—especially those related to exercise.

It is quite clear that many children in the first and second decades of life have not been exposed to age-old standards of nutrition, namely dairy products rich in calcium and vitamin D, and everyday activities such as playing outside for the exercise benefit and the exposure to sunshine to stimulate the production of vitamin D3, cholecalciferol.

Bone mass accrual continues after maximum height is reached to the end of the third decade. Therefore, attention to nutrition and physical exercise is essential for the development of the skeleton with significant peak bone mass to minimize the effects of dwindling bone mass occurring as normal decline in adult years—and an even more rapid decline in women at the time of menopause. In a number of studies, increasing fracture rates have been noted in children and teenagers due to this "deficiency syndrome"—a lack of proper nutrition and exercise.

The basic physiological role of calcium and vitamin D and their need in daily nutrition must be emphasized to parents. Bone mineral is 40 percent calcium, and 99 percent of human calcium stores are in bone. Therefore, most children need 1,300 mg of calcium daily, most easily obtained from dairy sources (300 mg/glass of milk) and adequate vitamin D to facilitate calcium absorption in the gastrointestinal (GI) tract, while also promoting muscle development. Milk fortified with vitamin D2, ergocalciferol, is the most available source. Although the skeleton requires numerous nutrients for full development, it is calcium and vitamin D that are proven mainstays of skeletal health in children, teens, and adults of all ages.

Exercise, including impact activities and muscle function, is clearly necessary for bone accretion and strength in formative years. By the same token, more physical activity also helps to quell obesity, which is epidemic among children of all ages as well as adults, while also addressing the now well-recognized, increased fracture rate of those individuals. Physical activity in early years accentuates periosteal bone growth more than trabecular or endosteal bone, but the latter is positively affected by exercise in later adolescence. Thus, while fostering peak bone mass development, these lifestyle commitments in the early years also create the setting for a lifetime of exercise to avoid the currently recognized, harmful triad of later years—osteoporosis, sarcopenia, and resultant falls, often with fracture.

Supplemental solutions
After peak bone mass is accrued, the next goal is its maintenance. After age 30 a gradual decline in bone mass is physiologic. Therefore, adequate calcium intake remains necessary in the amount of 1,000 mg daily before age 50. Thereafter, due to menopause, intake should increase to 1,200 mg daily in women. Men should increase to 1,200 mg daily at age 70. Divided doses are necessary because the gastrointestinal (GI) tract absorbs a maximum of 600 mg at one time. Most should be obtained through dietary sources such as dairy products (milk [300 mg/8 oz], yogurt [300 mg/serving]), and cheese, in addition to broccoli, kale, and almonds for some.

Supplements may be necessary to reach recommended levels, most commonly with some form of calcium carbonate (frequently present in antacids), which is best absorbed with food to create an acid medium in the stomach. Some older adults may be bothered by constipation, and those with a history of kidney stones should minimize this form of calcium. Thus calcium citrate, although slightly more expensive, may be a better choice since it does not cause the GI side effects or induce kidney stones to the same degree as calcium carbonate—and it can be taken on an empty stomach. In addition, most calcium supplements obtained over the counter are now fortified with vitamin D3 to assist in maintaining adequate vitamin D levels for calcium absorption.

Some questions continue to surround the use of calcium supplements and their possible role in the deposition of calcium in coronary arteries especially. Many in the cardiology community, however, have made the case that calcium is not directly deposited in coronary arteries after ingestion, because coronary calcification occurs only as a chronic, late response to an inflammatory reaction and repair, induced by injury to an atheromatous plaque. Nevertheless, calcium is required for a number of physiologic functions, and the skeleton is clearly the most available source to initiate those functions if calcium intake is inadequate. Therefore, calcium is an essential nutrient. These guidelines regarding calcium sufficiency apply not only to the general population but also quite clearly to patients with fragility fractures, who are often markedly deficient in calcium as well as vitamin D.

The importance of D
Now to the timely topic of vitamin D, which must be addressed separately. It is timely because with the advent of multiple, readily available assays for 25(OH) vitamin D levels in most hospital labs these days, countless people of all ages have been noted to have low levels of this most important vitamin and hormone. In addition, because of what is now recognized as a worldwide prevalence of vitamin D insufficiency, researchers are publishing papers on a daily basis about diseases associated with vitamin D. This is due to evidence that the vitamin D receptor is present in most, if not all, tissues and organ systems. Therefore, current research is directed to establishing the relationship of vitamin D to conditions other than its well-identified role in calcium metabolism and the parathyroid feedback loop necessary to maintain bone health and to prevent fractures. These associated clinical areas of investigation include improved muscle function for fall prevention; the renin/angiotensin axis and its relation to hypertension and insulin resistance; malignancies of the breast, prostate, and colon; and individual response to inflammatory, critical care disease processes.

There remains the ongoing debate about the desired level of 25(OH) vitamin D and the daily requirement to maintain that level. Commonly, a value of 30 ng/ml has been considered a sufficient level, with values less than that determined to be "insufficient" if between 20 and 30 ng/ml and "deficient" if lower than 20; however, many experts point to the current absence of vitamin D assay standardization, and thus some lab values may be open to question. Due to a specific "coefficient of variation" for each specific lab and assay, a patient's actual vitamin D level probably falls within a range above or below the actual value reported.

This situation is related to the current disparate recommendations made by well-regarded organizations pertaining both to levels of vitamin D and daily vitamin D requirements. For example, the Institute of Medicine states that a level of 30 ng/ml coupled with the daily intake of 800 IU of vitamin D3 is quite adequate, while the Endocrine Society recommends a level above 30 ng/ml with a daily intake between 1,000 and 2,000 IU per day.

It is well documented that individuals absorb and process vitamin D at variable rates; thus, lower daily amounts may not assure an adequate serum level. This has led many clinicians to suggest a daily dose of 2,000 IU of vitamin D3, with a resultant serum level goal of about 40+ ng/ml, which has been identified as the mean level seen in a population of individuals exposed only to sun. Patients who are markedly deficient may be treated with 4,000 to 6,000 IU vitamin D3 daily for a month or two, or 50,000 IU vitamin D2 weekly for 2 months, before resuming a 2,000 IU daily dose. While the routine supplement can be taken as a weekly dose, many suggest daily dosing as more physiologic and practical, since calcium must be ingested on a daily basis anyway. In addition, repeat vitamin D levels will not be valid for 3 to 4 months. Recall that these guidelines apply to all individuals, including patients with fragility fractures associated with low vitamin D levels, low bone mass and osteoporosis.

As mentioned in the discussion of younger individuals attaining peak bone mass, exercise for older adults—whether or not they have sustained a fracture—is just as important to maintain bone health. This usually necessitates some form of low- or medium-impact activity, with walking being a common, easily accomplished, and beneficial option. By the same token, muscle exercise of some degree is important to prevent the currently recognized problem of sarcopenia, which compromises stability and leads to falls. Muscle stability and balance exercise, such as tai chi, can be extremely helpful for the older adult population. Falls have become a major concern in the elderly population, a fact emphasized by a report from the Centers for Disease Control and Prevention in 2015, which noted that 55 percent of unintentional injury deaths in adults age 65 and older were due to falls.

In keeping with this public health goal, the Surgeon General last year issued to the American public a significant Call to Action, "Step It up!" to promote walking and walkable communities, in light of the well-documented benefit provided by walking for many health issues beyond osteoporosis prevention. In addition, other well-recognized lifestyle choices necessary for general, overall health, including adequate bone health, are the avoidance of smoking and only moderate alcohol consumption.

Andrew D. Bunta, MD, is on the faculty of Northwestern University Feinberg School of Medicine and is chair of the AOA Own the Bone Multidisciplinary Advisory Board. Joseph M. Lane, MD, is chief of the Metabolic Bone Disease Service at the Hospital for Special Surgery.

Editor's note: This is the first of a two-part presentation. Part two will cover considerations in diagnosis and treatment for bone health.