Vitamin D in Orthopaedics

Abstract

Vitamin D is an important component in musculoskeletal development, maintenance, and function. Adequate levels of vitamin D correlate with greater bone mineral density, lower rates of osteoporotic fractures, and improved neuromuscular function. Debate exists about both adequate levels required and intake requirements needed to prevent deficiency of vitamin D. Epidemiologic data have identified an increasing number of orthopaedic patients at risk for vitamin D deficiency, with potentially widespread consequences for bone healing, risk of fracture, and neuromuscular function.

Vitamin D Insufficiency in Patients With THA: Prevalence and Effects on Outcome

“…The Institute of Medicine, which is the institution that proposes dietary reference intakes for calcium and vitamin D, considers 25-hydroxyvitamin-D3 serum levels of 20 ng/mL or more as normal [21,22]. In contrast, the International Osteoporosis Foundation, Osteoporosis Canada, and many authors consider 30 ng/mL to be the lowest normal value based on responses of parathyroid hormone and optimal calcium reabsorption to vitamin D levels [18]. Disagreement exists today not only about the controversial associations of vitamin D deficiency with many pathologic conditions but also about its true prevalence in the general population.…”

“…It has also been implicated in the risk of overall mortality [26], cancer [19,21,26], diabetes [21,26], musculoskeletal disorders [16,26], hypertension [21,26], heart disease [21,26], multiple sclerosis [19], stroke [21], and even falls [4,8,20]. Recent epidemiologic data suggest a widespread deficiency of vitamin D [13,18]. It has been estimated that 1 billion people worldwide have subnormal levels of this nutrient [11].…”

“…Disagreement exists today not only about the controversial associations of vitamin D deficiency with many pathologic conditions but also about its true prevalence in the general population. Even though hypovitaminosis D is the accepted term for insufficient or deficient levels [18], in view of the current lack of consensus on what level defines the low end of the normal range (and much more on the derived terms), we will refer to all patients with subnormal levels as patients with insufficiency for the sake of simplicity. What appears clear is that this vitamin is associated with a number of diseases [16,18,26] and, in some reports, with poorer results after surgery [14,15,18]; however, findings on the latter point have varied among studies [24,25].…”

“…Fortified milk and breakfast cereals represent the major dietary sources of vitamin D in US and Canadian diets [18]. In the skin, solar radiation converts 7-dehydrocholesterol to previtamin-D3, which is transformed to vitamin-D3 (cholecalciferol).…”

“…Vitamin-D3 from the diet and skin is then transported to the liver where it is metabolized to 25-hydroxyvitamin-D3 (calcifediol); then it is metabolized in the kidneys to its active form, 1,25-dihydroxyvitamin-D3 (calcitriol). Afterwards, activated vitamin D binds to a single nuclear receptor (vitamin D receptor) that subsequently attaches to specific zones of DNA [17,18]. Production of 1,25-dihydroxyvitamin-D3 in the kidney is regulated by plasma parathyroid hormone levels, serum calcium, and phosphorus levels [11,18,23].…”