CHICAGO– Living in a southern, sunny climate is no safeguard against hip fractures, according to a new study by researchers at Kaiser Permanente showing that Vitamin D insufficiency is rampant among people hospitalized for hip fractures.
The study, presented at the recent annual meeting of the American Academy of Orthopedic Surgeons (AAOS), involved a retrospective review of records from 1,539 patients treated at a Kaiser Permanente orthopedic clinic in San Jose, CA, between December of 2010 and December of 2011.
Of the total, 1,091 of the patients underwent total hip or knee replacement, and 448 of were treated for acute hip fractures.
Of those patients with hip fractures, 65.8% were classified as having deficient or insufficient levels of vitamin D, compared to 54% of those undergoing joint replacement. The mean vitamin D level of patients in the hip fracture group was 26.4 ng/ml, compared to 29.9 ng/ml in the total joint replacement group; both measurements were classified as insufficient. The insufficiencies were found in both genders, especially among people over age 70.
Among the patients over 70 with hip fractures, 66.7% were judged deficient or insufficient in vitamin D, compared to 47.1% in the joint replacement group. Of the women in the study, 67.3% of those in the hip fracture group were deficient or insufficient, compared to 54.3% of women in the joint replacement group.
“It’s hard to say whether this is an historic trend, because we don’t have historical data,” said Amanda L. Johnson, MD, an orthopedic trauma surgeon at Kaiser Permanente who presented the data, which has been accepted for publication in the Journal of Orthopedic Trauma.
“There’s no consensus as to why we saw this phenomenon in our study, which runs contrary to most other studies of Vitamin D, but the general hypothesis is that we spend a lot more time indoors than we used to, and we wear sunscreen when we’re out,” added Johnson.
Dr. Johnson found that more than half of all patients aged 18 or older of both sexes with hip fractures had insufficient levels of vitamin D,
“There is no good consensus on what level of Vitamin D is appropriate,” she said, adding that the study assumed that a level of 10 ng/ml or below was deficient. “Insufficient means your Vitamin D is moderately low, while deficient means you really need to do something about it,” she explained.
“Having too low a level of vitamin D sets you up to have osteoporosis and could lead to a fracture,” said Johnson. The Kaiser data indicated that even young people, whom researchers assumed had healthy bones, had low levels of vitamin D.
One of the more troubling findings from this study was the fact that many of the patients with fractures were injured in relatively low-energy, low-impact events (as opposed to high-energy impacts like motorcycle accidents or falls from large heights). “If you’re healthy and you fall, you shouldn’t break your hip, so If you break your hip from a low energy event, such as a fall from standing position, you’re considered to have osteoporosis,” Dr. Johnson said.
She added that she was surprised by the findings. “Some studies show that if you live below the 32nd parallel, for example, in Los Angeles, you don’t need to worry about Vitamin D, because you get enough sun exposure to make your own.” This new study shows that for many people, this is simply not the case.
That said, the problem is easily remedied. “If you take enough Vitamin D or get it through products in your diet like milk, you should get enough to replace what you’re not getting.”