This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.
Approximately 20% of patients who undergo spine surgery have osteoporosis, which has a significant impact on spine-surgery complications such as failure of fixation devices and collapse fractures following fusion procedures. In a recent critical analysis review, authors focus on improving outcomes by identifying and optimizing patients with osteoporosis prior to spine surgery. The multidisciplinary team involved in that process should include primary care providers, endocrinologists, physical therapists, and orthopaedic surgeons.
The predominant tool for assessing bone mineral density (BMD) is dual x-ray absorptiometry. The diagnosis is based on a T score, which represents the number of standard deviations between the patient’s BMD and that of a healthy 30-year-old woman. Standard deviations ≤─2.5 define osteoporosis. The Z score is similar to the T score but compares the patient to an age- and sex-matched individual.
A history of low-energy fracture, such as a wrist fracture following a fall from a standing height, is considered a sentinel event for suspicion of fragility fractures. The combination of a fragility fracture and low BMD is considered to be severe osteoporosis. The most common form of osteoporosis is associated with a postmenopausal decrease in mineralization, but there are other causes. These include advanced kidney disease, hypogonadism, Cushing disease, vitamin D deficiency, anorexia and/or bulimia, rheumatoid arthritis, hyperthyroidism, primary hyperparathyroidism, and some medications (e.g., anticonvulsants, corticosteroids, heparin, and proton pump inhibitors).
Forty-seven percent of patients undergoing spine deformity surgery and 64% of cervical spine surgery patients have low vitamin D levels. Postoperative bone health can be enhanced in women ≥51 years old with daily intake of 800 to 1,000 units of vitamin D and 1,200 mg of daily calcium. There is no solid evidence that pre- or postoperative bisphosphonates have a positive impact on bone healing. Conversely, some series have shown that teriparatide, an anabolic parathyroid hormone, may improve time-to-fusion and help reduce screw pull-out after lumbar fusion in postmenopausal women.
Calcitonin has been shown to reduce the incidence of vertebral compression fracture, but there is no concrete evidence that it supports spine-fusion healing. Similarly, there is no strong evidence for the use of estrogen or selective estrogen receptor modulators in this surgical scenario. There is evidence that when the human monoclonal antibody denosumab is combined with teriparatide, spine-fusion healing may be improved relative to the use of teriparatide alone. Finally, the review article identifies screw size, screw position, and other surgical considerations that can improve fixation strength.
Using the “Own the Bone” practices promulgated by the American Orthopaedic Association and the technical considerations described in this review, we should be able to mitigate osteoporosis-related postoperative complications in spine-surgery patients.
On Thursday, December 10, 2015, from 6:00 to 6:30pm EDT, the Own the Bone initiative will offer a free webinar titled “Vitamin D in Chaos: A Common Sense Approach for Orthopaedics.”
Neil C. Binkley, MD, from the University of Wisconsin will review the physiology of vitamin D, current approaches to 25(OH)D testing, and recommendations for treatment of those whose levels are low. Defining “low” vitamin D status remains extremely controversial, but many fracture patients have vitamin D inadequacy that may contribute to low bone mass and fragility fracture risk.
The American Orthopaedic Association (AOA) developed Own the Bone as a quality improvement program to address the osteoporosis treatment gap and prevent subsequent fragility fractures.
In two separate studies published recently in the BMJ, New Zealand researchers concluded that increased calcium intake, through diet or supplements, is unlikely to have clinically meaningful effects on bone density or fracture prevention. The findings call into question recommendations from most health care professionals for daily calcium intake of at least 1,000 to 1,200 mg in older adults.
The first study reviewed 59 randomized controlled trials (nearly 14,000 patients total) that examined the association between bone mineral density (BMD) and either dietary or supplemental sources of calcium. Increases in BMD ranged from only 0.6% to 1.8% with increased calcium intake, regardless of the source and whether calcium was taken with vitamin D. The authors concluded that these small BMD effects were “unlikely to translate into clinically meaningful reductions in fractures.”
The second study reviewed 28 randomized trials and 44 observational studies (more than 58.000 patients total) that examined the relationship between increased calcium intake and fracture prevention among people older than 50 years. The analysis found that calcium supplements have “small inconsistent benefits on fracture prevention” but that overall “there is currently no evidence that increasing calcium intake prevents fractures.”
What do you make of these findings? Please comment by clicking on the “Leave a comment” button in the box next to the title.