Owning the Bone in Spine Surgery
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.
JBJS Editor’s Choice: Improving Function After Fragility Fractures
In the past several years, the orthopaedic community has become highly engaged in improving the follow-up management of patients presenting with fragility fractures. We have realized that orthopaedic surgeons are central to the ongoing health and welfare of these patients and that the episode of care surrounding a fragility fracture represents a unique opportunity to get patients’ attention. Using programs such as the AOA’s “Own the Bone” registry, increasing numbers of orthopaedic practices and care centers are leading efforts to deliver evidenced-based care to fragility-fracture patients.
In the November 16, 2016 edition of The Journal, Aspenberg et al. carefully examine the impact of the anabolic agent teriparatide versus the bisphosphonate risedronate on the 26-week outcomes of more than 170 randomized patients (mean age 77 ±8 years) who were treated surgically for a low-trauma hip fracture. This investigation is timely and appropriate because our systems of care are evolving so that increasing numbers of patients are receiving pharmacologic intervention for low bone density both before and after a fragility fracture.
The secondary outcomes of the timed up and go (TUG) test and post-TUG test pain were better in the teriparatide group, but there were no differences in radiographic fracture healing or patient-reported health status.
Although this study was designed primarily to measure the effects of the two drugs on spinal bone mineral density at 78 weeks, these secondary-outcome findings confirm the value of initiating pharmacologic intervention early on after a fragility fracture, whether it’s a bisphosphonate or anabolic agent. The orthopaedic community needs to continue leading multipronged efforts to deal with the public health issues of osteoporosis and fragility fractures.
Click here for additional OrthoBuzz posts related to osteoporosis and fragility fractures.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Preventing Atypical Femoral Fractures Related to Bisphosphonates
Physicians worldwide frequently prescribe bisphosphonates such as alendronate (Fosamax) and ibandronate (Boniva) to treat osteoporosis and prevent fragility fractures. Unfortunately, long-term bisphosphonate use has been linked to an increased risk of atypical femoral fractures. In the March 3, 2015 edition of JBJS Reviews, Blood et al. offer some guidance on how to prevent such fractures.
The authors note that prodromal thigh pain and a radiolucent line on X-rays of patients with a history of chronic bisphosphonate use are strong indicators of an impending fracture. Among bisphosphonate users who have an incomplete fracture with little or no pain, the authors recommend a trial of discontinued bisphosphonates, protected weight-bearing, calcium and vitamin-D supplementation, and possible teriparatide (Forteo) therapy. They add that prophylactic fixation should be considered if there is no radiographic or symptomatic improvement after two to three months of that conservative approach. Blood et al. further recommend that patients at high risk for atypical femoral fracture, should consider discontinuing bisphosphonate therapy after five years of continuous use. They also encourage orthopaedists to assess the contralateral femur for signs of impending fracture in patients who have already had an atypical femoral fracture.
The recommendations by Blood et al. notwithstanding, we should stress that the absolute risk of atypical femoral fractures fractures is low (3.2 to 50 cases per 100,000 person-years among short-term bisphosphonate users and about 100 cases per 100,000 person-years among long-term users). Consequently, for most people with osteoporosis, the proven fragility-fracture risk-reduction benefits of bisphosphonates outweigh the risks of atypical femoral fracture.
Readers interested in this subject may want to read a related Case Connections article, which springboards from a January 14, 2015 Case Connector article.
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