Spine injections may set stage for fractures

Spinal injections of steroids, intended to relieve back pain, increased bone fragility in the vertebrae of older patients, a retrospective analysis found.

Each successive translaminar lumbar epidural steroid injection (LESI) increased the risk of vertebral fracture by a factor of 1.21 (95% CI 1.08-1.30, P=0.003) after adjustment for covariates, according to the study, published online in the Journal of Bone and Joint Surgery.

A secondary analysis that allowed for the possibility of more than one fracture in a single patient produced similar results, with a hazard ratio of 1.29 (95% CI 1.22-1.37,P=0.001), wrote Shlomo Mandel, MD, MPH, an orthopedic spine surgeon, and his co-authors from the Henry Ford Health System.

The researchers used the records of 3,000 patients, ages 50 or older, who’d received at least one translaminar LESI in the Henry Ford Health System for compressive neuropathic pain. They compared this group to 3,000 patients, selected via propensity matching, who had not received a LESI for their pain.

Vertebral fractures were identified via keyword search of the radiology database using a list of words provided by musculoskeletal radiologists and neuroradiologists that could suggest fracture. The end of the evaluation period was 5 years or the end of the documented medical history, “whichever came first,” the authors wrote.

Though LESI is commonly prescribed for compressive neuropathic pain, and steroids are known to disrupt bone architecture and tensile stability, the association between LESI and risk of vertebral fracture has not been well studied, wrote the authors. They believe this to be the first study to take on the issue in a systematic way.

While the injections help many people, the findings are of clinical concern, they said, given that many patients who present with sciatica and spinal stenosis are elderly and already at increased risk for skeletal fragility.

“The results of our study suggest that use of LESIs in patients susceptible to osteoporotic fractures should be approached cautiously,” they wrote.

In an accompanying editorial, Andrew Schoenfeld, MD, an orthopedic surgeon at William Beaumont Army Medical Center in El Paso, cited the Hippocratic Oath’s maxim to “first do no harm,” and said the study results “represent novel contributions to the literature.”

The fracture risk documented in the study should be set against the best available evidence regarding the long-term efficacy of LESI, which is “less than robust,” he said. Especially, he said, given that “the impact of vertebral fractures on quality of life as well as mortality is well understood.”

Earlier studies have suggested that vertebral fractures are associated with a higher risk of mortality for both men and women.

The study had some limitations. The selection of codes used to identify spine-related disorders in the database of patient records was not comprehensive.

Some patients may have been treated with LESI within the Henry Ford Health System and then treated elsewhere for vertebral fracture, which could have led to an underestimation of the fracture rate, said Schoenfeld.

The study covered a 5-year period, which represents “a snapshot in time,” the authors wrote, “and does not account for any treatment provided earlier.”

The authors also did not control for variables such as history of smoking, exercise, or BMI. Additionally, they said, many vertebral fractures go undiagnosed and thus wouldn’t have been detected by the keyword search.

Given the limitations of the study, Schoenfeld cautioned against using it as a rationale to curtail LESI among all patients. The risk identified in the current study may not be typical of all patients, particularly younger ones he said. He called the study “a first step in the scientific process” and said it was “a call for further prospective research.”

A prospective trial on vertebral fractures and injection therapy is “in the works,” said the authors.

Disclosure:

Dr. Mandel received grant support for this work from the Nancy and James Grosfeld Foundation. Dr. Sudhaker received a speakers’ fee from Lilly in the 36 months prior to submission of this article.

Reference:

Mandel S, et al “A retrospective analysis of vertebral body fractures following epidural steroid injections” J Bone Joint Surg 2013; 95: 961-964.
Schoenfeld AJ “Primum non nocere” J Bone Joint Surg 2013; 95: e78 (1-2).