Nancy A. Melville

May 11, 2017

LOS ANGELES — Balloon kyphoplasty shows safety and efficacy in improving quality of life, pain, and functional outcomes, while reducing opioid use, among patients treated for vertebral compression fractures (VCFs), new research suggests.

"We found that all primary endpoints demonstrated statistical improvement and these were maintained or improved throughout a 12-month follow-up," said first author, John W. Amburgy, MD, a resident with the Department of Neurosurgery at the University of Alabama, Birmingham, in presenting the findings here at the American Association of Neurological Surgeons (AANS) 2017 Annual Meeting.

"Secondary endpoints, including opioid usage, activity, angulation correction, and height  restoration, also showed statistical improvement," he reported.

In balloon kyphoplasty, a minimally invasive treatment for VCFs caused by bones weakened from osteoporosis or cancer, the compressed bone is gently raised to its normal position and the cavity created is filled with orthopedic cement to stabilize the fracture.

The procedure differs from vertebroplasty only in the use of the balloon approach.

The prospective EVOLVE outcomes analysis, which Dr Amburgy noted is the largest prospective outcomes trial for kyphoplasty to date, involved 350 patients with painful, acute, or subacute VCF who were enrolled at 24 sites and underwent kyphoplasty.

The patients had a mean age of 78 years; 77% were female. All had one to three acute or subacute fractures less than 4 months old. Approximately half (54.9%) had bilateral kyphoplasty.

Most patients had VCF due to osteoporosis (343 of 350), and the remaining cases were due to cancer.

The patients' average pain scores were greater than 7 on a scale of 1 to 10, and disability on the Oswestry Disability Index (ODI) was greater than 30 on a scale of 0 to 100.

Follow-up data collected at 1-, 3-, 6-, and 12-month time points showed significant improvements in various measures.

In terms of the primary endpoints, patients showed significant improvements in the numeric rating scale for back pain, from an average of 8.7 at baseline (on a scale of 0 to 10) to 3.3 at 1 month, 2.7 at 3 months, 2.5 at 6 months, and 2.4 at 12 months.

Disability measures on the ODI showed improvement from 63.4 (on a 0-to-100 scale) to 32.9, 28.1, 27.1, and 27.2 at these time points, respectively.

Measures of quality of life on the Short-Form 36-question Physical Component Summary, averaging 24.2 at baseline (on a scale from 0 to 100), improved to 34.9, 36.6, 36.6, 37.6, and 38 at the same time points.

Average score on the EuroQol-5-domain, which also assesses quality of life, improved from 0.383 points (scale of 0 to 1) at baseline to 0.693, 0.731, 0.739, and 0.741, respectively.

All improvements were statistically significant (all P < .001).

Importantly, the percentage of patients taking opioids dropped from 71.5% at baseline to 55.3% at 12 months, Dr Amburgy said.

The patients' subsequent fracture rate was 35% at 3 months and 46% at 12 months, which Dr Amburgy noted was somewhat higher than previously observed with balloon kyphoplasty.  However, the results could have been associated with a population of older patients and with a relatively low number — just 18% — of patients taking bisphosphonates.

The mean number of days with limited activity per month declined significantly from about 11 days to approximately 2 over the 12-month follow-up (P < .001 for all time points).

The mean number of bed-rest days also dropped sharply from six per month to less than one (P < .001 for all time points).

In terms of measures of kyphotic angulation and vertebral height improvement, index fracture midline height improvements were observed at postoperative and 3-month time points (both P < .001), as well as at the 12-month time point (P = .002), while index fracture posterior height improvement was seen postoperatively (P < .001) but not at 3 or 12 months.

Cement extravasation occurred in 21.4% of cases, with most leaks into adjacent discs or paraspinal tissue (80.4%).

Twelve leaks went into epidural space and one leak went into foraminal space. None of the leaks extended more than 15 mm into the canal or foramina.

"All of the leaks were asymptomatic," Dr Amburgy said.

In terms of adverse events, there were five device- or procedure-related events (1.46%), all of which resolved with appropriate treatment.

The current findings are notable in light of previous research questioning the benefits of vertebroplasty, including a study in the New England Journal of Medicine  showing no improvement from the procedure over a sham treatment at all time points up to 6 months.

"With as many as 40% of people over the age of 80 having had developed VCFs during their lifetime, and about 1.5 million people developing VCFs annually, the development of kyphoplasty is a very positive," Dr Amburgy said.

The findings build on previous evidence of potential benefits of kyphoplasty, but an important limitation is the lack of a control group, said Paul Park, MD, director of the spine program and associate professor of neurological surgery at the University of Michigan Health System, Ann Arbor,  in commenting on the study.

"This study adds further evidence that kyphoplasty can be effective in treating painful osteoporotic compression fractures," he told Medscape Medical News.

"Previous randomized comparative studies have also shown benefit of balloon kyphoplasty vs medical treatment. Given that this study was not a comparative analysis with a control group, the level of evidence is not as high quality."

The EVOLVE trial was sponsored by Medtronic Spine. Dr Park has disclosed no relevant financial relationships.

American Association of Neurological Surgeons (AANS) 2017 Annual Meeting. Abstract 801. Presented April 24, 2017.

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