Issue: January 2014
December 12, 2013
2 min read

Panel highlights lack of support on safety, efficacy of spinal sphere devices for fusion

Issue: January 2014
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In a meeting about the FDA's recommendation to categorize spinal sphere devices for use in fusion procedures as class III, the Orthopaedic and Rehabilitation Devices Panel of the Medical Devices Advisory Committee noted the risks of the product as identified by the FDA are adequate with the addition of a significant or unacceptable risk of revision.

The panel also held there are no reasonable assurances of safety or efficacy of these devices for this indication and agreed with the FDA's assessments that the risk of injury is unreasonable given the lack of probable benefit. They found that insufficient information exists to determine that general and special controls are sufficient to provide reasonable assurance of the safety and effectiveness of spinal sphere devices.

The devices, intended to provide stability and aid in intervertebral body fusion, are placed between the vertebral bodies and into the disc space from L3 to S1.

During the panel meeting, the FDA presented its literature review of five articles about spinal sphere devices published up to Aug. 15. One of the articles was a biomechanical study.

"We could not identify any reports specifically describing spinal sphere devices for use in intervertebral fusion procedures,” Constance Soves, PhD, a member of the FDA's Review Team who presented the findings, said. "Consequently, we could not obtain any valid scientific evidence regarding the safety and effectiveness of spinal sphere devices when used for intervertebral body procedures based on this review."

A Manufacturer and User Facility Device Experience (MAUDE) database search up to June 30, revealed 21 unique medical device reports (MDR) on the devices. According to the FDA, there were 16 cases of removal/revision, 10 cases of pain and six cases of neurological impairment. Soves noted that multiple adverse events may be related to a single MDR. She added that most MDRs were received during the first few years after the initial clearance of the devices, and most adverse events occurred within the first year of implantation.

During the deliberation, non-voting panel members Bernard A. Pfeifer, MD, and Lynda J. Yang, MD, PhD, highlighted the potential risks of instability with the spinal sphere devices.

"In order to place anything in a vertebral space, there has to be a significant amount of work to clear out the material that was there previously," Yang said. "The other thing is that you would like for this shape that you create to fit this. In terms of needing to make this sort of spherical [shape] on either end of where the endplate is the weakest, I do not know how you would carve this circular space out in order to get it in there so that it does not rock."

The panelists debated about how exhaustive the list of risks should be and whether to include events such as subsidence, migration or endplate fracture.

"The worry that I have is that if you make this list real short, somebody who does not know will say, 'Well, this device does not have as much risk as putting in a cage.' Now it may have a little of a less risk by virtue of a smooth rounded surface, [but] it is similar to putting in a cage in my opinion."

Many members said they agreed with the FDA's recommendation for class III categorization.

"I applaud the FDA for looking at this because it is in the interest of patient safety, [and] we have to constrict our thinking in the context of spinal fusion," John D. Kelly IV, MD, panel chairperson and Orthopedics Today Editorial Board member, said. "I think our principle task is safety and effectiveness, and I think there are issues on both sides of the equation." – by Gina Brockenbrough, MA