ActivL Total Disc Replacement Device Found Noninferior to Conventional Devices
Commentary by Harel Deutsch, MD and Afshin E. Razi, MD
The activL total disc replacement (TDR) device demonstrated noninferiority in overall trial success compared to conventional TDR devices in a prospective, multicenter, randomized, investigational device exemption (IDE) trial. In a primary composite treatment success endpoint, activL was determined to statistically superior the conventional devices, as reported in the December issue of Spine.
The findings “add to the literature that artificial lumbar discs are effective in patients for the treatment of back pain,” said coauthor Harel Deutsch, MD, Associate Professor of Neurosurgery at Rush University Medical Center, Chicago, IL. “The study suggested some advantages to the activL device [over these other devices] with patients returning to work a month earlier with the activL device,” he noted. In addition, patient satisfaction with the activL total disc replacement device was over 90%, Dr. Deutsch said.
“Overall, the study showed that the activL device was not inferior to other devices, and was possibly a bit better than others in terms of some outcomes,” commented Afshin E. Razi, MD, Clinical Assistant Professor, Department of Orthopaedic Surgery, NYU Langone Medical Center, New York, NY. Dr. Razi also is a spokesperson for the American Academy of Orthopaedic Surgeons.
The activL is now the third artificial lumbar disc on the market in the United States, joining the ProDisc-L TDR and Charité TDR. The activL device is similar in design to the ProDisc-L and Charité, with the exception that the activL device may be more constrained, Dr. Deutsch said.
Noninferiority Study Design
The study involved 324 patients with symptomatic single-level lumbar degenerative disc disease that was unresponsive to at least 6 months of nonsurgical management were randomized to receive activL (n=218) or control devices (ie, ProDisc-L or Charité=106) at 14 sites between January 2007 and December 2009. The hypothesis of the study was that a composite effectiveness outcome at 2 years in patients treated with activL would be noninferior (15% delta) to that in controls.
Device Deemed Noninferior to Active Controls
The activL artificial disc was non-inferior to the control devices (P<0.001), but also had a greater overall success rate (P=0.02). A significantly greater proportion of patients in the activL group showed radiographic success compared with the control group (59% vs 43%: P<0.01) and an approximately 1 month shorter return to work (68 days vs 97 days; P=0.08). Patient satisfaction with treatment was high in both groups (>90%).
The activL group had a significantly lower incidence of serious adverse effects, regardless of cause (30% vs 43%; P=0.02). The most common device-related serious adverse events in both groups were lumbar/leg pain (6.9% vs. 15.1%; P=0.03) and implant subsidence (1.4% vs. 1.9%; P=0.66). A similar percentage of patients in both groups required surgical reintervention at the index level (2.3% vs 1.9%; P=1.0).
Both the study authors and Dr. Razi noted the need for long-term studies of the activL device. “At least five-years of follow-up may be necessary to compare outcomes, because adjacent level disease may show up later on,” Dr. Razi said.
Disc Replacement Versus Fusion Surgery
“For patients who have failed nonsurgical treatments for more than 6 months, fusion surgery continues to be the gold standard of care at this point,” Dr. Razi said. “When we do a fusion surgery, we stress the level above or below affected level, different studies call for different numbers of adjacent levels that may require fusion. Disc replacement devices were developed to maintain some motion at the index level where you do the surgery, and to maintain some motion—so there's less stress—above and below the affected level so there is less chance of development of adjacent level disease.”
This IDE study and others confirm that “disc replacements work and are as good as a fusion procedure,” commented Dr. Razi. In addition, “previous studies have shown that disc replacement has benefit over fusion surgery in terms of earlier return to work and greater improvement on the Oswestry Disability Index,” Dr. Razi added.1-3
Lack of Reimbursement Limits Use of TDR
Utilizing these TDR devices is complicated by lack of coverage by many health insurance companies. Dr. Razi explained. He noted that Centers for Medicare and Medicaid Services’ (CMS’) national coverage analysis for Charité and ProDisc-L determined that the devices are not indicated for patients older than 60 years of age (ie, patients who are typically on Medicare). In response, CMS decided that the devices are not covered under Medicare for patients age 60 years and older.4
“Many insurance companies followed in suit and do not cover it,” Dr. Razi noted.