Lumbar replacement discs have become the crazy old uncle at spine family gatherings.
But that didn’t stop Aesculap Implant Systems, LLC from submitting another PMA (pre-market approval) application to the FDA for its activL Artificial Disc for the treatment of one-level lumbar degenerative disc disease.
On June 15, 2015, the company announced that the FDA had approved it!
The disc, according to the company, features cobalt chromium endplates which affix to the patient’s vertebrae with bone-sparing spikes for initial stabilization. “It is the first lumbar artificial disc with a mobile ultra high molecular weight polyethylene core that supports both controlled translational and rotational movement similar to the movement of the healthy lumbar spine. It offers the widest range of footprints and heights, including an 8.5 mm design, which is the lowest height construct available on the market.”
Lumbar Disc Saga
Lumbar discs weren’t always looked at like the crazy uncle. After approving DePuy Spine’s Charité disc in October 2004, the FDA followed up two years later by approving Synthes Spine’s Pro-Disc. But payers never warmed up to the devices and when Charité left the market a couple of years ago, ProDisc was left all by itself.
While lumbar discs faltered, the pace of approvals for cervical discs seemed to have accelerated in the last three years. Secure-C, PCM and Mobi-C were approved by the FDA in 2012. Then last year, the FDA granted LDR Spine a 2-level indication for its Mobi-C.
National coverage for these cervical discs has been spotty but Aetna, UnitedHealthcare and Cigna have now announced national coverage.
Jack Zigler, M.D., Texas Back Institute’s medical director, says lumbar arthroplasty has been the “neglected sister” in disc replacement technology.
Rise of the Cervical Disc
Zigler told us that cervical total disc replacement gained broader acceptance for a variety of reasons. “Foremost is that it is indicated for reconstruction following a decompression for nerve root or spinal cord compromise. Neurologic pathologies, appropriately diagnosed, that fail to respond to reasonable conservative care have traditionally been treated by surgery, usually by ACDF [anterior cervical discectomy and fusion]. Cervical arthroplasty, once it overcame its safety and early efficacy hurdles, has allowed the seven FDA-approved devices to be approved and reimbursed by the majority of U.S. insurers.”
“Not so the case with lumbar arthroplasty, ” said Zigler.
He says the diagnosis of low-back pain has long been considered a “black box” by insurance companies “frustrated by a wide and ill-defined panoply of surgical indications, and by a mixed bag of results, often including extensive and expensive revision surgeries, leaving patients with failed back surgery chronic pain syndromes.
Despite the fact that the FDA studies did a “terrific job” of defining a specific patient population for whom one and two level lumbar arthroplasty (or fusion) would produce reproducibly good results among a broad swath of clinics and surgeons, “acceptance of lumbar arthroplasty as a reasonable surgical option has lagged far beyond that of its cervical cousin, ” continued Zigler.
Insurance approval for lumbar arthroplasty has failed to gain traction, “despite long term data showing maintenance of dramatically improved outcomes at five years in both fusion and arthroplasty groups (although better in the ADR [artificial disc replacement] patients), and statistically significantly reduced adjacent level radiographic degenerative changes above the ADR’s than above the fusions.”
In fact, says Zigler, it lost traction when Aetna, which covered lumbar arthroplasty as soon as the Charité disc was approved, “completely and unscientifically reversed its position after seven years of coverage, now deeming lumbar arthroplasty to be ‘investigational and experimental’ and currently refusing to cover it.”
“This is the maelstrom into which Aesculap enters and adds its level 1 database to that of the ProDisc-L, ” added Zigler.
activL Artificial Disc
Aesculap says the activL demonstrated non-inferiority in overall trial success compared to conventional total disc replacement designs (Charité and ProDisc-L) in the Investigational Device Exemption (IDE) trial. In the analysis of primary outcomes from the IDE trial, the disc was non-inferior to the control devices tested but also had a greater overall success rate (p < 0.0001). During their own respective IDE trials, the conventional discs were compared to fusion surgery.
Indications
According to the approval order, the device “is indicated for reconstruction of the disc at one level (l4-l5 or l5-s1) following single-level discectomy in skeletally mature patients with symptomatic degenerative disc disease (DDD) with no more than grade I spondylolisthesis at the involved level. DDD is defined as discogenic back pain with degeneration of the disc confirmed by patient history, physical examination, and radiographic studies. The activL artificial disc is implanted using an anterior retroperitoneal approach. Patients receiving the activL artificial disc should have failed at least six months of nonoperative treatment prior to implantation of the device. “
Zigler says “The activL is a somewhat less-semi-constrained disc than the ProDisc, allowing some translational movement of its UHMPE [ultra-high-molecular-weight polyethylene] core on its lower Co-Cr-Mb endplate. It uses a ball-and-socket articulation between the UHMPE and the upper metal endplate. Both metal endplates will be seated in bone with spikes instead of keels, and it offers a slightly lower profile in its smallest size than does ProDisc.”
According to Zigler, patients have done well on extended follow-ups at the TBI clinical site as well as at others.
Zigler: “Reinvigorated Interest”
“As a clinician deeply immersed in this technology since its inception, routinely seeing my own patients with 10+ year follow-up continuing to do well, without the problems of my long-term fusion patients, I welcome the entry of Aesculap to the lumbar arthroplasty marketplace. It is a good device with proven safety and efficacy, and it should help reinvigorate patient and surgeon interest in the technology.”
Unlike cervical arthroplasty, where every spine surgeon is familiar and comfortable with the surgical approach, Zigler points out that lumbar arthroplasty is done through an anterior retroperitoneal approach, and the majority of spine surgeons pair with an access surgeon (general or vascular), and “need to be very familiar with anterior lumbar spine surgery. Extensive experience with ALIF surgery, developing good techniques working in the retroperitoneum and around the great vessels, ureter, and bowel, is highly recommended before surgeons should even consider lumbar arthroplasty training. Preparing and mobilizing the disc space requires a different mental and physical skill set than does fusion surgery.”
Rolando Garcia, M.D. of Aventura Medical Center in Florida, says the activL IDE Trial outcomes “add to the extensive body of evidence supporting the use of lumbar total disc replacement in risk stratified patients.” Garcia was an activL IDE Trial lead investigator who earlier this year co-authored the International Society for the Advancement of Spine Surgery’s position statement on lumbar total disc replacement. “Lumbar Total Disc Replacement is a well-tested technology which should predictably lead to better outcomes and less complications than fusion surgery. I am excited to be able to offer the activL technology to my patients.”
The company will be offering a formal training program to surgeons who want to be certified in implantation of the disc. “This demonstrates their commitment to proper patient selection and to good surgical technique, the two essential elements towards good outcome results. With the introduction of this first new lumbar disc replacement to the U.S. market in ten years, we are hoping that lumbar arthroplasty may become more available to patients who are appropriate candidates, and who do not want to have a fusion, ” added Zigler.
McAfee’s Cautions
Paul McAfee, M.D. told OTW that the pathway to successful commercialization of a new lumbar disc implant has significant challenges even after FDA approval.
First, he says the individual patient differences (motivation, degree of underlying facet disease, disability, and employment factors) “are more important than the differences in type of lumbar disc prosthesis (fixed or mobile bearing, sizing, biomechanical factors, and biomaterials).” In other words, he says the variation in the patient’s indications and selection criteria are more important determinants of long term outcome than the selection or brand of lumbar disc prosthesis.
Second, MacAfee notes this was a non-inferiority study. “The prior IDE FDA trials look great but the insurers and private payers are not approving the surgery.”
Third, he says the complications of failed anterior surgery when “Joe Average” surgeon attempts to reproduce the outcomes of the FDA trials have been substantial. “The repeat dissections anteriorly at L4-L5 are so difficult and specialized that primary lumbar disc replacement is not a viable option at the present time.”
Fourth, according to McAfee, the imaging needs to be MRI compatible, such as PEEK-on-PEEK, especially for disk replacements in the cervical spine.
Waiting for the Payers
Whether or not Aesculap’ s contribution to the scientific literature and the successful regulatory effort to bring another lumbar spine disc to market are in vain is too soon to know.
As usual, the payers will decide.
