ISASS Policy Statement – Lumbar Artificial Disc

Background

Most of the major health insurance carriers in the US, including UnitedHealth, Aetna, Humana, and most Blue Cross Blue Shield affiliates, do not provide coverage for single level lumbar TDR even in patients meeting strict selection criteria. As a result, millions of Americans with chronic and debilitating lumbar degenerative disc disease who might reasonably benefit from a lumbar TDR are denied access to this technology based solely on their insurance carriers coverage policy.

The most common explanation for denying coverage for lumbar TDR is that the technology is considered “experimental and investigational.” Some carriers indicate that “the long-term clinical outcome of lumbar disc replacement is unclear. The evidence from uncontrolled long-term studies suggests that potential degeneration of adjacent discs and facets and wear of the polyethylene part of the disc may occur and that, in some cases, revision surgery may be needed.” Statements like this are disingenuous, choosing to ignore the long-term outcomes from well-controlled Level 1 studies demonstrating decreased adjacent segment degeneration, minimal component wear issues, and lower revision rates than fusion.

Rationale

A common definition of an experimental technique is one that is new and untested.

A common definition of an investigational technique is one that is not approved and under investigation in clinical trials.

Evaluation of peer reviewed published literature and publicly-debated scientific presentations provides extensive evidence that lumbar disc replacement is neither experimental nor investigational. It has been extensively tested and has received FDA approval after careful and lengthy evaluation of multicenter Level 1 data. Lumbar TDR is not new. The idea of replacing damaged or degenerated lumbar discs started in the 1950's.^{1, 2}

Over the last several decades, multiple attempts have been made to replace painful lumbar disc with implants that maintain motion at the operative level. The Charite artificial disc, developed in Berlin in the 1980s by Drs. Karin Buttner-Janz and Kurt Schellnack was first implanted in the US in 2000 to start a multicenter prospective randomized IDE study. Since 2000, tens of thousands of patients have been treated in the US and worldwide with an increasing inventory of lumbar disc implants. Although some critics speculated that the widespread availability of lumbar TDR would lead to large failure rates and high levels of revision, a detailed and unbiased review of the published literature demonstrates otherwise. Most clinicians and scientists agree that the majority of complications associated with lumbar TDR implantation are related to errors in patient selection, deviating from well established inclusion and exclusion criteria (Table 1, Table 2).

In 2005 Blumenthal et al³ published the result of the first prospective, randomized trial comparing lumbar disc replacement with the Charite to ALIF. The study represented the initial US experience with lumbar disc replacement. 375 patients were enrolled in 14 sites across the US. The authors reported lower levels of pain and disability at all follow up intervals between 6 weeks to 24 months. In addition, the disc replacement group reported higher patient satisfaction, and shorter hospital stay compared to the fusion group. The complication rates in both groups were similar for both groups, but the re-operation rate was significantly lower in the lumbar TDR group compared to the fusion group (5.4% vs. 9.1%).

In 2009, Guyer et al⁴, published the 5 year follow up results of the Charite IDE trial. One hundred and thirty-three randomized patients were evaluated at a minimum of 5 years post index operation. The authors reported that the Charite group had a statistically higher success rate than the ALIF group (58% vs 51%; p=0.0359). Although there were no significant differences between the 2 groups in terms of ODI, VAS, or SF-36, patient satisfaction and employment status were higher in the Charite group. The re-operation rate at the index level was 8% for the Charite group and 16% for the fusion group. The authors concluded that although there were no statistically significant differences between the 2 groups in clinical outcomes, the Charite group demonstrated higher patient satisfaction, higher employment status, and lower re-operation rates, while maintaining motion at the operative level.

Longer term follow-ups at 10 years have been reported in Europe, demonstrating durability of lumbar arthroplasty. Lemaire et al⁵ reported on 100 Charite patients with minimum 10 year follow-up. Clinically, 62% had an excellent outcome, 28% had a good outcome, and only 10% had a poor outcome. Of the 95 patients eligible to return to work, 91.5% did so. These outcomes compare favorably with results described in the literature for fusion for lumbar DDD.

David et al⁶ reported on 106 Charite patients with mean follow-up of 13.2 years. Clinical outcomes and the rate of return to work were excellent overall. The rate of adjacent level disease requiring operation (2.8%) compared very favorably with rates of up to 30% in patients treated with fusion.

In a more recent publication, Zigler et al⁷ reported the results of the 5 year follow up of the ProDisc-L study. Of the 236 original cohort of patients, 82% were available for follow up at a minimum of 5 years post-op. Although both groups demonstrated significant improvements in ODI compared to pre op values, the percentage of patients indicating they would have the surgery again was higher in the ProDisc-L group compared to the fusion group (82% vs. 68%). In addition, the re-operation at the index level was lower for the ProDisc group versus the fusion group (8% vs. 12%). The authors concluded that although fusion and disc replacement are reasonable alternatives for well selected patients, patients undergoing lumbar disc replacement have higher patient satisfaction and avoid the segmental stiffness associated with fusion.

As a companion article Zigler et al⁸ also reported on radiographic adjacent level degeneration as measured by independent radiologic analysis. Comparison of adjacent levels preoperatively and 5 years after surgery demonstrated a threefold increase in adjacent level degeneration in patients who randomized to single level 360 fusion over those who randomized to a ProDisc-L implant. Reoperation rates at the adjacent level were twice as high in the post-fusion patients at 5 years.

Although only ProDisc-L is currently FDA approved in the US for commercial use in the lumbar spine, there are several prospective studies published on the clinical and radiographic outcomes of other lumbar arthroplasty implants in the FDA pipeline. Several lumbar implants are used outside the US (OUS) with thousands of patients implanted, but have not yet gone through an IDE approval for sale in the US.

Gornet et al⁹ published results of the IDE trial using the Maverick metal on metal implant. The study was the largest prospective, randomized trial comparing lumbar TDR to ALIF with a metal cage and BMP. 577 patients were included in this study, including 405 in the TDR group and 172 in the ALIF group. The disc replacement group reported statistically superior outcomes (p<0.05) at all post-operative evaluations in ODI, back pain, and SF-36. Operative times and blood loss were higher in the Maverick group, whereas device related adverse events were lower in the Maverick group. The authors concluded that they had demonstrated statistical superiority of the Maverick arthroplasty versus fusion on key clinical outcomes including improved physical function, reduced pain, and earlier return to work. Maverick is implanted only OUS. Metal on metal arthroplasty devices are under intense scrutiny by the FDA as well as by the surgeon community. New MOM designs are likely to face an even more strenuous regulatory path in the future.

Sasso et al¹⁰ published their results on a metal on metal implant. The study included prospective data from 2 sites in a multicenter trial comparing lumbar TDR with the FlexiCore implant versus circumferential fusion. 67 patients were included in this prospective randomized trial. Operative time, blood loss, and hospital stay were statistically significantly lower in the FlexiCore group. The authors concluded that the FlexiCore compared very favorably to circumferential fusion for the treatment of lumbar DDD unresponsive to conservative treatment. This implant did not complete the FDA approval process.

In addition to US studies regarding patients enrolled in IDE trials, there are several published European studies comparing lumbar TDR to fusion. Skold et al¹¹ reported results of a prospective randomized studies comparing lumbar TDR to fusion. Of the 152 patients included in this study, 80 were randomized to TDR while 72 were assigned to the fusion group. 99% of the patients were available for follow up at 5 years post-op. At follow up the percentage of patients who were totally pain-free was significantly higher in the TDR group versus the fusion group (38% vs 15%; p<0.003). The authors also reported better improvement in VAS and ODI in the lumbar TDR group, with no difference in complications or reoperations.

Although not a randomized study, Siepe et al¹² reported their prospective outcomes 5 to 10 years after lumbar TDR with the ProDisc-L implant. The authors reported on 181 patients at an average follow up of 7.4 years. The authors reported significant improvements in VAS and ODI at all postoperative follow up stages (p<0.0001), and concluded that their results demonstrated satisfactory and maintained mid- to long-term clinical results after a mean follow-up of 7.4 years. The authors stated that the fears of excessive late complications or reoperations following TDR procedures cannot be substantiated with the present data.

Disclosures

Jack Zigler receives consulting fees from DePuy Synthes. Rolando Garcia receives royalties and consulting fees from Aesculap.

Additional Literature on Lumbar Total Disc Replacement