Seven-Year cTDR Outcomes with Mobi-C® Shows Superior Efficacy to ACDF

Two-level Cervical Total Disc Replacement with Mobi-C® Shows Superior Efficacy to ACDF at 7 Years

Decreased Need for Subsequent Surgeries Found With cTDR
Patients who received cTDR had a significantly lower overall rate of subsequent surgeries at the index levels (TDR 4.4% vs ACDF 16.2% at 84 months; P=0.0008). In addition, the rate of adjacent level secondary surgery also was lower in the disc replacement group (4.4% with TDR vs 11.4% with ACDF, P<0.01). (Figure 3).

Figure 3. Index level and adjacent level survival. Reprinted with permission from Kris E. Radcliff, MD.Figure 3. Index level and adjacent level survival. Reprinted with permission from Kris E. Radcliff, MD.Mean segmental range of motion was maintained in the cTDR group (flexion extension was approximately 10 degrees at the superior level and 8 degrees at the inferior level). “Therefore, the majority of TDR patients maintained range of motion out to 7 years. I believe that the preserved motion of the disc replacements was somewhat protective against adjacent segment disease,” Dr. Radcliff said.

Adverse Events and Radiographic Findings
The groups showed a similar rate of adverse events and radiographic failure at 7 years (Table 1). In addition, the rate of neurologic adverse events was significantly higher in the ACDF group (P<0.05; Table 1), but no catastrophic adverse events (such as paralysis) occurred in either group.

Table 1. Overall success and components of success for 2-level TDR and ACDFStudy Limitations
“As with any study it is important to consider potential sources of bias. In IDE studies, one such concern is confirmation bias, which can occur because patients may be more likely to report positive outcomes of an investigational device such as TDR compared to a traditional treatment such as ACDF, solely due to the novelty of the new device,” Dr. Radcliff noted. “The agreement between both subjective patient reported outcomes, and objective measures such as secondary surgery rates and radiographic analysis in this study suggests that confirmation bias is not a factor. I would hypothesize that early outcomes immediately after surgery may be more susceptible to confirmation bias. By 7 years, however, I would expect patient euphoria unsupported by clinical outcome to have worn off.”

Patient Selection Is Key for Optimizing Outcomes
“I am careful about not extrapolating the results of this study outside of the IDE study criteria,” Dr. Radcliff said. “These were a highly select group of patients who met inclusion and exclusion criteria.”

Exclusion criteria included previous spine surgery, marked cervical instability, disc height <3 mm, metabolic bone disease, active systemic infection or malignancy, autoimmune disease, BMI >40 kg/m2, smoking >1 pack per day, mental illness, or current/past use of high-dose corticosteroids.4

Findings Support the Safety and Efficacy of Cervical Spine Surgery
“Importantly, when you take a step back and look at this data as well as the other literature on cervical disc replacement, we see that cervical spine surgery is remarkably safe and effective,” Dr. Radcliff said. “Both groups of patients (ACDF and disc replacement) improved remarkably compared to baseline.”

“We also endeavored to present this data in a manner that was more digestible to patients. Therefore, we calculated the percentage of patients who were worse compared to baseline, as that is a common patient question. The percentage of patients who were rated as worse NDI compared to baseline at 7 years was 2.7% with cTDR and 3.8% with ACDF. Similarly, the percentage of patients with worse VAS neck pain compared to baseline was 5% with cTDR and 6.8% with ACDF. Dr. Radcliff emphasized.

“This is very important for patients, physicians, and payers to know,” he concluded.

Read the originating article

Disclosures: Kris E. Radcliff, MD
4 Web Medical: Stock or stock Options; Unpaid consultant
ACSR: Board or committee member
Altus Spine: IP royalties; Paid consultant
DePuy, A Johnson & Johnson Company: Paid consultant; Research support; Unpaid consultant
Globus Medical: IP royalties; Paid consultant; Research support
LDR: Unpaid consultant
Medtronic: Paid consultant; Research support
NEXXT Spine: Other financial or material support
Nuvasive: Other financial or material support
Orthofix, Inc.: Paid consultant
Orthopedic Sciences, Inc: IP royalties; Paid consultant
Pacira pharmaceuticals: Research support
Paradigm Spine: Research support
Stryker: Other financial or material support

Updated on: 10/26/17
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Two-level Cervical Total Disc Replacement with Mobi-C® Shows Superior Efficacy to ACDF at 7 Years
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