166. Thirty-six-month clinical outcomes of a prospective, controlled, multicenter study evaluating two-level cervical disc arthroplasty with a PEEK-on-ceramic artificial disc

BACKGROUND CONTEXT Adoption of cervical disc arthroplasty (CDA) continues to increase. Similarly, these devices continue to evolve in form, function, and materials. We present the data from the most recently FDA approved device for 2-level CDA. PURPOSE The purpose of this study was to evaluate the safety and efficacy of a PEEK-on-ceramic artificial disc implant used in the treatment of 2-level cervical disc disease at 36-months postoperation. STUDY DESIGN/SETTING Prospective, nonrandomized, multicenter FDA Investigational Device Exemption (IDE) trial evaluating the Simplify® Cervical Artificial Disc (NuVasive, Inc). PATIENT SAMPLE Subjects undergoing CDA and having 36-month data were included. All patients had 2-level, symptomatic cervical disc disease with radiculopathy and/or myelopathy. OUTCOME MEASURES We evaluated subjects clinically for 1) at least 15-point (of 100) improvement in Neck Disability Index (NDI) scores; 2) neurological status; 3) implant, procedure, or implant/procedure associated serious adverse events (SAEs); 4) additional index level surgery; 5) numeric rating scales assessing neck and arm pain intensity; and 6) patient satisfaction. METHODS Subjects were evaluated preoperatively, at hospital discharge, 6 weeks, and 3, 6, 12, 24, and 36 months after surgery. Thirty-six-month CDA data were compared to preoperative and 24-month CDA data to assess the durability of results over time. The nonconcurrent historic ACDF control data were not included in the analysis as these data were only available to 24 months. RESULTS A total of 155 subjects (85.2%) were available and completed 36-month follow up. Successful NDI outcome (improvement of >15 points at 24-mo follow-up) occurred in 92.9% of subjects at 24-month follow up and 93.5% at 36 months. Mean NDI scores improved from 58.6 preoperatively to 14.3 at 24 months and 13.9 at 36 months. Neurological status was normal in 93.4% and 92.9% at 24 and 36 months compared to 16.1% preoperatively. The rate of implant related SAEs through 36 months for all 182 was 2.2% of subjects. Procedure related SAEs occurred in 1.6%. SAEs attributed to both implant and procedure occurred in 2.2%. There were an additional two subsequent surgical interventions at 36 months (3.3%) compared to four (2.2%) at 24 months. Mean neck pain was 7.9 at preop, 1.8 at 24 months, and 1.7 at 36 months. Likewise, mean arm pain improved from a preoperative mean value of 7.5 to 1.8 at 24 months and 1.6 at 36 months. All preoperative outcome measures in this analysis were significantly improved (p0.05) between 24- and 36-month follow up for any variable. At 36-months, 94% of subjects responded Definitely True (87%) or Mostly True (7%) to the statement “All things considered I would have the surgery again for the same condition.” When asked about their perceived effect of surgical treatment, 91% replied they were “Completely Recovered” (56%) or “Much Improved” (35%). CONCLUSIONS Two-level CDA resulted in significant improvements in outcomes at 24 months; these improvements were maintained at 36 months. Patients are overwhelmingly satisfied with their results. These data are consistent with published mid-term results from other 2-level CDA clinical trials and warrant continued follow up of this patient cohort. FDA Device/Drug Status Simplify Disc (Approved for this indication) Adoption of cervical disc arthroplasty (CDA) continues to increase. Similarly, these devices continue to evolve in form, function, and materials. We present the data from the most recently FDA approved device for 2-level CDA. The purpose of this study was to evaluate the safety and efficacy of a PEEK-on-ceramic artificial disc implant used in the treatment of 2-level cervical disc disease at 36-months postoperation. Prospective, nonrandomized, multicenter FDA Investigational Device Exemption (IDE) trial evaluating the Simplify® Cervical Artificial Disc (NuVasive, Inc). Subjects undergoing CDA and having 36-month data were included. All patients had 2-level, symptomatic cervical disc disease with radiculopathy and/or myelopathy. We evaluated subjects clinically for 1) at least 15-point (of 100) improvement in Neck Disability Index (NDI) scores; 2) neurological status; 3) implant, procedure, or implant/procedure associated serious adverse events (SAEs); 4) additional index level surgery; 5) numeric rating scales assessing neck and arm pain intensity; and 6) patient satisfaction. Subjects were evaluated preoperatively, at hospital discharge, 6 weeks, and 3, 6, 12, 24, and 36 months after surgery. Thirty-six-month CDA data were compared to preoperative and 24-month CDA data to assess the durability of results over time. The nonconcurrent historic ACDF control data were not included in the analysis as these data were only available to 24 months. A total of 155 subjects (85.2%) were available and completed 36-month follow up. Successful NDI outcome (improvement of >15 points at 24-mo follow-up) occurred in 92.9% of subjects at 24-month follow up and 93.5% at 36 months. Mean NDI scores improved from 58.6 preoperatively to 14.3 at 24 months and 13.9 at 36 months. Neurological status was normal in 93.4% and 92.9% at 24 and 36 months compared to 16.1% preoperatively. The rate of implant related SAEs through 36 months for all 182 was 2.2% of subjects. Procedure related SAEs occurred in 1.6%. SAEs attributed to both implant and procedure occurred in 2.2%. There were an additional two subsequent surgical interventions at 36 months (3.3%) compared to four (2.2%) at 24 months. Mean neck pain was 7.9 at preop, 1.8 at 24 months, and 1.7 at 36 months. Likewise, mean arm pain improved from a preoperative mean value of 7.5 to 1.8 at 24 months and 1.6 at 36 months. All preoperative outcome measures in this analysis were significantly improved (p0.05) between 24- and 36-month follow up for any variable. At 36-months, 94% of subjects responded Definitely True (87%) or Mostly True (7%) to the statement “All things considered I would have the surgery again for the same condition.” When asked about their perceived effect of surgical treatment, 91% replied they were “Completely Recovered” (56%) or “Much Improved” (35%). Two-level CDA resulted in significant improvements in outcomes at 24 months; these improvements were maintained at 36 months. Patients are overwhelmingly satisfied with their results. These data are consistent with published mid-term results from other 2-level CDA clinical trials and warrant continued follow up of this patient cohort.