Five-year Follow-up of a Prospective Food and Drug Administration Investigational Device Exemption Trial Evaluating a PEEK-on-Ceramic Cervical Disk Replacement

Study design: Prospective trial comparing the investigation group to propensity-matched historic control group.

Objective: To evaluate five-year results of single-level PEEK-on-ceramic cervical total disc replacement (TDR) compared with a propensity-matched anterior cervical discectomy and fusion (ACDF) control group.

Summary of background data: Cervical TDR has gained acceptance as a treatment for symptomatic disk degeneration. The design and materials used in these devices continue to evolve.

Materials and methods: Data were collected in the Food and Drug Administration Investigational Device Exemption trial for the PEEK-on-ceramic Simplify Cervical Artificial Disc (n=150) with comparison to a propensity-matched ACDF control group (n=117). All patients were treated for single-level cervical disk degeneration with radiculopathy and/or myelopathy. Clinical outcome was based on composite clinical success (CCS), Neck Disability Index (NDI), visual analog scales (VAS) assessing pain, reoperations, and satisfaction. Radiographic measures included segmental range of motion (ROM), disk space height, and heterotopic ossification (HO). Evaluations were performed preoperatively and postoperatively within two and six weeks, and three, six, 12 months, and annually thereafter.

Results: At five-year follow-up, CCS was significantly greater with TDR than ACDF (91.1% vs. 74.6%; P <0.01). In the TDR group, the mean NDI score was 63.3 preoperatively, reduced significantly to 23.1 at six weeks, and remained below 20 throughout the five-year follow-up. In the ACDF group, the mean preoperative NDI score was 62.4, decreasing to 33.7 at six weeks, and ranged from 25.9 to 21.5 throughout follow-up. Mean NDI scores were significantly lower in TDR group at all postoperative points ( P <0.05). Mean TDR ROM was 7.3 o preoperatively and 10.1 o at five years. Bridging HO occurred in 9%. With TDR, there were six reoperations (4.0%) versus 11 (9.4%) with ACDF ( P >0.40).

Conclusions: PEEK-on-ceramic TDR produced significantly improved outcomes maintained throughout five-year follow-up that were similar or superior to ACDF, supporting TDR in appropriately selected patients.