Randomized Controlled Trial between Two Different Cervical Disc Arthroplasty Implants: Two Year Follow-Up
Authors: Berg Andrew , Killen Maire-Clare , Tankel Jamie , Khan Shoaib , Reddy Guru , Friesem Tai 
Published: May 2015

Introduction Motion preservation with cervical disc arthroplasty (CDA) implants has consistently been shown, in numerous randomized controlled trials, to produce equivalent or superior clinical outcomes to anterior cervical decompression and fusion. There has therefore been a call to compare outcomes between different arthroplasty implants. We report the clinical outcomes, at 2-years follow-up, of a randomized controlled trial comparing two fundamentally different implants—the NUNEC Cervical Arthroplasty System (RTI Surgical, Inc., Florida, United States), is a PEEK on PEEK articulating device with inferior ball and superior trough secured by cam lock screws and the PRESTIGE LP Cervical Disc System (Medtronic, Minnesota, United States), is a titanium ceramic composite articulating device with superior ball and inferior trough secured by keels. Material and Methods A review of 52 patients with symptomatic degenerative disc disease causing cervical radiculopathy and/or myelopathy enrolled in this United Kingdom National Health Service (NHS) Research Ethics Committee approved study has been performed. Preoperatively patients were randomized into the two treatment groups (surgery with NUNEC Cervical Arthroplasty System or PRESTIGE LP Cervical Disc System) and blinded until after surgery. All procedures were performed by or under direct supervision of two senior surgeons at the host institution. Patient reported outcome measures (neck disability index (NDI), visual analogue scale (VAS) for arm and neck pain and hospital anxiety and depression scale) were collected preoperatively and at follow-up. Surgical time, blood loss, and complications have also been reviewed. Outcomes have been compared between groups. Results Data for 47 patients is reported (1 withdrawal due to relocation, 4 nonattendance at follow-up excluded). There were 51 NUNEC implants used (3 one level, 12 two level, 4 three level, and 3 four level) and 52 PRESTIGE LP implants used (6 one level, 12 two level, 6 three level, and 1 four level). There was no statistically significant difference in the distribution of the number of operated levels between the two implant groups and therefore analysis of data has been performed using the means for each group. There was no statistically significant difference in the preoperative outcome scores or demographics between the groups. In the NUNEC group NDI improved from 49 to 45.6, VAS neck from 7.5 to 4.7, VAS arms from 7.2 to 4, depression from 8.5 to 8.3, and anxiety from 9.2 to 8.6. In the PRESTIGE LP group NDI improved from 56 to 44, VAS neck from 7.2 to 4.5, VAS arms from 6.4 to 4.5, depression from 9.1 to 8, and anxiety from 9.5 to 9.2. There was no statistically significant difference in the postoperative outcomes between the groups. There were no reoperations in either group for ASD. Conclusion There has been a call for studies comparing different CDA implants. We report the outcomes at 2 years of a randomized controlled trial comparing the NUNEC cervical arthroplasty system and the PRESTIGE LP cervical disc system. No statistically significant difference was found in outcome measures between the two implants. Further analysis is ongoing to compare the radiological outcomes, which may reflect longer term results.