Clinical and Radiological Outcome of a new Total Cervical Disc Replacement Design

Abstract

Study Design: Non-randomized prospective and single center clinical trial of the ProDisc Vivo prosthesis. Objective: Investigate the clinical and radiological results of a refined cTDR - the ProDisc Vivo - with two years of follow up (FU). The incidence of implant-related complications was recorded as a secondary outcome variable. Summary of Background Data: Previous generations of the ProDisc artificial cervical disc replacement generate high primary stability due to keel-based designs with opening of the anterior cortex during the implantation and subsequent high rates of heterotopic ossifications. Methods: Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), arm and neck pain self-assessment questionnaires. The radiological outcome included the range of motion (ROM) and the occurrence of heterotopic ossifications. The incidence of implant-related complications with new implant design was recorded as a secondary outcome variable. Results: A total of 55 patients received a single level treatment with the ProDisc Vivo cTDR between C3/4 and C6/7, with a follow up rate of 78%. The clinical outcome scores improved in all parameters significantly (p = 0.0001) (NDI: 68.3 → 17.4; VAS arm: 6.3 → 1.4; VAS neck: 4.9 → 1.6). The ROM of the index-segment didn't show a significant change (p = 0.26) (7.9° → 9.2°). Heterotopic ossifications at the index segment was found as grade 0 in 58%, grade 1 in 22%, grade 2 in 10%, grade 3 (with functional impairment of the prosthesis) in 7% and grade 4 in 3% of the cases. We observed three implant-related complications (5.5%), with two implant dislocations anteriorly and one low-grade infect. Conclusion: cTDR with ProDisc Vivo demonstrated a significant and sustained improvement of all clinical outcome parameters. A less-invasive implantation mechanism with lower primary stability of the cTDR might be a reason for a higher dislocation rate compared to the keel-based previous generation ProDisc C.