Study design: A nonrandomized, prospective, and single-center clinical trial of the ProDisc Vivo prosthesis.
Objective: The aim of this study was to investigate the clinical and radiological results of a refined total cervical disc replacement (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 did not 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 than the keel-based previous generation ProDisc C.
Level of evidence: 4.