Mobile Total Disc Replacement Prosthesis Mobi-C, our Experience - Results of the Study with Five Years Follow-up

Aim: To present clinical outcome and radiological findings in a group of patients five years after an implantation of mobile total disc replacement prostheses Mobi-C. Material and methods: Retrospection of prospectively collected data after five years from 17 patients with 18 disc prostheses Mobi-C implanted at the Department of Neurosurgery, Charles University Teaching Hospital in Plzen, Czech Republic. The surgery was indicated in the presence of symptoms of radiculopathy and/or myelopathy in correlation with soft disc herniation on magnetic resonance. Clinical condition was evaluated using the Visual Analogue Scale (VAS), modified Japanese Orthopaedic Association Scale (mJOA) and the Nurick Scale Range of motion of the operated spinal segment and the entire cervical spine was assessed with dynamic X rays. Heterotopic ossification was evaluated according to the Mehren classification. The results were statistically tested with non-parametric Wilcoxon test on the 0.05 significance level. Results: Range of motion five years after the implantation was not restricted, median remained the same. 7.0 (p = 0.2932), range of motion of the entire cervical spine was not significant; median increased from 36 to 48 (p = 0.0997). Heterotopic ossification grade 0 was found in 28%, bony fusion, degree IV, in 11%. Statistically significant improvement in neurological findings was found in all patients. The median score on VAS changed from 5.5 to 2 (p = 0.0009) and mJOA median from 16 to 18 (p = 0.0025). Conclusions: With respect to clinical outcome, total disc replacement with mobile prosthesis Mobi-C is an effective option in the treatment of cervical disc degeneration. The range of motion of the operated segment remained stable during five years after the implantation. No correlation was found between clinical outcome and range of motion of the prosthesis.