By: 21 April 2020
Cervical disc arthroplasty

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Degenerative cervical disc diseases are generally treated with a discectomy and fusion surgery after failure of a conservative therapy. Even if the patient’s satisfaction and the success of this procedure are well defined, this technique leads to reduced movement in the operated segment and potential degenerative changes can occur in the neighbouring segments. To avoid this phenomenon, cervical prostheses were developed in recent years.

ROTAIO®, the cervical disc prosthesis of SIGNUS, is a mobile prosthesis with a variable rotation centre. This prosthesis has a range of motion that is similar to the physiological one.

As already published in 2016 [1], 45 patients suffering from a mono-segmental degenerative disc disease have been examined prospectively for a period of two years in two different hospitals. Pain, complaints and problems by daily-life activities were evaluated by means of the visual analog scale (VAS) and the neck disability index (NDI) and radiological examinations were carried out. NDI and VAS values at last follow-up showed a statistical significant improvement in comparison to the pre-operative values. Concerning the global success of the intervention, 95.7 per cent of the patients showed good to excellent results. The drug intake was also reduced at this time point. The analysis of the X-ray images showed at last follow-up a significant increase of the range of motion in the index segment, no signs of anterior migration or dislocation and no subsidence of the prosthesis in the adjacent vertebral bodies. No major complications were observed and in only one case (2.2 per cent), a revision surgery was needed.

A long-term follow-up of the patients who were recruited in this study has been carried out in the form of a survey and the results of this follow-up have been presented at the annual meeting of the German Spine Society in 2019 [2]. Only 18 patients responded to the survey of the original 45 patients. Concerning the results, it could be shown that the visual analogue scale (VAS) and the Neck Disability Index (NDI) after a mean period of five years were not statistically different to the scores at three- to six-months.

“Regarding patient satisfaction, 13 had their expectations met, three had not the expected improvement but would have the same surgery again, and one patient was not satisfied with the surgical result.”

The results obtained from this survey are a good indication that the prosthesis serves for long-term patients’ satisfaction. However, care needs to be taken by the interpretation of these results, as only 18 patients responded to the survey and because of the non-interventional character of the study, no radiological examinations were carried out after this five-year period.

The ROTAIO® prosthesis is still currently examined in another bigger multicentre, multinational, prospective, non-randomised European study. The end of the study is planned for January 2021. A short interim analysis was carried out in 2019 and the results were presented at the annual meeting of the German spine society [2]. This preliminary analysis confirmed the results published in the previous publication and shows significant clinical improvement in this patient cohort two years postoperatively.

The experience made up to now with the ROTAIO® prosthesis shows, that the prosthesis can be considered as an alternative to discectomy and fusion surgery.

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[1] Obernauer, J et al. “Cervical arthroplasty with ROTAIO® cervical disc prosthesis: first clinical and radiographic outcome analysis in a multicenter prospective trial.” BMC musculoskeletal disorders vol. 17 11. 12 Jan. 2016, doi:10.1186/s12891-016-0880-7

[2] 14. Deutscher Wirbelsäulenkongress. Eur Spine J 28, 2660–2758 (2019).