The value of artificial disc replacement in cervical radiculopathy

Abstract

Background; Artificial disc replacement (ADR) is a motion-preserving implant and a further development of existing surgical implants for the treatment of cervical radiculopathy. Theoretically, an artificial disc could decrease stress on adjacent segment and thereby prevent rapid progression of degenerative changes in surrounding segments.

Aims; To compare a cervical ADR to fusion in terms of outcome and the most common complications associated with the surgical treatment. To evaluate motion and stability of implanted ADRs with a high accuracy 3DCT method. To develop and validate a questionnaire for the assessment of dysphagia after anterior cervical spine surgery and, to evaluate any difference in dysphagia between the treatment groups.

Patients and methods; 153 patients who met inclusion criteria were included and randomized to either treatment with the Discover artificial disc or fusion with iliac crest bone graft and plating. Randomization was concealed from both patient and caregivers until time for reconstruction of the segment. The patients were followed up for two years and outcome was primarily measured with neck disability index and secondarily with EQ-5D and VAS. Reoperations and complications were also registered in both groups. A subgroup of patients was also investigated with a 3DCT technique for evaluation of motion and stability in the artificial discs. A questionnaire for the assessment of dysphagia was constructed and validated in a group of 45 patients with manifest dysphagia. The questionnaire was then used for the evaluation of postoperative dysphagia after cervical spine surgery.

Results; Data on 137 (91%) patients was available at the follow-up at two years. Nine patients in the disc replacement group and three in the fusion group underwent revision surgery for various reasons during the follow-up. Both treatment groups improved significantly after surgery in all outcome variables. No statistically significant difference in any outcome variable could be seen when the two treatment groups were compared. The motion evaluation showed that a majority of the discs were stable and maintained motion. However, 8% were classified as instable and 5% as ankylotic. Dysphagia was common the first weeks after surgery, but declined and was on group level back to baseline one year postoperatively. When the treatment groups were compared, higher levels of dysphagia were associated with the fusion group.

Conclusion; There was no statistical superiority in any outcome variable in favour of the artificial disc replacement group. Reoperation rates were higher among patients with disc replacement and complications associated to surgery more frequent in the fusion group, but not statistically significant. Dysphagia was common during the first postoperative period, but back to baseline levels after one year. Long-term dysphagia had a higher association with the fusion group.