Artificial disc replacement versus fusion in patients with cervical degenerative disc disease and radiculopathy: a randomized controlled trial with 5-year outcomes

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The method of artificial disc replacement (ADR) has been developed as an alternative treatment to fusion surgery after decompression for cervical degenerative disc disease (DDD) with radiculopathy. Preserving the motion of ADR devices aims to prevent immobilization side effects such as adjacent-segment pathology (ASP). However, long-term follow-up evaluations using MRI are needed to investigate if this intent is achieved.


The authors performed a randomized controlled trial with 153 patients (mean age 47 years) undergoing surgery for cervical radiculopathy. Eighty-three patients received an ADR and 70 patients underwent fusion surgery. Outcomes after 5 years were assessed using patient-reported outcome measures using the Neck Disability Index (NDI) score as the primary outcome; motion preservation and heterotopic ossification by radiography; ASP by MRI; and secondary surgical procedures.


Scores on the NDI were approximately halved in both groups: the mean score after 5 years was 36 (95% confidence interval [CI] 31–41) in the ADR group and 32 (95% CI 27–38) in the fusion group (p = 0.48). There were no other significant differences between the groups in six other patient-related outcome measures. Fifty-four percent of the patients in the ADR group preserved motion at the operated cervical level and 25% of the ADRs were spontaneously fused. Seventeen ADR patients (21%) and 7 fusion patients (10%) underwent secondary surgery (p = 0.11), with 5 patients in each group due to clinical ASP.


In patients with cervical DDD and radiculopathy decompression as well as ADR, surgery did not result in better clinical or radiological outcomes after 5 years compared with decompression and fusion surgery.

Clinical trial registration no.: 44347115 (ISRCTN).

ABBREVIATIONS ADR = artificial disc replacement; ASP = adjacent-segment pathology; CASP = clinical ASP; CI = confidence interval; DDD = degenerative disc disease; DSQ = Dysphagia Short Questionnaire; HADS = Hospital Anxiety and Depression Scale; HADS-a = HADS-anxiety; HADS-d = HADS-depression; HO = heterotopic ossification; HR = hazard ratio; IDE = investigational device exemption; ITT = intention to treat; MCID = minimum clinically important difference; NDI = Neck Disability Index; NSAID = nonsteroidal antiinflammatory drug; RASP = radiographic ASP; VAS = visual analog scale.

Article Information

Correspondence Anna MacDowall: Uppsala University, Uppsala, Sweden.

INCLUDE WHEN CITING Published online January 11, 2019; DOI: 10.3171/2018.9.SPINE18659.

Disclosures DePuy Synthes Spine provided an unrestricted grant for this study. Dr. MacDowall reports being on the board of the Swedish Society of Spinal Surgeons. Dr. Skeppholm reports being a paid speaker for DePuy Synthes Spine. Dr. Robinson reports being on the speaker’s bureau and/or giving paid presentations for AOSpine, DePuy Synthes Spine, and Medtronic; and being on the board of the Cervical Spine Research Society (European Section) and AOSpine. Dr. Löfgren reports giving paid lectures for DePuy Synthes Spine. Dr. Olerud reports being on the speaker’s bureau for Anatomica, AOSpine, DePuy Synthes, and Medtronic; receiving clinical or research support for the study from Depuy Synthes; and being on the board of the Cervical Spine Research Society (European Section).

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Consort diagram. PP = per-protocol.

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    Imputed data, ITT analysis of ADR versus fusion. Graphs showing the mean values of the NDI (left) and the EQ-5D (right) at each time point for each group. Error bars are 95% CIs.

  • View in gallery

    Kaplan-Meier plot for reoperations stratified by sex.



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