The review authors recommended that total cervical disk replacement could be at least an alternative to fusion for patients with symptomatic cervical disk disease. This recommendation appears to be appropriate, but to determine equivalence of the two types of treatment or superiority of one would require further research.

To compare the effectiveness and safety of total disk replacement versus anterior cervical diskectomy and fusion for the treatment of cervical disk disease

The following databases were searched up to 2011: PubMed, Cochrane Central Register of Controlled Trials (CENTRAL) and EMBASE. Search terms were reported. Reference lists of reviews and included studies were searched for additional articles. Searching was limited to studies published in English.

Eligible studies were randomised controlled trials (RCTs) that compared total disk replacement with fusion for the treatment of cervical disk disease. Only trials with 24 months of follow-up results or long-term results were included in the review.

In included trials, the mean age of patients was 42 years. The percentage of men ranged from 26 to 64%. A range of cervical disk prostheses were used. Outcomes included: overall success rate; re-operation rate for secondary surgery and revision surgery; improvement of movement and functioning measured by the Neck Disability Index score; improvement in pain measured by a validated pain scale; and Short-Form (SF-36) Mental and Physical Health Surveys. Authors were contacted for numerical data if only graphical data were presented.

Two authors independently assessed studies for inclusion in the review.

The included trials were assessed for the quality components of generation of allocation sequence, allocation concealment, blinding, and follow-up. All four quality components were needed for a trial to be rated as adequate.

It appeared that two reviewers were involved in assessing the quality of included trials.

The overall trial success rate was defined as the percentage of individual patients who achieved success in all four component endpoints: 15 point or more improvement in Neck Disability Index scores; maintenance or improvement in neurological status; no serious adverse events related to the implant or procedure; and no subsequent surgery or intervention. Intention to treat data were used.

Two authors independently extracted data from the included studies.

Dichotomous variables were given as odds ratios (OR) with 95% confidence intervals (CIs). Continuous measures were presented as standardised mean differences (SMD) with 95% confidence intervals. The Cochran Q test and I² were used to assess heterogeneity of the included trials. Trials were combined with meta-analysis using a fixed-effect or random-effects model.

Eight RCTs (1,976 patients) were included in the review. Sample size ranged from 19 to 541 patients. All of the included trials were classified as of low methodological quality with a high risk of bias.

Trials with a two-year follow-up (six RCTs): Patients treated with disk replacement showed a significant increase in the overall success rate (OR 1.79, 95% CI: 1.37 to 2.33) compared with anterior cervical diskectomy and fusion, with no significant heterogeneity (four RCTs; 1,192 patients). Patients with a total disk replacement also showed a significant decrease in the overall re-operation rate (OR 0.36, 95% CI 0.21 to 0.61) with no significant heterogeneity (four trials; 1,328 patients), and a significant decrease in the re-operation rate for revision (OR 0.12, 95% CI 0.02 to 0.64) with no significant heterogeneity (three RCTs; 865 patients). There was a slight, but not significant, decrease in the neck disability index score (SMD -0.009, 95% CI -0.44 to 0.27) with significant heterogeneity (Ι²=73%; four RCTs; 720 patients). Patients showed a decrease in neck pain scores (SMD -0.48, 95% CI -0.91 to -0.05) with no significant heterogeneity (two RCTs; 87 patients). There was no significant differences in arm pain between the groups. Quality of life scores for individual trials were also reported.

Trials with four-year or five-year follow-up (two RCTs): These trials also showed that total disk replacement tended to be more effective than anterior cervical diskectomy and fusion for some outcomes (full details given in the paper).

The authors recommended that total cervical disk replacement could be at least an alternative for patients with single-level symptomatic cervical disk disease.

This review was based on defined inclusion criteria. Searching encompassed a number of databases and other sources, but the restriction to studies published in the English language may have led to studies being missed. There appeared to be two authors involved in the review processes, which helped to minimise the possibility of bias and error. The quality of included trials was assessed using appropriate criteria. The meta-analysis appeared to be appropriate.

The authors' recommendation that total cervical disk replacement could be used as an alternative to fusion seemed appropriate, but to determine equivalence of the two treatments or superiority of one would require further research.

Practice: The authors recommended that total cervical disk replacement could be at least an alternative for patients with single-level symptomatic cervical disease.

Research: The authors did not state any implications for practice.

Not stated.