Study design: Systematic literature review.
Objective: To assess the effect of total disc replacement for chronic low back pain due to lumbar degenerative disc disease compared with fusion or other treatment options.
Summary of background data: There is an increasing use in disc replacement devices for degenerative disc disease, but their effectiveness compared with other interventions such as fusion of the motion segment or conservative treatment remains unclear.
Methods: A comprehensive search in PubMedCentral, MEDLINE, EMBASE, BIOSIS, ClinicalTrials.gov, and FDA trials register was conducted. Randomized controlled trials comparing total disc replacement with any other intervention for degenerative disc disease were included. Risk of bias was assessed using the criteria of the Cochrane Back Review Group. Quality of evidence was graded according to the GRADE approach. Two review authors independently selected studies, assessed risk of bias, and extracted data. Results and upper bounds of confidence intervals were compared with predefined clinically relevant differences.
Results: We included 7 randomized controlled trials with a follow-up of 24 months. There is risk of bias in the included studies due to sponsoring and absence of any kind of blinding. One study compared disc replacement with rehabilitation and found a significant advantage in favor of surgery, which, however, did not reach the predefined threshold. Six studies compared disc replacement with fusion and found that the mean improvement in visual analogue scale score of back pain was 5.2 mm higher (2 studies; 95% confidence interval 0.2-10.3) with a low quality of evidence. The improvement of Oswestry disability index score at 24 months in the disc replacement group was 4.3 points more than in the fusion group (5 studies; 95% confidence interval 1.85-6.68) with a low quality of evidence. Both upper bounds of the confidence intervals were below the predefined clinically relevant difference.
Conclusion: Although statistically significant, the differences in clinical improvement were not beyond generally accepted boundaries for clinical relevance. Prevention of adjacent level disease and/or facet joint degeneration was not properly assessed. Therefore, because we think that harm and complications may occur after some years, the spine surgery community should be prudent to adopt this technology on a large scale, despite the fact that total disc replacement seems to be effective in treating low back pain in selected patients, and in the short term is at least equivalent to fusion surgery.