Although statistically significant, the differences between disc replacement and conventional fusion surgery for degenerative disc disease were not beyond the generally accepted clinical important differences with respect to short-term pain relief, disability and Quality of Life. Moreover, these analyses only represent a highly selected population. The primary goal of prevention of adjacent level disease and facet joint degeneration by using total disc replacement, as noted by the manufacturers and distributors, was not properly assessed and not a research question at all. Unfortunately, evidence from observational studies could not be used because of the high risk of bias, while these could have improved external validity assessment of complications in less selected patient groups. Non-randomised studies should however be very clear about patient selection and should incorporate independent, blinded outcome assessment, which was not the case in the excluded studies. Therefore, because we believe that harm and complications may occur after years, we believe that the spine surgery community should be prudent about adopting 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.
[Comparative study of short-term results between total artificial disc prosthesis and anterior lumbar interbody fusion].
The purpose of this study was to examine short-term clinical results with a lumbar disc prosthesis in comparison with anterior interbody fusion for the treatment of chronic low-back pain resulting from disc degeneration.
                This was a consecutive series of 32 patients who underwent surgery between 2002 and 2005 performed by the same surgeon. Patients were randomly assigned to one of two treatment arms: a Charité (Depuy) disc prosthesis was implanted in group 1; an intersomatic KLA cage (Scient'x) was implanted in group 2. All patients presented primary or postdiscectomy discopathy: Modic 1 or 2 on MRI and one level (L4-L5 or L5-S1) positive on discography. A visual analog scale (VAS) and the Oswestry test were noted preoperatively, at six months and at last follow-up and compared with Student's t test. The quantitative analysis was based on the rate of excellent results (60% gain on the VAS and 50% gain on the Oswestry), rate of return to work at three months and level of patient satisfaction.
                Patient follow-up ranged from one to three years. Mean age was 39 years in group 1 and 44 in group 2. The quantitative analysis showed an improvement in the VAS in both groups: 75% in group 1 and 67% in group 2. The difference was not statistically significant. For the Oswestry score, the gain in function was improved 51% in group 1 and 37% in group 2, with a statistically significant difference in favor of the prosthesis group (p=0.125). The qualitative analysis demonstrated that patient satisfaction (87 and 88%) was similar in the two groups, but with a clear difference for return to work at three months, with a better rate in the prosthesis group (61.5%) than the fusion group (42.8%). The rate of excellent outcome was greater in group 1 (77%) than in group 2 (55%).
                There is only one study in the literature, which can be compared with ours. Using the same methodology, that study observed less favorable results for the disc prosthesis than with anterior lumbar fusion.
                The lumbar disc prosthesis offers a possible alternative to lumbar arthrodesis for the treatment of severe disc degeneration at one level in the young subject. It has been found to enable more rapid and superior functional results.