Introduction Fusion has been the primary treatment for symptomatic disc degeneration unresponsive to non-operative care. The results for two-level fusion have generally been worse than for one-level. There is little information available concerning two-level total disc replacement (TDR), and none comes from prospective studies. The purpose of this study was to analyse the results of two-level disc replacement and compare these results to single-level cases performed at the same centre.

Methods This data was collected from a single center participating in a multicentre a prospective, FDA-regulated clinical trial evaluating the ProDisc. This study is based on data from the first 105 patients (36 2-level and 69 one-level) enrolled who have reached a minimum of 12 months follow-up (data for 18 and 24 month were included if available at the time of data analysis). All patients were treated for symptomatic disc degeneration unresponsive to non-operative care. Data were collected pre-, peri-, and 6 weeks and 3, 6, 12, 18, and 24 months post-operatively. Outcome data included visual analog scale (VAS) assessing pain, Oswestry Disability Questionnaire, patient satisfaction (VAS ranging from 0 to 10), and a question asking patients if they would have the same surgery again. Within the 1-level and 2-level subgroups, pre- and postoperative data were compared to determine if there was improvement. The percentage of change in the pre- to post-operative scores was compared to determine if there were differences between the 1- and 2-level subgroups.

Results The mean estimated blood loss (1-level= 57.7 cc vs. 2-level = 76.7 cc), operative time (1-level = 61.6 min vs. 2-level = 96.7 min) and length of hospitalization (1-level=1.86 days vs. 2-level= 2.36 days) were significantly less in the single-level cases (p< 0.05). VAS pain scores improved significantly (p< 0.05) in 1- and 2-level cases. The mean improvement in 2-level cases was 58.7% and in 1-level cases 62.4% (p> 0.05). Between the one and two-level cases, there was no significant difference in the percentage of patients who would have the surgery again (86.6% vs. 77.8%; p> 0.05). The mean satisfaction score in the single-level TDR group was 8.2 and was 7.1 in the 2-level group (maximum score of 10).

Discussion This study found that both 1- and 2-level TDR results in significant improvement in pain and function scores. Patients undergoing 2-level disc replacement yielded outcomes similar to 1-level cases. These results support TDR as a viable treatment for 2-level symptomatic disc degeneration.

INTRODUCTION: Two total disc replacement devices have been used in Europe for more than 10 years. However, there are few, if any, prospective studies evaluating their results. The purpose of this prospective study using standardised outcome evaluations was to evaluate surgical outcome following implantation of an artificial disc.

METHODS: This study is based on the consecutive series of the first 57 patients undergoing total disc replacement using the SB Charité (Link) disc prosthesis. Indications included single-level symptomatic disc degeneration, failure of at least six months of non-operative treatment including active rehabilitation, and no previous surgery at the operated segment. Data were collected prospectively pre-operatively and at six weeks, three, six, and 12 months post-operatively (24 month follow-up data collection is continuing). Primary outcome measures included visual analog scales (VAS) assessing pain and the Oswestry Low Back Pain Disability Questionnaire.

RESULTS: The mean operative time was 78.5 minutes and the mean estimated operative blood loss was 134.3 cc. Estimated blood loss and operating time were both significantly less for disc replacements at the L5-S1 level than at L4-5 (p< 0.05; t-test). As seen in Figures 1 and 2, there was a significant improvement in the VAS and Oswestry scores (p< 0.05) at the six week follow-up visit, and the improvements were maintained during subsequent follow-up visits.

There were no cases of device failure, displacement, or migration. Complications were comparable to those encountered with anterior interbody fusion.

DISCUSSION: The results of this prospective study, using patient self-report questionnaires, demonstrated significant improvement at six weeks and the improvement was maintained during the 12 months follow-up period (24-months data is being collected). The disc prosthesis can be implanted safely, with complications similar to those encountered with anterior lumbar inter-body fusion.

Introduction: There is a great deal of interest in intervertebral disc arthroplasty. These devices have been used in Europe for more than 10 years. There have been several reports published on the European results when using the SB Charité III (link) prosthesis and good results have been reported in 63% to 79% of patients^1,2,3. The purpose of this prospective study was to evaluate surgical outcome following implantation of an artificial disc.

Methods: The SB Charité III device has two cobalt chromium plates with a polyethylene core between them. Motion occurs through articulation between the concave/convex surfaces of the plates and core. The disc prosthesis is implanted using the same approach as used for anterior lumbar interbody fusion procedures. It comes in multiple sizes to accommodate variations in individual patient size.

The disc has been implanted in 39 patients in our clinic. This group includes 19 males and 20 females (mean age 39.8 years, range 26 to 54 years). The primary study inclusion criteria were single-level symptomatic disc degeneration, failure of at least six months of non-operative treatment, and no previous surgery at the operated segment. Outcome measures included neurological examination, radiographic assessment, Oswestry Low Back Pain Disability Questionnaire, visual analog scale (VAS) assessing pain, SF-36, and work status. Data were collected pre-operatively, and at six weeks, three, six, and 12 months post-operatively. To date, 22 patients have reached the 12 months follow-up point.

Results: Overall, patients demonstrated improvement in the self-reported outcome measures. The mean VAS score improved approximately 50% at the six weeks follow-up and this improvement was maintained during subsequent follow-up. The Oswestry scores improved 37% at six weeks follow-up and had improved by 50% at subsequent follow-ups. Radiographic assessment revealed no cases of device displacement or migration. Complications were comparable to those reported for anterior lumbar interbody fusion. There have been no cases of device failure.

Discussion: The results of this prospective study, using patient self-report questionnaires, demonstrated good clinical outcome. There was a significant improvement noted six weeks post-operatively that was maintained during the follow-up visits. The disc prosthesis can be implanted safely, with complications similar to those encountered with anterior lumbar interbody fusion. As with any surgical procedure, long-term prospective follow-up is needed and data will be collected as these patients reach 24 months follow-up.