5 - Outcome of 2-level Lumbar Total Disc Replacement: Results of a Long-term Follow-up Study

Introduction
Lumbar total disc replacement (TDR) has gained acceptance for the treatment of symptomatic disc degeneration unresponsive to non-operative care. Most of the literature has reported on the use of these devices at a single level; however, there are many patients with symptoms arising from two levels.
Aims/Objectives
The purpose of this study was to evaluate the long-term outcome of 2-level lumbar TDR.
Methods
The study was based on the consecutive series of 255 patients undergoing 2-level TDR beginning with the first case experience in 2002. Only patients who were at least 2 years post-operative were included. All patients were treated for symptomatic disc degeneration unresponsive to non-operative care. Data were collected from existing files, chart review, and for patients who had not been seen recently in clinic, mailings and/or telephone calls were conducted to attempt to collect current outcome data. Data collected included general descriptives, operative details, visual analog scales (VAS) separately assessing back and leg pain, the Oswestry Disability index (ODI), and re-operations since the index TDR surgery. The follow-up duration was a mean of 98.5 months with a median of 85 months, ranging from 0 to 217 months.
Results
The mean estimated operative blood loss was 107.9 ml. There were statistically significant (p < 0.001) improvements from pre-operative scores to final follow-up in the mean values of all three clinical outcome measures. VAS back pain scores improved from 7.0 to 2.8; VAS leg pain scores from 4.3 to 2.1; and ODI scores improved from 49.0 to 23.7. The change from pre-operative to follow-up scores on the VAS and ODI were compared between patients with 10 or more years follow-up vs. those with less than 10-year follow-up. The only significant difference in the changes was that the improvement in ODI scores was significantly greater in the group with longer follow-up (28.9 vs. 21.5; p< 0.025).
There were 6 re-operations involving the index TDR levels (2.4%): 1 (0.4%) involved TDR removal at both levels and fusion 6 days post-TDR due to vertebral body fracture and 5 involved supplemental posterior fixation at the index levels (2.0%). The duration from index TDR to re-operation involving an index level was less than 1 month in 3 of the patients, and at 3, 13, and 107 months in the remaining patients. Seven patients (2.7%) underwent subsequent surgery at levels other than the index level. Other re-operations included: 12 patients received a spinal cord stimulator, 1 a morphine pump, 1underwent sacroiliac joint fusion, and 2 underwent reoperation for superficial wound infections.
Conclusion
Significant improvements were demonstrated in pain and function scores with no deterioration in outcomes among patients with more than 10-year follow-up. These results support that TDR produces good outcomes sustainable through long-term follow-up for the treatment of 2-level symptomatic disc degeneration.