INTRODUCTION: Many patients with symptomatic lumbar degenerative disc disease (DDD) are affected at more than one level. When non-operative treatment fails to provide adequate relief, multilevel surgery may be considered. Lumbar total disc replacement (TDR) was introduced as an option to fusion. Some disc levels are not amenable to TDR and fusion is preferable at that level. Hybrid surgery, involving TDR at one level and fusion at the adjacent segment, has been introduced as an option to fusing multiple levels. The purpose of this study was to investigate the long-term clinical outcome of patients undergoing lumbar hybrid surgery for treating symptomatic lumbar DDD at more than one level.
METHODS: A consecutive series of 296 patients undergoing lumbar hybrid surgery was identified beginning with the first case experience in 2005. Operative data and clinical outcome data including visual analog scales (VAS) assessing back and leg pain as well as Oswestry Disability Index (ODI) scores were recorded from charts and previous study records. Current data were collected from charts, mailings, and telephone calls. Data on re-operations were also collected from charts and patient contact. All patients were at least 2 years post-operative. The mean follow-up duration was 67.9 months with a maximum of 196 months. A total of 647 levels were operated with TDR implanted in 319 levels and 328 levels undergoing either stand-alone ALIF or combined anterior/posterior fusion. The most common combination for hybrid surgery was TDR at L4-5 and fusion at L5-S1.

RESULTS: The mean blood loss was 100.7 ml. There were statistically significant improvements (p<0.001) in the mean values of all three clinical outcome measures:  VAS back pain scores improved from 6.7 to 3.2; VAS leg pain scores improved from 4.3 to 2.0; and ODI scores improved from 45.6 to 25.0. There was no significant differences in the pain and function scores for patients with minimum 10-year follow-up vs. those with shorter follow-up duration. Re-operation occurred in 16.2 % of patients (see table). The majority of these were for the removal of painful posterior instrumentation at the fusion level (6.1%). Re-operations directly involving the TDR level occurred in 9 patients (3.0%). One patient reported multiple re-operations on the returned mailing, but insufficient detail was provided to determine the procedure(s) performed.

DISCUSSION: The results of this study support that for many patients with symptomatic DDD arising from more than one disc, hybrid surgery is a viable surgical option. Significant improvement was demonstrated in pain and function scores with no difference in scores among patients with more than 10 year follow-up. The most commonly occurring re-operation was removal of painful posterior fixation, unrelated to the TDR.