492 - The Incidence of Adjacent Segment Disease and Index Level Revision and...

General Session: Lumbar

Presented by: M. Scott-Young - View Audio/Video Presentation (Members Only)

Author(s):

M. Scott-Young(1), L. McEntee(1), J. Cho(1), I. Luukkonen(1)

(1) Gold Coast Spine, Southport, QLD, Australia

Abstract

Multiple Class 1 studies have verified that lumbar total disc replacement (LTDR) is successful in reducing pain and improving function. LTDR is, at least, clinically equivalent to anterior lumbar interbody fusion. The purpose of this paper is to explore the other potential benefits of LTDR, including a reduced rate of revision at the index level and adjacent segment disease (ASD). A prospective study of 401 patients with single level symptomatic degenerative disc disease (DDD) (verified by clinical examination, MRI, discography, and EMG) underwent 1 level LTDR under a single surgeon between 1996 and 2014. Outcome measures included back and leg Visual Analogue Scores (VAS), Oswestry Disability Index (ODI), and Roland Morris Disability Questionnaire (RMDQ) and were collected pre-operatively, at 3 and 6 months post-operatively, and annually thereafter. Secondary surgical intervention at the index level and for ASD was documented at annual follow up. The results for the index level group, the ASD group and the general LTDR group were collated and compared. Statistical analysis was conducted separately for the 3 outcome groups using a two tailed paired t-test with an alpha level of 0.05. The overall rate of secondary surgical intervention was 8.2%. Of the 401, 17 patients had intervention for ASD (4.2%), of which 14 (82.4%), with either ALIF or LTDR. The mean improvement, compared to baseline level, was VAS back 42% (p< .01), VAS leg 20.2% (p=.43), ODI 40.4% (p< .01) and RMDQ 41.5% (p=.0013). The average time for this intervention was 77.8 months (9-146 months). In regards to index level revision, 16 out of 401 (4%), 14 underwent posterior spinal fusion (87.5%). The mean improvement, compared to baseline level, was VAS back 24% (p< .05), VAS leg 33.6% (p< .05), ODI 33.3% (p=.0017), and RMDQ 42% (p=.0027). The average time for this intervention was 37.6 months (3-120 months). This compared with the general LTDR group that had a mean improvement, compared to baseline level of VAS back 69.8% (p< .0001), VAS leg 78% (p< .0001), ODI 73.6% (p< .0001) and RMDQ 78.9% (p< .0001). This study reiterates that statistically significant reduction in pain and improvement in function can be achieved with LTDR. The secondary surgical intervention rate overall was 8.2% (the index level rate was 4% and ASD 4.2%). 87.5% of the index level group were revised via PSF/decompression for facet arthropathy and neural compression. The average revision (37 months) suggests that there is an incidence of kinematic mismatch creating facet arthropathy; however, the outcomes following revision show statistical improvements from baseline morbidity. In the ASD group, the intervention was predominantly anterior for symptomatic DDD at an adjacent level. The back VAS score in this group had a statistically significant improvement whilst the leg VAS did not. This reflects that the aetiology of ASD is symptomatic DDD, whereas the indication for revision in the index level group was a combination of back and leg pain, with the leg pain being more significant. The ASD rate in this study is low and, on average, occurs at 77.8 months post op and suggests that the aetiology reflects genetic influences, not necessarily related to the mechanics of LTDR.