Is it Necessary to Fuse to S1 for the Tilted L5 in the Treatment of Adult Degenerative Scoliosis?

Abstract

IntroductionThe extension of fusion to S1 compared with L5 and lower thoracic levels compared with L1 remains a highly controversial topic in the surgical treatment for adult degenerative scoliosis (ADS). As one of the criterion, if the tilted L5 were over 15°, the distal fusion level should extend to the sacrum. Could the tilted L5 be neutralized and the L5S1 be saved in the ADS correction? Material and MethodsPosterior one stage of facetectomy and interbody release combined with key segment anterior structural column support were used to treat 32 ADS cases. The thoroughly interbody release and fusion were done with both side in all involved segment, a little bigger inserter were inserted into L3,4 and L4,5 cave side to neutralize the tilted L5 maximally. The operating time and the blood loss were recorded. Mean follow-up was at least two years. All the subjects were analyzed by visual analog scale, Oswestry Disability Index (ODI), and SF-36 scores, SRS 22 before and after surgery and at follow-up. The scoliotic curve, thoracic kyphosis, lumbar lordosis, pelvic incidence (PI), pelvic tilt (PT), sacral slope, and C7 plumb line were measured. For the statistical analysis, multivariate multiple regression models were formulated, considering as significant (p < 0.05). ResultsThe average operating time were 150min and the mean blood loss were 520ml. A statistically significant clinical and radiological amelioration was noted after surgery and at final follow-up. The ODI, and SF-36 scores, SRS 22 improved. The Cobb angle of lumbar lordosis (7 plumb line) and spino-pelvic parameters (PI, PT, sacral slope) returned to the normal range after surgery. L5S1 radiological adjacent segment pathology (RASP) happened in two cases at the follow-up, one was extended to the S1,there is no symptom in another case. ConclusionThe tilted L5 can be neutralized and the L5S1 can be saved in the ADS correction. Even with a little movement, the saved L5S1 is important for a whole body to balance.