Clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease: a retrospective study

Abstract

Background: Non-fusion fixation is an effective way to treat lumbar degeneration. The present study evaluated the clinical effect analysis and radiographic outcomes of Isobar TTL system for two-segmental lumbar degenerative disease. Method: Forty-one patients with two-segmental lumbar degenerative disease who underwent surgical treatment by Isobar TTL dynamic stabilization system (n=20) and rigid system (n=21) from January 2013 to June 2017. The mean follow-up period was 23.6 (range 15–37) months. Clinical outcomes were evaluated by oswestry dysfunction index (ODI), visual analogue score (VAS) and modified Macnab. Radiographic evaluations included the height of intervertebral space and range of motion (ROM) of the operative segments and proximal adjacent segment. The intervertebral disc signal change was classified by the modified Pfirrmann grade and University of California at Los Angeles (UCLA) system. Results: The clinical outcomes including the ODI and VAS were significantly improved in two groups after operation, but the difference between two groups was not significant. In addition, the clinical efficacy of modified Macnab in two groups was similar too. Radiologic outcomes include height of intervertebral space, lumbar mobility and intervertebral disc signal. The height of intervertebral space of upper adjacent segments of L2/3 in the rigid group were significantly lower than those in the Isobar TTL group at the last follow-up. Furthermore, the number of fixed segment ROM of L3/4 in Isobar TTL group was significantly lower than pre-operation, suggesting that fixed segment ROMs in Isobar TTL group were limited. And, the ROM of upper adjacent segments of L2/3 in the last follow-up of rigid group increased significantly, while the ROM of L2/3 in Isobar TTL group haven’t changed after operation. At last, the incidence of adjacent segment degeneration was significantly greater in the rigid group than the Isobar TTL group according to modified Pfirrmann grading system and the UCLA system. Conclusion: Isobar TTL system could get a good clinical effect for treatment of two-segmental lumbar degenerative disease. Compared with rigid fixation, Isobar TTL system can get better radiographic outcomes and maintain the mobility of the stabilized segments with less influence on the proximal adjacent segment.