Author’s response to reviews Title: Clinical effect analysis and radiographic outcomes of Isobar TTL system for two- segmental lumbar degenerative disease: a retrospective study Authors:

Title: Clinical effect analysis and radiographic outcomes of Isobar TTL system for twosegmental lumbar degenerative disease: a retrospective study Authors: zhisheng ji (jizhisheng0521@163.com) Zhi-Sheng Ji (524007404@qq.com) Hua Yang (309888695@qq.com) Yu-Hao Yang (5463075072@qq.com) Shao-Jin Li (1120935776@qq.com) Jian-Xian Luo (545044058@qq.com) Guo-Wei Zhang (zgw24@qq.com) Hong-Sheng Lin (tlinhsh@jnu.edu.cn) Version: 1 Date: 13 Dec 2019 Author’s response to reviews: Chi heon Kim (Reviewer 1): I enjoyed to read the article titled as Clinical effect analysis and radiographic outcomes of Isobar TTL system for two segmental lumbar degenerative disease: a retrospective study. 1 The condition of patients should be same to be compared with each other. The radiological characteristics in both groups did not described in the table 1. How did the author decide surgical technique? Response: Thanks for the question. The patients were allocated into two groups by clinical symptoms, images result as well as patients’ willingness.