Objective:Comparision in clinical effects of modified posterior approach and paraspinal musclespace approach for thoracolumbar surgery.Methods:69 patients(including 23 cases of thoracolumbar fracture treated with internal fixation patients and 46 cases of lumbar degenerative diseases treated with lumbar intervertebral fusion)who were admitted to our orthopedic department from October 2016 to December 2017.Two sides of the spines of the same patient were treated with different surgical approache during the operation.One side was modified posterior approach while the other side was subjected to the paraspinal musclespace approach,So a total of 138 cases of data.To evaluate the clinical effects of the two surgical approaches,the data of the two approaches were compared,including duration and the volume of blood loss of exposure,miss probability of pedicle puncture,post-operative drainage and VAS score of back pain,degree of soft tissue swelling around the incision,as well as the VAS score at the last follow-up,degree of adipose tissue deposition and the area of paravertebral muscles measured with MRI scan.Results:All patients were successfully operated and followed up for 10~18 months.For the two approaches,there was no significant difference in the exposure time,volume of blood loss during exposure,miss probability of pedicle puncture,VAS score of back pain,degree of soft tissue swelling around the incision,and the deposition of adipose tissue in the paravertebral muscles and the area of paravertebral muscles at the last follow-up(P>0.05).Only the volume of post-operative drainage in the modified posterior approach group was larger than that in the paraspinal musclespace approach group（P<0.05）.Conclusion:In the course of surgical treatment of thoracolumbar diseases,compared with paraspinal musclespace approach,the modified posterior approach can also achieve good surgical effects,both of them accord with the idea of minimally invasion,while the modified posterior approach have the advantages of wider indication,simple operation and shorter learning curve.