Characteristics of the included trials.

RCT: randomized controlled trial. Uni vs Bi: the unilateral fixation group vs the bilateral fixation group. MIS-TLIF: minimally invasive surgery for transforaminal lumbar interbody fusion. In this study, MIS-TLIF refers to those assisted by a tubular retractor system. LSS: lumbar spinal stenosis. LS: lumbar spondylolisthesis. LDH: lumbar disc herniation. RLDH: recurrent lumbar disc herniation. SDDD: symptomatic degenerative disc disease. DLBP: discogenic low back pain. FBS: failed back surgery.