BACKGROUND: Posterior lumbar interbody fusion is the main repair method for senile degenerative lumbar spondylolisthesis. For elderly patients with osteoporosis, single screw rod system fixation regularly results in dislocation. The incidence of implant loosening is high, and therefore, effective internal fixation is not achieved. OBJECTIVE: This study will use the modified posterior lumbar interbody fusion procedure combined with bone cement augmentation for the treatment of senile degenerative lumbar spondylolisthesis so as to increase the stability of the vertebral body, make the fixator firm, and to maximize the recovery of postoperative motor function. METHODS: Totally 113 patients with senile degenerative lumbar spondylolisthesis, aged 65-70 years, irrespective of sex, will be recruited from the Department of Orthopedics of Affiliated Hospital of Qinghai University of China. The patients will be treated with modified posterior lumbar interbody fusion combined with bone cement augmentation. Follow-up will be performed at 3 and 12 months. The primary outcome measure is recovery of motor function as indicated by the postoperative Oswestry Disability Index score at 12 months. The secondary outcome measures are the change in the rate of excellent and good Oswestry Disability Index scores (comparing preoperative scores with the 4-month postoperative scores), Visual Analogue Scale scores, intervertebral space height, foraminal height, the preoperative and 4 and 14 months postoperative slip distance and slip angle, incidence of adverse reactions, success rate of vertebral fusion, and incidence of secondary slip 4 and 14 months postoperatively. This trial has been approved by the Medical Ethics Committee of Affiliated Hospital of Qinghai University of China (approval number: QHY023G). The study protocol will be proformed in accordance with the Declaration of Helsinki, formulated by the World Medical Association. Written informed consent will be obtained from all participants. This trial was designed in October 2017. The recruitment of subjects and data collection will begin in June 2018. The recruitment will be finished in December 2018. Outcome measures will be analyzed in January 2020. This trial will be completed in February 2020. The results of the trial will be reported in a scientific conference or disseminated in a peer-reviewed journal. This trial had been registered in the Chinese Clinical Trial Registry (registration number: ChiCTR1800015335). Protocol version (1.0). DISCUSSION: This trial aims to observe the efficacy of modified posterior lumbar interbody fusion combined with bone cement augmentation in the treatment of senile degenerative lumbar spondylolisthesis and to validate whether the procedure is safe and reliable. [ABSTRACT FROM AUTHOR]