ObjectiveTo compare the complications and clinical scores of posterior lumbar intervertebral fusion (PLIF) in middle-aged and older patients of different ages, and to assess the risk of complications of PLIF in different ages, providing a reference for clinical treatment.MethodsThe clinical data of 1 136 patients, who were more than 55 years old and underwent PLIF between June 2013 and June 2016, were retrospectively analyzed. According to the age of patients undergoing surgery, they were divided into 3 groups as 55-64 years old, 65-74 years old, and ≥75 years old. The general characteristics, comorbidities, and surgical data of the three groups were compared, with comparison the morbidity of complications. According to the minimal clinical important difference (MCID), the improvement of patient’s pain visual analogue scale (VAS) score and the Oswestry disability index (ODI) score were compared. Univariate logistic regression analysis was used to analyze the difference of complications and the improvement of VAS and ODI scores. Multivariate logistic regression analysis was performed for the risk factors of complications.ResultsThere were significant differences in the number of surgical fusion segments and osteoporosis between groups (P<0.05); there was no significant difference in gender, body mass index, operation time, preoperative American Society of Anesthesiologists (ASA) classification, and comorbidities between groups (P>0.05). All patients were followed up 6-62 months with an average of 27.4 months. Among the results of postoperative complications, there were significant differences in the total incidence of intraoperative complications, systemic complications, minor complications, and the percentage of improvement of ODI score to MCID between groups (P<0.05); but there was no significant difference in the total incidence of complications at the end of long-term follow-up and the percentage of improvement of VAS score to MCID between groups (P>0.05). Univariate logistic regression analysis showed that after adjusting the confounding factors, there were significant differences in intraoperative complications and the percentage of improvement of ODI score to MCID between 55-64 and 65-74 years old groups (P<0.05); systemic complications, minor complications, complications at the end of long-term follow-up, and the percentage of improvement of ODI score to MCID in ≥75 years old group were significantly different from those in the other two groups (P<0.05). Multivariate logistic regression analysis showed that age was a risk factor for systemic complications, minor complications, and complications at the end of long-term follow-up. Except for age, long operation time was a risk factor for intraoperative complications, increased number of fusion segments was a risk factor for systemic complications, the number of comorbidities was a risk factor for minor complications, and osteoporosis was a risk factor for complications at the end of long-term follow-up.ConclusionThe risk of surgical complications is higher in the elderly patients (≥75 years) with lumbar degenerative diseases than in the middle-aged and older patients (<75 years), while the improvements of postoperative VAS and ODI scores were similar. Under the premise of fully assessing surgical indications, PLIF has a positive effect on improving the elderly patients’ quality of life.