Risk factors for cage retropulsion after transforaminal lumbar interbody fusion in older patients

BACKGROUND: To investigate the incidence of cage retropulsion (CR) following transforaminal lumbar interbody fusion (TLIF) and the associated risk factors in older patients with lumbar disorders. METHODS: Between January 2015 and December 2017, 1,880 older patients (aged >60 years) who underwent open TLIF were preliminarily enrolled in this retrospective study. The patients’ medical records were reviewed, and the risk factors potentially associated with CR were analyzed. RESULTS: A total of 1,662 patients (692 males and 970 females, with an average age of 68.7±5.2 years) who met the eligibility criteria were finally enrolled in this study. Following TLIF, 29 older patients (1.74%) developed CR including 12 patients with spinal stenosis, 7 patients with degenerative spondylolisthesis, 5 patients had degenerative disc diseases, 3 patients had surgical history, and 2 patients suffered isthmic spondylolisthesis. Of the 29 patients, 21 patients suffered lower back pain and/or sciatica (72.4%), while 8 patients were asymptomatic (27.6%). In multivariate analysis, screw loosening [odds ratio (OR) =7.315; 95% confidence interval (CI): 3.4–15.7] and endplate injury (OR =4.947; 95% CI: 2.3–10.6) were found to be independently associated with CR in older patients after TLIF. CONCLUSIONS: The incidence of CR following TLIF in older patients is 1.74%. Screw loosening and endplate injury are risk factors for CR in older patients with TLIF.