Is the size of the transforaminal lumbar cage a risk factor for cage subsidence? a retrospective cohort study

Cage subsidence is a common complication after transforaminal lumbar interbody fusion (TLIF), leading to gradual loss of disc height and foraminal restenosis. The effect of cage size on early postoperative cage subsidence has barely been investigated. This study aimed to determine if there is an association between the size of the transforaminal lumbar cage and cage subsidence. This retrospective cohort study included patients who underwent single-level open TLIF at our tertiary hospital from 2018 to 2023. We collected demographics, comorbidities, preoperative data, and follow-up notes for one year. We defined cage subsidence as loss of disc height by more than 2 mm at the fusion level one year after TLIF. Our study included 81 cases with an average age of 45.12 years, including 37 males (45.67%). At the 1-year follow-up, cage subsidence occurred in 17 patients (20.98%). We divided the included cases into two groups: group (A) Cage non-subsidence group (64 cases) and group (B) Cage subsidence group (17 cases). The two groups had no significant difference in preoperative clinical and radiological variables. There was no significant difference between the two groups regarding the cage size. The fusion rate was statistically higher in the non-subsidence group. We didn't find an association between the size of the lumbar cage and cage subsidence one year after TLIF, suggesting that cage size is not a risk factor for cage subsidence. Future studies should focus on integrating bone quality assessment and surgical technique refinement.