Risk factors influencing cage retropulsion following lumbar interbody fusion in treating degenerative lumbar diseases: A comprehensive systematic review and meta-analysis

Background: Degenerative lumbar diseases (DLDs) often have significant impacts on patients' quality of life, particularly when cage retropulsion (CR) occurs following lumbar interbody fusion (LIF). In this study, we conducted a meta-analysis to assess the risk factors associated with CR after LIF.

Methods: We retrieved literatures analyzing the risk factors associated with CR following LIF from seven databases. We examined baseline characteristics, diagnosis, comorbidity, fusion level, surgical status, imaging assessment, and cage status to identify potential risk factors.

Results: Sixteen studies involving 8059 patients (251 in the CR group and 7808 in the Non-CR group) were included in the final analysis. The incidence of CR was 3.15 %. Results revealed that older age (mean difference [MD]: 2.35 [0.44, 4.26]), more fusion levels (MD: 0.64 [0.03, 1.25]), comorbidity-osteoarthritis (risk ratio [RR]: 2.02 [1.37, 2.98]), comorbidity-heart disease (RR: 2.95 [1.21, 7.21]), comorbidity-existing vertebral fracture (RR: 5.12 [2.52, 10.39]), endplate injury (RR: 2.93 [1.71, 5.02]), screw loosening (RR: 6.03 [1.90, 19.12]), pear-shaped disc (PSD, RR: 3.14 [1.46, 6.74]), greater mean disc height (MDH, MD: 1.65 [0.58, 2.72]), larger cobb angle (MD: 0.68 [0.10, 1.27] degrees), larger cage height (MD: 0.31 [0.01, 0.61]), and cage type-carbon (RR: 1.62 [1.16, 2.27]) were identified as risk factors for CR following LIF. The incidence of CR decreased with an increase in fusion level.

Conclusions: Older age, endplate injury, PSD, and nine other factors are identified as risk factors for CR following LIF. Patients with these factors should undergo close monitoring during follow-up to prevent serious complications, such as significant cage displacement.