'Rebound Phenomenon' - a Cause of Early Cage Back-out in Transforaminal Lumbar Interbody Fusion Surgery: Insights from Case Series of 1545 Patients.

Study Design: Retrospective case-control study. Purpose: To assess the various possible causative factors of cage retropulsion and the management strategies to be utilized for cage back-out following open transforaminal lumbar interbody fusion(TLIF) surgery in degenerative lumbar spine pathology. Overview of Literature: Factors like elderly age, low body mass index, placement of undersized cages, bony endplate damage and improper cage placement are several risk factors for cage back-out following TLIF surgeries. Despite this, lacunae remains regarding the other factors contributing to cage migration. Methods: We performed a retrospective analysis of prospectively collected data from patients who underwent TLIF surgery for degenerative disc disease with stenosis or instability between 2011 and 2024. We identified patients who presented with cage back-out and analysed the characteristics of these patients to elucidate the possible causes of cage retropulsion. Results: Among 1545 patients who underwent TLIF surgery, 16 patients (1%) experienced cage back-out. This included 11 single-level fusions and five two-level fusions, predominantly at the L4-L5 level. Eight patients had early cage back-out within 3 months, while four had back-out after 1 year. Eleven cases involved posterior migration, one case each for postero-lateral and anterolateral migration, respectively. Twelve patients were managed conservatively, whereas four required revision surgery. We identified inadequate disc space preparation and "rebound phenomenon" as significant risk factors for early back-out, necessitating revision for optimal outcomes. Late back-out may benefit from conservative management due to the potential for partial union, with surgery reserved for refractory cases or those with neurological symptoms. Conclusion: Cage migration is a recognized and severe complication in TLIF surgery, potentially impacting patient outcomes. Our study found that intraoperative rebound phenomenon and inadequate discectomy or endplate preparation were significant risk factors for cage migration. Surgeons should consider these factors and patient-specific variables to optimize clinical outcomes in TLIF patients. Supplementary Information: The online version contains supplementary material available at 10.1007/s43465-025-01493-4.