Recurrent lumbar disc herniation: a systematic review and meta-analysis of risk factors, surgical timing, and outcomes of revision discectomy versus fusion.

Recurrent lumbar disc herniation (RLDH) occurs in up to 15% of patients after primary discectomy and poses challenges in surgical decision-making. Both revision discectomy (RD) and spinal fusion (SF) is utilized for reoperation, but the optimal treatment strategy remains a topic of debate. Additionally, data on the ideal timing for reoperation are limited. This study systematically reviewed risk factors for RLDH, evaluated surgical timing, and compared outcomes between RD and SF. A systematic review and meta-analysis were conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines (PROSPERO-registered). The PubMed, Scopus, and CINAHL databases were searched through December 2024. Eligible studies included patients undergoing revision surgery for RLDH, with data on surgical technique, timing, and outcomes. The risk of bias was assessed using ROB-2 for randomized controlled trials and the Newcastle-Ottawa Scale for observational studies. Random-effects meta-analysis was employed to pool 12-month improvements in Visual Analog Scale (VAS) back, VAS leg, and Oswestry Disability Index (ODI) scores. Additional outcomes included perioperative metrics, complications, recurrence rates, and patient satisfaction. Ten studies (including 939 patients) met the inclusion criteria. Reported risk factors included male sex, obesity, smoking, diabetes, and large annular defects. Surgical timing was inconsistently reported, which limited the pooled analysis. SF was associated with significantly greater intraoperative blood loss ((p=0.039), while operative time and hospitalization duration did not differ significantly. Recurrence rates did not significantly differ ((p=0.262), although open fusion showed a trend toward reduced recurrence. No significant differences in 12-month VAS or ODI scores were found between the groups (p>0.3). Minimally invasive techniques (minimally invasive transforaminal lumbar interbody fusion and percutaneous endoscopic lumbar discectomy) were associated with fewer complications and greater patient satisfaction. Both RD and SF are viable options for RLDH, each presenting distinct risk-benefit profiles. Importantly, this study highlights the inconsistent reporting of surgical timing as a persistent knowledge gap. Further high-quality research utilizing standardized definitions of recurrence and reoperation timeframes, with long-term follow-up, is necessary to clarify optimal surgical timing and guide treatment selection (PROSPERO CRD42024570791).