1. 2018;21;337-350Prevalence of Recurrent Herniation Following Percutaneous Endoscopic Lumbar Discectomy: A Meta-Analysis
   Systematic Review
   Huiren Tao, MD, Chaoshuai Feng, MD, Chungguang Duan, PhD, Weizhou Yang, MD, Heng Du, MD, and Si Yin, MD.

BACKGROUND: Percutaneous endoscopic lumbar discectomy (PELD) is a minimally invasive surgery for the treatment of lumbar disc herniation (LDH) with a smaller incision, decreased damage to soft tissues, faster recovery, and fewer postoperative complications. However, the exactly epidemiological prevalence of recurrent herniation after PELD remains unclear.

OBJECTIVES: To investigate the epidemiological prevalence of recurrent herniation in patients following PELD and to analyze the potentially related risk factors.

STUDY DESIGN: Meta-analysis and systematic review of prospective and retrospective studies.

METHODS: We conducted a comprehensive search in MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials that mentioned the incidence of recurrent herniation after PELD. The overall prevalence estimate was calculated by an appropriate meta-analysis. Subgroup analysis, sensitivity analysis, and publication bias assessment were also performed in our study, respectively.

RESULTS: Our results showed the overall prevalence of recurrent herniation after PELD was 3.6% (95% CI 3.0-4.3%). The prevalence estimates after percutaneous endoscopic interlaminar discectomy (PEID) and percutaneous endoscopic transforaminal discectomy (PETD) were 4.2% and 3.4%, respectively. Individuals with older age (>/= 50 years) and higher BMI (>/= 25) had increased recurrence rates after PELD than those with younger age (4.3% vs. 2.7%) and normal body mass index (BMI) (4.8% vs. 1.5%). The prevalence was significantly higher at upper discs (5.4%) than that at L4-5 (2.7%) and L5-S1 (3.1%) level. The incidence of recurrent herniation at lateral disc was 4.7%, and the recurrence rate of migrated herniation was 3.8%. In most cases, the recurrent herniation occurred within 6 months postoperatively (accounting for 61.7%).

LIMITATIONS: A majority of the included articles were relatively low quality retrospective studies with significant heterogeneity among them. Furthermore, owing to the paucity of data focused on recurrence, many potentially predictive factors related to subgroup analyses could not be conducted, which might have influenced the accuracy and comprehensiveness of our meta-analysis.

CONCLUSIONS: PELD is associated with a certain rate of recurrence (3.6%), which usually occurred within 6 months postoperatively. Older age (>/= 50 years), obesity (BMI >/= 25), upper lumbar disc and central disc herniation might be independent risk factors for recurrence after PELD; however, different surgical approaches (PETD or PEID), lateral discs, migrated discs and foraminoplasty did not affect the incidence. These factors could be useful in preoperative evaluation, appropriate patient selection and informed consent before PELD.

KEY WORDS: Percutaneous endoscopic lumbar discectomy, prevalence, recurrent herniation, meta-analysis