title: Recurrence of lumbar disc herniation after microendoscopic discectomy.
abstract: BACKGROUND
  Although microendoscopic discectomy (MED) is a minimally invasive surgical method for lumbar disc herniation (LDH), early postoperative recurrence may outweigh that advantage. The purpose of the present study was to retrospectively investigate the recurrence rate after MED for LDH and to determine the risk factors for recurrence in patients treated by a single surgeon.
  
  
  METHODS
  The study included 344 patients who underwent MED (213 males and 131 females; mean age, 39.3 years; age range, 11-82 years; mean follow-up, 3.6 years; follow-up range, 2.0-6.5 years). The clinical outcomes were evaluated using the Japanese Orthopedic Association Score for Low Back Pain (JOA score). Recurrence factors investigated by logistic regression analysis included age; sex; level, laterality, and classified type of LDH; occupation; sports activity; and learning curve of the surgeon.
  
  
  RESULTS
  LDH recurrence was observed in 37 patients (10.8%). It was observed at the same level in the ipsilateral side as the original LDH in 30 patients, in the contralateral side in three patients, and at a level adjacent to the original level in four patients. The mean time interval between MED and the recurrence was 16.6 months (range, 0.5-52 months). Twenty patients (54.1%) developed recurrence within 1 year after MED. Twenty-two patients (59.5%) were treated by revision surgery (MED in 20 patients and microdiscectomy in two patients), and 15 patients (40.5%) were treated conservatively. The mean JOA score of all the patients was 14.7 ± 3.5 before surgery and 26.5 ± 2.2 at the final follow-up, yielding an average recovery rate of 82.3 ± 15.7%. The recovery rate was 83.1 ± 14.8% in patients without recurrence and 75.7 ± 20.4% in patients with recurrence (p = 0.006). By logistic regression analysis, we identified migration of LDH as a significant factor related to recurrence. The patients with caudal migration of LDH had recurrence more frequently (19.0%) than those with rostral migration (12.5%) or without migration (10.2%) (p = 0.04; odds ratio, 2.0; 95% confidence interval, 1.0-3.8).
  
  
  CONCLUSIONS
  The recurrence rate and reoperation rate for LDH after MED were comparable to those of conventional discectomy. More than half of the cases of recurrence occurred at an early postoperative phase, and patients with caudally migrated LDH experienced recurrence significantly more often than those with rostrally migrated or nonmigrated LDH.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan. morio@sc.itc.keio.ac.jp
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kota
authors.initials: K
authors.lastname: Watanabe
authors.forename: Naobumi
authors.initials: N
authors.lastname: Hosogane
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsuji
authors.forename: Ken
authors.initials: K
authors.lastname: Ishii
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Chiba
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D017586:Diskectomy / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D059032:Learning Curve; D016015:Logistic Models; D017116:Low Back Pain / Q000601:surgery; D008159:Lumbar Vertebrae / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D009790:Occupations; D016017:Odds Ratio; D011182:Postoperative Care; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D013177:Sports; D016896:Treatment Outcome; D055815:Young Adult