title: Contralateral reherniation after open lumbar microdiscectomy : a comparison with ipsilateral reherniation.
abstract: OBJECTIVE
  To evaluate the risk factors that may be responsible for the development of contralateral reherniations from ipsilateral ones after open lumbar microdiscectomy (OLM), and to compare surgical outcomes of revision OLM for contralateral reherniations with those for ipsilateral ones.
  
  
  METHODS
  Seventeen patients who underwent revision OLM for contralateral reherniation were enrolled into Group I, and 35 patients who underwent revision OLM for ipsilateral reherniation were enrolled into Group II. Using medical charts and imaging study results, the differences in the clinical and radiological factors were evaluated between the two groups. Clinical outcomes of each group were compared between the two groups.
  
  
  RESULTS
  Significant differences were found in the interval to reherniation from initial surgery (33 months for Group I and 18.6 months for Group II, p=0.009), as well as in the incidences of both protruded disc (35.3% for Group I and 8.6% for Group II, p=0.045) and mild disc degeneration (29.4% for Group I and 5.7% for Group II, p=0.031) at initial surgery. On binary multi-logistic regression analysis, significant differences were found in the interval to reherniation (p=0.027, Odds ratio=1.051) and incidence of mild disc degeneration (p=0.025, Odds ratio=12.03) between the two groups. There were no significant differences in the improvement of clinical outcomes after revision OLM between the two groups.
  
  
  CONCLUSIONS
  The interval to reherniation from initial surgery and the grade of disc degeneration at initial surgery were key factors that distinguished the development of contralateral reherniations from ipsilateral ones. Surgical outcomes of revision OLM were similar in both groups.
authors.affiliation: Department of Neurosurgery, Wooridul Spine Hospital, Seoul, Korea.
authors.forename: Kyeong Bo
authors.initials: KB
authors.lastname: Choi
authors.forename: Dong Yeob
authors.initials: DY
authors.lastname: Lee
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee