title: The surgical outcome and the surgical strategy of percutaneous endoscopic discectomy for recurrent disk herniation.
abstract: METHODS
  A retrospective analysis.
  
  
  OBJECTIVE
  To present the surgical outcome of percutaneous endoscopic discectomy (PED) for recurrent herniated intervertebral disk disease (HIVD) and to suggest a surgical strategy.
  
  
  BACKGROUND
  Revision discectomy is technically demanding because of the scar tissue, unclear anatomic planes, and retraumatization to the posterior structures. Although open microdiscectomy is a standard method, endoscopic techniques have emerged as a surgical alternative with comparable results. PED was performed with either the transforaminal (PETD) or the interlaminar approach (PEID). Previous reports have shown the surgical outcomes of PETD or PEID for recurrent HIVD, but the application of each approach was not addressed clearly.
  
  
  METHODS
  Consecutive 26 patients (M:F=16:10, mean age 53.1±12.4 y), who underwent PED for recurrent HIVD, were enrolled. The previous operation was an open discectomy in 22, a PETD in 2, and a PEID in 2 patients. PETD was considered preferentially, if it was feasible (n=11), because of the scar tissue formed by the previous operation. PEID was chosen (n=15) because of a high iliac crest (8), high canal compromise (3), high-grade inferior migration (2), and narrow neural foramen (2). All patients were followed up for 19.3±11.3 months.
  
  
  RESULTS
  In all patients, the recurrent disk material was removed successfully, and conversion to an open surgery was not necessary. Postoperative magnetic resonance imaging revealed that the ruptured disk was removed successfully in all cases. A favorable outcome (excellent or good outcome by MacNab's criteria) was achieved in 21 patients (81%). Re-recurrence occurred in 2 patients at 6 and 12 months postoperatively. Risk factors for an unfavorable outcome were not found in the present study (P>0.05).
  
  
  CONCLUSIONS
  The relevant utilization of updated surgical techniques may be helpful in overcoming the difficulty of revision surgery.
authors.affiliation: *Department of Neurosurgery, Seoul National University Hospital †Department of Neurosurgery, Seoul National University College of Medicine ‡Neuroscience Research Institute, Seoul National University Medical Research Center §Clinical Research Institute, Seoul National University Hospital ∥Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul ¶Department of Neurosurgery, Inje University Haeundae Paik Hospital, Pusan #Department of Neurosurgery, Seoul National University Boramae Hospital, Seoul, Republic of Korea.
authors.forename: Chi Heon
authors.initials: CH
authors.lastname: Kim
authors.forename: Chun Kee
authors.initials: CK
authors.lastname: Chung
authors.forename: Seil
authors.initials: S
authors.lastname: Sohn
authors.forename: Sungjoon
authors.initials: S
authors.lastname: Lee
authors.forename: Sung Bae
authors.initials: SB
authors.lastname: Park
mesh_terms: D000368:Aged; D017587:Diskectomy, Percutaneous / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007085:Ilium / Q000002:abnormalities; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008161:Lumbosacral Region / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D012008:Recurrence; D016896:Treatment Outcome