title: Predictors of Reoperation after Microdecompression in Lumbar Spinal Stenosis.
abstract: OBJECTIVE
  The risk factors of reoperation after microdecompression (MD) for lumbar spinal stenosis (LSS) are unclear. In this study, we presented the outcomes of MD for degenerative LSS and investigated the risk factors associated with reoperation.
  
  
  METHODS
  A retrospective review was conducted using the clinical records and radiographs of patients with LSS who underwent MD. For clinical evaluation, we used the Japanese Orthopedic Association (JOA) scoring system for low back pain, body mass index, and Charlson comorbidity index. For radiological evaluation, disc height, facet angle, and sagittal rotation angle were measured in operated segments. Also the Modic change and Pfirrmann grade for degeneration in the endplate and disc were scored.
  
  
  RESULTS
  Forty-three patients aged 69±9 years at index surgery were followed for 48±25 months. The average preoperative JOA score was 6.9±1.6 points. The score improved to 9.1±2.1 points at the latest follow-up (p<0.001). Seven patients (16.3%) underwent reoperation. Clinical and radiological factors except operation level and Pfirrmann grade showed a p-value >0.1. Patients with Pfirrmann grade IV and lower lumbar segment had a 29.1% rate of reoperation (p=0.001), whereas patients without these factors had a 0% rate of reoperation.
  
  
  CONCLUSIONS
  Moderate disk degeneration (Pfirrmann IV) in lower lumbar segments is a risk factor of disk herniation or foraminal stenosis requiring reoperation after MD in LSS.
authors.affiliation: Department of Neurosurgery, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Hee-Jong
authors.initials: HJ
authors.lastname: Hwang
authors.affiliation: Department of Neurosurgery, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Hyung-Ki
authors.initials: HK
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Gwang-Soo
authors.initials: GS
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: June-Young
authors.initials: JY
authors.lastname: Heo
authors.affiliation: Department of Neurosurgery, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Jae-Chil
authors.initials: JC
authors.lastname: Chang
keywords: Laminotomy; Lumbar spinal stenosis; Microdecompression; Outcome; Reoperation