title: Preoperative predictable factors for the occurrence of adjacent segment degeneration requiring second operation after spinal fusion at isolated L4-L5 level.
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  The purpose of this study was to clarify (1) the overall prevalence of radiologic and clinical adjacent segment disease (ASD), (2) the prevalence of radiologic ASD at cranial versus caudal adjacent segments, and (3) preoperative risk factors and preoperative radiologic features associated with radiologic disc degeneration of the cranial and caudal adjacent segments.
  
  
  METHODS
  A total of 154 patients who underwent posterior lumbar interbody fusion and screw-rod fixation at the L4-L5 level were retrospectively evaluated more than 2 years after surgery. We analyzed demographic factors and radiographic features. Special focus was preoperative radiographic features of patients who required additional surgery. These patients were studied to detect risk factors for clinical deterioration.
  
  
  RESULTS
  Of 154 patients, 103 (66.8%) showed radiologic degeneration at an adjacent segment after surgery-92 (59.7%) at the cranial adjacent segment and 61 (39.6%) at the caudal adjacent segment-and 10 patients (6.4%) required second operation because of radicular pain as well as severe back pain or spinal instability with back pain and neurologic deficits. Age, body mass index (BMI), and preexisting stenosis at the cranial adjacent segment were identified as important risk factors for clinical ASD requiring second operation.
  
  
  CONCLUSIONS
  Age, BMI, and preexisting stenosis at the cranial adjacent segment were the most important risk factors for clinical ASD requiring a second operation. Careful consideration is warranted when these risk factors are present.
authors: Department of Neurosurgery, Seoul Nanoori Hospital, Seoul, Republic of Korea.
authors: Tae-Koo
authors: TK
authors: Cho
authors: Department of Neurosurgery, Seoul Nanoori Hospital, Seoul, Republic of Korea.
authors: Jae-Hyeon
authors: JH
authors: Lim
authors: Department of Neurosurgery, Seoul Nanoori Hospital, Seoul, Republic of Korea.
authors: Sang-Hyuk
authors: SH
authors: Kim
authors: Department of Neurosurgery, Seoul Nanoori Hospital, Seoul, Republic of Korea.
authors: Woo-Tack
authors: WT
authors: Rhee
authors: Department of Neurosurgery, Seoul Nanoori Hospital, Seoul, Republic of Korea.
authors: Woo-Jae
authors: WJ
authors: Kim
authors: Department of Neurosurgery, Seoul Nanoori Hospital, Seoul, Republic of Korea.
authors: Seong-Il
authors: SI
authors: Ha
authors: Department of Neurosurgery, Seoul Nanoori Hospital, Seoul, Republic of Korea.
authors: Il-Tae
authors: IT
authors: Jang
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000601:surgery*; D017116:Low Back Pain / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D013123:Spinal Fusion; D016896:Treatment Outcome; D055815:Young Adult