title: Adjacent segment disease after interbody fusion and pedicle screw fixations for isolated L4-L5 spondylolisthesis: a minimum five-year follow-up.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  The purpose of this study are (1) to analyze prevalence of clinical and radiologic adjacent segment diseases (ASD), (2) to find precipitating factor of clinical ASD in each isthmic and degenerative spondylolisthesis groups, and (3) to compare clinical and radiologic change in isthmic and degenerative spondylolisthesis.
  
  
  BACKGROUND
  There is no clinical report regarding the use of magnetic resonance imaging (MRI) for evaluating ASD in patient who underwent 360° fusion with single-level spondylolisthesis with healthy adjacent segment.
  
  
  METHODS
  A total of 69 patients who underwent instrumented single-level interbody fusion at the L4-L5 level and showed no definitive degenerated disc in adjacent segments on preoperative MRI and plain radiographs were evaluated at more than 5 years after surgery. The patients were divided into 2 groups: group I was isthmic spondylolisthesis patients and group II was degenerative spondylolisthesis patients. The radiologic ASD was diagnosed by plain radiographs and MRI. Clinical ASD is defined as symptomatic spinal stenosis, intractable back pain, and subsequent sagittal or coronal imbalance with accompanying radiographic changes. Symptomatic spinal stenosis was defined as stenosis diagnosed by MRI and combined with neurologic claudication.
  
  
  RESULTS
  The prevalence of radiologic ASD on group I and group II was 72.7% and 84.0%, respectively. About 7 (15.9%) patients showed clinical ASD in group I and 6 (24.0%) patients showed clinical ASD in group II. MRI showed significant reliability for diagnosis of clinical ASD. Compared with patients with asymptomatic ASD, patients with clinical ASD showed significantly less postoperative lordotic angle at the L4-L5 level (i.e., less than 20°) in both groups.
  
  
  CONCLUSIONS
  Maintaining postoperative L4-L5 segmental lordotic angle at about 20° or more is important for prevention of clinical ASD in single-level 360° fusion operation. MRI is reliable method for diagnosing clinical ASD.
authors.affiliation: From the Departments of *Orthopedic Surgery, Hyundae General Hospital, Namyangju, Korea; †Department of Neurosurgery, ‡Radiology, and §Orthopedic Surgery, Wooridul Spine Hospital, Seoul, Korea.
authors.forename: Kyeong Hwan
authors.initials: KH
authors.lastname: Kim
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Chan Shik
authors.initials: CS
authors.lastname: Shim
authors.forename: Dong Yeob
authors.initials: DY
authors.lastname: Lee
authors.forename: Hyeon Seon
authors.initials: HS
authors.lastname: Park
authors.forename: Woei-Jack
authors.initials: WJ
authors.lastname: Pan
authors.forename: Ho-Yeon
authors.initials: HY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D065289:Pedicle Screws; D011859:Radiography; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome