title: The clinical characteristics and risk factors for the adjacent segment degeneration in instrumented lumbar fusion.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  The aims of this study were to evaluate the clinical significance of, characteristics of, and risk factors for adjacent segment degeneration (ASD) in patients who have undergone instrumented lumbar fusion.
  
  
  BACKGROUND
  ASD has been considered a potential long-term complication of spinal arthrodesis. However, the exact mechanisms and risk factors related to ASD are not completely understood.
  
  
  METHODS
  A total of 48 patients who underwent instrumented lumbar fusion at L4-5 and had minimal ASD preoperatively were evaluated. The patients were divided into 2 groups at follow-up according to the development of ASD defined by radiologic criteria. Through review of their medical records and the radiologic files, the following variables were evaluated in the 2 groups: basic demographic data, body weight, body height, body mass index, bone mineral density, types of surgical approaches, preoperative and postoperative segmental and lumbar lordosis, and clinical outcomes.
  
  
  RESULTS
  ASD was found in 30 (62.5%) patients. The variables that showed statistical intergroup differences were the mean age at surgery, the mean difference in the degree of preoperative from postoperative lumbar lordosis, and the proportion of patients who underwent anterior lumbar interbody fusion. However, there were no statistically significant intergroup differences in the Japanese Orthopedic Association score at 1-year postoperatively or at the final follow-up, or in the recovery rate, success rate, and complication rate.
  
  
  CONCLUSIONS
  Radiographic ASD is relatively common long-term finding associated with instrumented lumbar fusion. However, radiographic evidence of ASD does not necessarily correlate with a poor outcome. Our results suggest that advanced age, anterior lumbar interbody fusion, and the restoration of the preoperative standing lumbar lordosis may have a protective effect against the development of ASD.
authors.affiliation: Department of Neurosurgery, Gimpo Airport Wooridul Spine Hospital, Seoul, Korea.
authors.forename: Jun-Hong
authors.initials: JH
authors.lastname: Min
authors.forename: Jee-Soo
authors.initials: JS
authors.lastname: Jang
authors.forename: Byung joo
authors.initials: Bj
authors.lastname: Jung
authors.forename: Ho Yeon
authors.initials: HY
authors.lastname: Lee
authors.forename: Won-Chul
authors.initials: WC
authors.lastname: Choi
authors.forename: Chan Shik
authors.initials: CS
authors.lastname: Shim
authors.forename: Gun
authors.initials: G
authors.lastname: Choi
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D015519:Bone Density; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016268:Internal Fixators / Q000009:adverse effects*; D007403:Intervertebral Disc / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D007405:Intervertebral Disc Displacement / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery*; D008141:Lordosis / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology; D010024:Osteoporosis / Q000503:physiopathology; D018579:Patient Selection; D011183:Postoperative Complications / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation; D016896:Treatment Outcome