title: Adjacent segment degeneration after single-segment PLIF: the risk factor for degeneration and its impact on clinical outcomes.
abstract: OBJECTIVE
  To investigate: (1) the risk factors for radiologic cranial adjacent segment degeneration (ASD) after single-segment PLIF at the same level, and (2) the impact of the ASD on the clinical outcomes.
  
  
  METHODS
  From October 2004 to May 2009, 109 patients who underwent PLIF for degenerative instability at L4/5 and have more than 2 years follow-up were studied retrospectively. We measured the preoperative bone mineral density (BMD), lumbar lordosis, the lumbosacral joint angle, the lumbar inclination, the height and the dynamic angulation of the intervertebral space at the fused segments and the upper adjacent segment, the sliding displacement between L3 and L4. Clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) score and the Oswestry Disability Index (ODI). Patients were divided into two groups according to the progression of L3-L4 degeneration: Group A without progression of L3-L4 degeneration, Group B with progression of L3-L4 degeneration. Clinical outcomes and radiologic measurement index between the two groups were compared, and the risk factors for progression of L3-L4 degeneration were analyzed. The correlation between clinical outcomes and progression of L3-L4 degeneration were also investigated.
  
  
  RESULTS
  There were 11 patients (22%) classified into Group A. No significant difference was found between the two groups in terms of the lordosis angle at L1 and S1, the laminar inclination at L3, the pre-existing L3-L4 disk degeneration, the lordosis angle of L4-L5, the lumbosacral joint angle and preoperative BMD (P > 0.05). Significant differences were found between the two groups in age. No significant difference was found between the two groups in the ODI and the JOA score at the final follow-up (P > 0.05).
  
  
  CONCLUSIONS
  Radiologic degeneration of the cranial adjacent segment after single-segment PLIF did not significantly correlate with clinical outcomes. Age was a risk factor for radiologic degeneration, however, there was no significant correlation between degeneration and preoperative radiologic factors and bone mineral density (BMD).
authors: Department of Spinal Surgery, First Affiliated Hospital of Sun Yat-Sen University, NO. 183, Huangpu East Road, Guangzhou, Guangdong, China. berlinch2007@yahoo.com.cn
authors: Bai-Ling
authors: BL
authors: Chen
authors: Fu-Xin
authors: FX
authors: Wei
authors: Kazumasa
authors: K
authors: Ueyama
authors: Deng-Hui
authors: DH
authors: Xie
authors: Akio
authors: A
authors: Sannohe
authors: Shao-Yu
authors: SY
authors: Liu
mesh_terms: D000328:Adult; D000368:Aged; D015519:Bone Density; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D013122:Spinal Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects*; D016896:Treatment Outcome