title: MRI analysis of the ISOBAR TTL internal fixation system for the dynamic fixation of intervertebral discs: a comparison with rigid internal fixation.
abstract: OBJECTIVE
  Using magnetic resonance imaging (MRI), we analyzed the efficacy of the posterior approach lumbar ISOBAR TTL internal fixation system for the dynamic fixation of intervertebral discs, with particular emphasis on its effects on degenerative intervertebral disc disease.
  
  
  METHODS
  We retrospectively compared the MRIs of 54 patients who had previously undergone either rigid internal fixation of the lumbar spine or ISOBAR TTL dynamic fixation for the treatment of lumbar spondylolisthesis. All patients had received preoperative and 6-, 12-, and 24-month postoperative MRI scans of the lumbar spine with acquisition of both routine and diffusion-weighted images (DWI). The upper-segment discs of the fusion were subjected to Pfirrmann grading, and the lumbar intervertebral discs in the DWI sagittal plane were manually drawn; the apparent diffusion coefficient (ADC) value was measured.
  
  
  RESULTS
  ADC values in the ISOBAR TTL dynamic fixation group measured at the 6-, 12-, and 24-month postoperative MRI studies were increased compared to the preoperative ADC values. The ADC values in the ISOBAR TTL dynamic fixation group at 24 months postoperatively were significantly different from the preoperative values (P < 0.05). At 24 months, the postoperative ADC values were significantly different between the rigid fixation group and the ISOBAR TTL dynamic fixation group (P < 0.05).
  
  
  CONCLUSIONS
  MRI imaging findings indicated that the posterior approach lumbar ISOBAR TTL internal fixation system can prevent or delay the degeneration of intervertebral discs.
authors.forename: Jun
authors.initials: J
authors.lastname: Gao
authors.forename: Weihua
authors.initials: W
authors.lastname: Zhao
authors.affiliation: Department of Orthopedics, Changzhou Traditional Chinese Medicine Hospital, Nanjing Traditional Chinese Medical University, Changzhou 213003, China. XiZhangdoc@126.com.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Luming
authors.initials: L
authors.lastname: Nong
authors.forename: Dong
authors.initials: D
authors.lastname: Zhou
authors.forename: Zhengxiang
authors.initials: Z
authors.lastname: Lv
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Sheng
authors.forename: Xingbiao
authors.initials: X
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016268:Internal Fixators / Q000592:standards*; D007403:Intervertebral Disc / Q000000981:diagnostic imaging* / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000601:surgery