title: Adjacent segment degeneration after lumbar dynamic stabilization using pedicle screws and a nitinol spring rod system with 2-year minimum follow-up.
abstract: METHODS
  Prospective study evaluating the adjacent segment degeneration after lumbar dynamic stabilization using pedicle screws and a Nitinol spring rod system.
  
  
  OBJECTIVE
  To assess the changes of the adjacent and implantation segments after lumbar dynamic stabilization surgery using magnetic resonance imaging (MRI).
  
  
  BACKGROUND
  Lumbar fusion operations can accelerate the degeneration of adjacent levels. Recently, motion preservation surgery has been attempted for the treatment of lumbar degenerative diseases to prevent degeneration of adjacent levels. However, there is a controversy over whether lumbar dynamic stabilization accelerates degeneration of adjacent levels.
  
  
  METHODS
  We performed the dynamic stabilization procedure in patients with grade 1 degenerative lumbar spondylolisthesis, lumbar spondylotic stenosis with segmental instability, or a herniated lumbar disc with segmental instability. Postoperative MRI scans were taken for >2 years in all enrolled 25 patients. We compared the findings regarding disc degeneration in the cranial, implantation, and caudal segments between the preoperative period and 2-year-plus postoperative period using T2-weighted sagittal MR images. In addition, we investigated the progression of the central and foraminal stenosis of the adjacent cranial and caudal levels.
  
  
  RESULTS
  Three of the 25 cranial adjacent discs (12.0%) and 4 of the 25 (16%) caudal adjacent discs demonstrated progression of degeneration after dynamic stabilization. One of the 13 discs in the implantation segment demonstrated progression of degeneration, and 2 of the 13 discs in the implantation segment showed improvement of their disc degeneration (disc rehydration). A total of 5 (10.0%) of the 50 segments (3 cranial and 2 caudal adjacent) showed increased spinal stenosis postoperatively. Among the 5 cases, 3 patients had symptomatic adjacent stenosis.
  
  
  CONCLUSIONS
  According to our results, lumbar dynamic stabilization using pedicle screws and a Nitinol spring rod system may not prevent adjacent level degeneration completely.
authors.affiliation: Department of Neurosurgery, Spine Center, Chuncheon Sacred Heart Hospital, Hallym University Medical Center, Hallym University College of Medicine, Korea.
authors.forename: Dong Hwa
authors.initials: DH
authors.lastname: Heo
authors.forename: Yong Jun
authors.initials: YJ
authors.lastname: Cho
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Cho
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Choi
authors.forename: Suk Hyung
authors.initials: SH
authors.lastname: Kang
mesh_terms: D000368:Aged; D000497:Alloys; D001863:Bone Screws; D019299:Decompression, Surgical; D018450:Disease Progression; D017586:Diskectomy; D005260:Female; D005500:Follow-Up Studies; D059526:Foraminotomy; D006801:Humans; D016268:Internal Fixators; D055959:Intervertebral Disc Degeneration / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D007593:Joint Instability / Q000601:surgery*; D007796:Laminectomy; D008159:Lumbar Vertebrae / Q000473:pathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D011184:Postoperative Period; D011446:Prospective Studies; D013123:Spinal Fusion / Q000009:adverse effects*; D013130:Spinal Stenosis / Q000473:pathology / Q000601:surgery*; D013168:Spondylolisthesis / Q000601:surgery*; D055009:Spondylosis / Q000601:surgery*
chemical_list: D000497:Alloys; C013616:nitinol