title: Minimally invasive multilevel percutaneous pedicle screw fixation for lumbar spinal diseases.
abstract: OBJECTIVE
  There are rare reports on the result of multilevel (≥3 levels) percutaneous pedicle screw fixation (PPF). The purpose of this study was to report the clinical experiences for multilevel PPF of the lumbar spine.
  
  
  METHODS
  A total of 17 patients of lumbar spinal disease (7 degenerative diseases, 6 infectious diseases, and 4 traumatic instabilities) underwent neural decompression and multilevel PPF. There were 8 men and 9 women with a mean age of 61.4 years (range, 25-84) and a mean follow-up period of 23.2 months (range, 13-48). The average PPF level was 3.7. A retrospective review of clinical, radiological, and surgical data was conducted.
  
  
  RESULTS
  "Excellent" or "good" clinical results were obtained in 15 patients (88.2%) according to the Odom's criteria. The average improvement of visual analogue scale was 5.2 points (from 9.3 to 4.1), and the average improvement of Oswestry Disability Index was 36.2 (from 71.2 to 35.0) at the last visit (p<0.05). The fusion rate was 88.2%, but, screw loosening was occurred in 2 patients, and adjacent segmental degeneration was occurred in 2 patients. There was no statistical significance in the change of total lumbar lordotic angle. The average operation time was 5.9 hours, with an estimated blood loss of 550 ml and bed rest duration of 2.0 days.
  
  
  CONCLUSIONS
  Although the current study examined a small sample with relatively short term follow up periods, our study results demonstrate that multilevel PPF is feasible and safe for selective lumbar spinal diseases.
authors.affiliation: Department of Neurosurgery, Gachon University, Gil Hospital, Incheon, Republic of Korea.
authors.forename: Seong
authors.initials: S
authors.lastname: Son
authors.affiliation: Department of Neurosurgery, Gachon University, Gil Hospital, Incheon, Republic of Korea.
authors.forename: Sang Gu
authors.initials: SG
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Gachon University, Gil Hospital, Incheon, Republic of Korea.
authors.forename: Chan Woo
authors.initials: CW
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Gachon University, Gil Hospital, Incheon, Republic of Korea.
authors.forename: Woo Kyung
authors.initials: WK
authors.lastname: Kim
keywords: Bone screw; Lumbar vertebrae; Spinal fusion