title: A Multi-center Clinical Study of Posterior Lumbar Interbody Fusion with the Expandable Stand-alone Cage (Tyche(R) Cage) for Degenerative Lumbar Spinal Disorders.
abstract: OBJECTIVE
  This multi-center clinical study was designed to determine the long-term results of patients who received a one-level posterior lumbar interbody fusion with expandable cage (Tyche(R) cage) for degenerative spinal diseases during the same period in each hospital.
  
  
  METHODS
  Fifty-seven patients with low back pain who had a one-level posterior lumbar interbody fusion using a newly designed expandable cage were enrolled in this study at five centers from June 2003 to December 2004 and followed up for 24 months. Pain improvement was checked with a Visual Analogue Scale (VAS) and their disability was evaluated with the Oswestry Disability Index. Radiographs were obtained before and after surgery. At the final follow-up, dynamic stability, quality of bone fusion, interveretebral disc height, and lumbar lordosis were assessed. In some cases, a lumbar computed tomography scan was also obtained.
  
  
  RESULTS
  The mean VAS score of back pain was improved from 6.44 points preoperatively to 0.44 at the final visit and the score of sciatica was reduced from 4.84 to 0.26. Also, the Oswestry Disability Index was improved from 32.62 points preoperatively to 18.25 at the final visit. The fusion rate was 92.5%. Intervertebral disc height, recorded as 9.94+/-2.69 mm before surgery was increased to 12.23+/-3.31 mm at postoperative 1 month and was stabilized at 11.43+/-2.23 mm on final visit. The segmental angle of lordosis was changed significantly from 3.54+/-3.70 degrees before surgery to 6.37+/-3.97 degrees by 24 months postoperative, and total lumbar lordosis was 20.37+/-11.30 degrees preoperatively and 24.71+/-11.70 degrees at 24 months postoperative.
  
  
  CONCLUSIONS
  There have been no special complications regarding the expandable cage during the follow-up period and the results of this study demonstrates a high fusion rate and clinical success.
authors.affiliation: Department of Neurosurgery , Inha University, College of Medicine, Incheon, Korea.
authors.forename: Jin Wook
authors.initials: JW
authors.lastname: Kim
authors.forename: Hyung Chun
authors.initials: HC
authors.lastname: Park
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Yoon
authors.forename: Seong Hoon
authors.initials: SH
authors.lastname: Oh
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Roh
authors.forename: Dae Cheol
authors.initials: DC
authors.lastname: Rim
authors.forename: Tae Sung
authors.initials: TS
authors.lastname: Kim