title: Long-Term Outcomes of Posterior Lumbar Interbody Fusion Using Stand-Alone Ray Threaded Cage for Degenerative Disk Disease: A 20-Year Follow-Up.
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  To analyze outcomes of posterior lumbar interbody fusion (PLIF) stand-alone cages.
  
  
  BACKGROUND
  PLIF for degenerative disk disease using stand-alone cages has lost its popularity owing to implant-related complications and pseudoarthrosis.
  
  
  METHODS
  We analyzed the records of 45 patients (18 women, 27 men), operated between January 1994 and December 1996, with a mean follow-up of 18 years 3 months (20 years 3 months-22 years 3 months). Clinical outcomes were measured using visual analogue score (VAS), Oswestry disability index (ODI), Odom's criteria, and radiological measurements of fusion rate, Cobb angle, and implant-related complications conducted at the preoperative evaluation, hospital discharge, 12-month follow-up, and final follow-up.
  
  
  RESULTS
  Preoperative mean VAS (back) was 6.9 and VAS (radicular) was 7.2, with mean improvements (p<0.05) of 2.9 and 3.1, respectively, at the final follow-up. Median preoperative ODI was 64.5, with a mean improvement to 34 and 42 at the 12-month and final follow-ups, respectively (p<0.05). Odom's criteria at the 12-month follow-up were excellent in 11.2% patients, good in 57.7%, fair in 31.1%, and poor in none of the patients; at the final follow-up, no patient was classified as excellent, 71.1% as good, 22.2% as fair, and 6.7% as poor (p<0.05). Pseudoarthrosis was observed in five patients (11.1%), of whom, three (6.6%) required re-operation. Preoperative disk height was 9.23 mm, which increased to 13.33 mm in the immediate postoperative evaluation and was maintained at 10.0 mm at the final follow-up (p<0.05). The preoperative mean L1-S1 Cobb angle was 34.7°, which changed to 44.7° in the immediate postoperative evaluation and dropped to 39.7° at the final follow-up (p<0.005).
  
  
  CONCLUSIONS
  PLIF stand-alone cages were associated with good clinical outcomes. Although the fusion rate was excellent, maintenance of disk heights and a lordotic alignment were not achieved in the long term.
authors.affiliation: Division of Neurosurgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Saleh S
authors.initials: SS
authors.lastname: Baeesa
authors.affiliation: Spine Unit, Valladolid University Hospital, Royal Academy of Medicine and Surgery, Valladolid, Spain.
authors.forename: Belen G
authors.initials: BG
authors.lastname: Medrano
authors.affiliation: Spine Unit, Valladolid University Hospital, Royal Academy of Medicine and Surgery, Valladolid, Spain.
authors.forename: David C
authors.initials: DC
authors.lastname: Noriega
keywords: Degenerative intervertebral disks; Spinal fusion; Stand-alone implants; Treatment outcome