title: An analysis of fusion cage migration in unilateral and bilateral fixation with transforaminal lumbar interbody fusion.
abstract: OBJECTIVE
  To investigate if instrumentation (unilateral vs. bilateral fixation) has an effect on the rate of fusion cage migration.
  
  
  METHODS
  This clinical study of transforaminal lumbar interbody fusion involved a prospective group of 116 patients who were randomly assigned to either unilateral (n = 57) or bilateral (n = 59) fixation. Fourteen were lost to follow-up (11 from the unilateral group and 3 from the bilateral group).
  
  
  RESULTS
  The unilateral fixation group consisted of 20 male and 26 female patients. In the unilateral group, the mean age was 53.5 years (range, 18-77), and the preoperative diagnosis consisted of degenerative disc disease, with or without herniated disc (n = 44), and degenerative spondylolisthesis with spinal stenosis (n = 2). The bilateral fixation group consisted of 20 male and 36 female patients. In the bilateral group, the mean age was 55.7 years (range, 26-82), and the preoperative diagnosis consisted of degenerative disc disease, with or without herniated disc (n = 40), and degenerative spondylolisthesis with spinal stenosis (n = 16). A total of 17 cases of cage migration were found; of these, 11 were from the unilateral group and 6 from the bilateral group, resulting in rates of cage migration of 23 and 11 % (p = 0.03), respectively. In regard to migration cases, 5 were male and 12 were female. Ages ranged from 27 to 79 years (mean age, 55 years).
  
  
  CONCLUSIONS
  We conclude that unilateral fixation is not stable enough to prevent fusion cage migration in some patients who undergo TLIF.
authors.affiliation: Department of Orthopaedic Surgery, University of Southern California, Keck School of Medicine, 711 West College Street, Suite 625, Los Angeles, CA 90012, USA.
authors.forename: Jan William
authors.initials: JW
authors.lastname: Duncan
authors.forename: Richard Anthony
authors.initials: RA
authors.lastname: Bailey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019736:Prostheses and Implants; D011475:Prosthesis Failure; D013122:Spinal Diseases / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D016896:Treatment Outcome