title: Anterior lumbar interbody fusion: two-year results with a modular interbody device.
abstract: METHODS
  Retrospective case series.
  
  
  OBJECTIVE
  To present radiographic outcomes following anterior lumbar interbody fusion (ALIF) utilizing a modular interbody device.
  
  
  BACKGROUND
  Though multiple anterior lumbar interbody techniques have proven successful in promoting bony fusion, postoperative subsidence remains a frequently reported phenomenon.
  
  
  METHODS
  Forty-three consecutive patients underwent ALIF with (n=30) or without (n=11) supplemental instrumentation. Two patients underwent ALIF to treat failed posterior instrumented fusion. The primary outcome measure was presence of fusion as assessed by computed tomography. Secondary outcome measures were lordosis, intervertebral lordotic angle (ILA), disc height, subsidence, Bridwell fusion grade, technical complications and pain score. Interobserver reliability of radiographic outcome measures was calculated.
  
  
  RESULTS
  Forty-three patients underwent ALIF of 73 motion segments. ILA and disc height increased over baseline, and this persisted through final follow-up (p<0.01). Solid anterior interbody fusion was present in 71 of 73 motion segments (97%). The amount of new bone formation in the interbody space increased over serial imaging. Subsidence >4 mm occurred in 12% of patients. There were eight surgical complications (19%): one major (reoperation for nonunion/progressive subsidence) and seven minor (five subsidence, two malposition).
  
  
  CONCLUSIONS
  The use of a modular interbody device for ALIF resulted in a high rate of radiographic fusion and a low rate of subsidence. The large endplate and modular design of the device may contribute to a low rate of subsidence as well as maintenance of ILA and lordosis. Previously reported quantitative radiographic outcome measures were found to be more reliable than qualitative or categorical measures.
authors.affiliation: Division of Orthopaedic Spinal Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors.forename: Keith Lynn
authors.initials: KL
authors.lastname: Jackson
authors.affiliation: Landstuhl Regional Medical Center, Landstuhl, Germany.
authors.forename: Chevas
authors.initials: C
authors.lastname: Yeoman
authors.affiliation: Colorado Comprehensive Spine Institute, Englewood, CO, USA.
authors.forename: Woosik M
authors.initials: WM
authors.lastname: Chung
authors.affiliation: Spine Center Atlanta, Atlanta, GA, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Chappuis
authors.affiliation: Landstuhl Regional Medical Center, Landstuhl, Germany.
authors.forename: Brett
authors.initials: B
authors.lastname: Freedman
keywords: Interbody cage; Low back pain; Lumbar spine