title: Biomechanical characteristics of an integrated lumbar interbody fusion device.
abstract: BACKGROUND
  We hypothesized that an Integrated Lumbar Interbody Fusion Device (PILLAR SA, Orthofix, Lewisville, TX) will function biomechanically similar to a traditional anterior interbody spacer (PILLAR AL, Orthofix, Lewisville, TX) plus posterior instrumentation (FIREBIRD, Orthofix, Lewisville, TX). Purpose of this study was to determine if an Integrated Interbody Fusion Device (PILLAR SA) can stabilize single motion segments as well as an anterior interbody spacer (PILLAR AL) + pedicle screw construct (FIREBIRD).
  
  
  METHODS
  Eight cadaveric lumbar spines (age: 43.9±4.3 years) were used. Each specimen's range of motion was tested in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) under intact condition, after L4-L5 PILLAR SA with intervertebral screws and after L4-L5 360° fusion (PILLAR AL + Pedicle Screws and rods (FIREBIRD). Each specimen was tested in flexion (8Nm) and extension (6Nm) without preload (0 N) and under 400N of preload, in lateral bending (±6 Nm) and axial rotation (±5 Nm) without preload.
  
  
  RESULTS
  Integrated fusion using the PILLAR SA device demonstrated statistically significant reductions in range of motion of the L4-L5 motion segment as compared to the intact condition for each test direction. PILLAR SA reduced ROM from 8.9±1.9 to 2.9±1.1° in FE with 400N follower preload (67.4%), 8.0±1.7 to 2.5±1.1° in LB, and 2.2±1.2 to 0.7±0.3° in AR. A comparison between the PILLAR SA integrated fusion device versus 360° fusion construct with spacer and bilateral pedicle screws was statistically significant in FE and LB. The 360° fusion yielded motion of 1.0±0.5° in FE, 1.0±0.8° in LB (p0.05).
  
  
  CONCLUSIONS
  The PILLAR SA resulted in motions of less than 3° in all modes of motion and was not as motion restricting as the traditional 360° using bilateral pedicle screws. The residual segmental motions compare very favorably with published biomechanical studies of other interbody integrated fusion devices.
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, Maywood, Illinois ; Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, Illinois.
authors.forename: Leonard I
authors.initials: LI
authors.lastname: Voronov
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, Maywood, Illinois ; Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, Illinois.
authors.forename: Georgios
authors.initials: G
authors.lastname: Vastardis
authors.affiliation: Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, Illinois.
authors.forename: Julia
authors.initials: J
authors.lastname: Zelenakova
authors.affiliation: Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, Illinois.
authors.forename: Gerard
authors.initials: G
authors.lastname: Carandang
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, Maywood, Illinois ; Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, Illinois.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Havey
authors.affiliation: Orthofix, Lewisville, Texas.
authors.forename: Erik I
authors.initials: EI
authors.lastname: Waldorff
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, Maywood, Illinois.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Zindrick
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, Maywood, Illinois ; Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, Illinois.
authors.forename: Avinash G
authors.initials: AG
authors.lastname: Patwardhan
keywords: Integrated Lumbar Interbody Fusion; biomechanics; lumbar spine