title: In Vivo Assessment of Bone Graft/Endplate Contact Pressure in a Caprine Interbody Pseudarthrosis Model: A Preliminary Biomechanical Characterization of the Fusion Process for the Development of a Microelectromechanical Systems (MEMS) Biosensor.
abstract: BACKGROUND
  In this preliminary study we used a goat model to quantify pressure at an interbody bone graft interface. Although the study was designed to assess fusion status, the concept behind the technology could lead to early detection of implant failure and potential hazardous complications related to motion-preservation devices. The purpose of this study was to investigate the feasibility of in vivo pressure monitoring as a strategy to determine fusion status.
  
  
  METHODS
  Telemetric pressure transducers were implanted, and pressure at the bone graft interfaces of cervical interbody fusion autografts placed into living goats (Groups A and B) was evaluated. Group A constituted the 4-month survival group and Group B the 6-month survival group. One goat served as the study control (Group C) and was not implanted with a pressure transducer. An additional six cadaveric goat cervical spines (Group D) were obtained from a local slaughterhouse and implanted with bone grafts and ventral plates and used for in vitro biomechanical comparison to the specimens from Groups A and B.
  
  
  RESULTS
  All goats demonstrated an increase in interface pressure within the first 10 days postoperatively, with the largest relative change in pressure occurring between the sixth and ninth days. The goats from Groups A and B had a 200% to 400% increase in relative pressure.
  
  
  CONCLUSIONS
  Although this was a pilot study to assess pressure as an indicator for a fusion or pseudarthrosis, the preliminary data suggest that early bone healing is detectable by an increase in pressure. Thus, pressure may serve as an indicator of fusion status by detecting altered biomechanical parameters.
authors: OrthoKinetic Techologies, LLC.
authors: Lisa A
authors: LA
authors: Ferrara
authors: The Cleveland Clinic Foundation.
authors: Ilya
authors: I
authors: Gordon
authors: The Cleveland Clinic Foundation.
authors: Richard
authors: R
authors: Schlenk
authors: The Cleveland Clinic Foundation.
authors: Madeline
authors: M
authors: Coquillette
authors: The Cleveland Clinic Foundation.
authors: Aaron J
authors: AJ
authors: Fleischman
authors: The Cleveland Clinic Foundation.
authors: Shuvo
authors: S
authors: Roy
authors: The Cleveland Clinic Foundation.
authors: Daisuke
authors: D
authors: Togawa
authors: The Cleveland Clinic Foundation.
authors: Thomas W
authors: TW
authors: Bauer
authors: The Cleveland Clinic Foundation.
authors: Edward C
authors: EC
authors: Benzel
keywords: Pseudarthrosis; biomechanics; cervical spine; goat; pressure; telemetric; vertebral endplate