title: Reliability and validity of first metatarsophalangeal joint orientation measured with an electromagnetic tracking device.
abstract: OBJECTIVE
  To establish the reliability and validity of measurements of sagittal plane orientation of the first metatarsophalangeal joint using the Flock of Birds electromagnetic tracking device.
  
  
  METHODS
  Different joint orientations were reproduced on cadaver specimens in a specially designed jig with skin and skeletal application of the sensors.
  
  
  BACKGROUND
  The Flock of Birds provides a means for quantifying first metatarsophalangeal joint motion, however, the reliability and validity of such an application has not been determined.
  
  
  METHODS
  Joint orientation was measured in five cadaver feet with skin and skeletal sensor application. A specially designed jig allowed simulation of clinical tests of range of motion. Sagittal plane orientation was determined from 3-D, anatomically-based, reference frames embedded in the first metatarsal and proximal hallux.
  
  
  RESULTS
  Reliability of all measurements was high for skin and skeletal sensor application. There were no significant differences in joint orientation between either technique for any of the simulated motion tests.
  
  
  CONCLUSIONS
  The Flock of Birds provides reliable and valid measures of first metatarsophalangeal joint orientation with the sensors applied to the skin over the first metatarsal and proximal hallux.
  
  
  CONCLUSIONS
  An electromagnetic tracking device is suitable for measuring sagittal plane motion of the first metatarsophalangeal joint. This motion can easily be expressed using 3-D, anatomically-based reference frames.
authors.affiliation: Department of Orthopaedics, University of Rochester Medical Center, NY, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: Umberger
authors.forename: D A
authors.initials: DA
authors.lastname: Nawoczenski
authors.forename: J F
authors.initials: JF
authors.lastname: Baumhauer
mesh_terms: D002102:Cadaver; D055590:Electromagnetic Phenomena; D006801:Humans; D008683:Metatarsophalangeal Joint / Q000033:anatomy & histology / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results