title: Principal components of wrist circumduction from electromagnetic surgical tracking.
abstract: OBJECTIVE
  An electromagnetic (EM) surgical tracking system was used for a functionally calibrated kinematic analysis of wrist motion. Circumduction motions were tested for differences in subject gender and for differences in the sense of the circumduction as clockwise or counter-clockwise motion.
  
  
  METHODS
  Twenty subjects were instrumented for EM tracking. Flexion-extension motion was used to identify the functional axis. Subjects performed unconstrained wrist circumduction in a clockwise and counter-clockwise sense. Data were decomposed into orthogonal flexion-extension motions and radial-ulnar deviation motions. PCA was used to concisely represent motions. Nonparametric Wilcoxon tests were used to distinguish the groups.
  
  
  RESULTS
  Flexion-extension motions were projected onto a direction axis with a root-mean-square error of [Formula: see text]. Using the first three principal components, there was no statistically significant difference in gender (all [Formula: see text]). For motion sense, radial-ulnar deviation distinguished the sense of circumduction in the first principal component ([Formula: see text]) and in the third principal component ([Formula: see text]); flexion-extension distinguished the sense in the second principal component ([Formula: see text]).
  
  
  CONCLUSIONS
  The clockwise sense of circumduction could be distinguished by a multifactorial combination of components; there were no gender differences in this small population. These data constitute a baseline for normal wrist circumduction. The multifactorial PCA findings suggest that a higher-dimensional method, such as manifold analysis, may be a more concise way of representing circumduction in human joints.
authors.affiliation: School of Computing, Department of Mechanical and Materials Engineering, Queen's University, Kingston, K7L 3N6, Canada. brian.rasquinha@queensu.ca.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Rasquinha
authors.affiliation: School of Computing, Department of Mechanical and Materials Engineering, Queen's University, Kingston, K7L 3N6, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rainbow
authors.affiliation: Department of Surgery, Queen's University, Kingston, K7L 3N6, Canada.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Zec
authors.affiliation: Department of Surgery, Queen's University, Kingston, K7L 3N6, Canada.
authors.forename: David R
authors.initials: DR
authors.lastname: Pichora
authors.affiliation: School of Computing, Department of Mechanical and Materials Engineering, Queen's University, Kingston, K7L 3N6, Canada.|Department of Surgery, Queen's University, Kingston, K7L 3N6, Canada.
authors.forename: Randy E
authors.initials: RE
authors.lastname: Ellis
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D055590:Electromagnetic Phenomena; D005260:Female; D006801:Humans; D008297:Male; D009038:Motion; D009068:Movement; D025341:Principal Component Analysis; D016059:Range of Motion, Articular; D013514:Surgical Procedures, Operative / Q000379:methods*; D014953:Wrist; D014955:Wrist Joint; D055815:Young Adult
keywords: Circumduction; Electromagnetic tracking; Principal components analysis; Surgical navigation; Wrist motion