title: Quantifying normal 3D hip ROM in healthy young adult males with clinical and laboratory tools: hip mobility restrictions appear to be plane-specific.
abstract: BACKGROUND
  Hip mobility is known to affect lumbar spine motion, yet the literature is unclear as to what constitutes normal, limited or excessive motion, given differences in methods, postures, age, etc. The purpose of this study was to establish normative and percentile data for hip rotation and extension, in a young adult male population, using varying methods of quantification.
  
  
  METHODS
  77 males (age 18-35) were recruited. Position data was captured using the Vicon Motion capture system, as participants were passively positioned in hip extension (using the Modified Thomas test) and prone hip rotation. 22 of these participants also had measurements obtained with a goniometer. 3D hip extension angles were calculated using Euler angles, and compared to those calculated in 2D. Goniometric results were compared to 2D measurements.
  
  
  RESULTS
  Normal distribution of hip extension and rotation range of motion was established, as were average values for the 5th through 95th percentiles. No significant differences existed between hip extension angles measured with the 2D and 3D approaches. Goniometric measurements of hip extension averaged 3.9° less than 2D, less than 1° different for external rotation, and not different for internal rotation.
  
  
  CONCLUSIONS
  The normative and percentile data documented here for hip rotation and extension appear to be validly quantified with goniometric techniques when compared to more objective techniques. Further, hip restriction in one plane may not predict restrictions in other planes.
authors.affiliation: Spine Biomechanics Laboratories, University of Waterloo, Canada.
authors.forename: Janice M
authors.initials: JM
authors.lastname: Moreside
authors.forename: Stuart M
authors.initials: SM
authors.lastname: McGill
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001696:Biomechanical Phenomena; D006615:Hip / Q000502:physiology*; D006621:Hip Joint / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D009038:Motion; D009068:Movement; D016059:Range of Motion, Articular; D012399:Rotation; D055815:Young Adult