title: In vivo ultrasound measurement of posterior femoral glide during hip joint mobilization in healthy college students.
abstract: METHODS
  Descriptive study.
  
  
  OBJECTIVE
  To measure femoral translational glide in vivo during posterior hip joint mobilization and to interpret data in the context of the normal arthrokinematic glide necessary for hip flexion.
  
  
  BACKGROUND
  Joint play, or translational glide available at a joint, is largely influenced by the geometry of the articular surfaces. The high degree of congruence between the articular surfaces at the hip and the substantial arc of concavity of the acetabulum suggests that the amount of translational glide available at the hip should be very small.
  
  
  METHODS
  Twenty subjects received manual posteriorly directed hip mobilization at a force equal to 50% of their body weight, while concurrent ultrasound imaging of the joint was performed. Images were captured before and during application of the target mobilization force. Femoroacetabular distance for each image was measured, and the average of the 3 greatest differences between corresponding before/during mobilization values represented the translational glide produced. The amplitude of arthrokinematic glide (tangential glide) was calculated using the measured femoral head radius and hip flexion passive range of motion for each subject.
  
  
  RESULTS
  The average posterior femoral translational glide was 2.0 mm (range, 0.8-4.2 mm). The average calculated tangential glide required for hip flexion passive range of motion was 53.8 mm (range, 43.2-64.8 mm). The average translational glide as a percentage of tangential glide was 3.8% (range, 1.5%-7.9%).
  
  
  CONCLUSIONS
  Translational glides at the hip are small, particularly in the context of the amplitude of glide necessary for normal hip flexion range of motion.
authors.affiliation: Doctoral Program in Physical Therapy, School of Rehabilitation and Medical Sciences, Central Michigan University, Mount Pleasant, MI 48859, USA. Peter.V.Loubert@cmich.edu
authors.forename: Peter V
authors.initials: PV
authors.lastname: Loubert
authors.forename: J Tim
authors.initials: JT
authors.lastname: Zipple
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Klobucher
authors.forename: Eric D
authors.initials: ED
authors.lastname: Marquardt
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Opolka
mesh_terms: D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging* / Q000502:physiology*; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D014463:Ultrasonography; D055815:Young Adult