title: In vivo quantification of capsular end-point in the nonimpaired glenohumeral joint using an instrumented measurement system.
abstract: METHODS
  Single-group factorial.
  
  
  OBJECTIVE
  Quantify glenohumeral joint translations as a function of force using an instrumented measurement system. Our first specific aim was to compare the magnitude of force (N) required to reach capsular end-point between the anterior, posterior, and inferior directions. Our second specific aim was to compare the magnitude of translation (mm) at capsular end-point between the anterior, posterior, and inferior directions.
  
  
  BACKGROUND
  Manual force-displacement techniques are subjective in nature, and the clinician must rely on "feel" to determine capsular end-point. Several investigators have attempted to utilize more objective measures at the glenohumeral joint, however none have quantified the force or displacements necessary to achieve a true capsular end-point.
  
  
  METHODS
  An arthrometric technique was used to measure anterior, posterior, and inferior glenohumeral translations in 20 nonimpaired shoulders (11 women and 9 men with a mean age of 20.9 +/- 3.6 years).
  
  
  RESULTS
  The magnitude of applied force required to reach capsular end-point was significantly different between directions of translations. Anterior-directed translations required a significantly greater magnitude of applied force to reach capsular end-point than inferior-directed translations. The magnitude of translation was not significantly different between directions at capsular end-point.
  
  
  CONCLUSIONS
  Applied forces in the range of 181 to 203 N are necessary to reach capsular end-point in subjects with nonimpaired shoulders. Anterior translation required significantly higher forces (203.1 +/- 13.1 N) to reach capsular end-point than inferior translation (181.4 +/- 31.9 N).
authors.affiliation: Division of Kinesiology, University of Michigan, Ann Arbor 48109-2214, USA. borsap@umich.edu
authors.forename: P A
authors.initials: PA
authors.lastname: Borsa
authors.forename: E L
authors.initials: EL
authors.lastname: Sauers
authors.forename: D E
authors.initials: DE
authors.lastname: Herling
authors.forename: W F
authors.initials: WF
authors.lastname: Manzour
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000886:Anthropometry / Q000379:methods*; D001696:Biomechanical Phenomena; D023381:Endpoint Determination; D004867:Equipment Design; D005260:Female; D006801:Humans; D017746:Joint Capsule / Q000502:physiology*; D007593:Joint Instability / Q000175:diagnosis; D008297:Male; D012785:Shoulder Joint / Q000502:physiology*