title: Scapulohumeral rhythm relative to active range of motion in patients with symptomatic rotator cuff tears.
abstract: BACKGROUND
  Some patients with rotator cuff tears feel pain without functional limitation, whereas others show a decrease in range of motion. To investigate this distinction, the scapulohumeral rhythm was used to conduct a functional evaluation of shoulder joints' coordination. The objective was to characterize patients according to their active range of motion without pain and their scapulohumeral rhythm compared with healthy individuals.
  
  
  METHODS
  Fourteen patients with rotator cuff tears and 14 healthy individuals were set up with 35 reflective markers on the trunk and upper limb tracked by an optoelectronic system to measure the scapulohumeral rhythm. Five scapular plane maximal arm elevations were executed without pain. Patients were separated by maximal arm elevation of 85° (category A) and 40° (category B). Three-way mixed-design analysis of variance with factors of group (patients and healthy), arm elevation, and motion direction was applied to the scapulohumeral rhythm.
  
  
  RESULTS
  A main effect of group (P = .032) was observed in patients in category A, who showed inferior scapulohumeral rhythm. An interaction between group and arm elevation (P = .044) was observed for patients in category B, where their scapulohumeral rhythm increased more during arm elevation than in the healthy individuals.
  
  
  CONCLUSIONS
  Patients who reached at least 85° compensated for the loss of glenohumeral motion by increased scapulothoracic contribution, suggesting that structural damage interferes with motion mechanics. In contrast, patients who reached less range of motion underused the scapulothoracic joint, which is likely to create subacromial impingement at low arm elevation. A patient's maximal range of motion without pain may indicate a pattern of scapulohumeral rhythm alteration.
authors.affiliation: Département de Kinésiologie, Université de Montréal, Montréal, QC, Canada; Institut de Recherche Robert Sauvé en Santé eten Sécurité du Travail (IRSST), Montréal, QC, Canada. Electronic address: xavier.robert-lachaine@umontreal.ca.
authors.forename: Xavier
authors.initials: X
authors.lastname: Robert-Lachaine
authors.affiliation: Département de Kinésiologie, Université de Montréal, Montréal, QC, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Allard
authors.affiliation: Hôpital Notre-Dame, Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, QC, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Godbout
authors.affiliation: Hôpital Notre-Dame, Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, QC, Canada.
authors.forename: Patrice
authors.initials: P
authors.lastname: Tétreault
authors.affiliation: Département de Kinésiologie, Université de Montréal, Montréal, QC, Canada.
authors.forename: Mickael
authors.initials: M
authors.lastname: Begon
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D000070636:Rotator Cuff Injuries / Q000503:physiopathology*; D012785:Shoulder Joint / Q000503:physiopathology*
keywords: Rotator cuff; coordination; kinematics; motion; range; scapulohumeral rhythm; shoulder joints; tear