title: In vivo 3-dimensional analysis of scapular and glenohumeral kinematics: comparison of symptomatic or asymptomatic shoulders with rotator cuff tears and healthy shoulders.
abstract: BACKGROUND
  Alteration in shoulder kinematics has been suggested as one cause of symptoms in shoulders with rotator cuff tears (RCTs). However, only a few studies comparing symptomatic and asymptomatic RCTs using kinematic analysis have been performed. The purpose of this study was to compare 3-dimensional (3D) scapular and glenohumeral kinematics during scapular-plane abduction among symptomatic RCTs, asymptomatic RCTs, and healthy shoulders.
  
  
  METHODS
  This study included 7 healthy shoulders in subjects with a mean age of 62 years, 5 symptomatic RCTs in subjects with a mean age of 70 years, and 7 asymptomatic RCTs in subjects with a mean age of 67 years. All shoulders with RCTs had medium-sized tears (1-3 cm in the coronal plane) that were confirmed with magnetic resonance imaging. Biplane fluoroscopic images during scapular-plane abduction were recorded, and computed tomography-derived 3D bone models were matched with the silhouettes of the bones on the fluoroscopic images using 3D/2-dimensional model-image registration techniques. Angular values of the scapula and glenohumeral kinematics were compared among the 3 groups.
  
  
  RESULTS
  Posterior tilt of the scapula was significantly smaller in the symptomatic RCTs (3.1° ± 1.8°) than in healthy shoulders (10.4° ± 0.8°) (P = .049). The humerus of the symptomatic shoulders was less externally rotated relative to the scapula throughout the activity than the healthy shoulders and asymptomatic RCTs (P = .006 and P = .028 respectively). However, there were no kinematic differences between the asymptomatic RCTs and healthy shoulders.
  
  
  CONCLUSIONS
  Kinematic changes in symptomatic RCTs might be associated with development of symptoms. Improvement of these kinematic changes may be a key to successful conservative treatment for symptomatic RCTs.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan. Electronic address: kijima0602@yahoo.co.jp.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kijima
authors.affiliation: Shoulder and Elbow Center, Funabashi Orthopedic Hospital, Chiba, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuki
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Ochiai
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sasaki
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Eiko
authors.initials: E
authors.lastname: Hashimoto
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Sasaki
authors.affiliation: Department of Orthopedic Surgery, Chiba Medical Center, Chiba, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Yamazaki
authors.affiliation: Department of Orthopedic Surgery, Kitasato University, Kanagawa, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Kenmoku
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Department of Radiology, Chiba University, Chiba, Japan.
authors.forename: Yoshitada
authors.initials: Y
authors.lastname: Masuda
authors.affiliation: Department of Radiology, Chiba University, Chiba, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Umekita
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Banks
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000368:Aged; D058070:Asymptomatic Diseases; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D017006:Rotator Cuff / Q000000981:diagnostic imaging / Q000503:physiopathology; D000070636:Rotator Cuff Injuries; D012540:Scapula / Q000000981:diagnostic imaging* / Q000502:physiology; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000502:physiology; D014057:Tomography, X-Ray Computed
keywords: 3-dimensional kinematics; 3D/2D registration techniques; Shoulder; asymptomatic; rotator cuff tear; scapular kinematics