title: In vivo kinematic analysis of the glenohumeral joint during dynamic full axial rotation and scapular plane full abduction in healthy shoulders.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the kinematics of healthy shoulders during dynamic full axial rotation and scapular plane full abduction using three-dimensional (3D)-to-two-dimensional (2D) model-to-image registration techniques.
  
  
  METHODS
  Dynamic glenohumeral kinematics during axial rotation and scapular plane abduction were analysed in 10 healthy participants. Continuous radiographic images of axial rotation and scapular plane abduction were taken using a flat panel radiographic detector. The participants received a computed tomography scan to generate virtual digitally reconstructed radiographs. The density-based digitally reconstructed radiographs were then compared with the serial radiographic images acquired using image correlations. These 3D-to-2D model-to-image registration techniques determined the 3D positions and orientations of the humerus and scapula during dynamic full axial rotation and scapular plane full abduction.
  
  
  RESULTS
  The humeral head centre translated an average of 2.5 ± 3.1 mm posteriorly, and 1.4 ± 1.0 mm superiorly in the early phase, then an average of 2.0 ± 0.8 mm inferiorly in the late phase during external rotation motion. The glenohumeral external rotation angle had a significant effect on the anterior/posterior (A/P) and superior/inferior (S/I) translation of the humeral head centre (both p < 0.05). 33.6 ± 15.6° of glenohumeral external rotation occurred during scapular plane abduction. The humeral head centre translated an average of 0.6 ± 0.9 mm superiorly in the early phase, then 1.7 ± 2.6 mm inferiorly in the late phase, and translated an average of 0.4 ± 0.5 mm medially in the early phase, then 1.6 ± 1.0 mm laterally in the late phase during scapular plane abduction. The humeral abduction angle had a significant effect on the S/I and lateral/medial (L/M) translation of the humeral head centre (both p < 0.05).
  
  
  CONCLUSIONS
  This study investigated 3D translations of the humerus relative to the scapula: during scapular plane full abduction, the humerus rotated 33.6° externally relative to the scapula, and during external rotation motion in the adducted position, the humeral head centre translated an average of 2.5 mm posteriorly. Kinematic data will provide important insights into evaluating the kinematics of pathological shoulders. For clinical relevance, quantitative assessment of dynamic healthy shoulder kinematics might be a physiological indicator for the assessment of pathological shoulders.
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan.
authors: Naoya
authors: N
authors: Kozono
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan. t-okada@ortho.med.kyushu-u.ac.jp.
authors: Takamitsu
authors: T
authors: Okada
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan.
authors: Naohide
authors: N
authors: Takeuchi
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan.
authors: Satoshi
authors: S
authors: Hamai
authors: Department of Biorobotics, Faculty of Engineering, Kyushu Sangyo University, 2-3-1, Matsukadai, Higashi-ku, Fukuoka City, Fukuoka, 813-8503, Japan.
authors: Hidehiko
authors: H
authors: Higaki
authors: Department of Biorobotics, Faculty of Engineering, Kyushu Sangyo University, 2-3-1, Matsukadai, Higashi-ku, Fukuoka City, Fukuoka, 813-8503, Japan.
authors: Satoru
authors: S
authors: Ikebe
authors: Department of Information and System Engineering, Faculty of Information Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka City, Fukuoka, 811-0295, Japan.
authors: Takeshi
authors: T
authors: Shimoto
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan.
authors: Go
authors: G
authors: Miake
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan.
authors: Yoshitaka
authors: Y
authors: Nakanishi
authors: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan.
authors: Yukihide
authors: Y
authors: Iwamoto
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: 3D-to-2D model-to-image registration techniques; Glenohumeral; Humeral translation; Kinematics; Shoulder