title: Elucidating the scapulo-humeral rhythm calculation: 3D joint contribution method.
abstract: The scapulo-humeral rhythm quantifies shoulder joint coordination during arm elevation. The common method calculates a ratio of gleno-humeral (GH) elevation to scapulo-thoracic upward rotation angles. However the other rotations also contribute to arm elevation. The objective is to propose a 3D dynamic scapulo-humeral rhythm calculation method including all rotations of the shoulder joints and compare with the common method. Twenty-nine skin markers were placed on the trunk and dominant arm of 14 healthy males to measure shoulder kinematics. Two-way repeated measures ANOVAs were applied to compare the two methods of calculation of joint contributions and scapulo-humeral rhythm during arm elevation. Significant main effects (p < 0.05) were observed between methods in joint contribution angles and scapulo-humeral rhythms. A systematic overestimation of the GH contribution was observed when only using the GH elevation angle because the scapula is moved outside a vertical plane. Hence, the proposed 3D method to calculate the scapulo-humeral rhythm allows an improved functional shoulder evaluation.
authors: a Laboratoire d'Ingénierie du Mouvement, Département de Kinésiologie , Université de Montréal , Campus Laval, 1700 rue Jacques-Tétreault, Laval , QC , Canada H7N 0B6.
authors: Xavier
authors: X
authors: Robert-Lachaine
authors: Patrick
authors: P
authors: Marion
authors: Véronique
authors: V
authors: Godbout
authors: Jacinte
authors: J
authors: Bleau
authors: Mickael
authors: M
authors: Begon
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D006811:Humerus / Q000502:physiology*; D021621:Imaging, Three-Dimensional; D008297:Male; D016059:Range of Motion, Articular; D012399:Rotation; D012540:Scapula / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology*
keywords: coordination; joints; kinematics; scapulo-humeral rhythm; shoulder