ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

and teres minor rest inactive throughout the whole movement. The reaction force in the glenohumeral
joint shows a local maximum at an abduction angle of 90° of 65% BW (Fig. 5). For abduction
angles larger than 120° the reaction force rises again up to 85% BW at abduction angle of 150°.
Vertical humeral head displacement starts at -5.5 mm, goes up to 6.8 mm and back down to -4.2
mm. Horizontal humeral head displacement goes from 5.4 mm to -5.4 mm in anterior direction (Fig.
6). The direction of the glenohumeral reaction force is restricted by the applied direction criteria
throughout the whole movement (Fig. 7). Loading patterns on the glenoid cartilage show maximal
pressure of 3 MPa for the articular contact area with the humeral head and 4 MPa on the scapula
side.
Fig. 3: Deltoid muscle forces (clavicular,
acromial and scapular part)
Fig. 5:Reaction force in glenohumeral joint.
Fig. 7: Direction of glenohumeral reaction
force (red). Sterographic projection on
glenoid cavity (blue).
Fig. 4: Rotator cuff muscle forces
Fig. 6: Vertical (blue) and horizontal (red)
humeral head translation
Fig. 8: Cartilage contact pressure for
abduction angle of 90°