Modelling Prone to Supine Breast Deformation Under Gravity Loading Using Heterogeneous Finite Element Models - Computational Biomechanics for Medicine - page 27

Fig. 2 Allocation of muscle ( red/grey ) and fat/fibroglandular ( white ) tissue at Gauss points within
the FE breast model
Fig. 3 Modelling procedure for obtaining the supine gravity loaded breast shape from the prone
gravity loaded breast (see text for details)
It was assumed that the breast tissues and muscles were firmly attached to the rib
cage, and therefore fixed kinematic boundary conditions (BC's) were applied on the
rib surface of the breast model. These constraints were also applied to the nodes at
the sternum and axilla ends of the model and the shoulder. With reference to Fig. 3 ,
the supine position was obtained from the prone fitted model (Fig. 3a ) by first
determining the unloaded state (Fig. 3b ), which removes the effect of gravity [ 13 ].
Once this unloaded state was determined, the model could be re-aligned to the
supine position (Fig. 3c ) after which gravity loading in the supine position was
simulated (Fig. 3d ). In order to obtain an accurate estimate of the direction of
gravity in the supine position and therefore take into account any rigid body motion