  Proximal humerus impacted fractures are of clinical concern in the elderly
population. Prediction of such fractures by CT-based finite element methods
encounters several major obstacles such as heterogeneous mechanical properties
and fracture due to compressive strains. We herein propose to investigate a
variation of the phase field method (PFM) embedded into the finite cell method
(FCM) to simulate impacted humeral fractures in fresh frozen human humeri. The
force-strain response, failure loads and the fracture path are compared to
experimental observations for validation purposes. The PFM (by means of the
regularization parameter $l_0$) is first calibrated by one experiment and
thereafter used for the prediction of the mechanical response of two other
human fresh frozen humeri. All humeri are fractured at the surgical neck and
strains are monitored by Digital Image Correlation (DIC). Experimental strains
in the elastic regime are reproduced with good agreement ($R^2 = 0.726$),
similarly to the validated finite element method [9]. The failure pattern and
fracture evolution at the surgical neck predicted by the PFM mimic extremely
well the experimental observations for all three humeri. The maximum relative
error in the computed failure loads is $3.8\%$. To the best of our knowledge
this is the first method that can predict well the experimental compressive
failure pattern as well as the force-strain relationship in proximal humerus
fractures.
