Proximal humerus fractures (PHFs) are common osteoporotic fractures in adults and the elderly, leading to significant disability and reduced quality of life. Current treatment options for displaced PHFs include locking plate fixation (LCP) and various augmentation techniques, but there is no consensus on the optimal treatment. Although, femoral allografts have shown promising results, there is a need for more definitive evidence regarding the utilization of femoral graft augmentation in addition to locking plate fixation in 3- and 4-part PHFs. This study aims to evaluate the effectiveness of using a mushroom-shaped femoral allograft combined with LCP fixation compared to LCP fixation alone. We hypothesize that femoral allograft augmentation with LCP fixation will result in better clinical and functional outcomes than LCP fixation alone at 24 months post-operative