What are the possible predisposing and precipitating factors that contribute to femur fracture?=)?

Not to be silly, but the #1 factor is trauma. Beyond that, anything that compromises the density ("thickness") of bone will. Osteoporosis is probably the most well known. It can be caused by a number of factors. Young athletic women (those with really low body fat and who don't have periods because of the intensity of exercise) are prone to it. Those with problems regarding calcium or vitamin D intake or metabolism, elderly (especially post-menopausal), congenital problems (such as osteogenesis imperfecta), hypothyroid or thyroid issues, some medications (long term steroid use - the antiinflammatory kind, not the body building ones) ... all are at higher risk for weaker bones and therefore easier femur fractures.