Risk factors for severity and type of the hip fracture.

More severe hip fractures such as displaced femoral neck (FN) fractures and unstable intertrochanteric (IT) fractures lead to poorer outcomes, but risk factors for severe fractures have not been studied. To identify risk factors for severe types of hip fracture, we performed a prospective cohort study and obtained preoperative hip radiographs from women who sustained an incident hip fracture (excluding traumatic fractures). A single radiologist scored the severity of FN fractures by the Garden System: grades I and II, undisplaced; grades III and IV, displaced. The severity of IT hip fractures was rated by the Kyle System: grades I and II, stable; grades III and IV, unstable. A total of 249 women had FN fractures: 75 (30%) were undisplaced. A total of 213 women had IT fractures: 59 (28%) were stable. Both types of hip fracture increased with age, but older age was even more strongly associated with more severe hip fractures. Low BMD was more strongly related to undisplaced FN fractures (p interaction BMD x FN type, p = 0.0008) and stable IT fractures (p interaction BMD x IT type, p = 0.04). Similar findings were observed for estimated volumetric BMD and hip geometric parameters. Corticosteroid use was only associated with displaced FN fractures, and Parkinson's disease was only associated with stable IT fractures. Little difference was reported in the self-reported circumstances surrounding each type of fracture. In conclusion, the lower the BMD, the greater the likelihood of experiencing a hip fracture that is less displaced and more stable.