Final answer:
The symptoms described suggest a fracture of the femoral neck, often associated with osteoporosis in the elderly, requiring surgical treatment and rehabilitation.
Step-by-step explanation:
A 95-year-old female presents to the ER after a fall in her home with a left leg that is shortened and externally rotated. The most likely diagnosis for these symptoms is a fracture of the femoral neck, commonly referred to as a "broken hip." This condition is particularly common in elderly individuals with weakened bones due to osteoporosis. The hallmark signs of this type of fracture include the shortening of the affected limb and its external rotation. Femoral neck fractures typically require surgical treatment, and the recovery process often involves a prolonged period of assisted mobility and rehabilitation.