4. Stresses in Bending

Mabel Able, 80 years old, lived alone in a two-story house taking care of her own needs, such as cooking, cleaning, and tending a small garden and a flower bed. Until about two years ago she also walked around the block every day but recently has confined herself to her house and yard. Her next-door neighbor comes by to check on her every day and helps her with her grocery list, mails packages for her, and so on. On Monday morning when the neighbor went to check Mabel, she found Mabel lying on the kitchen floor, moaning and complaining of pain in her right hip. The neighbor could see that the leg was turned out and shortened, and she immediately suspected that Mabel had slipped on the linoleum when she came downstairs to make her morning coffee. The rescue squad was called, and Mabel was transported to the hospital, where the suspicion of a fractured hip was confirmed by a radiograph. After her family doctor came in and pronounced Mabel fit for surgery, she was taken to the operating room, where internal fixation with a compression screw and side plate was accomplished without any complications. The pre- and intra-operatice X rays are shown in Figure 4.1. What were the mechanical factors c ausing Mabel’s hip to break?