Interesting observation. My wife (works in orthopedics) has a similar theory/observation about the elderly and hip fractures. Often times, a hip fracture late in life is the harbinger of death within six months. Life expectancy can be short after such a fracture in the elderly. Theories of why this is are abundant - loss of mobility, slow healing at age, physical inactivity due to pain/mechanical issues, depression, etc. My wife's theory is that the hip fracture does not cause the typical short lifespan thereafter, but is more a single event in an already-in-motion chain of events that would ultimately lead to death anyways. Just a theory. But similar in concept to what Tjin expressed above. [ Often times hips are surgically repaired in the elderly not for long term recovery, but for pain relief and comfort during the time that is left. ]