Prognosis depends on many factors. The following are very important:
1.Overall health of patient.
2.Surgeon's skill, experience and ability to do what's necessary (often put in a pin) quickly. Less time in the operating room means less blood loss, less anesthesia, less trauma, which should make initial recovery easier. (Surgery causes more trauma in the elderly than in the young.)
3. Excellent physical therapy.
Researching and using the rehab center with the best physical therapists is so important--the therapy is hard work. My 97-year-old mother-in-law for whom the prognosis was very good, didn't disappoint. She will go home tomorrow with a cane and a walker and will continue physical therapy 2x a week for another month as an outpatient--after which the expectation is she can walk without a cane.
Even if the latter doesn't happen, she proves age alone doesn't lessen the chance for a good prognosis after falling and breaking a hip. If interested, there are more details on my blog: http://helpparentsagewell.com. where the 1/24/11 post features her broken hip recovery. Good luck