I heard the new mini-surgery for hip replacement takes less time and fewer days in the hospital. How much less?

The answer to your questions really depends on the surgeon. If the mini-incision method is fairly new to the surgeon, the operation itself can take longer. If all things are equal (the doctor has done the same number of both operations: open and mini), then the time is about the same.

Length of hospital stay also varies. The hope is that the newer mini-incision method will mean a shorter hospital stay. But hospitalization may be longer if there are any complications during or after the operation. For example, fractures and dislocations may happen more often when a surgeon is learning a new technique.

A recent study from the University of Missouri reports on this. An experienced surgeon had an overall rate of 42 percent for problems after a two-incision mini-invasive hip replacement. That was compared with six percent for the single-incision method. The surgeon also reported a 25 percent rate of nerve injuries. Any of these (or other) problems can extend a patient's stay in the hospital.