Certainly, you can ask your doctor "what happened"? Don't be surprised if you find out a smaller cut just wasn't possible. The new minimally invasive surgery or MIS does try to limit the size of the incision. But sometimes it isn't possible to keep it down to only five inches.

In some cases the doctor is just learning how to do this operation. Making a larger incision may be needed until the surgeon gets better at the technique. Space is limited for the surgical tools. Special smaller-sized surgical instruments must be used.

The cuts made must be done in a specific order. With each cut, more room is made. The strategic order of the cuts isn't as important as when doing the traditional knee replacement.

And finally, sometimes the shape of the patient's bones makes a difference and a larger incision is needed.