Questions about total knee replacement surgery

My mom had it done, but with her surgery she had a newer style of surgery where the doctor didn't have to cut as much of the quad tendon, just enough to slide the kneecap instead of totally flipping it off to the side. Her incision is about 5.5 inches long. so the timeframe was shorter than the older style which is more invasive and takes more time for the quad tendon to heal. She did all the rehab faithfully and then some. (She's a nurse so she knows the importance). I asked her. She was on pain meds for about ten days, took her rented walker back a bit before 3 weeks. She was walking the steep stairs in the house at about 3 weeks or so, still using the railings for support. She was 55 when she had it done, in reasonably good shape, and was in miserable pain because she had worn away almost 1/4 inch of bone on the inside of her knee. So her pain tolerance was pretty high. She thinks if you have the minimally invasive surgery like she had a month is probably ok, if you have the more invasive one possibly closer to 6 weeks. She also said the key is in the rehab. It sucks and hurts, but she walks with no limp in her stride at all and has no limitations on what she can do- 3 years after she hiked in Yosemite with me.