Waves,

My father was medicated with perhaps morphine and oxy the first three or four days after his hip replacement even though they had him walking and moving a little with the guidance of a physical therapist.
After he left the hospital and moved to rehab they dropped the morphine but kept the oxy. They increased the physical and occupational therapy at rehab.
Yeah, knees are not the same as hips.

I think that medication and therapy depends on the age and physical conditioning of the patient. Other variables as well.

M