How recently was your hip replacement?
Are you still on dislocation precautions?
(turning your toes in/heels out to get out of the clipless is internal rotation of the hip)
Many of us ride just fine without clipless pedals. And even without toe clips. I have a fondness for BMX platform pedals, BleeckerStGirl likes PowerStraps, lots of folks like the large platform MKS pedals offered by Rivendell.
Can you talk to your surgeon and ask how much internal rotation of the hip he expects you to get? That could help decide what kind of pedal system you buy once you are past that 6-12 months of dislocation precautions. (if you aren't already)
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson