My wife has had one hip reconstruction and one hip replacement. She rides a recumbent tadpole trike and has no problems with her hips during or after a ride. She is currently doing 15-17 miles a day. She is going to need surgery, shortly, on one of the hips to replace the discs. Her surgeon said it would be fine for her to use her trike (on a trainer with slight resistance) for her rehab. This makes it nice because she won't have to get a gym membership for rehab.