Exercises With Hip Replacement

I used to love doing squats, due to arthritis I was forced to have a hip replacement. I still do them but the Doc says 50 pounds, (that is not much weight) I have taken it to 100 pounds with no problems. I know there is no real subsitute for squats however do you have some ideas that I could subsitute. I am 62 and feel great and in decent condition. Thanks!!!