Hey heater81, i also had a hip replacement mine was in 2008, crazy shit huh.
About 5 weeks after my surgery the Doc put me back on my medicine which is a Subcutaneous injection.
In June of this year my Endo put me on Test E injections for TRT. Like you i was also scared shit i was going to get an infection due to the Hip Replacement, however the doctor said i wouldn't have a problem with that since it's been 3 years and im all healed up.
But she did say as a precaution not to inject into the quad where the Hip Repl. took place. So i have both of my deltoids, left quad, and left glute to inject into.
Hopefully this answers your question, remember always take extra precautions when doing IM injections.