After I tore my bicep and had surgery, 16 weeks after, the surgeon asked me how my strength was. I told him I was loading it, but was real careful and did higher reps and didnt load absolutely maximally. He said no, at 16 weeks you are cleared to load it maximally, the goal is to get you like before, not merely to get some function in it. Just avoid yanking the weights. So the expert told me to do heavier weights, not to be afraid.
Everyone should listen to their doctor but I think patients tend to avoid challenging rehab, to limit themselves and then deteriorate. An aunt of mine had knee replament and now is scared to even go outside, she feels the knees feel like they are failing and has pain. The docs said there's nothing wrong with your knees, you just have to challenge yourself.
I know some friends had severe joint issues and they feel like the worst thing is to stop training, and the docs say the same, pain just gets worse just now they are weaker because of fear. Of course it differs from case to case. A friend is a former world class powerlifter and started feeling severe pain in his foot but he kept training like before, he always had some type of pain when training anyway, When the foot completely collapsed he had to go to the docs and they find they can't do surgery and attach pins because he has osteoporosis in that leg only. He has had a cast on it and now has an orthopedic boot on it to relieve loading and to not have it deteriorate further. But yesterday I saw him do reps on the deadlift 375 with the boot. Maybe not the best idea.