Why is it that some people can have a surgery such as a knee or back surgery and never get back to their former level of being able to move around while professional athletes can have multiple serious injuries and surgeries and still play a tough sport at a pro level to get them signed again and again to making millions of dollars? I would say good genetics helps, and being physically strong in the first place helps too. A good surgeon is a must, and so is the drive to get better. However, the best strength and conditioning coach helping you with sports rehabilitation is, in my mind, the difference maker.
I have noticed that your average person who has a surgery, such as a knee surgery, will not even go through regular physical rehab let alone strength and conditioning exercises to lose fat, build muscle and restore range of motion. I know a lady who had both knees replaced and she can barely walk. Getting her knees replaced was to help her get walking again. She is in constant pain. She is also very overweight and obviously does not have the motivation and drive to go through intense physical retraining to get back on her feet.
I would say that there is also a mental aspect to it that helps with how pain is processed. Athletes, special warfare soldiers and some others can take pain and put it in a place off to the side in order to get the job done. They kind of look at pain as just another challenge to overcome while many others see it as a reason to slow down or even quit. This is also why you need the best strength and conditioning coach on your side for rehab if your are into pro sports so you do not end up overdoing it and hurting yourself even more.