To have you in the best physical condition before major surgery many surgeons send you for a pre-operative assessment by a physician—does it help? When a child has persistent cold symptoms, it might be sinusitis and require antibiotics. If a child faints it's really only a worry when it causes an injury. But there might be an abnormality of the heart's electrical system, called congential Long QT syndrome, and prompt parents to have their child checked.  Rehab after knee replacement is controversial because some hospitals keep you in for it, but if you go home soon after the surgery, maybe digital rehab will become an option.