Reflex sympathetic dystrophy (RSD) is currently a challenging condition to understand, diagnose and manage. As a result, the severity of the problem is more complex for the knee. Late diagnosis is the major factor, affecting the prognosis of the disease. The reason for RSD is mostly posttraumatic structural changes of the knee. There is no direct correlation between the severity of the culprit and pain. Initially, sympathetic dysfunction develops. It may lead to RSD, if left untreated. There is a hypersensitive and swollen joint with color deformation in the involved knee. The most definitive and rapid diagnosis is based on sympathetic blockage. The treatment coverage is also limited. Sympathetic blockage in combination with nonsteroidal anti-inflammatory drugs and physical therapy may give successful outcomes.