In recent years, technology has evolved significantly to intervene in the treatment of diseases through diagnosis online before going to the specialist doctor, where it become possible for the patient to know the name of his illness, the specialist doctor who can treat him and the multiple treatment methods through specially designed systems called expert systems. The expert system is based on the principle of asking the user gradual questions about the symptoms he feels, leading him to the result of (...) diagnosing the illness, dealing with it quickly, and tips for permanent treatment. These systems may also help both trainee physicians and physiotherapists. This research paper is a living example of these effective applications, explaining in a simplified manner some of ankle diseases, how to deal with them and methods of physical therapy. The ankle is a small region in the leg. It is two joints, the first consist of three bones (tibia, fibula and talus underneath) which is called true ankle joint. The other is called subtalar joint have two bones: talus on top and calcaneus on the bottom. This tarsus between the end of the leg and the start of the foot facilitates the movement up-down and left-right with no problems in normal case, although, it needs a special case as Physiotherapist when gets injury. We have identified seven ankle diseases: Ankle Sprain, Fracture (of Fibula), Rheumatoid Arthritis, Rheumatoid Fever, Gout, and Osteoarthritis (Degenerative Joint) using SL5 Object Expert System Language in the work of the expert system. (shrink)