Osteoarthritis of the knee is one of the most common causes of knee pain and difficulty in walking. When the cartilage wears out, the thigh muscles become thin, the knee shape turns inward, and the affected knee often becomes smaller due to excessive wear. In this video, you will see: • Why most people’s knees wear out from the inside (medial compartment) first. • The reason behind duck-like walking (waddling gait) when the joint gap disappears. • Different types of osteoarthritis (Type 1, 2, 3)