Why are elbow and knees Called hinge joint?

What are some disorders that can occur in joint

Movements of joints and orientation of bones forming the elbow and knee joint results in a hinge type joint used for extension and flexion of arm and legs.

Explanation:

Knees and Elbow exhibits as the major sectional parts in the body and it is used to move arms and legs. Hinge Joint present in the elbow and knees provides flexibility in moving the arms and legs in our body. The common disorder occurs in the joint is Osteoarthritis and it mostly affects the age of people around 40-50. These disorders cause pain in joints of the leg and elbow.