Which part of the patella?

The patella is

the largest sesamoid bone in the human body. It can move up, down, left and right. It can protect the cartilage behind the patella and the joint of the femur. It can help stabilize the knee joint, protect the knee joint and maintain normal activities.

Exercise should pay attention to knee joint protection. Patella damage will affect normal activities. If it is due to improper exercise or rheumatoid arthritis and other diseases, patella damage should be treated under the guidance of a doctor.