kneecap

The kneecap, medically called the patella, is a small, flat bone located at the front of the knee. It is a sesamoid bone that develops within the quadriceps tendon and sits anterior to the knee joint. The patella forms part of the patellofemoral joint, articulating with the femur, and it protects the knee while improving the leverage of the quadriceps muscle during leg extension.

Functionally, the patella acts as a fulcrum that increases the angle at which the quadriceps muscle pulls on the tibia, enhancing extension efficiency and reducing wear on the thigh muscles. It also helps guide the tendon during knee movement and distributes compressive forces across the joint.

Development and anatomy-wise, the patella ossifies from one or more centers in childhood and becomes a single bone as it matures. The articular surface is covered with hyaline cartilage. Variations such as bipartite patella occur when a secondary ossification center fails to fuse completely; most cases are asymptomatic and discovered incidentally.

Clinical significance includes a range of injuries and conditions. Patellar injuries include fractures and dislocations, often occurring laterally, as well as overuse injuries such as patellofemoral pain syndrome and chondromalacia patellae. Treatment varies with the severity and may involve rest, physical therapy, bracing, or surgical options to restore patellar tracking and knee function.