Patella

Patella bipartita

Patella baja

Insall-Salvati ratio of patella baja

Patella is a small, flat, round bone located at the front of the knee joint, within the quadriceps tendon. Often referred to as the kneecap, it is a sesamoid bone that is embedded in a tendon or muscle. The patella is crucial for the function of the knee, playing a key role in the mechanism of extension of the knee joint. It protects the knee joint and increases the leverage of the tendon of the quadriceps femoris muscle, the muscle responsible for extending the knee.

Anatomy

The patella is triangular in shape with a superior base and an inferior apex. The apex points downwards and is attached to the patellar ligament, which in turn is attached to the tibia. The posterior surface of the patella is covered with articular cartilage, which is the thickest in the human body. This cartilage is essential for reducing friction between the patella and the femur during knee movements.

Function

The primary function of the patella is to increase the leverage of the quadriceps femoris muscle, enhancing the muscle's ability to extend the knee. Additionally, it serves to protect the front of the knee joint from physical impacts. The patella also plays a significant role in the biomechanics of the knee, contributing to the stability of the joint during movement.

Clinical Significance

1. 1. 1. Patellar Fractures ###

Fractures of the patella can occur due to direct impact or a sudden contraction of the quadriceps muscle. Treatment may vary from immobilization in a cast to surgical intervention, depending on the severity of the fracture.

1. 1. 1. Patellofemoral Pain Syndrome ###

Also known as runner's knee, this condition is characterized by pain around the patella, often caused by overuse, misalignment, or other factors that put extra stress on the patella. Treatment typically involves physical therapy and exercises to strengthen the muscles around the knee.

1. 1. 1. Patellar Dislocation ###

Dislocation of the patella occurs when the bone slips out of its position, usually laterally. This can be due to a direct blow or a sudden twist of the knee. Treatment often involves immobilization followed by physical therapy.

Evolution

The patella has evolved as a sesamoid bone to increase the mechanical advantage of the quadriceps muscle in extending the knee. Its presence varies among different species, being most commonly found in mammals that use their anterior limbs for locomotion.

See Also

• Knee
• Quadriceps femoris muscle
• Sesamoid bone
• Tendon