Patella
The kneecap - a small, triangular bone at the front of the knee that protects the joint and improves the mechanical advantage of the quadriceps muscle.
Extended Definition
The patella (kneecap) is the largest sesamoid bone in the human body—a bone embedded within a tendon. It sits within the quadriceps tendon at the front of the knee joint.
Functions
- Protects the knee - Shields the joint from direct trauma
- Increases leverage - Acts as a pulley, increasing quadriceps power by 30-50%
- Reduces friction - Cartilage-covered underside glides smoothly on the femur
Patellofemoral Arthritis
The underside of the patella can develop arthritis (patellofemoral OA):
- Causes pain with stairs, squatting, and prolonged sitting
- Often occurs alongside tibiofemoral (main knee compartment) OA
- Visible on X-rays as joint space narrowing between patella and femur
Treatment Considerations
Hyaluronic acid injections can help patellofemoral OA by improving lubrication throughout the entire knee joint, including the patellofemoral compartment.
Related Terms
More Anatomy Terms
View allAcetabulum
The cup-shaped socket of the pelvis that holds the head of the femur (thigh bone) in the hip joint.
Articular Cartilage
The smooth, white tissue covering the ends of bones in joints. Its breakdown is the primary feature of osteoarthritis.
Bursae
Small, fluid-filled sacs that act as cushions between bones, tendons, and muscles near joints, reducing friction during movement. Singular form is 'bursa.'
Bursa
Small, fluid-filled sacs that cushion bones, tendons, and muscles near joints. Bursitis (inflammation of a bursa) can cause joint pain similar to arthritis.
Cartilage
A smooth, rubbery connective tissue that covers and protects the ends of bones where they meet to form joints, allowing them to glide smoothly during movement.