Femur
The thigh bone - the longest and strongest bone in the body. The lower end of the femur forms the upper part of the knee joint.
Extended Definition
The femur (thigh bone) extends from the hip to the knee. Its lower end, called the femoral condyles, forms the upper half of the knee joint and is covered with articular cartilage.
Knee Joint Anatomy
The femur meets two bones at the knee:
- Tibia - The main weight-bearing connection (tibiofemoral joint)
- Patella - The kneecap glides over a groove in the femur (patellofemoral joint)
Osteoarthritis Location
Knee OA is classified by which femoral surface is affected:
- Medial compartment - Inner side of femur (most common)
- Lateral compartment - Outer side of femur
- Patellofemoral - Front groove where patella tracks
- Tricompartmental - All three areas affected
Clinical Significance
The condition of the femoral cartilage—visible on X-ray as “joint space”—is a key measure of OA severity. Hyaluronic acid injections add cushioning between the femur and tibia, reducing bone-on-bone contact.
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.