Acetabulum
The cup-shaped socket of the pelvis that holds the head of the femur (thigh bone) in the hip joint.
Extended Definition
The acetabulum is the concave surface of the pelvis that forms the socket of the hip joint. Together with the femoral head, it creates one of the most stable joints in the body while still allowing substantial range of motion.
Structure
- Formed by three pelvic bones - Ilium, ischium, and pubis meet here
- Lined with articular cartilage - Smooth surface for movement
- Surrounded by labrum - Fibrocartilage rim that deepens the socket
- Covered by joint capsule - Contains synovial fluid
Hip Osteoarthritis
In hip OA, both the acetabular cartilage and femoral head cartilage deteriorate:
- Joint space narrows on X-ray
- Bone spurs form around the socket rim
- Range of motion decreases
- Pain develops, often felt in the groin or thigh
Treatment Relevance
Hip HA injections (often done under imaging guidance) can provide relief by improving lubrication between the femoral head and acetabulum. However, this is typically off-label use, as most HA products are FDA-approved only for knee OA.
Related Terms
More Anatomy Terms
View allArticular 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.
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.