The hip joint is one of the largest, most stable joints in the human body. Located at the upper end of the thigh bone, or femur, the hip joint allows for a variety of leg movements and helps provide a solid, smooth base to reinforce the body's centre of gravity. Several main structures make up the hip joint.
Ball and Socket Articulation
The hip joint is a traditional ball and socket type of a joint, whereby the articulation of the hip bone, or femoral head, with the hip socket, or acetabulum, forms the hip joint. The hip bone fits snugly into the hip socket and allows for smooth, stable function.
Femoral Head Articular Cartilage
Covering the end of the femoral head is a layer of smooth, fibrous tissue called articular cartilage, which allows for easy, almost friction-free movement of the femoral head within the acetabulum. This layer of articulating cartilage helps to stabilise loading across the hip joint.
The acetabular labrum, which is a form of articular cartilage located deep within the hip socket, meshes with the articular cartilage covering the end of the femoral head and helps to increase overall stability and function of the entire hip joint. The acetabular labrum also helps to anchor the femoral head firmly into the acetabulum.
Hip Joint Capsule
The hip joint capsule, which is a sheath of muscle encircling and enclosing the entire hip joint, helps to stabilise the hip joint and minimise the risk of hip joint dislocation when the hip joint is hyperextended. The hip joint capsule also contains a series of tendons that serve to anchor various muscle attachments directly to the femoral head.
The greater trochanter is a bony protuberance extending from the lateral side of the upper femoral head, from which point a series of muscles attach that help to rotate and flex the hip joint. The greater trochanter is a very prominent feature of the femur bone that helps to give the hip joint its unique appearance.