What Does a Healthy Hip Look Like?
The hip is one of the body's largest joints. It is a "ball-and-socket" joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone).
The bone surfaces of the ball and socket are covered with articular cartilage, a smooth, slippery substance that protects and cushions the bones and enables them to move easily. The surface of the joint is covered by a thin lining called the synovium. In a healthy hip, the synovium produces a small amount of fluid that lubricates the cartilage and aids in movement. Joints allow movement between the bones and to absorb shock from movements like walking or repetitive motions.
There are 3 distinct movements associated with the hip joint which are:
Hip flexion and extension - moving the leg back and forth;
Hip abduction and adduction - moving the leg out to the side (abduction) and inward toward the other leg (adduction); and
Rotation - pointing toes inward (internal rotation) or outward (external rotation) and then moving the straightened leg in the direction of the toes.
The hip joint is made up of the following important structures:
Hip bones – the femoral head (ball at the end of the thigh bone ) and the acetabulum (pelvic socket)
Hip articular cartilage – a hard and slippery coating that decreases friction between the bones and allows for a smooth gliding motion. It also acts as a shock absorber, cushioning the underlying bones against impacting each other
Hip ligaments and tendons – these are tough, fibrous tissues that provide structure to the hip, reducing strain on the joint, they link bones to bones and muscles to bones
Synovial membrane and fluid, which surrounds the hip joint and lubricates it, respectively, keeping the cartilage smooth and healthy.
Hip muscles that both support the joint and enable movement – the muscles associated with the hip are as follows:
Gluteal muscles | found in the back of the hip (buttocks) |
The adductor muscle | located in the inner thigh |
The iliopsoas muscle | extends from the lower back to upper thigh |
Quadriceps | a group of four muscles located at the front of the thigh |
Hamstrings | a group of muscles found at the back of the thigh and extend to just below the knee |
References
National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2019, Handout on Health: Osteoarthritis, U.S. Department of Health and Human Services, viewed 29 December 2020
Arthritis Health, 2020, Hip Anatomy, viewed 27 December 2020,
Arthritis Foundation, Anatomy of the Hip, viewed 27 December 2020,