Ball and socket joint Ball and socket joint The ball and socket joint (or spheroid joint) is a type of synovial joint in which the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. The distal bone is capable of motion around an indefinite number of axes, which have one common center. It enables the bone to move in many places (nearly all directions). An enarthrosis is a special kind of spheroidal joint in which the socket covers the sphere beyond its equator. Examples of this form of articulation are found in the hip, where the round head of
Hip dislocation classification system for anterior hip dislocations. "Central dislocation" is an outdated term for medial displacement of the femoral head into a displaced acetabular fracture. It is no longer used. Hip dysplasia is a condition in which a child is born with a hip problem. Hip dysplasia is when the formation of the hip joint is abnormal. The ball at the top of the thighbone which is known as the femoral head is not stable within the socket (which is also known as the acetabulum). Hip dysplasia is the preferred term because it provides a more accurate description of the spectrum