An upper ball joint replacement is a procedure during which a surgeon removes the upper part of the patient's femur and replaces the end with an appropriately sized ball to fit in the hip socket, according to MedlinePlus. The procedure refers to the ball-and-socket model of the hip.
After the patient is put under anesthesia, the surgeon removes the top of the femur and removes arthritic tissue from the inside of the hip joint, reports MedlinePlus. The doctor may insert a new hip socket into this space. Then the surgeon inserts a metal rod into the top of the femur and attaches an appropriately sized ball to this. The femur is popped back into place and the surgical site stitched shut.