AVN begins as a painless bone abnormality and it can remain painless. In its early stages, AVN typically has no symptoms; however, as the disease progresses, it becomes painful. Initially, patients may experience pain when pressure is applied to the affected bone. Eventually, the pain becomes persistent. If the disease progresses, the bone and surrounding joint collapse, leading the patient to experience severe pain that interferes with joint function. For instance, if a hip joint develops AVN in the ball of the hip joint, pain can be noted, especially upon weight-bearing. As the ball of the hip joint collapses from the degeneration of the bone from aseptic necrosis, pain in the groin can be felt with hip rotation, and pain can sometimes be noted with rest after weight-bearing. AVN of the knee is often associated with pain or limping with walking. The time between the first symptoms and collapse of the bone may range from several months to more than a year.