Hip impingement, or femoroacetabular impingement (FAI), occurs when extra bone is formed on either the acetabulum, the femoral head, or both. The extra bone formation, often called bone spurs, typically form during early childhood years, but we do not yet know the cause. Many people do not know they have this bone formation and can live pain-free for a long time.
Exercise or being active may cause hip pain in people with FAI, but exercise does not cause FAI. When the bone spurs grow on the femoral head (ball of the hip) slams up against the acetabulum (cup of the hip) and this is called a CAM Lesion. If you have bone growth around the acetabulum this is called a Pincer Lesion. If you have both we call this a combined lesion. Many times this can be treated conservatively with physical therapy (mostly stretching and hip strengthening), a cortisone injection and activity modification.
If the pain continues, treatment can be done by surgeons that specialize in hip arthroscopy. If left untreated damage to the labrum (cartilage that surrounds the acetabulum) can occur, causing hip stiffness and pain, and can lead to arthritis over time.