Hip impingement occurs when the ball and socket of the hip joint don't fit together properly. The restricted motion damages cartilage and can cause pain and arthritis in young adults.
In some cases, the ball is too misshapen to fit properly into the socket. Sometimes, the exterior edge of the socket extends to the point that it covers too much of the ball. Hip impingement also can be caused by a combination of these two problems.
Most people with hip impingement experience pain in the groin area during or after flexing the hip, as when running, jumping or sitting for a long time. You may also have difficulty flexing your hip beyond a right angle.