Hip Impingement (FAI)

Hip impingement is a mechanical mismatch between the two moving parts of the hip joint, the femoral head and the acetabulum.  There are three types of hip impingement.  Cam Type occurs because of a lack of roundness of the femoral head and femoral neck junction.  This is the most common type.  Pinscher Type occurs because of over coverage of the acetabulum on the femoral head.  There can be a Mixed Type which is a combination of Cam and Pinscher types.  The mismatch of structure produces increased stress where contact occurs between the moving parts.  The repetitive stress causes degeneration of the acetabular labrum and eventually the articular cartilage, which is arthritis.  The symptoms of hip impingement include pain in the groin with hip flexion and with hip flexion with internal rotation. The pain is worsened by sitting for prolonged periods or activities with maximal hip flexion.  There can be an associated clicking or popping in the hip.  The treatment is directed at making the mechanical environment of the hip more normal.  This can be accomplished arthroscopically by recontouring the femoral head and neck junction in Cam impingement.  It can also be accomplished by reorienting the acetabulum with a periacetabular osteotomy in Pinscher impingement.