Femoro-acetabular impingement and hip pain with conventionally normal x-rays

There has in recent years been a fundamental change in the understanding of hip pain in the young adult and hip pain without plain radiographic findings of arthritis. Pain in these groups has long represented a diagnostic and therapeutic challenge. With new appreciation of hip biomechanics, pathological processes and the arrival of modern imaging modalities we now have a greater understanding of non-arthritic hip pathology. One of the commonest yet least well recognized 'new' diagnoses around the hip is femoro-acetabular impingement (FAI). FAI is a developmental condition of the hip joint that is associated with abnormal anatomical configuration and thus joint mechanics on either the femoral or acetabular sides or both. It is hypothesized to have a variety of precipitants and may ultimately lead to labral and chondral injury and what has previously been referred to as 'primary' or 'idiopathic' hip osteoarthritis.