**1. Introduction**

Hip arthroscopy requires a thorough knowledge of acetabular and pelvic anatomy. Acetabular and pelvic anatomy is complex yet important for any procedure to be done on hip joint. The articular surface of acetabulum can be visualized as being supported between the limbs of an inverted "Y". These two limbs are considered anterior and posterior columns of acetabulum. On radiographic view, anterior column is represented by iliopectineal line and posterior column by ilioischial line. Discontinuity in any of these lines is considered fracture of anterior or posterior column. The external iliac and internal iliac arteries lie in close relation to these columns. An anomalous connection of these two arteries called circle of death or corona mortis should be identified and ligated properly as injury to this artery can lead to catastrophic results. Lumbar plexus and its various nerve roots traverses the lesser and greater sciatic notches and are vulnerable to injury in portal placement and various other hip surgeries. This chapter mainly focuses on various aspects of surgical anatomy of acetabulum and biomechanics relevant to hip arthroscopy in detail.
