(a) Intraoperative image of hip arthroscopy of a 42-year-old male patient operated for femoroacetabular impingement (FAI). The assessment of the cartilage in the acetabulum (Ac.) shows an extensive unstable focal lesion in the anterolateral region near the acetabular labrum (La.). (b) The evaluation with a probe shows complete instability of the full-thickness chondral flap as well as exposure of the subchondral acetabulum bone (arrow).