(1a–1d) Overview of arthroscopic progression of chondral damage. In early stages of joint damage, a chondro-labral instability (chondromalacia, 1a) occurs in the anterolateral part of the acetabulum. The impact of the femoral bump leads to a disruption at the chondro-labral union (1b) or to degenerative lesions of the labrum. With the progression of the joint damage, chondral flaps were created toward the central area of the acetabulum (1c and 1d). Until these flaps do not reach the load-bearing surface, these damages can be considered early stages of osteoarthritis and satisfactory outcomes with hip arthroscopy can be expected. (1e and 1f) More advanced stages of osteoarthritis lead to thinning and ulceration of the cartilage in the acetabulum load-bearing surface (1e, white arrow), progression of degenerative cartilage damage of the femoral head (1e black arrow), and formation of osteophytes (1f). These advanced lesions should be considered beyond effective treatment with hip arthroscopy.