[Femoroacetabular impingement: association between the over-coverage and acetabular cartilage delamination areas].

BACKGROUND Femoroacetabular impingement (FAI), it is a clinical syndrome relatively recently recognized as source of hip mechanic pain and early osteoarthritis. Two types of FAI have been described, based on the bone morphology and pattern of chondral and labral damage; the cam type is frequently associated with chondral delamination; and the pincer type is associated with a contre-coup injury of the posteroinferior acetabulum. A close relationship between the zone of acetabular overcoverage or retroversion and the area of acetabular chondral delamination has been observed. OBJECTIVE To evaluate the relationship between the acetabular overcoverage or retroversion zone, and the cartilage delamination area; and if by treating the overcoverage zone, the cartilage delamination area itself is also treated. METHODS A prospective evaluation was conducted on 16 patients (17 hips) with FAI and chondral delamination treated with acetabular trimming and labral reinsertion, and femoral bump resection. RESULTS All cases had chondral delamination in the anterosuperior acetabular area, corresponding to the overcoverage or retroversion zone. In the 16 patients (94% of the hips) after the acetabular overcoverage bone resection, the remaining cartilage was stable and without delamination. Only one case (6%) required microfractures to treat the exposed subchondral bone after delaminated cartilage debridement. CONCLUSION The acetabular chondral delamination area has a very close relationship with the acetabular overcoverage zone, meaning that the delamination area can be treated by trimming the overcoverage zone.