Pincer-Type Femoroacetabular Impingement (FAI)

Pincer-type impingement is a condition characterized by abnormal contact between femoral head–neck junction and acetabular rim causing labrum and cartilage degeneration; over time these morphologic changes might end up in early hip osteoarthritis (OA). It occurs predominantly in young and active women, but not all patients with radiographic signs of pincer-type impingement will be symptomatic. We describe two main types: primary pincer-type impingement, that includes focal anterior overcoverage (i.e. focal retroversion), relative anterior overcoverage (i.e. global retroversion), and global acetabular overcoverage; secondary pincer-type impingement comprising subspine impingement. Diagnosis requires a triad of symptoms (i.e. groin pain), clinical signs (i.e. positive FADDIR test) and imaging findings (i.e. radiographic signs and measurements). Complementary studies like magnetic resonance imaging (MRI) and computerized tomography (CT) scan are necessary to show soft tissue damage and bone morphology abnormalities. First line of treatment is non-operative and includes physical therapy, activity modification, anti-inflammatory medication and eventually corticosteroid infiltration. If the first line of treatment fails, the next step is surgical management: hip arthroscopy, surgical hip dislocation, or reverse periacetabular osteotomy (PAO) depending on each specific case. Long-term outcomes are good to excellent when treatment modality is selected according to each patient’s characteristics.