Explanation:
Cam-type femoroacetabular impingement occurs due to an aspherical femoral head that reduces the head-neck offset. During hip flexion and internal rotation, the abnormal femoral head impinges on the acetabular rim. This leads to labral tears and cartilage damage. Arthroscopy often reveals chondrolabral separation at the anterosuperior acetabulum. Surgical treatment involves osteoplasty to restore normal head-neck offset. Early recognition prevents progression to osteoarthritis. Reference: Ganz R. "Femoroacetabular Impingement: A Cause for Osteoarthritis of the Hip." Clinical Orthopaedics and Related Research, 2003.