From anatomical curiosity to mechanical disease: the history of femoroacetabular impingement

The concept of femoroacetabular impingement (FAI) has fundamentally changed our understanding of hip pain and early osteoarthritis in young adults. Although first formally described in 2003, many of the anatomical observations and surgical principles underlying the concept were recognized decades earlier. This narrative review traces the historical evolution of FAI from the earliest anatomical descriptions of femoral and acetabular abnormalities in the late nineteenth century through the development of surgical hip dislocation, which enabled direct visualization of dynamic mechanical conflict within the hip joint and ultimately led to the formulation of the FAI concept. The review highlights early observations of cam-like deformities, acetabular version abnormalities, and pioneering hip-preserving procedures performed long before the pathomechanical significance of these findings was understood. It also discusses the shift from the traditional concept of primary osteoarthritis to a mechanical model of hip degeneration and examines how the original concept has evolved through advances in arthroscopy, three-dimensional imaging, and increasingly individualized assessment of hip morphology and biomechanics. The history of FAI shows that transformative advances in orthopaedic surgery often arise from the integration of previously disconnected anatomical, radiographic, and surgical observations into a unified biomechanical framework. More than 2 decades after its introduction, the FAI concept remains the cornerstone of contemporary hip-preserving surgery and continues to shape research into the prevention and treatment of degenerative disease of the young adult hip.