Femoroacetabular impingement (FAI) has been increasingly recognized as a cause of hip pain in athletes at all levels of competition [1–6]. Despite the increased awareness, it continues to be an underrecognized cause of hip pain. In 2006, Burnett et al. published a study reporting that the average time for an athlete to receive an accurate diagnosis from the time of injury was 21 months and required evaluation by 3.3 different health-care providers [7]. Since then, there have been multiple studies demonstrating an increase in the incidence of FAI along with a concurrent increase in the use of surgical procedures [8, 9]. Studies have also demonstrated that a high percentage of asymptomatic patients have radiographs suggestive of FAI [10, 11]. This suggests that although significant investigational and educational advances have been made, further studies are needed to increase our understanding of the prevalence of FAI pathology.
FAI refers to the impingement which occurs due to an abnormal bony morphology of the proximal femur and/or the acetabulum [12]. Two distinct types of impingement have been described, the cam and the pincer [13]. Cam impingement occurs as a result of an abnormally shaped femoral head repeatedly impinging upon an acetabulum that cannot accommodate the increased radius of the femoral head [13, 14]. The primary pathology for pincer-type impingement, on the other hand, is the acetabulum with the resultant over-coverage of the femoral head leading to abutment of the femoral head–neck junction on the acetabular rim in flexion [13, 14]. Both pathologies can lead to labral tears and traumatic intra-articular injuries from repetitive minor trauma or acute injury such as hyperabduction, direct hip impact and joint subluxation or dislocation [15, 16]. Certain positions and motions have been purported as risk factors for hip injury, in particular, flexion combined with internal rotation [17, 18]. Our focus for this study will be on cam-type impingement.
