Prevalence of Increased Alpha Angles as a Measure of Cam-Type Femoroacetabular Impingement in Youth Ice Hockey Players
Philippon MJ, Ho CP, Briggs KK, Stull J, LaPrade RF. American Journal of Sports Medicine. 2013, Epub ahead of print.
Take Home Message: Evidence of increased alpha angles has been shown in ice hockey players as compared to non-hockey playing matched controls. Even at young ages, signs of bony abnormality linked to femoroacetabular impingement are present.
Femoroacetabular impingement (FAI) is a common radiographic finding among athletes participating in sports requiring hip flexion, hip internal rotation, and repetitive cyclic motions. Cam-deformity FAI is marked by the aspherical shape of the femoral head, and is radiographically defined by an alpha angle > 55˚. Hockey players employ a skating pattern that is suspected to cause cam-deformity but it remains unclear how common cam-deformities are among asymptomatic young ice hockey players. Therefore, Philippon and colleagues conducted a cohort study to determine how common a large alpha angle was among 61 youth hockey players and 27 youth skiers. The athletes were ages 10-18 years with no hip pain or history of hip surgery and underwent physical examination. After the physical screening, the athletes received a magnetic resonance (MR) imaging exam of their dominant leg’s hip. A radiologist reviewed the MR images for pathological hip abnormalities and measured the alpha angle. The authors found that 75% of ice hockey players versus 42% of skiers had an alpha angle > 55˚. Among youth ice hockey players, older players tended to have a larger alpha angle; but, this was not the case among youth skiers. For example, 93% of hockey players age 16 to 18 years had an alpha angle > 55˚ compared to 37% of hockey players aged 10 to 12 years. Hockey players that were 16 to 18 years of age were the only age group of hockey players to have chondral lesions (20% of players versus 8% of similarly aged skiers).
These results show an alarming trend in youth sports. Youth athletes appear to have an increased risk of bony abnormalities that may lead to cartilage damage, joint symptoms, and eventually osteoarthritis. This study is the fourth to be reviewed by SMR discussing the prevalence of FAI in youth athletics (see related posts below). The prevalence of cam deformity for the older aged youth hockey players is similar to that of collegiate football players, suggesting the pathology is exacerbated by time and continual load. This poses clinical questions such as “is this something that may be prevented” or “how do we target individuals for prevention”?
Questions for Discussion: How can we prevent cam deformities and the risks they infer in clinical practice?
Written by: Meghan Maume Miller
Reviewed by: Jeffrey Driban