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.

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

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”?

for Discussion: How can we prevent cam deformities and the risks they infer in
clinical practice?

Written by:  Meghan Maume Miller
Reviewed by: Jeffrey

Related Posts:

Philippon, M., Ho, C., Briggs, K., Stull, J., & LaPrade, R. (2013). Prevalence of Increased Alpha Angles as a Measure of Cam-Type Femoroacetabular Impingement in Youth Ice Hockey Players The American Journal of Sports Medicine DOI: 10.1177/0363546513483448