Sports Medicine Research: In the Lab & In the Field: Cam-Type Femoroacetabular Impingement in Youth Ice Hockey Players (Sports Med Res)


Friday, May 24, 2013

Cam-Type Femoroacetabular Impingement in Youth Ice Hockey Players

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

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


Kelsey Croak said...

Often times we look at adolescent athletes as being very resilient and quick to recover from injury. The point was made that as athletes get older, time and continuance of sport exacerbate pathologies. With FAI it is difficult to determine if the pathology is caused by a boney abnormality or overuse, especially if the athlete is asymptomatic. I agree that the issue here are we able to prevent these types of injuries form occurring. Should early prevention programs consisting of strength training, proper technique and stretching exercises should be incorporated into regular practice schedule?

I am wondering in the course of this study did you happen to look at how long these athletes had been playing in correlation with presence of pathology? Could it be that year round participation in the same sport could be part of the problem?

Meghan M. Miller said...

Thanks so much for your comment, Kelsey. I think you raise a great point about not having the ability to recognize these issues until they become problematic. As this is a new diagnosis, there is little to no prospective literature examining prevention programs. Early speculation would suggest just what you are...strengthening, proper form, and range of motion. It's unclear if these elements would prevent pathology, but they certainly would not cause a negative affect.

I provided the summarization of the original article, but was not involved in the original research. Therefore, I cannot directly speak about the unpublished results of this study, although those descriptive statistics would be interesting to analyze. I do believe that you pose another excellent point with regard to sport specialization at young ages. This association has been discussed with other overuse injuries seen in skeletally-immature athletes. Without prospective examination, it is difficult to definitively answer your question. However, these are interesting points that should be further explored in the literature.

Catherine LeBlanc said...

I also agree with Kelsey. Specialization within sports like football and ice hockey may be a larger component to significant bony abnormalities like CAM lesions. It would be interesting to take a look to see if the ice hockey athletes within the study had been participating year round for several years. As far as I know, it is more difficult to practice skiing year round at the same intensity as ice hockey.

I wonder if maybe clinicians should consider incorporating some rehabilitative exercises that are not as sports specific to provide more variation to the athlete to attempt to prevent overuse pathologies associated with specialization.

Meghan M. Miller said...

Thanks for your comment, Catherine. It's very true that the hockey players may have more opportunity to specialize than skiers, though this point was not mentioned in the article. You make an interesting point with regard to less specific rehabilitation exercises. It is hard to say definitively if less specificity would help prevent the onset of FAI, as the etiology is yet to be fully understood. However, it makes sense to say that broader training and rehabilitation would help reduce overuse syndromes, such as FAI.

Jake Meyer said...

These are all interesting findings and comments. I had commonly associated FAI with some sort of overuse component that was more muscular driven, but I had not really ever thought too much about a boney deformity (potentially caused from overuse in skeletally immature athletes) that may be a possible contributor to this impingement, but it makes some sense!

As far as prevention goes, it seems to me that these injuries can be prevented in the skeletally immature athlete by resting them. It seems like these boney deformities do not happen acutely, but more of an insidious onset microtrauma-type mechanism and maybe present with some early signs of pain and discomfort. We need to start moving away from the notion that we are going to push these young athletes through pain. Maybe this pain that they are feeling is not a muscle burning type of pain that we get when we work our muscles, but maybe the pain is actually something more serious. Once these boney deformities are present, it seems logical to think that the likelihood of preventing chronic hip pain is very low.

As more and more cases of FAI are coming to light, it seems that clinicians are becoming better educated on this issue and are starting to catch these injuries before they become debilitating. I hope that, because of what seems to be an increase in FAI diagnoses, clinicians do not begin overlooking other injuries, such as sports hernia, which may present with very similar signs and symptoms.

Meghan M. Miller said...

Thanks for your comment Jake. Avoiding repetitive trauma in the young athlete is extremely important, but with the activity level of youth, equally as difficult. I think that such injuries underline the importance of teaching proper technique above all else at early ages. With kids participating in organized sports at younger ages, it is imperative they learn correct form before advancing the skill. Form drills are often utilized solely as warm-up exercises performed with less than maximal effort. Adding these drills into conditioning or rehabilitative programs may help stress fundamentals and, in turn, help reduce these types of injuries.

Unknown said...

Sport specialization is becoming a more common occurrence among young athletes. I think that these overuse injuries and conditions such as FAI are strongly related to specialization. Studies have shown that overuse injuries are not necessarily connected to the amount of time spent playing a sport, but rather the repetitive motions performed by an athlete who only plays one sport. Performing the same motion over and over during childhood can impede on the development of proper neuromuscular control, which aides in preventing injury.

In hockey, skating is an abnormal motion for the hip. The hip is designed to perform in the sagittal plane such as walking or running. Any deviation outside of this plane places the hip in a more unstable position. With skating, the combination of internal rotation with flexion and external rotation with abduction puts the hip in a very vulnerable position. How often hockey players put their hips in this position creates a very high risk for injury.

I think one way to decrease the prevalence of FAI and overuse injuries in youth athletes is to discourage early sport specialization. Encourage kids to participate in multiple sports during their younger years in order to properly develop their neuromuscular control before they decide to focus on a single sport.

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