Radiographic Prevalence of Femoroacetabular Impingement in Collegiate Football Players: AAOS Exhibit Selection
Kapron AL, Anderson AE, Aoki SK, Phillips LG, Petron DJ, Toth R, Peters CL. J Bone Joint Surg AM 2011;93:e111(1-10)
In recent years, an increase in diagnosis of femoroacetabular impingement syndrome (FAI) has been seen in athletes. It has been suggested that increased stress applied to developing bones of adolescent athletes may initiate bone remodeling and osteophyte (bone spur) formation, causing abnormalities associated with FAI. These abnormalities, when paired with repeated joint stress, may increase the occurrence of hip pain and labral tears seen in athletes (e.g., football players). The purpose of this study was to use radiographic imaging to quantify the prevalence of FAI in asymptomatic football players. Sixty-seven Division IA football players agreed to participate; each hip was examined separately. Each player filled out a questionnaire based upon the Hip Outcome Score survey on the same day that their hip radiographs were performed. Nearly every subject reported a score of 90% or better; indicating that all but one of the football players were asymptomatic. Anteroposterior and frog-leg views were used for anterior and lateral inspection, respectively. Two orthopaedic surgeons independently evaluated the images and assessed five anatomical measurements that characterize the shape of the femoral head and neck. Cut-off values were specified for each of the 5 measures; each hip either exhibited a sign of FAI or didn’t (see the article for additional information regarding the two forms of FAI). At least one sign of FAI was seen in 95% of hips. When an anatomic abnormality associated with FAI was detected in a player it occurred bilaterally in more than 48% of players (three of the abnormalities, when present, occurred bilaterally in more than 80% of the players with the abnormality).
These results suggest that collegiate football players presenting with hip pain should be evaluated for bony abnormalities to determine if FAI is the underlying cause. As the body mass of football players is different than that of other sports, it would be interesting to see this study conducted in a different population of high-level athletes. Studying the prevalence of FAI in other athletic populations may help explain the role of body mass, repetitive loading, and age at the onset of competitive sport participation. One thing uncontrolled for was the position of the pelvis. As pelvic tilt may affect bony alignment, it would be of interest to compare the prevalence results of this study to one in which pelvic positioning was controlled for. Have you seen an increase in the number of FAI cases you treat? What other sports seem to have a high prevalence of FAI cases?
Written by: Meghan Miller
Reviewed by: Jeffrey Driban
Kapron AL, Anderson AE, Aoki SK, Phillips LG, Petron DJ, Toth R, & Peters CL (2011). Radiographic prevalence of femoroacetabular impingement in collegiate football players: AAOS Exhibit Selection. The Journal of Bone and Joint Surgery. American volume, 93 (19) PMID: 22005872
Great post Meghan, what are your thoughts regarding that 95% of the x-rays showed at least one sign of FAI? It would appear that x-ray finding of FAI occur often in asymptomatic patients? Is it possible that the bony abnormality associated with FAI is not the cause of their pain in symptomatic patients? Similar to the issue with low back pain that many asymptomatic folks have disc bulges or herniations so it may not be the pain generator. What are the outcomes post FAI surgery? Does the bony abnormality of FAI cause other issues (glute inhibition, decrease glute control or other hip stabilizers) that is the real cause of the pain and dysfunction and not the FAI?
Thanks so much for your comment, Dustin. With regard to the 95% positive x-rays in assymptomatic athletes, it certainly suggests that the prevalence of FAI does not directly imply dysfunction. It seems likely the bony abnormalities seen with symptomatic FAI may not have always been present, but rather remodeled in this fashion due to the joint stresses produced from football participation (excessive flexion). One possibility is that the 95% positive x-rays, though currently asymptomatic, could become problematic in the future as repetative trauma cumulates with continued high-level activity. With regard to post-surgical outcomes, current literature only provides qualitative patient reported outcomes, which have been reported favorably. As far as other possible causes, those are areas yet to be studied and merely speculative at this time.
Meghan M. Miller
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