FAI, or femoro acetabular impingement, is a hip “abnormality” in the shape of either or both of the femoral head and acetabulum. If you have it, or suspect you have it, you’re probably relatively young (seemingly too young for hip problems), and you’ve probably been dealing with hip and/or groin pain for a while without knowing what was going on, until someone finally came up with FAI.
I was diagnosed with it in 2007 after almost two decades of on-again, off-again hip pain and dysfunction. Since then, I’ve read a lot, chatted with many people who have it, and have trained many clients with it. I recently wrote briefly about my own experience with FAI, and have also written an at-home exercise ebook for FAI (Coming in November!).
As more is known about FAI, more research is being published. I’ve pulled out five particularly interesting facts (or so I think) from the research, and have included my interpretation of them and their potential relevance. Enjoy, and please ask questions in the comments and I’ll get to them as soon as I can. One note: use of the term “young” in this post refers to people under the age of fifty. Funny how our concept of “young” changes as we age! With respect to hips and FAI, studies tend to focus on people under fifty.
Fact #1: FAI is much more prevalent among men than women, with studies suggesting anywhere from 14% to 24% occurrence in young men with asymptomatic hips , but only 6% in young women with asymptomatic hips.
Interpretation: FAI is a real thing, even among people with no symptoms. The question is, what does it mean? If someone has FAI but has no symptoms, should we do anything about it? Take my hips for instance. I had twenty years of hip pain in my left hip, and zero years of pain in my right hip, but I have FAI in both. My sense as a trainer is that it’s important to recognize that not all hips are built “to spec” and that the two biggest areas where we should keep FAI in mind are in relation to stretching and squats. With hip stretches, I keep tabs on whether it causes pain or discomfort. If it does, I’m going to tend to assume we’re pushing into a bony end range (maybe FAI; maybe another hip structural anomaly), and I’m going to back off that stretch. I’ll talk about squats down a few facts.
Fact #2: FAI is twice as common among men with limited hip internal rotation as those with normal hip rotation range of motion.
Interpretation: I think an important question to ask about this finding is whether FAI is more common in the presence of reduced internal hip rotation, or whether reduced internal hip rotation is an early sign of FAI. Either way, I think the take home is similar to the take home for fact#1: If someone has limited hip internal rotation, there might be a structural contribution, so be careful with your efforts to increase internal rotation range of motion. In fact this might be a situation where seeking input from a good physical therapist, athletic therapist, or chiropractor would be in order.
Fact #3: “We performed a database review of pelvic and hip radiographs obtained from 157 young (mean age 32 years; range, 18-50 years) patients presenting with hip-related complaints to primary care and orthopaedic clinics…At least one finding of FAI was found in 135 of the 155 patients (87%)”
Interpretation: Yikes! 87% of young, symptomatic hips had FAI? I think the take home here is obvious: Don’t ignore comments of hip pain. Perhaps this is a good reminder that the body is pretty good at telling us when something is wrong, if we’re willing to listen. I always hate to suggest this, but feel I would be remiss if I didn’t: If your hip hurts after you play your chosen sport, maybe you should question whether playing that sport is appropriate for you? That’s not to say that if something hurts a bit, you should stop playing. Definitely not! But if your hip constantly hurts during or after a specific activity, despite having spent months (or years in my case) with a manual therapist and a good training program, maybe your body isn’t built to do that activity. For me, this brings a flashback to the 2007 Canadian Ultimate Championships, and me sitting in the stands between games with a big bag of ice on my left hip while snacking on vitamin I (Advil). Note I did this “in between games”; not after stopping playing because my body was clearly telling me that I was damaging my hip. So yes, this is me suggesting you aim to be smarter than I was.
Fact #4: People with FAI have less range of motion in body weight squats than do people without FAI.
Interpretation: People who have FAI probably shouldn’t squat. How can you tell? Is it painful? Does your pelvis shift to one side during the squat? Do you start to round your back at the bottom? These are signs that you lack the range of motion or stability required to squat so your body is finding alternative ways. If you see this, try to fix it, and if you can, great. But if you can’t fix it, then you are probably someone who shouldn’t squat. Thankfully it is possible to be awesome without squats in your workout.
Fact #5: Hockey players have a higher prevalence of FAI than do skiers and soccer players, and the rate increases as they move up, with particularly high levels noted at the midget level.
Interpretation: FAI might be something people develop in response to biomechanical forces? And it would appear that there is something in the way hockey players skate that produces higher rates of adaptation. It would be interesting to see if similar numbers are seen in figure skaters, to see if it is a skating thing, or if it is a skating with the torso in a flexed position thing? In terms of what I suggest, I need to disclose that I have a conflict of interest: I am Canadian. And that means I can’t suggest that someone consider not playing hockey, because I don’t want to have my passport revoked. But you may want to re-read fact #3.
If you have FAI, are you a hockey player? How’s your hip internal rotation? How does your squat look? Do squats cause hip pain? Do you keep doing them anyway? It’s interesting to think that our bones change in response to our activities. That may seem revolutionary, but in fact it’s a long-known truth. In fact it’s even got a name: Wolff’s Law. I’ll talk more about Wolff’s Law in the next FAI post, sometime in the next few weeks. And I’m very excited to be launching my new ebook: Training Around Injuries: At Home Exercises for FAI in November. Did I mention it’s a video-embedded ebook?
If you want to be notified when more of my FAI blog posts come out as well as when the FAI ebook comes out, sign up for the Training Around Injuries mailing list. As with all my stuff – I’ll keep it spam-free.
 KA Jung, et al, “The prevalence of cam-type femoroacetabular deformity in asymptomatic adults”, The Journal of Bone and Joint Surgery, 2011.
 Michael Leunig, “Basic and Clinical Science Advances in Understanding FAI”
 Leah M. Ochoa et al. “Radiographic Prevalence of Femoroacetabular Impingement in a Young Population with Hip Complaints Is High”, Clin Orthop Relat Res. Oct 2010,
 Mario Lamontagne, et al, “The Effect of Cam FAI on Hip and Pelvic Motion during Maximum Squat”. Clin Orthop Relat Res. 2009 March.
 Marc J Philipon Et al. “Prevalence of Increased Alpha Angles as a Measure of Cam-Type Femoroacetabular Impingement in Youth Ice Hockey Players”. Am J Sports Med 2013 Apr.