The ridiculous truth about femoral acetabular impingement diagnoses

A while back, I wrote a long post about femoral acetabular impingement (FAI) and how I think the diagnosis sounds shaky beyond belief. I presented you with some research evidence that showed just how ridiculous it is to base a diagnosis off radiological findings. I also made a video that talked about FAI and how, again, I think it’s a load of crap.

I got a lot of feedback from a lot of people. The feedback ranged from “I think you’re totally right…can you help me?” to “IF YOU HAVE FAI YOU SHOULD GO GET SURGERY BECAUSE THAT’S WHAT MY DOCTOR SAID.”

One of the most interesting pieces of feedback I got was from a radiologist who makes the FAI diagnosis on a daily basis. He said, “I too think FAI is a bunch of voodoo crap, even though orthos make me look for it every day.” He said other things as well, but that pretty much summed things up for me and encouraged me to look even deeper.


I’ve been occupying my time still putting out YouTube videos to explain and help people who have hip issues (and you can watch here). I’ve also been doing a lot of research into the FAI diagnosis, because everything I’ve seen and experienced tells me the diagnosis makes no sense, and I’m going to share some more evidence of that with you today.

If you read the first post on FAI, you will recognize the diagnostic process:

You have pain in your groin and you can’t flex your hip fully. You see a doctor. He says to rest it. It doesn’t improve (may even get worse since sitting is known to actually makes things worse). You go back to the doctor. He gives you NSAIDs. You rest more. It still doesn’t improve. You go back and the doctor (the same one or possibly a new specialist) does an X-ray or MRI and sees a labral tear and possibly some wear and tear on the joint surfaces.

You have pain and range of motion restriction, and you want an answer. The doctor needs to give you some kind of diagnosis! Abracadabra!

YOU HAVE FAI! There you go! Now go sand off part of your hip joint.

So that’s the diagnostic process in a nutshell. There are plenty of places where it falls apart and just ends up seeming ridiculous.

First, of course, is the radiological findings. My first post on FAI talked about how reliable the x-ray/MRI route is. So if you want to hear about that, read that.

This post is more about the range of motion tests, namely the anterior hip impingement test or the FADIR.

I’ve had people tell me that they’ve been diagnosed with FAI and that the doctor says that the pain they experience with hip flexion and internal rotation (FADIR test) is because the labrum is being pinched and smashed. Anyone who’s gotten the FAI diagnosis knows this test. I have one client who had this done, and it actually made his asymptomatic hip start hurting (we’re working on fixing that with proper retraining).


As someone whose job it is to know where muscles attach and where things get uncomfortable, I have long found this labrum assertion hard to swallow. As someone who has spent his free time pulling his groin in multiple ways (you try playing ice hockey goalie for a few years with no understanding of how your body needs to be cared for and see how you do), I knew it was B.S. We have multiple muscles that attach in the groin that can easily be smashed, pinched, overworked, and just plain annoyed — to speak NOTHING of a labrum. To say that pain from the FADIR is definitively from a labral tear is a very odd degree and direction of wishful thinking. That’s like saying you could never have a sore or irritated shoulder muscle, and that any pain near your shoulder joint must be from the labrum being torn.

Sound stupid?

That’s because it is.

But that was just my own opinion. I figured nobody would bother to study this. I knew I wasn’t going to take the time and money to do a study on that (because I have neither the time nor the money).

Well, we’re in luck!


A 2011 article in the British Journal of Sports Medicine titled: Prevalence of radiological signs of femoroacetabular impingement in patients presenting with long-standing adductor-related groin pain goes over the relationship between groin pain, radiological findings (x-ray/mri), and range of motion tests.

Dr. Weir in the Netherlands and his team of researchers set out to determine how reliable the diagnostic process was for FAI. They wanted to see if the range of motion tests, radiological findings, and groin pain matched up to produce reliable diagnoses.

Basically, if the story of FAI is true, what they should have found was that someone with an x ray that shows FAI would also have range of motion problems and would have pain.


That’s what they should have found if the FAI diagnosis makes any sense.


Here’s how they started: 34 athletes with groin pain (inner thigh near the pubic bone). They had clinicians assess them on range of motion tests and then other clinicians assess their x-rays for signs of FAI.

Each person has two hip joints (good!) for a total of 68 hip joints to assess. 64 of those hips (94% of them!!) had x-rays that had indications of FAI. Well, all these athletes with groin pain must have FAI! Right? Because the x-ray is always right, right?


Only 9 hips tested positive in the anterior hip impingement test.

There was no relationship with the number of radiological signs. There was no correlation between hip ROM and the number of radiological signs.

“Wait, wait, wait!” you say. “How could there be no relationship between the x-rays and the range of motion?! How could you say someone has FAI if there is no correlation (let alone causation) between what’s in the x-ray and how the person moves?!”

And I would say, “You CAN’T say someone has FAI because the diagnostic criteria make no sense!” And then I would quote this same study:

To our knowledge, the validity (OF THE ANTERIOR HIP IMPINGEMENT TEST) has not been examined in patients with extra-articular causes of groin pain. The movement performed during the test could also cause movement and stress at the pubic symphisis, which is one of the possible sources of pain in patients with chronic adductor-related groin pain. The motion may also twist and compress the iliopsoas muscle which has been reported to be a secondary source of pain in many patients presenting with adductor-related groin pain. Until the validity of the anterior hip impingement test has been further examined, it should be interpreted with caution…

So what does that all mean? Extra-articular causes of groin pain is “science” for causes of pain that are not in the joint. That is in contrast to FAI. FAI is a diagnosis that means your pain is from inside the joint (intra-articular).

But these guys are saying that pain can be caused from elsewhere, not JUST the joint. And they spell it out for you: muscles can get compressed and irritated and smashed up against the pubic bone. I would say there are some other motor control issues that will contribute to this pubic bone smashing, but that’s beside the main point.

This is simply not a reliable test.

And moving on to the conclusion of the study…

Radiological findings of hip impingement are often present without the anterior hip impingement test being painful. The anterior hip impingement test may not be specific for femoroacetabular impingement. Clear diagnostic criteria for femoroacetabular impingement and other causes of groin pain are needed.

Translation: we can’t reliably diagnose FAI in ANYONE 

Unfortunately, when you’re a doctor, you need to make a show of some kind of diagnosis based on something, and the anterior hip impingement test is pretty much all you can do while still looking like you know what you’re doing. You can provide a definitive “it’s FAI!” and send your patient to treatment…Even if the treatment is worse (or certainly no better) than the problem itself.

I’ll leave you with one more quote from the middle of the study that I find remarkably telling:

There was no association between the number of radiological signs and the anterior hip impingement test being positive. In fact, the two hips with the highest number of radiological signs of FAI had a negative anterior hip impingement test.

The diagnosis doesn’t make sense.


About the Author

Matt Hsu is a trainer and orthopedic massage therapist. He fought a long battle with chronic pain all over his body and won. He blends the principles he learned in his journey, empirical observations with clients, and relevant research to help others get their lives back.

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