We work with a lot of clients who have been told they have hip impingement (otherwise known as femoroacetabular impingement / FAI). We’ve seen people with this diagnosis improve their hip function without surgery, and this has made us look deeper into the diagnosis.
In this article, we’re going to look at the FADIR test. The FADIR test is one of several tests doctors use to arrive at the hip impingement diagnosis. But how useful is it really?
Read on to find out.
A while back, I wrote about femoral acetabular impingement (FAI) and the shoddy science behind it.
To get an overview of the problems with the diagnostic process and how FADIR fits in, check out the following video.
FADIR - the big hip impingement test...
FADIR stands for “Flexion - ADduction - Internal Rotation”. It’s also known as “anterior hip impingement test”. Theoretically, if this test is painful, you have FAI. That sequence of movements smashes the labrum and causes pain. Theoretically.
But there’s a catch. We have multiple muscles that attach in the groin and can easily be smashed, pinched, overworked, or just plain annoyed — to speak NOTHING of a labrum. That sequence of movements can trigger pain from muscles as well.
And the science is pretty clear. Your FADIR test results have no link to having a labral tear or femoroacetabular impingement bone shapes.
That may seem like a big claim, but it's in line with findings in high quality research studies for shoulders and the spine.
You can have a labrum tear in your shoulder, and it won’t necessarily cause you pain. The same is true in the hip. You can have labral tears and NO pain whatsoever. The science is very clear on that.
...But in a medical setting, if you have a hip labral tear and/or abnormal bone shape AND a positive FADIR, doctors will claim you are the perfect candidate for hip surgery.
But does FADIR actually identify hip impingement?
Let's see what the science REALLY says about FADIR.
A 2011 article in the British Journal of Sports Medicine looked at the relationship between groin pain, radiological findings (X-ray/MRI), and range of motion tests.
The researchers wanted to determine if ROM tests (like FADIR), X-rays, and pain matched up to produce reliable diagnoses of hip impingement.
Based on the current hip impingement medical model, if you have an X-ray showing FAI, you should also have range of motion problems and groin pain. FADIR should show a problem. Simple.
What the hip impingement study on FADIR actually found
Here’s how they started: they gathered 34 athletes with groin pain (inner thigh near the pubic bone). A group of clinicians assessed them on ROM tests. Another group of clinicians assessed their X-rays for signs of FAI.
The people with the “worst” FAI bone shapes didn’t even have pain on the FADIR test!
From the total of 68 hip joints, 64 (94% of them!) had X-rays with indications of FAI.
All these athletes with groin pain must have FAI, right? The X-rays show it. So they will fail FADIR.
Only nine hips tested positive for the FADIR test.
There was no relationship with the number of radiological signs. There was no correlation between hip ROM and the number of radiological signs.
More simply: FADIR didn’t have anything to do with the presence of FAI bone shapes.
Even more simply: FADIR was pointless.
Quoting the study:
(...) 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.
So what does that all mean?
There was no link between FADIR and FAI bone shapes. Zip. Zero.
The people with the “worst” FAI bone shapes didn’t even have pain on the FADIR test.
Can FADIR predict hip impingement?
Another study published in the Journal of Science and Medicine in Sport in 2018 takes a look at the FADIR test as well.
These researchers wanted to know if the FADIR could detect "abnormal" FAI bone shapes. They compared the FADIR outcomes to MRI’s from 74 youth male ice hockey players.
The athletes had ages between 13-20 years old. They had an average playing experience of 11 ± 2 years. None of them had any hip diagnosis or previous hip surgery. These players did not have hip pain.
The idea behind this study was that if the FADIR produces pain, the player should have FAI signs on the MRI.
Wait, why young ice hockey players for this FAI study?
Surgeons have long pushed the idea that hockey players have hip impingement in high numbers. The prevalence of cam morphology is reported to range between 45% and 75% in ice hockey players. (Note: this is actually not any higher than in the general population, but surgeons don’t talk about that).
Hockey is a high impact, highly demanding sport for the hips. Surgeons claim this overload can allegedly produce a femoral-bone adaptation, i.e. cam morphology.
So young ice hockey players are supposedly at high risk for developing FAI symptoms as a result of these bone shapes.
How accurate was the FADIR test for hockey players?
Well, from those 74 hockey players:
- Only 7 had a positive FADIR and an abnormal shape shown in the MRI. The test could predict only 7 out of 74. That's 7 true positives.
30 had a positive FADIR and a normal bone shape. That's 30 false positives.
- 10 had MRI findings of abnormal shape, but no pain with the FADIR. The test failed to predict 10 abnormal shapes. That's 10 false negatives.
- 27 didn’t have pain with the FADIR and had a normal bone shape. That's 27 true negatives.
WOULD YOU TRUST THIS TEST?
The FADIR had a 40% false positive rate. And it was only able to accurately identify FAI bone shapes 9% of the time.
There was zero link between the bone shapes and pain on this test.
To highlight the most salient point, the FADIR test had a 40% false positive rate. And a 9% true positive rate.
That means FADIR is totally useless in identifying "abnormal" bone shapes. It also demonstrates that the FAI bone shapes are NOT linked to pain!
Put another away: you can have the FAI bone shapes, no hip pain, and have no pain on the FADIR. That means the bone shapes are irrelevant AND the test is pointless.
Using a test like this to convince someone to get surgery is misguided at best and irresponsible at worst.
Bottom line: is the FADIR test reliable for hip impingement?
Short answer: FADIR is NOT reliable as a hip impingement test. If doctors and therapists want to act on the best available evidence they should abandon this as a clinical tool.
From the first 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: Having FAI bone shapes has no relationship to a positive or negative FADIR test. It's NOT reliable for diagnosing hip impingement.
From the second study:
The FADIR test is inadequate for screening cam and pincer morphology in youth ice hockey players without diagnosed hip disorders (...). Future studies should investigate the accuracy of other hip examination tests (...).
Translation: FADIR isn’t reliable for predicting abnormal bone shapes. It’s not reliable for diagnosing hip impingement.
And, when you look deeper, you discover that NONE of the tests for hip impingement work - and that there’s very little evidence for the entire theory!
In the end, we’re left with a lot of medical tests and images that create the illusion of the need for surgery.
Our (non-medical) advice if you have hip pain?
Tread carefully. The medical model of hip pain drives people toward injections and eventual surgery. This tendency is driven by surgeons' biases and is not backed by evidence.
The real answer is to learn how to retrain your muscles for proper motion and function. That is the simplest, least invasive, and natural means to reclaiming your life.
Is surgery guaranteed to help you with hip pain?