Femoral acetabular impingement: what you need to know and what your doctor won’t tell you

If you’ve been told you have femoroacetabular impingement (FAI, femoral acetabular impingement, or hip impingement), you have probably heard that arthroscopic hip surgery is the only answer. The conventional medical approach to hip pain associated with femoroacetabular impingement bone shapes is surgery, after all.

We’ve successfully helped countless people beat their hip pain without surgery - despite having femoroacetabular impingement bone shapes. In this article, we'll look at how this is even possible. And we'll see why you and your doctors should be skeptical of the entire theory of femoroacetabular impingement.


An overview of the medical theory of hip impingement

In short, surgeons claim that misshapen bones lead to reduced range of motion, increased bone on bone contact, and therefore higher levels of hip pain.

If a person complains of hip pain and physical examination tests (like FADIR) come back positive, they may have femoral acetabular impingement related pain. If X-rays and MRI show that the hip bones are of cam, pincer, or mixed morphology, then the bad bone shapes are definitively the cause of the hip pain.

A group of surgeons first introduced this theory in 2001 in a paper touting the benefits of a new hip surgery technique (Ganz et al. 2001). This technique allowed surgeons to fully remove the femur from the socket without catastrophic consequences. The surgeons claimed that the procedure successfully treated hundreds of cases of hip pain.

Over the next decade, many of the same surgeons published more papers, citing their own research papers as proof of their own theory (Siebenrock et al. 2003, Beck et al. 2005, Ganz et al. 2008). 

This created the appearance of rigorous scientific inquiry, but nobody seemed to notice some major problems with the theory. And, to this day, surgeons and other doctors continue to ignore clear evidence that the theory is not based on any solid scientific evidence.

tools for surgery


A little history on orthopedic surgeons and joint pain...

Pain in and around the joints historically has been the responsibility of orthopedic surgeons. Yes, there are some other specialties that do deal with joint pain (like rheumatology or physiatrists), but the most authoritative voices in "joint pain" are the orthopedic surgeons.

Orthopedic surgery as a field has an obvious bias to perform surgery. It's a practice that evolved from battlefield surgery tents in World War I and II - where swift and invasive surgeries save lives. 

Orthopedic surgeons look for structural deformities to correct. That makes sense in a battlefield tent. Shrapnel, a bullet, or a bone fracture could be threatening the life of a patient.  

In the world of chronic joint pain, orthopedic surgeons apply this same mentality. They look for a discrete structure that can be fixed through surgical means. 

If your hip hurts, it's because your hip is damaged. If your back hurts, it's because your spine is arthritic. If you shoulder hurts, it's because your bones are deformed. If your knee hurts, it's because the padding is torn and needs to be removed. 

But did you realize that those are all examples of ideas that have been proven to be false over time? That the medical community is trying to get away from those treatments because they are expensive, risky, and can make patients worse off? 

Recent research has consistently shown that pain often has nothing to do with the structures surgeons keep cutting.  

For more on this listen to: the Secret History of Joint Pain


The science on femoroacetabular impingement and hip pain

In 2008, a high quality study on over 4000 people came to a shocking conclusion. There was no link at all between femoral acetabular impingement bone shapes (cam or pincer type), dysplasia, groin pain, or hip pain. They found that 17% of men and 4% of women had the FAI bone shapes - and that it had no effect at all on their hip health (Gosvig et al. 2008).


Study after study shows there is simply no link between the bone shapes and the development of hip arthritis


  • Another study in 2010 found that the femoroacetabular impingement bone shapes were quite common in people with no hip pain (Reichenbach, et al. 2010). 25% of young men in Switzerland with no hip pain had femoroacetabular impingement bone shapes. And more recent studies with large numbers of people show the same thing.
  • High quality studies consistently find that there is NO link between the alleged femoral acetabular impingement bone shapes and pain or range of motion (Weir 2011).
  • The hip pain tests surgeon's use to justify surgery have been consistently shown to be unreliable at best. Several studies on the FADIR test have shown that the FADIR test is completely useless and the results are totally unrelated to femoroacetabular impingement bone shapes (Read more on the useless FADIR  and FABER tests here).
  • In another study, senior-age athletes with femoroacetabular impingement bone shapes had zero link to hip pain (Anderson et al. 2015). If a surgeon has ever told you "you MUST get surgery now or your hips will deteriorate in a few years," this should be reassuring. Even in these older athletes, the femoroacetabular bone shapes were irrelevant to their pain levels. 
  • Cam impingement had no relationship to the development of arthritis whatsoever. (Hartofilakidis et al. 2011).
  • And in still another study, pincer impingement was associated with a LOWER risk of hip arthritis (Agricola et al. 2013). 

Again, if a surgeon has ever told you "you MUST get surgery now or your hips will deteriorate in a few years," these studies should be reassuring. Study after study shows there is simply no link between the bone shapes and the development of hip arthritis. 

Here’s a simple analogy. Imagine a doctor living in Japan comes up with a theory that having black hair causes migraine headaches. To cure his patients, he cuts off their black hair with a straight razor. He reports excellent results. Based on this theory, he believes that if you have black hair, you will eventually develop migraines.

A rigorous study of the population shows that huge numbers of people have black hair and NO migraine headaches. And an overwhelming number of senior age Japanese with black hair never develop migraine headaches. So it’s highly unlikely that the black hair is the cause of the migraine headaches.

Even if the treatment of shaving off all the hair did work for a few patients with migraines, it would be due to reasons completely unrelated to the black hair. The theory of the black hair as migraine-cause would be completely debunked. 

Hip surgeons came up with a theory of hip pain that makes surgery the best and only treatment. But the science completely debunks the theory.


Why does surgery for femoroacetabular impingement work then?

First, we need to ask if femoroacetabular impingement surgery works at all.

performing hip surgery

In the early publications on hip impingement, surgeons claimed that the surgery was over 90% effective.

These were highly biased, low quality studies in which “success” was poorly defined and was not subject to outside verification. Luckily, some recent studies are a little less biased. We'll look at those in a second. 

There’s also the issue of money influencing research. Some highly-published orthopedic surgeons receive a great deal of funding from medical device manufacturers. These device manufacturers make the tools used in surgery.

They profit from every needle and every suture. They profit from every tube, retractor, or scalpel that gets used.

It's in their financial interest to promote surgery. Unsurprisingly, they give money to surgeons to do "research" and publish papers. This is similar to marketing efforts pharmaceutical companies used to pump up the use of opioids and conceal the true risks of opioid use.

The femoral acetabular impingement surgery wave started in 2001. Unfortunately, we don’t have data on how medical device industry money influenced research papers on femoroacetabular impingement until 2013. But since 2013, doctors in the U.S. have been required to report money they receive from pharmaceutical and device manufacturers.

So we can take a look at a couple of the most recognizable names in American arthroscopic hip surgery research papers and see their relationships to medical device manufacturers. It's quite easy to find financial relationships that incentivize these surgeons to strongly believe that more surgery is the answer to hip pain. 

Surgeon (click name for link to data source)

Device Manufacturer Payments (2013-2017)




Imagine: you’re a surgeon trained to do hip surgery, you’re paid to do hip surgeries, and a company pays you to tell the world that hip surgery is a good thing. You have no incentive to do research that might show that hip surgery doesn’t work.

If you do a study that shows hip surgery isn’t great, that’s your gravy train down the drain.

You have every financial incentive to publish papers that say hip surgery works - and that it works nearly all the time. 

But that’s not good science. (See an example of more bad hip surgery science here)

Even surgeons who don’t publish papers and don't receive industry money have a strong incentive to see their procedures as effective, even when patients tell them otherwise. We’ve heard countless stories where a patient tells the surgeon after the hip surgery, “my hip pain is the same.”

And the surgeon’s reply is some version of “The surgery was a success because we fixed the bone shape. If you still have pain, you might have a muscle issue or need more surgery somewhere else.” 


Both of these young adults got zero results from hip surgery. Their surgeons insisted that surgery was "successful." 


So is hip surgery for FAI effective?

So what does rigorous research on femoroacetabular impingement surgery say? Recent studies show that the success rate of femoroacetabular impingement surgeries is nowhere near 90%. Real satisfaction rates top out at around 66%.

But to date, nobody’s done rigorous research on hip arthroscopy for femoroacetabular impingement against a placebo. And there is a known placebo effect with orthopedic surgeries.

It has been observed clearly throughout orthopedic medicine history: real or fake surgeries often yield the same or similar benefit to patients. And the most invasive surgeries often have the strongest placebo effect. (Read more). ​

As surgeon and author Ian Harris puts it: “the real benefit from surgery is lower and the risks are higher than you or your surgeon think.” His book is well worth the read - Surgery: the Ultimate Placebo (affiliate link).


But hip surgery does work sometimes! 

We can't say that people don't EVER improve from hip surgery. Sometimes people come out of hip surgery for FAI and do feel better. That begs a very important question about FAI hip surgery: WHY DOES IT WORK SOMETIMES? 

Listen to "why does hip surgery work?"

Since bone shapes, joint space, and labral tears don't seem to correlate to hip pain, we need to look elsewhere for explanations. 

We could say "it's the placebo effect" and leave it at that, but that's probably not the entire picture. It would be too simplistic an answer AND probably wouldn't be accurate. 

The theory that seems to make the most sense is that the muscles are where the problem is.

And surgeries affect the muscles. 

Muscles hurt. Everyone has had sore muscles, aching muscles, irritated muscles. 

The hip joint is surrounded by muscles large and small. 

When surgeons perform hip surgery for FAI, they cut into some of the muscles, move some of the muscles out of the way, and then dislocate the femur from the socket. 

Suffice it to say that this is a lot of stuff happening to the hip muscles. And that alone would be enough to affect muscle function and sensation. 

Now is this hip surgery theory proven yet? Absolutely not. The only way to test this would be to perform sham hip surgeries in which the surgeons ONLY perform the surgery up to the point of dislocation and then do no shaving or "repairing" of alleged structural damage. 

And it's pretty unlikely a study like that will be happening any time soon. 


If surgery for hip impingement doesn’t work, how do you fix the hip pain?

First, don't let fear guide your actions. We've heard surgeons make fear-inducing statements like "if you don't do the surgery soon, your hip will deteriorate rapidly." Research shows this is a myth as you saw earlier. 

Our belief is that focusing on retraining muscles is the key. Muscles are the drivers of ALL movement.

Due to largely sedentary lives and the highly specialized/repetitive activities we all participate in (whether work or sport related), the hip muscles often become imbalanced. Read the book Move Your DNA (affiliate link) for a great primer on this topic.

When you do not use a muscle, it weakens. And there are a great many hip muscles that go unused or underused (like the adductors and gluteals). There are a great many motions that people NEVER do, and this results in poor overall hip function.

Of course, this also means every individual has a unique set of muscular challenges. That is why the solution to your hip pain may be very different than the solution to another person’s hip pain. A ballet dancer’s hip pain solution will look different from a weightlifter’s solution. A hockey player will likely have different compensatory patterns than a skateboarder.

You must address every person on an individual basis.

The main point is one that the Sports Surgery Clinic in Ireland echos: femoroacetabular impingement is a training problem, not a bone problem.


Exercises you may find helpful for hip pain with an FAI diagnosis

Below you’ll find a few videos that thousands of people have found helpful. As mentioned above, every person has unique muscular challenges.

These videos will help you start your own process of identifying issues and potential solutions for yourself.

Train your body to be more flexible, strong, and resilient! 

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