Practical Science on Movement and Pain

Assessment of Pelvic Tilt

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How do you know where your pelvis is at? Does it rotate or tilt forward/back, left/right, up/down? A new study suggests that if your only method of finding out involves palpation of bony landmarks on the pelvis, you will likely have no clue.

In this study (full text available) the authors had the excellent idea of taking thirty five cadavers and then measuring all the bony landmarks in the pelvis to determine variations in pelvic shape between people, and between the left and right sides of the pelvis on the same person.

The information gained in the study suggests that it would be very difficult to determine the exact orientation of a client’s pelvis based solely on palpation of bony landmarks. Here’s some more detail.

Assessing anterior pelvic tilt

Many therapists believe that excessive anterior tilt of the pelvis is a significant cause of chronic pain because it increases lumbar lordosis and hip flexion. I have previously pointed out that despite the common sense appeal of this theory and its widespread acceptance, there is considerable evidence that calls it into question. Many studies have found little or no correlation between measures of anterior pelvic tilt and other similar measures (sacral angle, lumbar lordosis, thoracic kyphosis) and chronic pain. If anterior tilt was a significant cause of chronic pain, we would expect to see that people with more anterior tilt have more pain, but that is not what we consistently see.

But hey, I am open to the idea that determining the habitual position of the pelvis relative to the legs and low back might be a useful thing for a therapist to know when trying to improve a client’s movement. But the question remains, how do we do this?

jmmt0016-0113-f01Therapists commonly assess the degree of sagittal plane pelvic tilt by comparing the height of the PSIS to the ASIS in standing. The higher the PSIS relative to the ASIS, the greater degree of anterior pelvic tilt.

The problem with this method is that different people have different PSIS/ASIS angles as a result of the shape of their pelvis, not the position. In this study, even when the pelvises were in neutral*, the PSIS/ASIS angles were all over the place. The biggest difference between individuals was twenty three degrees, and the standard deviation was five degrees. This means that if you measure the standing PSIS/ASIS angle as a way to determine the degree of anterior pelvic tilt, you don’t know whether you are measuring the tilt of the pelvis or the shape of the pelvis.

Assessing pelvic asymmetry 

Manual therapists will often try to measure many other aspects of pelvic positioning. For example, they may assess whether the pelvis is rotated in the transverse plane or tilted in the frontal plane relative to the legs or low back. Even more complex, they may assess how one side of the pelvis is positioned relative to the other side (as a result of asymmetrical positions at the two SI joints.) Now things are getting difficult, and to succeed you better have a pretty good way of measuring pelvic position precisely. If your method relies on the implicit assumption that the right and left sides of the pelvis have the same shape (as most do), then it is likely not valid. The study shows that pelvic shape if often different from left to right.

For example, the study found that the PSIS/ASIS angle varied from left to right (up to eleven degrees), even when the pelvis was in neutral. The asymmetrical shape of the pelvis in this respect could make it appear that one side is rotated forward compared to the other.

The study also found significant differences from side to side in the height of the pelvis, as measured from the acetabulum to the iliac crest. This difference might make it appear that one leg is longer, or that the pelvis is tilted to one side in the frontal plane.

The study also found left/right differences in the angle of the iliac spine to the ASIS. I’m not sure what kind of palpation technique this difference might invalidate, but I’ll take it as just more evidence in support of my guess that no matter what bony landmark you choose to measure, you can expect to find some significant differences from left to right.

This shouldn’t be too surprising. We don’t need sophisticated measuring techniques to look at our hands and feet and see that the bones one side are not quite like the other. We should just assume that this low grade wonkiness is pervasive.

The lesson? Make sure your assessments don’t depend on an assumption that the bones are the same shape from side to side. They are probably not!

(*Note – In the study, the authors put the pelvis in “neutral” by aligning the left and right ASISes in the horizontal plane, and aligning the pubic symphysis and the ASISes in the vertical plane.) 

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27 Responses to Assessment of Pelvic Tilt

  1. Great piece, Todd.

    Pelvic assessment and treatment used to be such a large part of my eval/treatment, as well as my teachings. I was taught to check and treat all of the things that you rightly point cannot be determined accurately. Therapists flock to pelvis classes, especially in my native MFR-land, seeking to learn the correction for the supposed keystone of the body. A funny thing happened a few years back; I stopped evaluating the pelvis so closely and stopped treating pelvic obliquities as I was taught. My outcomes did not diminish, they actually improved. Keep fighting the good fight!

    Walt

    • Todd Hargrove says:

      Thanks Walter!

      My point in this article was not to trash all forms of pelvic assessment, just assessments based solely on bony palpations. Interesting that you were able to dispense with the whole thing and still get great results! Congrats on that!

  2. Ross says:

    I don’t use postural assessment unless the patient has some very curious pain patterns. Even then it is a shot in the dark. I learn more by listening to their story and asking intelligent questions. It is a little known often over looked fact that when it comes to bones, form follows function. Very few bones are the same. That is why I have two right scapulae to show students and patients the differences. We are all unique in form and function. As always, great post.

    • Todd Hargrove says:

      Thanks Ross. Great idea on the two scapulae! A picture is worth a thousand words, so two scapulae are probably worth, like, a million words.

      • Margy Verba says:

        Check out this amazing “bone gallery” on Paul Grilley’s website (Yin Yoga): http://www.paulgrilley.com/category/2.html. I show this to almost all my private therapeutic clients. Thanks for a great post! I am currently trying to study the S/I joint, and find it perplexing that world experts (e.g. Mitchell DO, DonTigny, Diane Lee) describe the mechanics — particularly sacral torsions in gait — so differently. Who is correct (asked rhetorically)???

  3. Betsy says:

    I like the way you think, Todd. The premise that pain is a function of misalignment which, when ‘corrected’ will abolish said pain, has always set uncomfortably with me. Like Ross, I look, listen, ask hopefully intelligent questions, then approach the client much more globally than I was taught (Greenman, muscle energy). And like Walt Fritz, I have equal and often better outcomes.
    You bring a fresh perspective that always jumps, refreshingly, outside the box.

  4. Margy Verba says:

    “(*Note – In the study, the authors put the pelvis in “neutral” by aligning the left and right ASISes in the horizontal plane, and aligning the pubic symphysis and the ASISes in the vertical plane.) ” p.s. doesn’t the point of your post refute the whole concept of neutral?

    • Todd Hargrove says:

      Hi Margy,

      Thanks for the link to the bone gallery, looks like a very cool resource. In answer to your question about neutral, I put it in quotes because there is probably no way to objectively define it. But I do believe it is a useful concept, and that some joint positions are more neutral or centrated or functional than others though. It’s just that because of bony differences between people, putting one joint in neutral won’t necessarily put others there as well. I wrote about this a little in my “dem bones” article.

  5. Sharon Gary says:

    Great piece – thanks for posting it! I especially liked the part about the unique shape of the pelvis creating apparent leg length differences. Many years ago, I learned from an experienced PT that the best, if not only, way to accurately determine leg length differences is on x-ray. Oh, that’s why when I tried all the ways to measure for leg length in PT school, the measurements were NEVER consistent. Inconsistent means unreliable, right?

    In 22 years of practice, I’ve only seen a handful of leg length differences, and most of those were congenital and 2 inches or greater.

    Apparent leg length differences are just that: apparent. Usually they are because of something to do with the pelvis. And now, here’s another study to point to. Recently a colleague posted online that he regularly treats leg length discrepancies, that this is a common phenomenon. I was stunned. But I did not correct him. I hope he reads this article.

    • Todd Hargrove says:

      Yes I have heard lots of conflicting info on leg length discrepancy (and on everything else I guess.) One key piece for me is that Lancet review finding it is not correlated with back pain.

  6. Ryan says:

    Great info for us uneducated movers out there! Had chronic joint pain high up where the right leg joins the torso my whole life, always thought it was because my right leg is longer than my left… now wondering if it may be because the right side of my pelvis is simply higher than my left?

    Also, if you can, please shed some light on the distinction between the hip and the pelvis! Been trying to find info but nothing clear, and I’d like to be able to speak about what’s going on in my body with more precision.

    Thank you!

    -ry

    • Jason Brown says:

      Thanks for the great piece, Todd! One of my anatomy students just forwarded this article to me… and I’m looking forward to reading more ;-)

      Ry, it’s easy to see how you’d get confused about the pelvis and hip. The pelvis is a body part… like the thigh is a body part. The bones of the pelvis include the two hip bones and the sacrum/coccyx… which are usually referred to collectively as the bony pelvis. You have a right hip bone and a left hip bone, which are also called the coxal bones. Each hip bone has a socket, called the acetabulum (which means “vinegar cup”), that articulates with the head of the femur bone to form the hip joint. The hip joint is a ball-and-socket joint, like the shoulder joint.

      So you have hip bones and hip joints. If someone says “put your hands on your hips” they’re probably talking about the hip bones. If they say they have pain in their hips, they’re probably talking about their hip joints.

    • Todd Hargrove says:

      Hi Ryan,

      Your pain could be from …. almost anything! See my pain articles for more info.

  7. Keith Walker says:

    Great post. As a student I and three others were taken by an wise old tutor and told to palate this guy’s pelvis and write down our findings without concurring. We fancied ourselves as SIJ experts and had all sorts of wonderful relationships written down.
    When we came to compare all of us were different and then the tutor gave us the grand slam by telling us that the patient had AS and both joints were fused. Never palpated an SI for movement since. I often tell my patients we are not symmetrical and not to worry about a raised shoulder here or a little leg length diference here. Enjoyed the piece.

  8. Without entering into a long riff on the many ways MET style palpations of functional hip alignments might be inaccurate considering the variation in shapes of ASIS and PSIS landmarks and the studies that show low inter-tester reliability with these methods….or even if those variations in sagittal plane or coronal actually cause movement dysfunction, pain, all legit discussions to be had, IMO. The problem with this study is that they used cadavers and placed them themselves on a dissecting table, thus eliminating many of the reasons folks who use these assessment methods feel are often at play in the variations they’re palpating to find. Working with folks who have donated their bodies for dissection one increases the odds one is working with an older population, subject to the wear and tear of aging, arthritis etc. All of which would effect these purely structural measurements. Small group, 35.

    Here’s one using CT scan that shows very little structural variation in a much larger group: http://www.ncbi.nlm.nih.gov/pubmed/12811280

  9. Jan Hetherington says:

    Ha – not to mention with an amazingly 3-D structure the languaging around pelvic movements needs to be incredibly precise. Rotate …. does that mean about the middle, about an edge, about a horizontal or vertical axis — or does one really mean shift the vertebrae in some way, in relation to each other or the pelvis ….. (& of course everything’s connected …..). And as Jason commented above, we even use the word ‘hip’ when meaning different things. When someone says ‘move your hip’ — what do they REALLY mean? Or ‘move your hip joint’ ……. those of us teaching movement classes (Feldenkrais Awareness Through Movement in my case) must be very clear on what we mean, so that our students can get a clearer picture of their own structure. I guess I’m really in love with my skeleton ….

    • Todd Hargrove says:

      Yeah the language gets confused. The pelvis isn’t a joint, so its tilt just refers to its relative place in space, not the movement of a joint. E.g. I could tilt my pelvis forward by leaning at the ankles, with no movement in the low back or hip joint at all ….

      • Jan Hetherington says:

        And then, of course, leaning forward – what does THAT mean ?

        :)

        Which is where we discover all the nuances of what WE think a movement is, vs what our n’bor thinks, vs what COULD be possible, but perhaps unknown or forgotten …..

        Jan

  10. Ritvik J says:

    Hi Todd,

    As a weekend warrior, recreational athlete, I used to be obsessed with any practice that could make me stronger/faster and give me an advantage over others.

    One of the ideas I became stuck to was regarding pelvic tilt and whether or not it can affect athletic performance. What is odd is that no solid research has proven that pelvic tilt is a predictable measure in athletes, and nothing shows that it is directly correlated with athletic performance.

    While researching about pelvic tilt, I discovered something called anterior femoral gliding syndrome in the pelvic region.(https://www.youtube.com/watch?v=qDRGKc9D-q0)

    Do you think this syndrome can be related to improper pelvic function, and is it related to pelvic tilt?

    Thanks,
    -RJ

    • Todd Hargrove says:

      Hi Ritvik,

      I don’t know to much about this syndrome except that I think it was described by Sahrmann, who is pretty credible in terms of biomechanics. It is certainly related to pelvic function, but it is just one of many different movement syndromes that one might have. Assessing, diagnosing and correcting these are a complicated matter tat is probably not easily done without a trained therapist. (And even then it is not so easily done!)

      My advice about pelvic tilt in general is don’t worry much about it – train function not your static posture.

  11. Tony says:

    Though I read that more people are questioning whether or not asynchronous alignment is a problem or not, I have continued to find that unilateral low back pain is almost always tied to pelvic asymmetry and relative leg shortening.

    I find the pelvis to be the most confusing area to assess of them all. In practice, I have found that the vast majority (all but one or two)of patients I have treated for unilateral back pain have a leg length discrepancy that is related to the pelvic girdle. A simple way to assess this for yourself is to lie down supine, and have your heels parallel to each other (as if doing a situp). Then look at the tops of your knees. The side that is painful is (in my experience) the side that is lower (shorter). Using Don Tigney’s method of adjustment, a practically idiot-proof (meaning I can do it) results in a nearly instantaneous removal of a) the back pain and b) the leg length discrepancy. It has gotten to be such a reliable thing that when a patient comes to me with lower back pain, I can tell them which side it’s on by checking this relative discrepancy in leg length (e.g. right side shorter, right LQ back pain). That said, WHY the discrepancy keeps reoccurring is more complex.

    A emergency physician who works with me was astounded to see how the adjustment (<1 minute's worth of work) a) resolved the low back pain and b) caused such a dramatic resolution of 1/2" of knee height/leg length with such a simple adjustment. Mega-kudos to Don Tigney for his insight on this matter!

  12. It is always curious to me that therapists choose to look at where the pelvis is in space rather than whether it moves through normal range and can stabilize through that range. That is how we look at every other joint in the body. Why not the pelvis?

  13. reggy says:

    I see you have written a book. I used a book to fix my tilted pelvis!
    It was a hardcover, 3/4 inch thick and covered the length of my pelvis. I put it under my pelvis and laid down on it till my muscles
    relaxed (about twenty minutes). As I was doing this I tightened my butt muscles off and on and I felt the pelvis shift to the correct position.

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