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Dear Cara – or -The Problem of Wiberg

Dear Cara,

My book, Save Your Hips, does talk about dysplasia, a concept first put forth in 1939 by Gunnar Wiberg. By this time, radiology was well established and the practice of orthopedics focused primarily on bones. Throughout the previous century a deep level of understanding had been centered on imbalances in the soft tissues surrounding the joint as the initial, fundamental pathology in common hip disease.

I believe The Problem of Wiberg (I just coined this phrase) to be the tipping point in changing current understanding of chronic hip disease.

Center Edge Angle of Wiberg

Center Edge Angle of Wiberg

Wiberg saw on AP radiograph that some acetabulae provide less coverage to the femoral head than others. Working with impressive 2D images that were easy to manipulate mathematically, he produced a theory stating that at a certain point in his diagnostic parameter, called the center edge angle of Wiberg (CEA), a hip could be considered dysplastic or not.

The CEA contains a large margin of error, however, because it does not take into account the major musculoskeletal movement that positions the acetabular roof over the femoral head which is, of course, sacral nutation (i.e. lordosis). When we lie supine for a standard AP radiograph, the femoral head moves slightly up and out of its socket. When we stand up, the femoral head moves down and medially. The hip joint follows the sacrum in this movement. Therefore, none of the images Wiberg was working with gave a true representation of how much of the weight-bearing joint was actually covered by the acetabular roof. No doubt he saw some very abnormal joints. But his parameter is largely erroneous because it measures spacial relationships in a non-weight-bearing position. This wouldn’t be a problem if the joint didn’t radically change from supine to standing…but it does! Wiberg and all the diagnosticians after him never really knew from an AP radiograph which hips were going to be covered-enough as the lumbar spine extended with standing. There are other imaging technologies today, but no one has wanted to confront The Problem of Wiberg. Therefore the images are digitally manipulated to give a standard AP view of the pelvis (“anterior pelvic plane”).

Crazy, but true. This is what Save Your Hips is all about.

But what were Wiberg and others through the century seeing in a dysplastic acetabulum? That it is “shallow” and “oval-shaped”, instead of more circular (it is actually a spiral, which my daughter, who is also my artist, and I realized at the same moment).

Dysplastic Acetabulum

Normal Acetabulum

The only possible gravitational dynamic capable of creating such an acetabular shape is bearing the center of mass on the front aspect of the joint. One bears the COM in this way by flattening lumbar curvature while weight-bearing. The degree to which the lumbar spine is flattened from its natural, wide-radius curvature, is the same degree the femoral head is moved up and laterally.

It is also true that there is another, far less common, condition where the femoral head has been held slightly out of the joint from birth or early childhood. Thus, we have a true developmental dysplasia, and also an acquired (degenerate) condition. Spinal and/or pelvic obliquity (scoliosis) can also cause the hip joint to twist and elongate.

So how should a thirty or forty-year-old who has new-onset or slowly progressing hip pain with radiologic signs of dysplasia be categorized? You would not be able to determine (other than by history) which hip dysplasia was acquired and which was developmental. The trained eye, however, would be able to tell by subtle differences in the bones themselves. But this distinction is not studied and therefore not mentioned in orthopedic literature. It is all classified as developmental.

Acquired dysplasia causes the anterior aspect of the symmetrical, arched acetabular roof to (1) stretch – as gravity pulls the joint downward, elongating the acetabulum like taffy, and (2) apply bone to what becomes the anterior-superior aspect of the acetabulum in the counternutated position (lumbar curve flattened). This area becomes thickened and protruding as it tries to cover and protect the joint.

Normal Acetabulum

Dysplastic Acetabulum

The process of stretching and bone deposition at the anterior-superior aspect of the joint is probably largely responsible for other popular orthopedic theories, acetabular retroversion and pincer FAI, which describe the same architectural characteristics. This is why I describe in my book how orthopedics creates new diseases out of thin air.

To convolute matters further, the practice of orthopedics believes this dysplastic area to be the weight-bearing roof of the normal acetabulum, due to a 500 year-old misconception of pelvic orientation in the bipedal position.

Orthopedics has used flawed, circular logic to justify the mutilation of millions of hips.

Which kind of dysplasia do you believe you have, Cara?

Wishing you well,

{ 3 comments… add one }
  • Cara August 7, 2014, 9:08 am

    Thank you, Christine- I learned a lot from this post. As for me, I’m not really sure how this came about. My mom noticed the “knock-kneed” posture when I first began to walk. My pediatrician thought the shoes with the bar between them (standard at the time, perhaps?) were inhumane and suggested ballet instead. He may have been doing me more of a disservice, as we now know. I had no trouble or pain until my 20s- in fact, I danced and did big time gymnastics on two seemingly normal hips. I began to feel weakness in the hip flexor, compared to my other hip (which is still dysplastic as well and gives me no pain- strange, huh?).

    At any rate, now I am trying to correct this with good posture. After sucking and tucking for years, sometimes it’s hard to remember to remind myself to relax. Some days my hips respond well, and I can walk and work out. Other days are not quite as good and I do get the “pinchy” pain we are all familiar with. I’m actually relieved that I’m not a candidate for a PAO- what are horrible decision to have to make. But I do believe in the mind-body connection, and I try to tell myself to have faith, that with the best posture I can achieve, it may be possible to eliminate the need for a THR entirely. We’ll see. I’m so grateful for resources like you- they give us all hope!

  • admin July 15, 2014, 10:44 pm

    Whether acquired or congenital, they would all be dysplastic if the acetabulum is misshapen and shallow. I appreciate several of the quotes I was able to find and include in SYH. Such as, (paraphrasing) that many people live long, healthy lives with significant dysplasia. I think the entire issue speaks to the truth that in the 21st century we actually know very little about common hip disease, even with all the spectacular technology and heroic operations.

  • Louiseds July 15, 2014, 9:58 pm

    Thankyou Christine, for explaining that all hip dysplasias are not the same in cause, and that some might not be dysplasia at all. Just because dysplasia is evident on an AP x-ray, and there is pain that could be related to it, doesn’t mean that a surgical procedure will fix the pain. My daughter’s triple osteotomy may have fixed the dysplasia at age 16, but she still has some pain, nerve damage and discomfort 12 years later, which may be related to architectural changes to the way her left hip works, or may be damage from the procedure itself, or may be that it didn’t entirely fix the problem. What will the future hold for her? We don’t know. Did we make the right decision to allow this major, major surgery? We don’t know. I suspect we did, as the shallow acetabulum showed up on x-ray at age six, after being clear at all her earlier hip checks, so it probably was true developmental dysplasia.

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