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<v ->Let's start at the beginning.

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And this was, I believe,

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the first article where the concept

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of transient osteoporosis of the hip was introduced.

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So of interest was introduced

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by a friend of mine, Michelle Lequesne

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who was a radio rheumatologist living in Paris.

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And for many years after this

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we should discuss this particular entity.

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He described a series of patients generally fairly young

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but also in middle age, as you can see,

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and these patients had the rapid development of pain, limp

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and some disability involving one or sometimes both hips.

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And what was seen as shown in these images

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taken from his article was osteopenia involving the entire

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or a portion of the femoral head.

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If you get up close to a case like this and look carefully

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you'll see that the subchondral bone plate is still intact.

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It looks gone here, but it's intact.

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The joint space looks normal.

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So we're dealing with osteopenia involving the femoral head.

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Now, this was new.

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And what he found out is

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that the osteopenia went away over a period of time.

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So I learned very early on about this condition

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particularly when I started my residency in New York City.

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I learned every single thing about it,

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and I'm listing them here for you,

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more common in men than in women,

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but in women, sometimes occurring

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in late pregnancy or in the postpartum period.

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Typically young and middle aged adults who presented

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with pain, a limp and limited hip motion.

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And it was a self limited condition

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resolving over a period of months

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occasionally associated with osteopenia in the opposite hip.

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I knew all of that,

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but unfortunately I was called up to discuss a case.

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You're looking at the exact case.

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This was the first case that I discussed when

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I was a resident in radiology.

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And I looked at it and I saw that big thing in the pelvis,

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and I said to myself,

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that's the largest bladder calculus that I had ever seen.

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Now, if I had recognized that as a fetal head

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rather than that calculus, I would have a much better idea

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of what was going on in that left hip.

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Three months later, they showed me this.

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You can see the calculus has been delivered.

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And now, as you look at this particular image,

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of the subchondral bone plate.

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This is classic transient osteoporosis of the hip

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occurring in the third trimester of pregnancy,

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but boy, did I mess up this case when I discussed it.

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Now,subsequent to that, an article appeared

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from radiologists at the Mallinckrodt Institute in St.Louis

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that said, you know, when you look at this condition

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of transient osteoporosis, and you apply MR imaging to it,

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you're going to see marrow edema.

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And they in fact discovered that not only

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with regard to the femoral head as shown here,

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these are images from their article,

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but similar condition they found could involve the knee

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particularly the femoral side of the knee joint,

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and again, what they found was marrow edema.

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So we've taken our first step.

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We began with transient osteoporosis causing pain,

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and now as MR became available, we were seeing marrow edema

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as the finding with MR imaging.

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Now we were taught what the MR Images looked like

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in this transient painful marrow edema of the hip.

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On T1, we looked for low signal.

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And of diagnostic importance,

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sometimes the medial aspect of the femoral head was spared.

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In the fluid sensitive sequence,

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we often would see high signal sometimes involving then

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the entire femoral head.

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The edema typically extended down into the femoral neck.

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And sometimes, as you can see here,

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into the proximal portion of the femoral shaft.

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Here's another case, T1

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and a fat suppressed T2 weighted image.

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in this case , homogeneous low signal on T1

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diffuse high signal.

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Note the extent of it,

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and this is going to become important later on

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We're not talking about a condition limited

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to the femoral head, or for that matter, the femoral neck

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but often the edema would extend

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down into the proximal portion of the femoral shaft.

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Typically the condition would begin in one hip

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and then often would disappear over a period of time.

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Some of the patients never would had any other involvement

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of any other joint,

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but occasionally we would then

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see involvement of another joint.

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And the most common pattern was involvement

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of the opposite hip.

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So this is an example of asynchronous involvement of

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both femoral heads shown by fluid sensitive sequence.

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Along came a report from Japanese

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that appeared in skeletal radiology in 2001

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that questioned whether or not transient osteoporosis

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of the hip or transient painful marrow edema might relate

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to an insufficiency fracture.

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This was a description of 12 hips in 11 patients

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who had osteopenia and marrow edema of the femoral head.

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And they found, in fact, in some of these patients

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that there were linear regions in the subchondral bone.

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I'm showing you one of their images here

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in the bottom of this slide

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that they thought might represent fracture lines.

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The second author in this paper is a Dr. Yamamoto.

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I remind you, you're going to see his name quite a bit

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as we talk about insufficiency fractures.

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A more definite association of these conditions

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with insufficiency fractures involving the femoral head

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was proposed in this paper in 2015

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by Contes and his associates

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a description of 155 hips in 141 patients, more often a man.

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Subchondral femoral fractures were present

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in almost 50% of hips.

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Here are pictures taken from that article,

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and clearly now we are seeing a linear or curvilinear

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shadow within that edeminis subral head that

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clearly does look like an insufficiency fracture.

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So where have we come? From transient osteoporosis

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of the hip to transient painful marrow edema,

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now to the association with insufficiency fracture.

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But one of the things that I think is remarkable about this,

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it is not clear which comes first.

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And in my experience, when looking at sequential imaging

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in these patients, the marrow edema generally comes first

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probably leading to weakening a bone,

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and later on the insufficiency fracture appears.

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So I have the belief

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that the insufficiency fracture is not the cause

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of the marrow edema, but the result

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of marrow edema and weakening of the bone.

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Here, an example of marrow edema

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with a subchondral insufficiency fracture.