Okay, we have a really interesting question here.
A 24-year-old male presents with heal pain that is persistent for three weeks.
He is bothered by the feeling of significant pressure and swelling in his ankle.
He has also having difficulty walking due to pain in his hip.
Upon physical examination, there is evidence of swelling and warmth over the Achilles tendon.
Imaging of the sacroiliac joint reveals soft tissue involvement and narrowing of the joint spaces.
This patient also appears to have a low to moderate kyphosis of his spine.
He has no family history of any bone or rheumatological diseases.
The patient most likely presents with clinical features of which disease?
Answer choice A: Osteoarthritis.
Answer choice B: Ankylosing spondylitis.
Answer choice C: Reactive arthritis.
Answer choice D: Osteoma, or -
Answer choice E: Fibromyalgia.
Now take a moment to come to an answer yourself before we go through it together.
Okay, this is a very, very good question for USMLE.
Now, looking at the question characteristics, this is an internal medicine question and it’s a musculoskeletal question.
You have someone coming in, they have heel pain, joint pain.
Then we see some kind of spine abnormalities on X-ray, this is MSK.
Now, this is actually a one step question and when you think one step you think easy,
but there’s a reason it’s one step -- it’s hard.
You gotta go through the question stem and really dissect out all the key information to figure out the right answer,
and of course then the stem is required cuz that’s where all the information is hidden.
So let’s do that now, let’s walk through, let’s determine the diagnosis here.
Now, looking at the question stem, we have a young otherwise healthy male, 24 year old guy
and he’s coming in with a chief complaint of having pain in a specific region of his foot.
He describes heel pain, he describes ankle discomfort, they mentioned his Achilles tendon swelling
and that pain is persistent and it’s been there for three weeks.
Okay, now, what we see is that it’s not just there in his ankle or his foot, the hip is also affected.
Not only does he have hip pain, he has also have difficulty walking.
Now, in a addition to having both hip and ankle, that actually gave us some imaging findings in the question
where they say that he actually has some degree of soft tissue involvement and narrowing of his joint spaces.
A normal 24-year-old guy should not have swelling or narrowing especially of joint spaces and on exam,
they mentioned, that he actually has low to moderate kyphosis of his spine.
Again, a young healthy guy should not have that so taking into account that he’s a healthy young guy,
coming in with joint pain with some type of spine and hip involvement,
with narrowing of joints -- of all the answer choices, Answer choice B is the most likely answer, ankylosing spondylitis.
This question really is, can you identify the clinical picture and components of this disease ankylosing spondylitis
which is a condition, and again, what you should have thought of or what I’m thinking of which maybe you should be, too,
is generalized joint inflammation, you know, inflammation -
narrowing; kyphosis of the spine due to fusion of the vertebrae; these are the red flags.
A guy with no other history, he’s young - these are all things we need to be worried about.
Okay, now ankylosing spondylitis, now this is really the prototypical example of what’s called a seronegative spondyloarthropathy.
Now these are seen in 1% of the population.
Now, when we see that it’s ankylosing spondylitis, we need to think, okay, how was this different than arthritis?
Well, Answer choice B is the right answer, ankylosing spondylitis,
but A is osteoarthritis and C is reactive arthritis, now those are arthritis.
Now what is arthritis? This is high yield.
Arthritis is a group of disorders that affect the joints and the main symptoms you have in these patients is joint pain and stiffness.
Now, the most common type of arthritis is what’s called osteoarthritis or Answer choice A here
which is joint degeneration over time that can happen to injury and malformation and that causes pain and stiffness;
and another very common type of arthritis is called rheumatoid arthritis which is when which you had inflammation and antibodies.
Now arthritis in general occurs much more commonly in the elderly but it can be seen in all ages but classically.
Now, how does that differ from ankylosing spondylitis?
A very high-yield test topic. Now, that is also, ankylosing spondylitis, a type of arthritis so it fits in that category
but this is very important, it is a seronegative spondyloarthropathy.
Now, that’s really fancy, but what does it mean? It means that it affects the joints of the spine
hence the word, spondyloarthropathy, but when you test the patient,
they are negative for rheumatoid factor antibodies, that’s what seronegative means.
Now, to understand the pathophysiology of ankylosing spondylitis, refer to the image that has the four section of the spine.
Now, answer number 1 there on the top left corner is like a normal spine,
but looking at two, three, and four, that’s like the sequelae of ankylosing spondylitis.
That’s very important to cuz cause if you can memorize this progression of disease
and image you’ll then understand the symptoms and it’ll make much more sense to you.
So if you look first, you actually will have inflammation of the vertebral joints.
Now, remember in the question stem, they mentioned that there were soft tissue involvement.
Now, in addition to having that inflammation of the ligament and joints,
we’re gonna have something that’s called formation of syndesmophytes, okay,
and that’s part of the healing process.
Now what that is you will end this disease have inflammation of the subchondral bone
that leads to reabsorption and periosteal new bone formation.
Now, this inflammatory process affects the joints and also leads to the formation of new bones in this process
and that’s what that means, syndesmophytes, the formation of new bones
and over time, you can actually have these bones fusing together
and then you will actually have fusion occurring within the spine or vertebral fusion
and that can commonly be seen as to what’s called bamboo spine in which the spinal cord looks like a piece of bamboo
cuz the different bones are being fused together. Very high yield.
Now, that’s the pathophysiology of this condition and if you imagine the swelling, the new bone formation and the fusion,
you can understand why you would expect to see signs of swelling on imaging,
why you would have fusion over time, as to what’s seen in ankylosing spondylitis.
Now, the cause of this condition really is unknown.
It’s a combination of genetic and environmental factors but very, very high yield; tattoo this in your brain,
is that it has a very high association with being HLA B27 positive
and this is actually expressed in around 90% of people who have ankylosing spondylitis.
Now, this arthritis is more commonly seen in young people.
Like we said, arthritis is usually in the old and you can imagine some old lady having osteoarthritis
but this ankylosing spondylitis is usually seen in the young and seen actually more in males than in females.
You know, classically, arthritis is seen in women, rheumatoid very commonly in women.
This is a unique condition where it’s in young people not old, and it’s in guys not girls.
And the treatment of ankylosing spondylitis is really symptomatic.
There is no cure available and treatment includes medication
such as NSAIDS, steroids, disease modifying agents and biologic agents and even surgery and of course physiotherapy.
So that’s ankylosing spondylitis.
Once you understand that pathophysiology, when you read the question stem,
you identified it’s really there and you can go straight to the answer.
But let’s go through some of the other answer choices to make sure we can eliminate those to help narrow our odds if
on real exam day we're having a hard time coming to this answer.
Now, Answer choice A, osteoarthritis.
We talked about it earlier, that’s joint degeneration that could be due to injury or malformation.
Now, that’s going to be seen with someone who is usually older who has kind of a chronic condition
or some kind of injury not in a young guys, so we don’t expect that.
Reactive arthritis, Answer choice C, can actually be seen a few weeks after a gastrointestinal or genitourinary infection
and it can also have urethritis or conjunctivitis.
There’s no preceding infection here that we can see.
Now, so we can get rid of reactive arthritis because we have nothing to react to.
Now, answer choice D is an Osteoma.
There’s no any comment here about any kind of B type symptoms, no mass, no weight loss, no night sweats -
nothing for us to think about a bone tumor and we can really cross this one off, it doesn’t even fit.
And the last one is Answer choice E, which is fibromyalgia, which this is actually a systemic joint pain
that patients have and they actually have trigger points that you can hit to diagnose the condition.
This is seen much more commonly in females than males and very much it’s -- you’ll see it coexist with depression.
So, that’s a pain syndrome not really a form of arthritis, now that’s different condition so from that,
you can see you can eliminate all those cuz they really don’t fit the clinical picture of ankylosing spondylitis
which is what this question is really testing.