Chapter 24: Acute Low Back Pain Assessment

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Welcome back to the Deep Dive.

Today we are tackling a beast of a topic.

It's one of the most common reasons people walk, or more accurately, limp into a primary care clinic.

We're talking about acute low back pain.

It is the nemesis of the primary care provider.

I mean, if you're going into practice, you absolutely cannot avoid it.

It is ubiquitous.

Exactly.

And to guide us, we're diving deep into chapter 24.

Low back pain, acute from the text, advanced health assessment, and clinical diagnosis in primary care.

A fantastic chapter.

Very dense, but very practical.

It is.

And, you know, I know the temptation here.

I know what some of you listening are probably thinking.

Back pain.

It's a strain.

Give them some microprofen.

Tell them to stretch and send them on their way.

The classic brush off.

But as we work through this chapter, it became, well, crystal clear that that casual attitude is actually dangerous.

It can be catastrophic.

And that's really the mission of this Deep Dive, isn't it?

It isn't just to tell you how to diagnose a simple strain.

It's to help you master the art of the clinical detective.

Because when a patient comes in clutching their lower back, your job is to filter through all the noise.

You have to distinguish the common, the boring mechanical issues from the life threatening emergencies.

That's the whole game.

Right.

And before we get into all the scary stuff, you know, the tumors and the infections, let's start with the statistic that probably lets most providers sleep at night.

The text opens with a pretty comforting number.

It does.

And it's important to keep this in mind.

It states that about 90 % of acute low back pain episodes in adults are mechanical in nature.

Mechanical.

And they resolve within four weeks without any serious consequences.

So nine out of 10 people who walk through your door are going to be fine, almost regardless of what we do.

Correct.

That is the statistical baseline.

It's usually, you know, muscular ligamentous injuries, sprains, strains, or some age related degeneration.

But.

And this is the crux of the entire chapter.

And frankly, why we're doing this Deep Dive.

If you get lazy because of that 90%, you are going to miss the other 10%.

The dangerous 10%.

Precisely.

The fractures, the tumors, the infections, the spinal cord compressions.

To catch those, you need a holistic approach.

The text makes a really important point early on.

Back pain isn't just physiological.

It has these deep psychological and even economic components.

Also.

Well, it affects a patient's ability to work their daily routine, their it causes stress, anxiety.

If you just look at the spine and ignore those factors, you're missing half the diagnosis.

That's a great point.

So let's get our definition straight before we start poking around.

How is the text specifically defining acute low back pain?

Because acute can mean different things in different contexts.

Sure.

Here it is defined as activity intolerance, producing symptoms in the lower back or back related leg symptoms for less than three months.

Okay.

Less than three months.

And are we treating adults and children the same here?

I mean, I feel like back pain sounds like an old person problem.

And that is a very dangerous assumption to make.

The chapter is really specific about pediatric considerations.

Oh, really?

Yes.

Children are not just small adults when it comes to back biomechanics.

They have what the text calls anthropometric variations.

Okay.

Anthropometric variations.

That sounds like something I'd pay to fix.

Let's unpack that.

What does it actually mean for a kid's spine?

It basically means their body structure, their proportions predispose them to different kinds of risks.

Okay.

For example, children often have reduced hip mobility compared to adults.

They also have much, much tighter hamstring muscles, especially during growth spurts.

Right.

I remember that.

And crucially, they often have lumbar hyperlordosis.

That's the sway back, right?

The really deep inward curve in the low back.

Exactly.

That significant inward curve.

Now imagine a child who plays sports.

You've got tight hamstrings pulling down on the pelvis.

You have reduced hip mobility that limits how they move.

And you've got this deep curve in the spine.

It sounds like a recipe for disaster.

It is.

All of those factors place them at a significantly higher risk for excess strain on the vertebrae during extension, like leaning way back in gymnastics or doing certain football drills.

So if a kid walks in with back pain, your antenna should already be way up.

The mechanics are just working against them differently than they are for a 50 year old.

Definitely.

And to help us organize our thinking, the text uses a fantastic framework from the agency for healthcare research and quality, the AHRQ.

Okay.

They categorize the causes of back pain into five main buckets.

And it's a great mental shelf to have so you don't get completely overwhelmed.

Let's run through those five buckets.

I like a good list.

Okay.

Bucket one is where all the anxiety lives.

Potentially serious conditions.

This is your fracture, your tumor, infection, or coda aquina syndrome.

The do not miss list.

Exactly.

Bucket two is sciatica.

This suggests nerve root compression of some kind.

Got it.

Bucket three is nonspecific back problems.

This is your strain, your sprain, or what's called discogenic pain.

That's the mechanical stuff that makes up the bulk of that 90%.

Okay.

That covers the spine itself.

What about the other two?

Bucket four is non -spinal causes.

This is fascinating stuff.

This is referred pain from internal organs.

The gallbladder, the kidneys, the aorta.

The back hurts like crazy, but the spine is actually fine.

And the last one.

And finally, bucket five, psychological causes, stress, the work environment,

somatization.

The brain body connection is powerful.

That is a solid roadmap.

So let's start with the danger list.

We're moving into section one.

Diagnostic reasoning and the focused history.

The text calls this the red flag hunt.

And I love that phrasing.

It's exactly what it is.

The history is where you rule out the danger.

You really cannot rely solely on imaging later on.

You have to ask the right questions right now.

So the priority is nailing down those potentially serious conditions from bucket one.

That's your first job.

Rule out the killers.

Let's get into the interrogation room, or I guess the exam room.

What is the very first question the text tells us

it starts with something that seems, you know, almost totally unrelated to the spine, which is which acts as a distinct pivoting point because if I strain my back lifting a couch, I don't get a fever.

Exactly a mechanical injury, a muscle tear, a ligament strain that doesn't reset your hypothalamic thermostat.

So if you have a patient standing there clutching their back and they're running a temp, you have to immediately stop thinking about strains and start thinking about invaders.

Invaders meaning infection.

Right.

You're looking for osteomyelitis, an infection of the bone itself, or maybe an epidural abscess, which is even scarier.

Okay.

But the text adds another layer of complexity here.

It's not always infection.

Fever can also signal what I call systemic fire, like a spondyloarthropathy.

That's a mouthful.

Break that down for us.

It's an umbrella term for a bunch of inflammatory diseases.

The classic one is ankylosing spondylitis or reactive arthritis.

So autoimmune conditions.

Yes, exactly.

These are autoimmune conditions where the body is literally attacking the joints of the spine.

That creates massive systemic inflammation, which can manifest as a low grade fever.

So fever equals systemic, not just mechanical.

There is a specific call out here for pediatrics that gave me chills reading it.

It says if a child refuses to walk and has a fever, you must suspect dicitis.

Dicitis.

It's an infection or inflammation of the intervertebral disc space.

And here is why that clinical detective work is so critical.

A toddler can't say, my L4, L5 disc is inflamed.

They just stop walking.

They might go back to crawling or they might just sit there and scream if you try to stand them up.

If you see a fever, plus a refusal to walk, you are not sending that kid home with Tylenol.

That is an immediate, urgent workup.

That's a huge takeaway.

Okay.

Next question on the hunt.

Trauma.

Have you experienced any trauma to the spine or back?

This seems obvious, but you have to dig a little deeper.

It could be major trauma, like a car accident or a fall from a ladder, which points directly to a possible fracture.

But the text also emphasizes something called repetitive microtrauma.

Explain that.

Think about someone whose job involves constant lifting or pulling, a package handler, a construction worker, or think about a gymnast doing repetitive hyperextension day in and day out.

They didn't have one big crack moment, but that accumulation of stress can cause a stress fracture, particularly in a part of the vertebra called the pars

interarticularis.

Now here is one that scares me.

Systemic disease and cancer.

We need to ask about a history of cancer.

You absolutely have to ask.

The spine is one of the most common sites for metastasis.

If someone has a history of breast, lung, or prostate cancer, and they develop new back pain.

It's cancer until proven otherwise.

You have to assume it's metastasis until proven otherwise.

But you also need to know about the mimics.

The text mentions a really tricky one,

Ewing sarcoma.

That's a primary bone tumor, right?

Not a metastasis.

Yes.

And it's a tricky one.

It is a highly malignant tumor, but it can present just like a spinal infection.

The patient comes in with back pain, and sometimes they even have a fever and elevated inflammatory markers.

So it looks just like osteomyelitis.

It looks and feels like an infection, but it's actually a malignancy.

And age plays a huge role in risk profiling here, doesn't it?

Huge.

If the patient is under 20 or over 50, the risk for a tumor goes way up.

If they're over 50, you also have this massively increased risk for compression fractures just from baseline osteoporosis.

There is a very specific age -related red flag for people over 30 regarding sudden pain.

Yes.

This is a critical one.

If a patient over the age of 30 has sudden severe low or even middle back pain that isn't relieved by rest, I mean tearing pain,

you have to consider a dissecting aortic aneurysm.

Wow.

That's a vascular emergency, not a muscle strain.

Not even close.

The aorta runs right down the front of the spinal column.

If that vessel wall starts to tear or dissect, the patient feels that tearing sensation deep in their back.

If you misdiagnose that as a muscle strain, the patient could die.

Okay, we need to pause on this next one.

The text puts a massive do not miss warning label on it.

We're talking about coda equina syndrome.

I feel like we hear this term in medical school like a boogeyman, but let's actually visualize it.

What is physically happening inside the spinal canal?

It helps to know your Latin.

Coda equina literally means horse's tail.

That's a great visual.

It is, because your spinal cord, the solid cord itself, actually ends higher up than most people think.

It terminates around the L1 or L2 vertebra.

Okay.

Below that, it's not a solid cord anymore.

It splinters off into this bundle of free -floating nerve roots that drift down the spinal canal inside a sac of cerebrospinal fluid, and it looks exactly like a horse's tail.

So we have this bundle of nerves just floating down low in the spine.

Right, and these are the nerves that control all the downstairs functions.

They innervate the legs, the bladder, the anal sphincter, and the entire pelvic floor.

Now imagine you have a massive herniated disc at L4, L5.

It pushes backward into the canal.

Now, because these nerves are floating, they can usually dodge a little bit of pressure, but what if that herniation is massive?

It traps the whole bundle.

It strangles the horse's tail.

It compresses the entire sac of nerve roots against the back of the spinal canal, and this is why the symptoms are what they are.

You don't just get back pain.

You get what the calls saddle anesthesia.

Numbness, where you would sit on a saddle.

Inner thighs, perineum, buttocks, but the silent killer here, the one the text warns you might miss, is urinary retention.

Wait, retention?

Not incontinence.

I would assume if you lose control, you'd have leaking.

Eventually, yes, you get overflow incontinence, but the first thing that happens is the bladder, which is a muscle, gets paralyzed.

The nerves telling it to squeeze are cut off.

So it just fills up?

It comes a flaccid bag.

It fills up and fills up, but the patient literally cannot pee.

They lose the sensation of fullness.

Then eventually it just overflows.

So if a patient with acute back pain says, you know, I haven't peed since this morning, that isn't dehydration.

That's a five alarm fire.

Precisely.

That is a surgical emergency.

You have hours, literally hours, to get them to a surgeon to decompress that spine before those nerves die permanently, and the patient is left with permanent incontinence or paralysis.

Is it harder to spot this in kids?

It can be.

The text notes that children might be embarrassed to discuss their toileting habits, or if they're younger, a spinal cord tumor compressing those nerves might present as a developmental delay in bladder or bowel control.

So a potty trained child who starts having accidents and also has back pain.

Pay attention.

Do not write it off as simple behavioral regression.

It could be something sinister.

One last history question here.

Medications.

What drugs are red flags for back pain?

Two main categories you have to ask about.

First, long -term corticosteroid use.

Like prednisone.

Right.

It leeches calcium from the bones, causing osteoporosis.

This dramatically increases the risk of compression fractures, even with very minor trauma like a hard sneeze.

Wow.

And the second category.

IV drug use.

And the mechanism there.

It's a direct highway for bacteria to the bloodstream.

That bacteria circulates and it loves to settle in the highly vascular areas of the spine, leading to osteomyelitis or an epidural abscess.

Okay, so we've hunted for the big scary red flags.

Now we need to understand the pain itself.

Section two is all about characterizing the pain.

And this is what helps us narrow the differential diagnosis.

First, location.

In adults, this is usually pretty straightforward.

They can point to the spot.

It hurts right here.

Children,

however, are often very vague.

They might not be able to localize it well at all.

They might just rub their whole back or point to their tummy.

The text gives us a very specific definition for sciatica.

It's not just any leg pain.

Correct.

And this is so important.

True sciatica is sharp burning pain that radiates down the posterior or the lateral aspect of the leg, often all the way to the foot or ankle.

It follows a very specific nerve path.

And we have to be able to differentiate that from referred pain from our organs.

Right.

Visceral pain behaves differently.

For example, as the book notes, gallbladder pain often radiates around the trunk to the right scapula.

Kidney pain is usually felt deep in the flank.

And moving the back muscles won't necessarily reproduce it.

Exactly.

Bending over won't make your gallbladder hurt more, but it will definitely aggravate a herniated disc.

What about the onset and duration of the pain?

Sudden onset is extremely common.

And interestingly, the text says 50 % of patients can't even name a specific precipitating event.

Really?

Half?

Half.

They didn't lift anything heavy.

They just woke up with it or bent over to tie a shoe and bam.

And the timeline definitions are pretty clear.

Yes.

Acute is less than four weeks.

This usually resolves.

Subacute is defined as 6 to 12 wits.

And chronic is anything lasting over three months.

There is another really important pediatric red flag here regarding the duration.

Yes.

In a child, if back pain lasts longer than three weeks, it is often organic and serious.

You have to assume something is wrong.

Why is that?

Because kids bounce back so quickly from simple strains.

If they aren't healing, you have to dig deeper.

It's not normal.

Let's talk about night pain.

The text highlights this as a major, major warning sign.

Why is night pain so different from day pain?

It all comes down to distraction and inflammation.

Mechanical pain, like a muscle strain or some arthritis, usually feels better when you lie down and rest.

It sleeps when you sleep because you aren't loading the spine.

But tumor pain or infection pain is constant.

It's biological.

In fact, it can feel even worse at night because there are no other distractions from the pain.

It's just you and the pain in a dark room.

So if a patient says, the pain is so bad, it wakes me up from a dead sleep at 3 a .m.

That is not a strain.

Correct.

Your differential has to immediately shift to tumor, infection, or severe inflammation.

It is a mandatory question to ask every single patient with back pain.

What about aggravating and alleviating factors?

What can we learn there?

This gives you a ton of mechanical clues.

If it's better with rest, it's likely musculoskeletal.

If it's worse with standing, sneezing, or coughing.

Ah, the classic sneeze test.

Exactly.

A sneeze or a cough dramatically increases interathletal pressure, pressure of the fluid inside the spinal canal.

If that sharp increase in pressure causes pain down the leg, it strongly suggests a space -occupying lesion like a herniated disc is pushing on a nerve root.

The text also mentions some specific sports connections here.

Yes.

This relates to spondyloesthesis, which is the slippage of one vertebra over another.

It's often caused by repetitive hyperextension.

Gymnasts doing back handsprings, divers arching their back, or even swimmers doing the butterfly stroke.

And for the general school -age population, there's a more common culprit.

Backpacks.

Heavy, poorly fitted backpacks carried daily are a significant risk factor for mechanical back injury in children and adolescents.

Okay, let's get our hands dirty.

We're moving to section three, diagnostic reasoning,

the focused physical examination.

And we start with just observation.

Even before you touch the patient, you just look at them.

Are they ill -appearing?

Do they look pale, sweaty, uncomfortable?

That suggests infection.

And what about their posture?

Look at their posture.

Are they listing?

Listing.

Leaning to one side.

A patient with a herniated disc might lean away from the painful side to try and open up the space and relieve pressure on that nerve root.

And then there's the skin inspection.

This part of the chapter always fascinates me.

The strange but true clues you can find on the lower back.

You are looking for markers of underlying spinal anomalies, or what we call spinal dysraphism.

By go ahead.

Hairy patches, dermal cysts, a deep dimple, or even a lipoma, a fatty tumor, which is sometimes called a FOMS beard on the lower back.

These can indicate an underlying issue, like spina bifida occulta, or a tumor that's extending into the spinal cord.

It sounds like something from folklore, but it's real anatomy.

And eyes.

Why on earth are we looking at a patient's eyes for back pain?

It connects back to that systemic inflammatory disease we mentioned earlier.

Uveitis, or iridus inflammation of the eye, is strongly associated with conditions like juvenile rheumatoid arthritis and ankylosing spondylitis.

Everything in the body is connected.

Moving down to the legs.

The tech says we need to check for leg length discrepancy.

Yes.

And you do this properly.

You measure from the anterior superior iliac spine,

down to the medial malleolus, that bone on the inside of the ankle.

And what are we looking for?

A difference of greater than one centimeter is considered significant.

It can cause a pelvic tilt and a functional scoliosis, leading to secondary back pain because the spine has to constantly curve to compensate for that uneven foundation.

Now, pal, patient and percussion.

We are actually pressing on the spine.

You're looking for point tenderness.

If you press directly on a spinous process and the patient jumps off the table, that suggests something is wrong with the bone itself, a fracture or an infection like osteomyelitis.

And if the tenderness is off to the side?

If the tenderness is in the paraspinal muscles, the muscles alongside the spine, it's much more likely to be a simple muscle strain.

And what about fist percussion?

That's the thump on the costo vertebral angles, the CVA.

That's the flank area on the back over the kidneys.

If that causes exquisite pain, you aren't dealing with a back problem, you're dealing with a kidney problem like pylonephritis.

The text mentions a specific maneuver called the Faber test, and it references figure 24 .2.

Could you walk us through that visually?

Of course.

Faber is an acronym, flexion, abduction, and external rotation.

Okay.

You have the patient lie supine flat on their back.

They flex one leg up and place that foot on the opposite knee.

This makes a figure four shape with their legs.

Right.

I can picture that.

Then you as the provider gently press down on that bent knee pushing it toward the table.

And what does that tell us?

If pressing down causes pain deep in the groin or the buttock, it indicates pathology in either the sacroiliac joint or the hip joint itself.

It's a great test to help distinguish hip or SI pain from true lumbar spine pain.

Because if the hip joint is the problem, all the back stretches in the world won't fix it.

Excellent.

Now let's get into the mechanics.

Section four, mobility and neurological testing.

We start with the basic range of motion.

You want to check their flexion, extension, and rotation.

But to really objectively assess lumbar mobility, the text describes the modified Schober test, which is shown in figure 24 .3.

This one involves some measuring tape and a little bit of math.

Let's visualize it.

I'm standing behind the patient.

The patient is standing up straight.

You first find the dimples of venous, those two little dimples at the base of the back, which correspond anatomically to the L5 level.

You make a mark on the skin right there.

Then you take your measuring tape.

You measure 10 centimeters above that mark and make another mark.

And then five centimeters below it for a third mark.

So you have a total 15 centimeter span marked on their back skin when they're standing straight.

Okay, 15 centimeters marked out.

Then what?

You ask the patient to bend forward and try to touch their toes.

As the spine flexes forward, the vertebrae open up and the skin over them stretches.

That 15 centimeter distance should expand.

And how much should it expand?

It should increase by at least six centimeters.

So when they bend over, the top and bottom marks should now be at least 21 centimeters apart.

Exactly.

If it increases less than that, say it only goes to 17 or 18 centimeters, it indicates a significant decrease in lumbar mobility.

That stiffness is a classic, classic sign of ankle losing spondylitis, where the spine is literally fusing itself together.

That is a fantastic objective test.

Next up, let's move to probably the most famous move in the back pain playbook, the straight leg raise or SLR.

Everyone does it, but the text suggests a lot of people do it wrong.

It is, without a doubt, the most commonly botched test in primary care.

Most people just lift the leg and ask, does that hurt?

Which if you have tight hamstrings like I do, the answer is always going to be yes.

Exactly.

And that's the trap.

Hamstring pain is not a positive SLR test.

We are trying to test purely for dural tension.

We want to see if the L5 or S1 nerve root is being stretched over a herniated disc.

So walk us through the perfect textbook SLR.

The patient is supine, completely flat on their back and relaxed.

You, the provider, do all the work.

It is a passive test.

You cup their heel with one hand, keep their knee straight with the other, and slowly lift the leg.

And you're watching the patient's face, not the leg.

And what is the magic zone we're looking for?

The pain has to occur between 30 and 70 degrees of hip flexion.

If you get pain before 30 degrees, there just isn't enough tension on the nerve yet.

That might be malingering or a sign of something else.

And after 70 degrees.

If you get pain after 70 degrees, it's almost always just tight hamstrings or gluteal muscles.

So we are looking for that sweet spot.

30 to 70 degrees.

And the location of the pain is critical.

It is everything.

If they say, ouch, my back hurts, that is a negative test.

If they say, ouch, my hamstring hurts, that is a negative test.

It is only positive if the pain shoots like an electric shock below the knee.

It has to recreate that specific sciatic zap down the leg.

Now the text adds a pro tip here to confirm it.

The dorsiflexion maneuver.

This is how you outsmart the hamstrings.

It's a brilliant move.

Let's say you lift the leg to 45 degrees and they yell, ow.

You stop.

You lower the leg just an inch or two until the pain goes away.

And then you push their foot up.

You dorsiflex the foot.

So you're bending their toes toward their nose.

Right.

This action stretches the sciatic nerve without stretching the hamstring muscle any further.

If that simple foot movement brings all that radiating pain rushing back, that is a hundred percent nerve root irritation.

You've just nailed the diagnosis.

And then there's the cross -legged sign.

This one feels like black magic.

The crossed straight leg raise.

This is a very specific sign.

You lift the healthy leg, the one that doesn't hurt.

And as you lift it, the patient screams in pain on the bad side.

That seems physically impossible.

How does that work?

It's pure mechanics.

When you pull the nerve roots on the good side, it tugs the entire dural sac slightly across the midline of the spinal canal.

If there is a mass, and I mean a massive herniation on the bad side, even that tiny tug is enough to pull the inflamed nerve against the disc.

So if you see this sign.

If you see this sign, the specificity is incredibly high.

That patient almost certainly has a significant herniated disc.

Now we enter the neurological assessment.

This is where we check dermatomes and strength to figure out exactly which nerve root is angry.

The text breaks this down by level.

L3, L4, L5, S1.

And it proposes a really simple functional test for each.

This is critical for localization, and you don't need any fancy equipment.

You just need gravity and the patient's body weight.

So how do we do it?

To test the S1 nerve root, you have them walk on their toes.

That tests plantar flexion, the calf muscles.

To test the L5 nerve root, you have them walk on their heels.

That tests dorsiflexion, the muscles that lift the foot up.

And L3 and L4.

To test L3 and L4, which supply the quadriceps, you just have them do a full squat and stand back up.

I love that.

Toes for S1, heels for L5, squat for L34.

It's so simple.

Exactly.

Then you quickly check reflexes.

The knee -jerk reflex tests L3, L4.

The ankle -jerk reflex, or Achilles reflex, tests S1.

And don't forget to check for the Babinski sign.

That's stroking the bottom of the foot.

Yes.

You take a key or the end of your reflex hammer and stroke it firmly up the lateral side of the sole of the foot.

In adults, the toes should curl down.

And if they don't?

If the big toe goes up and the other toes fan out, that's a positive Babinski sign.

That indicates an upper motor neuron lesion, meaning the problem is in the brain or the spinal cord itself, not just a pinched peripheral nerve in the back.

That is a very bad sign.

And feel your tummy 4 .4 in the text.

Maps out the dermatomes for sensation.

Right.

It's a great visual.

It shows the sensory strips.

L3 is the anterior thigh.

L4 crosses the knee to the medial part of the calf.

L5 is the lateral leg and the top of the foot.

And S1 is the lateral foot and the sole.

You just test these with light touch or a pinprick to see if there's any numbness.

Finally, for the exam, the text lists the abdominal and rectal exams.

You have to palpate the abdomen, especially in an older patient with sudden pain, to feel for a pulsating mass, that aortic aneurysm we mentioned earlier.

And the rectal exam.

It's not pleasant for anyone, but it is absolutely necessary if you have any suspicion for Cata Aquina syndrome.

You are checking for rectal sphincter tone.

A loss of that tone is a hard sign that confirms the diagnosis.

Okay, we've poked, prodded, and marched them around the room.

Now the patient asks the inevitable question, Doc, do I need an x -ray?

An MRI.

Section 5 covers laboratory and diagnostic studies.

And here is the golden rule, which is supported by the evidence -based practice box in the text.

It's a big one.

No diagnostic tests in the first four weeks for acute low back pain, unless there are neurological signs or red flags.

Four weeks?

That's a long time for a patient in pain to wait.

Why the hard line on that?

For a couple of reasons.

First, as we said, 90 % resolve on their own within that time frame.

So routine imaging doesn't actually improve outcomes, it just adds radiation exposure and a ton of cost to the system.

And the second reason.

The bigger risk is finding incidentalomas.

Incidentalomas, I like that word.

Things you find by complete accident that aren't actually causing the pain.

You might see a bulging disc on an MRI in a perfectly healthy asymptomatic person.

If you MRI every single person with a back stream, you're going to find these abnormalities, and that leads to unnecessary anxiety, more tests, and sometimes even unnecessary surgery.

But if there are red flags, or if the pain persists beyond that four to six week mark, what do we order then?

X -rays or plain films are the first step, especially for trauma, or if the patient is over 50, has a history of cancer, or is on chronic steroids.

You're looking for fractures, bone lesions, or instability.

What about a bone scan?

When would that be useful?

A bone scan is great for spotting things that have high burn turnover.

It's very sensitive, so think infection, inflammation, or tumors.

It can often catch things an X -ray might miss early on, because X -rays need a significant amount of bone loss before illusion becomes visible.

And the big one, the MRI.

MRI is the gold standard for soft tissue.

It shows the discs, the spinal cord, ligaments, and infections beautifully.

You order this if pain persists, usually for more than a month, or you order it immediately if there are severe neurological deficits, like that drop foot from heel walking, or any signs of cauda equina.

And what about labs?

Any blood work?

Yes.

A simple urinalysis to rule out kidney issues.

And some basic blood work.

A CBC and an ESR.

The ESR.

The erythrocyte sedimentation rate.

It's a non -specific marker for inflammation, but the text notes that it is elevated in 90 % of serious spinal infections.

So if you're worried about osteomyelitis or an abscess, you have to check the ESR.

We have gathered all our clues.

Now we have to name the suspect.

Let's move to section six.

Differential diagnosis.

The serious causes.

We've touched on these, but let's solidify the clinical picture for each so we recognize them instantly.

Okay.

First up, spinal fracture.

You're looking for major trauma in a young person, or very minor trauma, like lifting a bag of groceries, in an osteoporotic elderly patient.

The key finding.

A very specific point tender is directly over the bone.

Next on the scary list.

Tumors.

In adults, it's usually metastasis from another cancer.

In children, it's more likely to be a primary bone tumor.

You're listening for weight loss, fatigue, and that classic unrelenting night pain we discussed.

Infection osteomyelitis, dyscytis, epidural abscess.

The key organism is usually staphylococcus aureus.

The key history is celly drug use, a recent surgery or invasive procedure, or a recent infection somewhere else in the body.

And the pediatric presentation.

The child with dyscytis who refuses to walk and often has a history of a recent respiratory infection.

And remember, the epidural abscess is particularly dangerous because it can expand rapidly and compress the spinal cord, causing permanent paralysis.

This is the most common cause of true sciatica.

You'll see that radiating pain and a positive straight leg raise test.

It usually resolves on its own, but you have to monitor closely for any progressive neurological deficits.

And finally, to round out the serious causes, Cauda equina syndrome.

The one and only surgical emergency on the list.

Saddle anesthesia, urinary retention leading to overflow incontinence, and bilateral leg weakness.

I cannot stress this enough.

This is an immediate referral to the emergency department.

Okay, let's all take a collective breath.

Those are the nightmares.

Now let's look at section seven.

Differential diagnosis.

The common and non -spinal causes.

These are the things we're going to see every single day in clinic.

Let's start with the big one.

Non -specific mechanical problems.

The most common is a simple muscle strain.

You'll get a history of overuse, often with no specific precipitating event.

The pain is relieved by rest and heat, and the neurological exam is completely 100 % normal.

What about spondylicthesis?

That's the slippage of one vertebra on another, usually L5 on S1.

On exam, you might actually be able to feel a step off, a literal dip in the spine when you palpate the spinous processes.

And remember, tight hamstrings are a major clue here.

Okay, ankle -losing spondylitis.

This is that inflammatory disease we keep mentioning.

The classic patient profile.

A young male, usually in his 20s or 30s.

The key clue.

Morning stiffness that improves with exercise.

This is the complete opposite of a mechanical strain, which feels worse with activity.

The key clue.

And the classic x -ray finding is the bamboo spine where the vertebrae fuse together over time.

And spinal stenosis.

This is a condition of older adults, usually over 50.

It's what we call neurogenic claudication.

The key clue.

Pain that gets worse with walking or standing up straight, and is relieved by sitting or bending forward.

This is the famous shopping cart sign.

Patients love to lean over the shopping cart in the grocery store because that forward flexion opens up the spinal canal and relieves the pressure on the nerves.

Let's quickly revisit the pediatric specifics again.

Two big ones in the chapter.

First, Scheuermann disease.

This is a fixed pyphosis, a hunchback deformity that develops in adolescence.

The pain typically worsens at the end of the day due to muscular fatigue.

And second,

spondylolisis, which we mentioned earlier.

That's the stress fracture of the pars interticularis, common in young gymnasts and dancers.

And finally, the non -spinal or visceral mimics.

The things that aren't the back at all, but pretend to be.

Right.

An aortic aneurysm presents with that tearing pain.

And you might find asymmetric pulses in the legs.

Gallbladder disease or cholecystitis gives you right upper quadrant abdominal pain that can radiate to the right scapula and a positive Murphy sign.

What else?

Pylonephritis, a kidney infection that gives you fever, cloudy urine, and that CVA tenderness when you thump the flank.

And in sexually active females, don't forget pelvic inflammatory disease or PID.

They'll have back pain plus cervical motion tenderness on a pelvic exam.

And lastly, the text touches on psychogenic causes.

It even mentions the term malingering.

It does.

And it advises you to look for inconsistent exam results.

For example, if a patient has a dramatically positive straight leg raise when they're lying down, but then can sit up straight on the exam table with both legs fully extended to talk to you, which is mechanically the same position, that's a discrepancy you should note.

But you have to be careful with that label.

Very careful.

Psychological distress is real and it can genuinely amplify physical pain.

The goal isn't to catch someone in a lie, but to get a complete picture of their health.

Wow.

We have covered a lot of ground from the truly scary to the mundane.

Let's head to the outro and try to synthesize all of this.

The whole journey of the clinical detective and acute low back pain is about rigorous filtering.

It's a funnel.

You start with that 90 % likelihood that it's something simple and mechanical.

But you don't stop there.

You never stop there.

You use your history to hunt for those red flags.

You use your observation and palpation to find objective physical signs.

You use mechanical testing like the Schober test and the SLR to test function.

And you use imaging selectively only when the evidence demands it.

It's a logical step -by -step process that keeps the patient safe without over -medicalizing what is likely just a simple sprain.

Exactly.

It's about being thorough, but also being a good steward of resources.

Now for our final provocative thought, I want to go back to that evidence -based practice note in the text, the one regarding adolescents.

This one really stuck with me.

Oh, this is a fascinating and humbling piece of data.

A study followed over 200 ,000 adolescents who presented with low back pain after one full year.

After one year, more than 80 % of them had no identifiable diagnosis.

80%.

So we do all this, the history, the exam, maybe even some tests.

And for 8 out of 10 kids, we still don't have a specific name for what was wrong.

That is the reality.

And it challenges us as clinicians to be comfortable with a certain amount of uncertainty.

As long as you have diligently ruled out the red flags, the tumors, the infections, the fractures, it is okay not to have a precise anatomical label for the pain.

The body often heals in ways we can't fully visualize or understand.

Our primary goal is ensuring safety and restoring function, not always finding a perfect name for the pain.

That is a very humbling thought to end on.

We're detectives, but sometimes the mystery remains unsolved, even as the patient gets better.

Indeed, and that's okay.

Thank you so much for joining us on this deep dive into acute low back pain.

We really hope this roadmap helps you the next time a patient walks in clutching their lumbar spine.

A warm thank you from the last minute lecture team.

Keep learning, and we'll see you in the next deep dive.