So let's take a look at
a patient with knee pain.
A 52-year-old obese man presents
with acute on chronic right knee pain.
It's been waxing and waning for the
past five years, and it's worse with activity.
After strenuous exercise yesterday, he
now has warmth and swelling of the knee.
It will be important for us to review
our anatomy before we move on
to thinking about the different
causes of knee pain here.
So always remember that we have a medial
collateral ligament and a lateral collateral ligament,
also known as the fibular collateral ligament.
There's the ACL or anterior cruciate and
posterior cruciate ligaments in the middle.
In addition, around the patellar
tendon, around the patella,
you have a proximal quadriceps tendon
and then a patellar tendon, more distally.
We're going to review some mechanical
causes of knee pain, inflammatory causes,
infectious causes and a
variety of other causes as well.
In terms of mechanical, it's important to think
of the knee as a joint with three compartments.
You have a medial compartment, a lateral compartment,
and then the patellofemoral compartment.
And certainly osteoarthritis is the most common
cause of knee pain in men and women who are older.
In younger women in particular,
we can have malalignment issues
such as patellofemoral pain syndrome,
where the different forces acting on the patella
have caused it to be laterally displaced
and that can cause problems with ambulation,
even with prolonged sitting.
Musculotendinous strains like quadriceps
tendinitis or patellar tendinopathy,
ligament sprains and tears will
want to come up with some good tests
to rule out an MCL tear or ACL tear
versus just a strain of those ligaments.
Certainly meniscal injuries are relatively
common and they're inside the knee
so we have to come up with some good
tests to really identify what's going on with them.
Some patients with knee pain
simply have a bone bruise or contusion.
And then, of course, we want to rule out
stress fractures, particularly of the tibial plateau,
as these can occur with too much use
of that joint over time in the right patient.
There's also inflammatory
etiologies for knee pain.
Rheumatologic, crystalline and simply
bursitis like pes anserine bursitis.
It's going to be important that we know
how to assess for warmth in both knees
and how to look for an effusion.
In patients who do have risk factors
for an effusion, like, for example,
having recently undergone a procedure
like an injection or recent surgery
or any recent trauma to the skin, it's important
for us to know that we're dealing with bacteria,
most commonly Staph aureus.
And this is a high stakes
diagnosis to identify a septic joint.
So we have to, again, know our anatomy and
know how to access the joint if we need to.
So in summary, for this particular patient,
we're thinking this could just be a
flare of osteoarthritis, which can
manifest with a small effusion,
or is this acute gout?
He's in the right age group for that.
Pes anserine bursitis just on the
medial distal aspect of the knee.
Does he have an acute meniscal tear?
or has he potentially strained one of
his ligaments while he was doing that
strenuous exercise yesterday?
Well, let's move on with our physical exam.