Acute Knee Pain: Differential Diagnosis

00:01 So, in terms of differential diagnosis, getting the location of the pain is very important.

00:07 So, anterior knee pain, you can think about patellar tendinitis, jumper’s knees, so that's very common among – particularly among younger athletes.

00:15 And if they are doing a lot of jumping – basketball, volleyball players – and it is really a pain right over that patellar tendon.

00:22 So, it’s pretty easy to find.

00:24 Patellofemoral syndrome, we’ll cover in more detail later, but it is the most common cause of anterior knee pain.

00:30 For medial pain, you could think of a sprain of the medial collateral ligament, think of medial meniscal tears, and that's also the site of the pes anserine bursa.

00:39 So, those athletes who may be overusing, particularly in overtraining with running, you get a pes anserine bursitis.

00:47 That's on the medial side.

00:49 On the lateral side, you have, of course, lateral meniscus tear, but that's where the iliotibial or IT band lives.

00:57 So, that’s – so, a more medial side pain in runners, pes anserine bursitis; lateral pain, think of IT band syndrome.

01:06 So, let’s work through our differential diagnosis of knee pain, particularly among children and adolescents as well.

01:12 So, these are commonly going to be your athletes that you see.

01:15 And I think one thing to remember is patellar subluxation in itself can be painful.

01:20 And females are more likely to have greater degrees of patellar subluxation versus males.

01:28 Tibial apophysitis, or also commonly known Osgood Schlatter disease, deserves some calling out specifically as a cause of knee pain because it happens pretty frequently.

01:38 The nice thing is it's almost always presents the same way, which is pain over the tibial tuberosity.

01:45 It's often associated with a growth spurt among adolescents.

01:48 The pain gets worse with squatting, going upstairs or a strain in the quadriceps.

01:54 And that's why having the patient extend their knee against resistance is a great way to cause the pain and draw it out, so that can point you in the right direction.

02:05 And remember, this is below the knee joint, so you shouldn't see an effusion with tibial apophysitis.

02:10 If there's an effusion within the knee, that means there’s something going on as well.

02:15 And x-rays don't really help too much with tibial apophysitis.

02:19 They’re often negative.

02:20 You can see an avulsion of the apophysis.

02:23 If you do or not, the management is generally going to be conservative.

02:26 It’s going to be rest, analgesics and follow-up.

02:30 And another thing that’s important to remember among children and adolescents is that a more serious condition, slipped capital femoral epiphysis, can result in referred pain for the knee.

02:40 So, this is a condition in the hip, which is dangerous because of its associated risk of avascular necrosis, which can present as a generalized kind of vague knee pain.

02:50 So, therefore, checking the hips are important too.

02:53 So, the joints above and the joints below are always in question when you see somebody with knee pain.

02:58 So, think about ankle and, in particular, in this case, hip injuries among children and adolescents with knee pain.

03:05 Whereas among adults, I mentioned IT band or iliotibial band syndrome, this is another one where pain is worse going up the stairs, and it has again a very specific physical finding.

03:14 Find your lateral epicondyle of the knee, about 3 cm above that joint line, that's where you should – that's where you should have tenderness with IT band syndrome.

03:24 And generally, it’s related to stress on that tendon.

03:29 Therefore, it's best to try to provide some rest for the patient, some ice and analgesics and monitor.

03:36 Meniscal tears, they can be in place for years before the patient necessarily presents to you.

03:42 The classic is that twisting motion with the foot planted, tears the meniscus.

03:46 This is going to be associated with an effusion, if it’s at all serious because of the inflammation within the joint.

03:52 And as I mentioned, you really need an MRI for a good diagnosis of a meniscal tear.