published 5/17/07, updated 4/28/10

Paul Ingraham is a runner and a former Registered Massage Therapist. He’s been studying, treating and writing about runner’s knee for ten years — and had it himself, of course!

The Runner’s Knee Diagnostic Stand-Off

How to tell the difference between the two most common knee pain problems in runners, IT band syndrome and patellofemoral pain

by Paul Ingraham, Vancouver, Canada

This quick guide and checklist will quickly help most people with runner’s knee pain figure out which kind, and then direct you to (much!) more detailed resources for the diagnosis that fits you best. There are two common kinds of “runner’s knee” conditions:

pain on the side (iliotibial band syndrome, or ITBS)
pain on the front (patellofemoral pain syndrome, or PFPS)

Of course, there are some other causes of knee pain. However, the great majority of knee pain in runners is going to be one of these two suspects. They usually don’t occur together, although that can happen.

Knee pain in runners is usually no big deal, but it can get ugly

Both kinds of runner’s knee are usually easy to recover from — most people just need a little ice, rest, and perhaps a temporary change in running technique.

But both conditions also have a nasty tendency to become chronic and extremely frustrating in a few unlucky runners — several new cases in every marathon! The trouble is, when the pain is new, it’s impossible to know which way it’s going to go. Maybe it will go away quickly … and maybe it won’t.

So it’s a great idea to be well prepared and well informed just in case, because both conditions are shockingly hard to get competent treatment for. Both are misunderstood by most doctors and therapists. Virtually all professionals know the basics and conventional wisdom … but much of that is wrong.

Many runners with knee pain simply don’t prepare for the worst. They get help slowly, and then it takes weeks to realize that they aren’t getting good help. But, by that time, your training schedule is blown to hell.

Tell the difference at a glance

The easiest way to tell the difference between the two conditions is simply by the location of the symptoms. PFPS affects the kneecap and surrounding area. Don’t confuse it with iliotibial band syndrome (ITBS), which definitely affects primarily the side of the knee. PFPS may be felt in a wider area, but will still have an epicentre on the kneecap. ITBS will rarely spread much beyond its hot spot on the side of the knee.

ITBS has a narrow definition: it refers only to strong pain on the side of the knee at a specific anatomical location (the lateral epicondyle of the knee). Pain that is primarily in the hip or thigh is often mistakenly diagnosed ITBS. This is not possible by definition.

PFPS has a much broader definition: it is a “condition of conditions,” with many possible variations and causes.

Diagnose your runner’s knee

Just check the knee symptoms that apply to you. Whichever side gets more checks … that’s what you’ve probably got. Check all that apply. (Note: this is not a form, you do not have to “submit” it … just count checks!)

Iliotibial Band Syndrome (ITBS)
	The epicentre of the pain is on the side of the knee. Symptoms may occur nearly anywhere around the entire knee, particularly in severe cases, but the worst spot has to be on the side of the knee.	The epicentre of the pain is somewhere under or around the kneecap. As with ITBS, symptoms may occur nearly anywhere, but it will usually be mainly on the front of the knee.
	There is a spot on the side of your knee, right around the most sticky-outy bump, that is sensitive to poking pressure, and your kneecap is not particularly sensitive when pushed firmly straight into the knee.	It’s not very comfortable pushing your kneecap straight into your knee, but there is no particularly sensitive spot on the side of your knee.
	Pain tends to be worse when descending stairs or hills, and is either not painful at all or noticeably less painful when ascending.	Pain tends to be worse when ascending stairs or hills, but may be painful both ascending and descending.
	Pain first started while going downhill.	Pain first started while going uphill.
	Both PFPS and ITBS can start over the course of a few hours or a day, but ITBS almost always does. If the pain started relatively quickly, check this box.	If your pain grew relatively slowly, over months or years, check this box.
	Doing a deep knee bend does not especially hurt.	Doing a deep knee bend definitely hurts.
	Pain is not particularly affected by sitting, although it might get worse after sitting for quite a while (longer than an hour).	Pain is clearly aggravated by sitting with knees bent. When you get up, it hurts more than it did when you sat down.
	You do not have any obvious structural problems in the legs.	You are a little knock-kneed, have flat feet, or kneecaps that seem to be kind of at a funny angle.
	Symptoms tend to be quite consistent and predictable, with only minimal changes in the intensity of the epicentre over time, and almost no change in the exact location of the hottest spot.	PFPS may also have consistent symptoms, in which case you can’t really check either side for this point. However, if you experience seemingly mysterious fluctuations in intensity or location — if you find that the problem is just not very predictable — this is a strong indicator that you have PFPS, not ITBS, and so you should check this side.
I have published an enormous, exhaustively detailed pair of tutorials about each of these knee pain conditions. Now that you have a better idea what kind of knee pain you have, continue by reading more about it. Much more! Fun fact: after publishing this document for five years now, I have quite good statistics on it, so I know that 60% of visitors will choose to read more about ITBS, and 40% will choose PFPS.
	Continue reading about iliotibial band syndrome	Continue reading about patellofemoral pain syndrome

Shouldn’t you get your knee pain diagnosed by a health care professional instead of here on the “internets”?

That would be the correct thing to say in a legal disclaimer (and I do). But the truth is that a lot of knee pain is misdiagnosed by so many health care professionals that you are just as well off — perhaps even better off — starting with a detailed and referenced self-help guide.

Of course, if your symptoms don’t seem to match either column very well, then it probably is a good idea to consult a professional. ITBS and PFPS are not the only causes of knee pain!

Lots of knee pain is misdiagnosed by “health care professionals.”

But if you fit one profile or the other fairly well, then you can trust this diagnosis as a starting place. It’s based on years of study and experience writing and teaching about runners’ injuries. This website is devoted to offering the most level-headed, evidence-based information possible.