Sensible advice for aches, pains & injuries

The Runner’s Knee Diagnostic Stand-Off

How to tell the difference between the two most common kinds of runner’s knee: IT band syndrome versus patellofemoral pain

updated (first published 2007)
by Paul Ingraham, Vancouver, Canadabio
I am a science writer and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I was the Assistant Editor of for several years. I’ve written hundreds of articles and several books, and I’m known for readable but heavily referenced analysis, with a touch of sass. I am a runner and ultimate player. • more about memore about

This brief guide and checklist will quickly help most people with runner’s knee pain figure out which type of runner’s knee you have, and then direct you on to (much!) more detailed information for the diagnosis that fits you best. There are many myths about both conditions that need busting, like the one about IT band stretching or the importance of kneecap tracking (full list of related articles below).

There are two common runner’s knee injuries:

  1. pain on the side: iliotibial band syndrome (ITBS)
  2. pain on the front: patellofemoral syndrome (PFPS)

There are other causes of knee pain, of course, but most knee pain in runners is one of these two — they are extremely common1. They rarely occur together.

Diagram of the knee showing IT band syndrome on the side of the knee, and patellofemoral pain syndrome on the anteriorof the knee.

Where’s the pain?

IT band syndrome dominates the side of the knee. Patellofemoral pain is more variable, but usually more in front.

Beware of chronicity! Although humans are “born to run,”2 and most cases are easy to recover from,3 these injuries do have a nasty way of dragging on and on in some unlucky runners — please be aware of that risk.4

In the rest of this article:

Front or side? Location is major difference between ITBS and PFPS

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, whereas ITBS definitely affects primarily the side of the knee (the side facing outwards).

The location of PFPS is less predictable,5 but it usually still has an anterior epicentre. ITBS does not spread much beyond its hot spot on the side of the knee.6

ITBS has a specific definition: it refers only to strong pain on the side of the knee, at or just above the lateral epicondyle. Pain in the hip or thigh is something else. For more detail about this common point of confusion, see Iliotibial Band Syndrome: Location, Location, Location!

“Ow! Damn! The side of my knee hurts!”

— every single IT band syndrome victim ever

Diagnose your runner’s knee: a detailed comparison of ITBS and PFPS

Note the knee symptoms that apply to you. Whichever side has more, place your bet on that diagnosis.

Check the knee symptoms that apply to you. Whichever side gets more checks … place your bet on that diagnosis. Check all that apply. (Note: this is not a form, you do not have to “submit” it … just count checks!)

Iliotibial Band Syndrome
Patellofemoral Pain Syndrome
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, but 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, so you should check this side. has very detailed tutorials about each of these knee pain conditions. Now that you have a better idea what kind of knee pain you have, read more about it. Much more! (Fun fact: after publishing this document for ten 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

Symptoms that don’t fit either ITBS or PFPS

It’s possible to have more than one significant knee condition at once, of course — including both ITBS and PFPS. However, it’s unusual. Here is a short list of symptoms that you should not see with either ITBS or PFPS:

If your symptoms don’t seem to fit either condition, then by all means consult a professional.

Of course, you should probably get your knee pain diagnosed by a health care professional instead of on the Internet. That would be the right thing to say in a legal disclaimer, and I do. But beware! Myths about these injuries are everywhere, and misdiagnosis is rampant. You could do worse than sticking to a trusted website. 😉

About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer, former massage therapist, and I was the assistant editor at for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.

Much more reading about IT band pain and patellofemoral pain

What’s new in this article?

Significant revision. The article now gets to the point quicker, and is less wordy overall. Several side points were been moved into footnotes. Added some links and a couple citations.

Improved some formatting, especially on mobile.


  1. Taunton JE, Ryan MB, Clement DB, et al. A retrospective case-control analysis of 2002 running injuries. Br J Sports Med. 2002;36(2):95–101.

    This report on two year’s worth of injuries among Vancouver runners — many of whom I probably run with every day on Vancouver’s sea wall — found that “patellofemoral pain syndrome was the most common injury, followed by iliotibial band friction syndrome, plantar fasciitis, meniscal injuries of the knee, and tibial stress syndrome.”

  2. Bramble DM, Lieberman DE. Endurance running and the evolution of Homo. Nature. 2004 Nov;432(7015):345–52. PubMed #15549097. This historically significant paper injected a huge dose of scientific credibility into the idea of “natural running,” concluding “The fossil evidence of these features suggests that endurance running is a derived capability of the genus Homo, originating about 2 million years ago, and may have been instrumental in the evolution of the human body form.” BACK TO TEXT
  3. Most people just need a little rest, some stretching that’s probably just a placebo, and maybe a change in running style. But mostly rest and then baby steps back to normal training loads. BACK TO TEXT
  4. 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 stubborn cases of both conditions are shockingly hard to get good help for. Both are misunderstood and mistreated by most doctors and therapists. They know the conventional wisdom … but much of that is wrong. Many runners with knee pain don’t prepare for the worst by educating themselves about the condition. They get help slowly — if at all — and then weeks later realize they aren’t getting good help. By that time, their training schedule is blown to hell. BACK TO TEXT
  5. “Patellofemoral pain” is a symptom with several possible causes. In many cases, a more specific diagnosis is possible, but it’s just called PFPS if a more specific diagnosis can’t be made. BACK TO TEXT
  6. Some small amount of variation is possible thanks to the variety of human anatomy and the weirdness of chronic pain. BACK TO TEXT
  7. About “tendinitis” versus “tendonitis”: Both spellings are considered acceptable these days, but the first is technically correct and more formal, while the second is an old misspelling that has only achieved respectability through popular use. The word is based on the the Latin “tendo” which has a genitive singular form of tendinis, and a combining form that is therefore tendin. (Source: Stedmans Electronic Medical Dictionary.) BACK TO TEXT