Pain •Sensible advice for aches, pains & injuries
[Picture of runners disappearing into the mist. Some portion of them undoubtedly have patellar pain.]

Stubborn patellar pain?

Patellofemoral syndrome is a common and usually chronic problem, causing pain mainly on the front of the knee.

Save Yourself from Patellofemoral Pain Syndrome!

Patellofemoral pain syndrome (aka runner’s knee) explained and discussed in great detail, including every imaginable self-treatment option and all the available scientific evidence

66,000 words, updated Mar 10th, 2015 — What’s new?
by Paul Ingrahambio
I am a science writer, the Assistant Editor of, and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I’ve written hundreds of articles and several books, and I’m known for sassy, skeptical, referenced analysis and a huge bibliography. I am a runner and ultimate player, and live in beautiful Vancouver, Canada. • full bioabout
 & Tony Ingram, PT, MScbio
I am a licensed physical therapist and PhD level research scientist with expertise in human movement. I did my Masters thesis on knee pain, and have treated countless painful knees. As a dancer, I have lots of experience using (and hurting) my own knees! I live in Halifax, Canada, and blog at • full bio

illustrations by Paul Ingraham, Lindsay McGee

Welcome to the most detailed guide to patellofemoral pain syndrome available. This is not just a web page — it’s a full-length e-book for patients and professionals. Every anterior knee pain base is covered: what it is and how it works, the myths and controversies, diagnostic help, worst case scenarios, analysis of every possible treatment method. I have yet to meet the patient who has actually “tried everything.”

Patellofemoral pain syndrome (PFPS), also known as runner’s knee, is the most common of all kinds of knee pain, causing pain around and under the kneecap. Almost anyone can get it, but it particularly affects runners, cyclists and hikers, and also office workers or anyone else who sits for a living. It’s also common in teens. Almost 40% of pro cyclists will get anterior knee pain in any given year,1 but runners are by far the most numerous victims, and often the most frustrated ones. PFPS is the most common of all knee injuries in runners2 … and there are a lot of runners out there.

Knee pain may be common, but it’s tricky to find good information about it. Patellofemoral pain also seems to be one of the most misunderstood of all knee pain problems. There are countless brief descriptions and definitions of it online, but most just repeat the same points of oversimplified conventional wisdom.3 And while every doctor and therapist has basic knowledge of the condition, few are prepared for a tough case.

“I survived a brain tumor. The knee has been worse rehab than that.”

— a reader, commenting on how much knee pain has affected her life

About footnotes. There are 214 footnotes below. Click to make them “pop up” without losing your place, of two types: more interesting extra content,1Footnotes with more interesting and/or fun extra content are bold and blue, while dry footnotes (citations and such) are lightweight and gray. Type ESC to close footnotes, or re-click the number.

and boring reference stuff.2“Boring” footnotes usually contain scientific citations from my giant bibliography of pain science. Many of them actually have pretty interesting notes.

Example citation:
Berman et al. Acupuncture for Chronic Low Back Pain. New England Journal of Medicine. 2010. PubMed #20818865. ← That symbol means a link will open in a new window.
Try one!

A tale of two authors

This book had one author, Paul Ingraham, for many years. In the first half of 2014, Tony Ingram, PT, MSc, masterminded a major new edition, beefing up the science and particularly adding a much stronger emphasis on the value of exercise. (The similarity in our surnames is just a weird coincidence.) Tony is now on board for the long haul, and we will both be keeping the book current over the years. So, who exactly are we?

Photo of Paul Ingraham

Paul I am a science writer & amateur athlete in Vancouver, Canada. I’ve been writing about patellofemoral pain for over a decade. I’ve been interested in the topic ever since my own severe case of IT band syndrome (the other kind of runner’s knee.)

Throughout the book, it’s usually me “talking.” Because the book was all mine for so long, we found it easier — for now — to keep most of the text in my voice. When you see the pronouns like I, me, mine, and so on, it’s usually me. Unless it’s Tony…

Photo of Tony Ingram

Tony Hi. Sometimes I just have to be heard — perspective from my career, or about something Paul got wrong. (Fortunately not too much of that.)

I am a licensed physical therapist and PhD level research scientist with expertise in human movement. I did my Masters thesis on knee pain, and have treated countless painful knees. As a dancer, I have lots of experience using (and hurting) my own knees! I live in Halifax, Canada.

Getting good care for patellofemoral pain is a challenge

Many popular treatments for PFPS are of dubious value:

  • Correcting muscle imbalances is by far the most common prescription for PFPS. The idea is to teach muscles to pull more evenly on your kneecap — which good science has shown to be difficult at best, possibly impossible, and quite likely irrelevant.4
  • Quadriceps massage is a popular alternative treatment, but massage — while good medicine for many painful conditions — is really not very helpful for kneecap pain, which is a very “jointy” problem.
  • “Stay active” is one of the most common recommendations — but it can be the worst therapy of all for patellofemoral pain. It’s just knee jerk advice, given by professionals unfamiliar with the nature of PFPS. While exercise can be useful, “staying active” is overly simplistic advice, and can seriously backfire.
  • Treating PFPS like arthritis is a basic misunderstanding of the condition. Family doctors usually do this, but they are generally poorly informed about PFPS.5 It’s an understandable mistake — the distinction between PFPS and arthritis is complex — but it’s bad news for the patient with serious chronic pain!
  • Knee surgery is rarely a good option and often prescribed prematurely. Specialists6 and orthopaedic surgeons cannot be counted upon to provide good advice for PFPS.7 Experts believe surgery to be quite risky,8 , and the research is very discouraging.

You should try to find good professional help, but it’s a great idea to be as well informed as possible when you do it, or you can easily waste a lot of time and money on dubious therapies — even if this tutorial can’t give you “the answer,” I hope it can at least help you avoid ineffective treatment.

How can you trust this information about patellofemoral pain?

I apply a MythBusters approach to health care (without explosives). I question everything and I have fun doing it. I assume that anything that sounds too good to be true probably is. I make no big promises, and I do not claim to know the “one true cause” of patellofemoral pain syndrome. When I don’t know something, I admit it. I actually read scientific journals, I clearly explain the science behind every key point (there are more than 220 footnotes here, drawn from a huge bibliography) and I always link to the original sources.

TONY The sheer volume of sources and the lack of miracle cure claims should be enough to convince you. But if you’re a stickler for credentials, I’m a licensed physical therapist and previous knee pain researcher. See the bio above for more.

I don’t offer a miracle cure because (duh!) there is none! It’s important to state this clearly. Wouldn’t it be great if there were a proven treatment with minimal cost, inconvenience, or side effects? But medical science is nowhere close to this for most chronic pain conditions, and especially for patellofemoral pain.9

However, there are good reasons for optimism.

I can explain all the options, help you to confirm your diagnosis, and debunk bad ideas. It may or may not lead to a “cure,” but it will get you as close as you can get. Some readers will finally break free of their patellar pain. Others will make progress after ditching a counter-productive therapy, or trying an option they didn’t know about before. And maybe that is kind of miraculous! But probably not!

A quick overview of patellofemoral pain

[Diagram: illustrating the difference between patellofemoral pain syndrome and iliotibial band syndrome, showing how the former causes pain primarily on the front of the knee, while the latter causes pain primarily on the outside of the knee.

PFPS affects the kneecap and surrounding area. Don’t confuse it with iliotibial band syndrome (ITBS) which definitely affects primarily the outside of the knee (the lateral or outward-facing side of the knee). This picture is of a right knee.

Patellofemoral pain syndrome (PFPS) is a problem with pain that feels like it is mainly on the front of the knee, specifically on the underside of or somewhere around the edges of the kneecap. One or both knees can be affected. The pain is usually worse when climbing stairs or hills, or after sitting for a long time.

In average cases, the pain is not severe and the problem often goes away with basic physical therapy.10 “Basic physical therapy” probably isn’t actually effective, but recovery proceeds anyway simply because the body is pretty good at healing.11 But many cases get worse instead of better. For the unluckiest patients, “basic therapy” completely fails and patellar pain becomes permanent and almost crippling.

Honest professionals know that the causes and cures for patellofemoral syndrome are unknown. But most doctors and therapists buy into the conventional wisdom: that the problem is essentially “mechanical.” Unfortunately, those theories have serious errors that are rarely discussed. Fortunately, a few medical experts suggest good alternatives, which will be explained in detail in this tutorial.

What’s in a name? The many labels of patellofemoral pain

“Patellofemoral pain syndrome” is a surprisingly meaningless name. It basically means “strange kneecap pain,” but in Latin. “Anterior knee pain syndrome” is another common name, and it’s a little more direct and honest: it’s pain, and it’s on the front of your knee, ‘nuff said.

Sometimes the “pain” part is dropped and it is just called “patellofemoral syndrome” or PFS.

The words “patellofemoral pain syndrome” are often used as a catch-all diagnosis in practice, without any diagnostic certainty — they may refer to nearly any pain roughly on the front of the knee, which may have any of several possible causes, none of which are particularly clear. Technically, it’s a diagnosis of exclusion — what’s left when everything else has been eliminated.12 The problem gets “syndrome” status because of this lack of clarity, and the fact that this particular kind of joint pain is so common.

[Picture: a woman in a chair. Chair workers often suffer from patellofemoral pain syndrome.]

Do you live in a chair?

“Chair warriors” who spend more than 4–6 hours per day suffer as much from knee pain as many runners. Woe to you if you both run and work in a chair …

“Runner’s knee” is a popular description among runners, of course, and they do get it more often than anyone else. But it is not a good term to use, because there are at least a half dozen other conditions that could be meant by it, especially iliotibial band syndrome. And of course it excludes other people who get the condition — all those people with cyclist’s knees and hiker’s knees, for instance!

Runners get anterior knee pain more often than anyone else.

Calling it “runner’s knee” particularly leaves out people whose knees hurt while sitting and because of sitting. Office workers and other chair-bound workers really do suffer from PFPS in droves. In fact, another name for this condition is moviegoer’s knee because of the tendency of the condition to cause pain after sitting for a long time. This also explains the use of the term “theatre sign” among professionals, as in, “He’s got theatre sign — must be a case of movie-goer’s knee.” In my professional experience, however, you could just as well say, “He’s got desk job sign — must be a case of office worker’s knee.”

One more naming note: occasionally you’ll hear therapists or doctors call this condition “patellofemoral tracking syndrome” (PFTS) or even chondromalacia patellae (definitions coming soon), but these are blatantly in error: these are things that might be causes of the condition, but they are not the condition itself.

About patellofemoral pain in teens

Patellofemoral pain in teens isn’t specifically covered in this book. However, the book is still useful for young patients.

The incidence of patellofemoral pain in adolescents is only a little bit higher than it is in the general population, and it is generally less serious and stubborn. It is mostly a temporary condition: they recover from or grow out of more easily than adults do. Although serious cases certainly can and do occur in teenagers, their age is not particularly relevant to those cases. A serious case in a teenager has to be handled in pretty much the same way that you would handle a serious case in an adult. So although age is a factor I haven’t focussed on, everything that I have focussed on should be of interest to teens with persistent knee pain.

Part 2

Nature of the Beast

The (many) possible causes of patellofemoral syndrome

Officially, no one knows what causes it. Here is an entertaining selection of typical disclaimers from some scientific papers dating back to 1988:

  • Back in 1988 Potter et al. summed it up: “Ironically, as simple as its presentation is, lack of consensus on the fundamental factors associated with PFS remains. No agreement exists on the exact pathophysiology ….”
  • In 1993, the Clinical Journal of Sports Medicine published an editorial called “The myth, mystic and frustration of anterior knee pain,”13 a title that certainly reveals a degree of medical uncertainty on the subject!
  • You would hope for progress over the next few years, but in 1998 Journal of Orthopaedic & Sports Physical Therapy published the opinion that “there is no consensus on the most effective method of treatment … the indications and contraindications of each approach have not been well established … [and] there is no generally accepted classification scheme for patellofemoral disorders.”14
  • Not long after, in 1999, the journal American Family Physician, in one of its excellent physician tutorials, said that “Managing patellofemoral pain syndrome is a challenge, in part because of lack of consensus regarding its cause and treatment,” and “no single biomechanical factor has been identified as a primary cause of patellofemoral pain.”15
  • And things haven’t really improved. In 2006, with resounding negativity, Näslund declared that “no consensus on the definition, classification, assessment, diagnosis, or management has been reached.” So, no consensus on anything — wow — and that is still true to this day.

That’s the official, reasonable position. Any honest doctor or therapist should be happy to admit that almost everything about PFPS is basically a mystery. But in practice, most doctors and therapists think and act like the conventional wisdom is adequate.

The conventional wisdom

I’m pleased to say that American Family Physician came around. They say that the mystery of PFPS has been solved. (It hasn’t really, of course. I’m being sarcastic.) In a new tutorial for physicians published last year (2007), they confidently declared the cause of PFPS:

[Patellofemoral pain syndrome] is caused by imbalances in the forces controlling patellar tracking during knee flexion and extension, particularly with overloading of the joint.

Dixit et al. Management of patellofemoral pain syndrome. American Family Physician. 2007. PubMed #17263215.

Well, thank goodness! That’s nice and clear, isn’t it? The conventional wisdom says that patellofemoral pain syndrome is painful degeneration of the cartilage on the underside of the kneecap, caused by a “mechanical” failure of that joint. What kind of failure? A “tracking” problem, in which the patella doesn’t slide evenly in its groove or “track” on the femur. For this condition, we need yet another multisyllabic name: “patellofemoral tracking syndrome.”

Another syndrome? I’m afraid so. It even has almost the same acronym: PFTS instead of PFPS. The conventional wisdom is so entrenched that many professionals consider the “tracking” syndrome to be virtually synonymous with PFPS itself.

The conventional wisdom is so entrenched that patellar “tracking” syndrome is virtually synonymous with patellofemoral pain itself.

But the idea that tracking problems cause patellar pain has not been proven beyond a reasonable doubt. In fact, as I will show in the sections ahead, it’s incredibly difficult to even prove that these problems even coexist, let alone how much they have anything to do with each other … if anything at all. Even stranger, it turns out that tracking problems are extremely difficult to even identify, let alone blame for anything. And as if this wasn’t enough trouble for the conventional wisdom, it turns out that even the “degeneration” of the kneecap’s cartilage is a scientific myth … a myth that probably has little or nothing to do with patellofemoral pain syndrome!

Wow. That’s a lot of myths.

The evidence that tissue pathology does not explain chronic pain is overwhelming (e.g., in back pain, neck pain, and knee osteoarthritis).

Teaching people about pain — why do we keep beating around the bush?, by Lorimer Moseley, pp2–3

Assault on the conventional wisdom about patellofemoral pain syndrome

Joints wear out, right? Comedian Louis CK:16

The doctor shows me an x-ray of my ankle and he’s like, “Yeah, your ankle’s just, uh… worn out.”

“What do you mean? I injured my ankle?”

He’s like, “No, it’s just shitty now.”

And yet! Pain in the patellofemoral joint mostly does not appear to be associated with any identifiable tissue degeneration or damage, dysfunction or malfunction, asymmetry or weakness.1718 Sometimes it just hurts, even though the knee — indeed, the whole leg — seem to be healthy in every way that we can measure knee health. And if that seems a bit odd, you ain’t seen nothing yet!

Even when the joint is degenerating…


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Part 2.3



Thanks to Dr. Scott Dye for helping me to understand and believe in my own unconventional ideas about patellofemoral pain syndrome, and by extension every other joint problem.

This document and all of was, for many years, created in my so-called “spare time” and with a lot of assistance from family and friends. Undying thanks to my wife, Kimberly, for countless indulgences large and small, and for being my “editor girlfriend”; to my parents for (possibly blind) faith in me, and much copyediting; and to Mike Gobbi, buddy and digital mentor, for many of the nifty features of this document (hidden and obvious). And thanks to all of the above, and many others, for many (many) answers to “what do you think of this?” emails.

Thanks finally to every reader, client, customer, and big tipper for your curiosity, your faith, and your feedback and suggestions and stories. Without you, all of this would be pointless.

And a few thanks to some health professionals who have been particularly inspiring to me: Dr. Steven Novella, Sam Homola, DC, Dr. Harriet Hall, Simon Singh, and Dr. Stephen Barrett.

Reader Comments

Here is what some readers have said about the patellofemoral pain syndrome tutorial over the years. Feedback is always welcome. I focus on the positive in this section, but I want to acknowledge that I certainly do receive some criticisms as well. In many cases I respond by making improvements to the tutorial. However, the vast majority of feedback is enthusiastic. Thanks, everyone!

This has already served as a massive eye opener for me. It makes a huge amount of sense where previously there was only confusion.

— Greg Bruce, “struggling masters athlete”

Thanks for a hugely informative tour of the dark continent of knee pain.

— Bob Maul, former nationally ranked Masters swimmer (Bob says, “Bad knees ended that chapter of my life.”)

I am so impressed with your tutorial on patellofemoral pain that I cannot find words strong enough for the praise due to you. After exhaustive research, your tutorial is the most thoughtful, comprehensive analysis of this issue I have found. It ties together and explains everything else I have read, makes sense of all the confusion, and finally gives me a clear direction. Thank you so much for your painstaking investigation and shedding some real light on this source of chronic pain. Every orthopaedic and family doctor every where should read this tutorial. You know more about this than they do.

— Heather Stanton, school psychologist, Elmira, New York

You can put another check mark on your satisfied customers list. My knee has no more pain or ache or problems. I have started doing tai chi again, which entails deep knee bends. I was ready to expect some knee pain from that, but it has been fine.

— Floyd Rudmin, Tromsø, Norway

One more special comment. In the Spring of 2009, I received an incredible endorsement from Jonathon Tomlinson, a GP in Hackney, East London, praising the whole website and every tutorial:

I'm writing to congratulate and thank you for your impressive ongoing review of musculoskeletal research. I teach a course, Medicine in Society, at St. Leonards Hospital in Hoxton. I originally stumbled across your website whilst looking for information about pain for my medical students, and have recommended your tutorials to them. Your work deserves special mention for its transparency, evidence base, clear presentation, educational content, regular documented updates, and lack of any commercial promotional material.

— Dr. Jonathon Tomlinson, MBBS, DRCOG, MRCGP, MA, The Lawson Practice, London

High praise indeed! Thank you, Dr. Tomlinson — testimonials just don’t get much better than that.

About the 2nd Edition

The 2nd edition of the PFPS tutorial was launched on July 28, 2014, after many months of collaboration with new co-author, Tony Ingram (bio). The book was updated many times over the years, but changes were too small and spread out to constitute an “edition”: that had to wait for this, by far the largest ever major change to the book.

Major changes for the 2nd edition are highlight in the table of contents. However, there were many other changes made.

About the collaboration

I must be doing something right, because a guy like Tony is a catch of a co-author: a Physical Therapist and a researcher in hot pursuit of his PhD. We’ve been working on a new edition of the patellofemoral pain syndrome book since late last year. It’s now available with new sections, a lot of new science, and a strong (and overdue) new emphasis on the evidence-based value of exercise — reversing my grumpy anti-exercise position. That’s the biggest change. Practically the first thing Tony said to me when we got down to work was, “I have to turn you around on exercise,” and so he did. Getting my mind changed on a key point or two was the whole point of teaming up with him — more about that below.

Tony also did his Masters thesis on anterior knee pain, and has serious the credibility of someone who has pushed his body to new limits as a dancer. Few people can combine serious academic credentials with that kind of athletic experience.

It has been an interesting and successful collaboration. Although Tony was a fan of many aspects of the previous edition, he did challenge me on several points. I think he sent some of those emails with great trepidation! Although our preliminary conversations had all been promising, you just don’t know how someone is going to cope with serious criticism until it’s happening. But I’m an old hand at this, and I couldn’t possibly be any kind of a success as a writer if I didn’t know how to shut up and listen attentively and humbly when a real expert is talking. Time and again, I think Tony was relieved when my emails came back calm and appreciative. I like being corrected. The alternative is to be be wrong and not know it.

The tables were turned near the end when I had to ask Tony “Where’s the beef?” about one of his new sections — a matter of editorial expertise more than knee knowledge. Tony looked a little startled at first, but he took it like a scientist, and proceeded with a significant upgrade to that section. It was my turn to be relieved!

Effective writing and publishing partnerships are rare, and I’ve had many of them fall through or just fail to thrive. But Tony and I had great time on this first project, and we’re seriously considering expanding our collaboration into other books. Stay tuned!

More about the exercise change

Making the 2nd edition more positive about exericse has been a great example of responding to new evidence — and a good example of a treatment that works, but probably doesn’t work how most people think it works. I was anti-exercise before because the evidence just wasn’t there for it yet, and too many professionals fancied that they were prescribing exercise to change biomechanical parameters (e.g. patellar tracking) that correlated poorly with the condition. Such prescriptions tended to be overzealous: too much exercise, too soon for patients suffering from what is fundamentally an overuse condition.

Now there is good evidence that exercise is effective — hallelujah, some much-needed good news — but dosage and timing are key, and the biomechanical rationale still needs to be taken out with the trash.

The new edition explains it all in the signature style of detailed, but sassy and whimsical, a pleasure to read if you’re remotely interested in the subject.

Not just one guy’s theory any more

The previous version of the book had a significant weakness, a major idea about the nature of the beast (basically the whole “it’s the homeostasis, stupid,” ). The idea was plausible and elegant, but lacked adequate scientific support for an important basic point of the book. One advanced reader complained:

I didn’t buy your book so I could get one guy’s theory about how patellofemoral pain syndrome works.

Fair enough. She went on to say that it was probably a pretty good idea, just painfully unsupported. Simple as it is, that’s one of the best single constructive criticisms I’ve ever received. On the one hand, I unapologetically offer my take on these complex subjects. They are my books, and this is not a medical journal. On the other hand, I don’t want my take to be based solely on private speculation — if my opinion is to have much value, it should be clearly based on a diversity of expert and scientific sources. And so this is one of the major repairs in the 2nd edition: Tony and I agreed early that my basic point was sound, but badly needed some scientific and expert support — and now it has it.

Further Reading

  • “The pathophysiology of patellofemoral pain: a tissue homeostasis perspective,” an article in Clinical Orthopaedics & Related Research, 2005.. This article by Scott F. Dye, MD, an orthopaedic surgeon from San Francisco, was by far the most influential source for this article. I do not normally recommend scientific articles to my readers, most of whom are ordinary people with knee pain, and not especially interested in slogging through medical jargon. However, in this case, I have to make an exception: although Dr. Dye’s writing is certainly intended for a professional audience, patients should still be able to get something out of it. It’s clear (for a scientific paper) and sensible, and even somewhat visionary in tone. Despite the fact that it’s certainly harder reading than this article, and despite the cost — the article will set you back US$10 to access — I still think it’s worth it. If you really want a good depth of understanding of PFPS, it’s required reading.
  • This article, Massage Therapy for Your Quads, will add to your understanding of the quadriceps muscle group and its relationship to the kneecap.
  • There are other kinds of knee pain, and it’s not always easy to tell which kind you’ve got. For the scoop on another common knee problem, see PS Save Yourself from IT Band Syndrome! — All your treatment options for Iliotibial Band Syndrome reviewed in great detail, with clear explanations of recent scientific research supporting every key point. Not sure what kind of knee pain you’ve got? See The Runner’s Knee Diagnostic Stand-Off.
  • The journal American Family Physician publishes free tutorials for doctors which may also be useful for patients. I have come to trust those tutorials as one of the best sources available when I am trying to understand conventional medical opinion. They are usually well-written and beautifully illustrated, and determined patients can often get plenty of value out of them despite the jargon. See “Patellofemoral pain syndrome: a review and guidelines for treatment” for a 1999 tutorial for doctors, and “Management of patellofemoral pain syndrome” for their 2007 article on the subject. Bear in mind that these articles present only the conventional wisdom, however, and primarily discuss structural explanations for knee pain. As such, I do not think that they are useful to my patients and readers except as the best available representation of conventional wisdom.

What’s new in this tutorial?

The original publication date of this tutorial has been lost, but I think it was in 2004. It remained quite rudimentary until 2007, when significant upgrades began. This change log was started in May ’07, along with many major improvements. As you can see, the tutorial has been updated many times since, and remains a live document.

A major feature of my tutorials is that I actively update them as new science and information becomes available. Unlike regular books, and even ebooks — which can be obsolete by the time they are published, and can go years between editions — this tutorial is updated at least once every three months and often much more. I also log updates, making it easy for readers to see what’s changed. This tutorial has gotten 64 major and minor updates worth logging since I started logging carefully in late 2009, and countless more minor tweaks and touch-ups.

Science update (Mar 10 '15, section #2.6)Added strong evidence from Freedman et al that Q-angles aren’t worth measuring. See section #2.6, Q is for quadriceps: the dubious role of the Q-angle.

Minor update (Feb 9 '15, section #2.4)Added an interesting subsection about “fabella syndrome.” See section #2.4, Under pressure.

Correction (Dec 22 '14, section #2.11)Reduced confidence in the results of a major study of special footwear (Knapik, the subject of the last update). See Boot Blooper for more information. See section #2.11, What about pronating?

New section (Sep 23 '14, section #8.21)A short new section, finally, on PRP injections. I’ve also published a more detailed free article about this. See section #8.21, Regenerative medicine? Platelet-rich plasma injections.

Minor update (Aug 23 '14, section #7.3)General editing, plus a stronger and clearer statement about targetting the vastus medialis. See section #7.3, Is one part of the quadriceps — the vastus medialis — important?

Minor update (Aug 23 '14, section #7.2)General editing and polish, now that the dust has settled from the 2nd edition launch. See section #7.2, If exercise works, how does it work?

Minor update (Aug 23 '14, section #7.1)General editing and polish, now that the dust has settled from the 2nd edition launch. See section #7.1, Does exercise work?

Major update (Jul 29 '14, section #7.4)Extensive revision for the 2nd edition. See section #7.4, How do you exercise without pissing off your knee?

Major update (Jul 29 '14, section #7.3)Extensive revision for the 2nd edition. See section #7.3, Is one part of the quadriceps — the vastus medialis — important?

New section (Jul 29 '14, section #7.2)A new section for the 2nd edition. See section #7.2, If exercise works, how does it work?

New section (Jul 29 '14, section #7.1)A new section for the 2nd edition. See section #7.1, Does exercise work?

New section (Jul 29 '14, section #7)A new section for the 2nd edition. See section #7, Then exercise: The long term solution.

New section (Jul 29 '14, section #3.10)A new section for the 2nd edition. See section #3.10, Pain is weird: the surprisingly fallible role of the brain in all this.

Updated (Jul 29 '14, section #2.8)Significant revision and expansion for the 2nd edition. See section #2.8, Females versus males: is there really a difference?

New edition (Jul 29 '14)Major revision of the book with new co-author, Tony Ingraham, PT, MSo. The new edition has a few new sections, a strong new focus on the value of judicious exercise therapy, and updated and expanded citations for many key points. Read more about the 2nd edition.

Science update (Dec 23 '13, section #2.11)Added another bad-news citation, and type of evidence. See section #2.11, What about pronating?

Science update (Nov 21 '13, section #8.16)Added a bad-news citation. Sorry about that. See section #8.16, Taping and strapping.

New section (Nov 7 '13, section #3.8)Intriguing new evidence of circulatory impairment in PFPS patients. See section #3.8, Like getting blood from a bone.

New section (Oct 24 '13, section #5.3)No notes. Just a new section. See section #5.3, “Maybe you’re just not built for running”.

Science update (Sep 20 '13, section #6.1)Added some science, to start building an evidence-based case for resting. See section #6.1, The art of rest: the challenge and the opportunity for patients who have supposedly “tried everything”.

Science update (Sep 20 '13, section #2.2)Another good news science update: more about how surprisingly well knees handle running. See section #2.2, Assault on the conventional wisdom about patellofemoral pain syndrome.

Science update (Aug 20 '13, section #2.5)Added a new study to the pile of evidence that abnormalities are common in healthy people and vice versa. See section #2.5, Patellofemoral Tracking Syndrome.

Science update (Jul 9 '13, section #2.2)A particularly “good news” science update about how running is, counterintuitively, actually pretty good for joints — not hard on them. See section #2.2, Assault on the conventional wisdom about patellofemoral pain syndrome.

Minor update (Jun 5 '13, section #2.10)Added a reader anecdote about stretching the IT band helping her anterior knee pain. See section #2.10, Tight IT bands.

Minor update (May 2 '13, section #2.2)Apt aging joints humour added, via comedian Louis CK. See section #2.2, Assault on the conventional wisdom about patellofemoral pain syndrome.

Minor update (Mar 29 '13, section #8.5)Upgraded risk and safety information about Voltaren Gel. See section #8.5, You and “vitamin I”: anti-inflammatory meds, especially Voltaren® Gel.

Science update (Dec 18 '12, section #8.17)The writing was on the wall, but a new comprehensive review of knee lube jobs has confirmed that knee lube jobs are all washed. The section now reflects that. See section #8.17, Should you get a lube job? Artifical synovial fluid injections.

Science update (Dec 5 '12, section #2.13)Two new studies of the connection between knee pain and the inner thigh muscles, showing … modest correlations of dubious significance. See section #2.13, Weak and uncoordinated muscles, perhaps?

Minor update (Nov 24 '12, section #8.9)Some customizing of “brain wrangling” for patellofemoral pain syndrome. See section #8.9, Brain wrangling: what to do about sensitization.

Science update (Nov 20 '12, section #8.11)Weak but interesting new evidence on natural running and injury prevention. See section #8.11, Should you run naked? On faddish running styles and running shoes (or the lack thereof).

Major update (Nov 16 '12, section #8)Greatly expanded. Now offers a comprehensive summary of all treatment options: the good, the bad and the ugly. See section #8, Other Treatments: What else can you do about PFPS?

New section (Nov 16 '12, section #5.4)New standard section I’m introducing to most of the tutorials to “manage expectations.” Too many readers assume there’s going to be a specific miracle treatment plan. See section #5.4, So what’s the plan? Some expectations management.

New section (Nov 15 '12, section #9)An important new section created as a direct response to reader demand. See section #9, Now what?: An action-oriented summary of recommendations.

Medium update (Nov 13 '12, section #8.13)Added a few paragraphs about foam rolling and trying to “elongate” the IT band. See section #8.13, Quadriceps massage.

Science update (Oct 28 '12, section #8.10)A minor but interesting new item about high heels. See section #8.10, Orthotics and shoes.

New section (Sep 29 '12, section #8.9)No notes. Just a new section. See section #8.9, Brain wrangling: what to do about sensitization.

Minor update (May 14 '12, section #6.1)Another nice swimming update: I added some excellent perspective from an experienced competitive swimmer. See section #6.1, The art of rest: the challenge and the opportunity for patients who have supposedly “tried everything”.

Minor update (May 4 '12, section #6.1)Very simple swimming tip added. Hat tip to reader Eric C. See section #6.1, The art of rest: the challenge and the opportunity for patients who have supposedly “tried everything”.

Updated (Mar 8 '12, section #6.8)Answered some common reader concerns about planning. See section #6.8, Jan’s Phase I: Preparation (July and August).

Updated (Feb 23 '12, section #4.4)Bone scans and the reason for getting them are now described much more thoroughly. Added some new science confirming that many PFPS knees are “hot.” See section #4.4, Hot kneecaps! Should you get an x-ray, MRI, or bone scan?

Major update (Feb 23 '12, section #4.1)Expanded and heavily edited. In particular, the concept of a “diagnosis of exclusion” is now explained thoroughly. See section #4.1, Eliminate other concerns.

New section (Dec 30 '11, section #7.4)No notes. Just a new section. See section #7.4, How do you exercise without pissing off your knee?

New section (Dec 13 '11, section #8.7)Not a beefy update: just a few quick thoughts about heat. See section #8.7, Heat (very briefly).

Minor update (Dec 13 '11, section #6.3)Addressed some common fears about the threat of getting out of shape while resting. See section #6.3, 1. Common Resting Pitfall No. 1: The runner’s natural stubbornness.

Minor update (Sep 28 '11, section #8.10)Added reference to Kong et al, about the effect of shoe wear. See section #8.10, Orthotics and shoes.

New section (Aug 22 '11, section #8.10)Expanded the section so much that it’s effectively new. It was just a single paragraph about orthotics. Now it is a much more thorough discussion of orthotics, shoes, and impact reduction. In particular, it features an unusual endorsement of Oesh shoes. See section #8.10, Orthotics and shoes.

Minor update (Jul 29 '11, section #1)Added a reference about the poor overall quality of online information about common injuries. See Starman. See section #1, Introduction.

Minor update (Jul 8 '11, section #6.1)Added an item about swimming to the “activities that may strain the knee” chart. See section #6.1, The art of rest: the challenge and the opportunity for patients who have supposedly “tried everything”.

Major update (Jun 21 '11)Major improvements to the table of contents, and the display of information about updates like this one. Sections now have numbers for easier reference and bookmarking. The structure of the document has really been cleaned up in general, making it significantly easier for me to update the tutorial — which will translate into more good content for readers. Care for more detail? Really? Here’s the full announcement.

New section (Mar 20 '11, section #8.11)Finally, long overdue, a new section on this topic (for all the running injury tutorials, in fact). See section #8.11, Should you run naked? On faddish running styles and running shoes (or the lack thereof).

Important new info (Feb 8 '11)Where’s the fire? Recently I published a major new article about repetitive strain injuries (like patellar pain), in which I explain that these injuries are rarely actually inflamed. Instead of being “on fire,” excessively stressed tissues tend to break down without inflammation — a kind of rot. This significant fact of biology is not yet given proper attention in this tutorial, and it should be. I learned the science of this myself only just recently, and it is going to take me a while to revise all of the tutorials and articles that are affected by it. Meanwhile the new RSI article is available, free to all, and I have also mentioned and linked to it where necessary throughout all tutorials. For the full scoop on inflammation and repetitive strain injuries, see: Repetitive Strain Injuries Tutorial: Five surprising and important facts about repetitive strain injuries like carpal tunnel syndrome, tendinitis, or iliotibial band syndrome.

New section (Dec 2 '10, section #4.7)New short section for both this book and the iliotibial band syndrome book covering potentially confusing alternative diagnoses, such as politeal artery entrapment syndrome (PAES). See section #4.7, Other possible diagnoses and sources of diagnostic confusion.

New section (Nov 27 '10, section #1.5)Brief new section — just a note, really, but quite important to some readers. See section #1.5, About patellofemoral pain in teens.

Minor update (Sep 29 '10, section #8.4)Added some data on the incidence of PFPS in cyclists. See section #8.4, Treating for inflammation: is there any point?

New cover (Aug 6 '10)At last! This e-book finally has a “cover.” SHOW

New section (Jul 27 '10, section #8.18)No notes. Just a new section. See section #8.18, Glucosamine, chondroitin sulphate and other “nutraceuticals” have failed every large, fair test.

Major improvements (Jul 8 '10, section #3)Substantial changes related to new science summarized in Am I wrong? An update on the conventional wisdom. See section #3, A Modern Perspective: Patellofemoral pain as “the itch you can’t scratch”.

Major improvements (Jul 8 '10, section #2.13)Substantial changes related to new science summarized in Am I wrong? An update on the conventional wisdom. See section #2.13, Weak and uncoordinated muscles, perhaps?

Major improvements (Jul 8 '10, section #2.12)Substantial changes related to new science summarized in Am I wrong? An update on the conventional wisdom. See section #2.12, Misc other possible biomechanical bogeymen.

New section (Jul 8 '10, section #2.3)A flurry of substantive updates and re-writing today inspired by some new scientific papers. See section #2.3, Am I wrong? An update on the conventional wisdom.

New section (Jun 29 '10, section #8.8)No notes. Just a new section. See section #8.8, Steroid injections are powerful, but where would you put the needle?

New section (Jun 14 '10, section #8.20)No notes. Just a new section. See section #8.20, Prolotherapy is not relevant to patellofemoral pain syndrome.

Minor update (Apr 2 '10, section #8)Miscellaneous upgrades, and a nice anecdote from a reader See section #8, Other Treatments: What else can you do about PFPS?

Minor update (Apr 2 '10, section #6.1)Added thoughts about the effect of and some other minor updates. See section #6.1, The art of rest: the challenge and the opportunity for patients who have supposedly “tried everything”.

Older updatesListed in a separate document, for anyone who cares to take a look.


  1. Clarsen et al. Overuse Injuries in Professional Road Cyclists. American Journal of Sports Medicine. 2010. PubMed #20847225. BACK TO TEXT
  2. Taunton et al. A retrospective case-control analysis of 2002 running injuries. British Journal of Sports Medicine. 2002.

    This study of a year’s worth of injuries among Vancouver runners — many of whom I probably run with every day on Vancouver’s sea wall — reported 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.”

  3. In 2010, the Journal of Bone & Joint Surgery reported that “the quality and content of health information on the internet is highly variable for common sports medicine topics,” such as knee pain and low back pain — a bit of an understatement, really. Expert reviewers examined about 75 top-ranked commercial websites and another 30 academic sites. They gave each a quality score on a scale of 100. The average score? Barely over 50! For more detail, see Starman et al. BACK TO TEXT
  4. The science of this controversial claim will be discussed in great detail below. BACK TO TEXT
  5. Doctors lack the skills and knowledge needed to care for most common aches, pains, and injury problems, especially the chronic cases, and even the best are poor substitutes for physical therapists. This has been proven in a number of studies, like Stockard et al, who found that 82% of medical graduates “failed to demonstrate basic competency in musculoskeletal medicine.” It’s just not their thing, and people with joint or meaty body pain should take their family doctor’s advice with a grain of salt. See Medical Blind Spot for Aches and Pains: Most doctors are unqualified to care for many common pain and injury problems. Especially the stubborn ones. BACK TO TEXT
  6. Sports medicine specialists are probably the least of all evils — although no professional category seems generally well-informed about PFPS, you probably stand a somewhat better chance of getting competent help from a sports medicine doctor than from any other kind of health care professional. Although they are more or less as prone to the toeing the line of conventional wisdom as any other health care professional, at least their expertise is directly concerned with non-surgical management of conditions like PFPS — and so there is at least some respectable chance that a doctor in this speciality will have paid some attention to the scientific controversies. BACK TO TEXT
  7. Orthopaedic surgeons are surgeons — not only do surgeons strongly tend to perceive musculoskeletal problems only in terms of surgical solutions, but they are (quite correctly) professionally preoccupied with their surgical expertise and professional development, which means that they are typically not knowledgeable about conservative physical therapy methods for relatively minor overuse injuries like PFPS. Many of them certainly try to make a professional point of avoiding the overprescription of surgery, but that doesn’t necessarily make them experts in what to do instead of surgery. And PFPS is a particularly bad problem to take to a surgeon for the simple reason that, among knee injuries, PFPS is just about the last one that you’d want to operate on. This will be fully explained as we continue with the tutorial. BACK TO TEXT
  8. Surgeons often oversimplify patellofemoral pain syndrome as simply a case of “arthritis” of that joint, and recommend a debridement (filing or smoothing) of the knee cartilage, either of the patellofemoral joint, or of the main joint between the tibia and femur (which is particularly irrelevant to patellofemoral pain). However, debridement has been proven to be ineffective even for arthritis (let alone PFPS, which isn’t arthritis), originally and most spectacularly by Moseley in 2002, then most authoritatively by The Cochrane Collaboration in early 2008 (see Laupattarakasem), and most recently by New England Journal of Medicine in September 2008 (see Kirkley). This is one of the most straightforward scientific slam dunks in surgery research in recent history — debridement doesn’t work! BACK TO TEXT
  9. There isn’t even a reasonably reliable surgical Plan B for patellar pain, as there are with several other common joint problems. BACK TO TEXT
  10. Dixit et al. Management of patellofemoral pain syndrome. American Family Physician. 2007. PubMed #17263215. “ …although management can be challenging, a well-designed, non-operative treatment program usually allows patients to return to recreational and competitive activities.” BACK TO TEXT
  11. As we’ll discuss in detail below, most “basic” physical therapy for PFPS consists of minor interventions of highly questionable value, yet the clinical impression of most professionals is that mild patellofemoral pain does go away with conservative advice. The most likely explanation for this — and it’s a common “problem” in physical therapy — is simply that most of those cases would have gotten better regardless of the therapy. Of course, in some cases, some good advice may be mixed in with bad advice, and that may help. And there may be some placebo effect: being therapized really does help a lot of people to feel better, regardless of whether or not the therapy makes any sense, and yes this phenomenon can occur even with something as seemingly un-psychological as knee pain! See Moseley. BACK TO TEXT
  12. In practice the diagnosis is more inclusive — as is this book, much of which is useful even for the patient who turns out in the end to have something a little better defined. BACK TO TEXT
  13. Reid. The myth, mystic and frustration of anterior knee pain. Clinical Journal of Sports Medicine. 1993. BACK TO TEXT
  14. Wilk et al. Patellofemoral disorders: a classification system and clinical guidelines for nonoperative rehabilitation. Journal of Orthopaedic & Sports Physical Therapy. 1998. BACK TO TEXT
  15. Juhn. Patellofemoral pain syndrome: a review and guidelines for treatment. American Family Physician. 1999. BACK TO TEXT
  16. A one-minute excerpt from his 2008 stand-up show Chewed Up is embedded below, but you can also watch the full segment (2:30) on YouTube. Funny stuff! BACK TO TEXT
  17. Näslund et al. Comparison of symptoms and clinical findings in subgroups of individuals with patellofemoral pain. Physiotherapy Theory and Practice. 2006. PubMed #16848349. In this study of 80 patients with a diagnosis of PFPS, with all other likely diagnoses already eliminated from consideration, signs of pathology were found in only 17 of 75 patients, and the authors conclude that even these “cannot be detected from ... commonly used clinical tests.” That’s quite a few mysteriously painful knees. BACK TO TEXT
  18. Piva et al. Associates of physical function and pain in patients with patellofemoral pain syndrome. Archives of Physical Medicine & Rehabilitation. 2009. PubMed #19236982.

    Researchers tested 74 patients diagnosed with patellofemoral pain syndrome for the presence of several factor that are commonly suspected to be associated with that condition, the “usual biomechanical suspects”: muscle weakness and tightness, coordination, and postural and anatomical abnormalities. They also considered psychological factors, which is quite unusual for a study of knee pain.

    They found no correlation at all with between the biomechanical factors and chronic anterior knee pain.

    (Interestingly, the researchers did find that “psychologic factors [anxiety and fear-avoidance beliefs about work and physical activity] were the only associates of function and pain in patients with PFPS.”)


There are 196 more footnotes in the full version of this book. I like footnotes, and I try to have fun with them.

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