In October 2007, physician Elizabeth Arendt published a nice little summary of gender differences in kneecap pain in the The Journal of the American Academy of Orthopaedic Surgeons. With refreshing style and sass, the journal published it with the fun title, “Putting a little sex in your orthopaedic practice.”
She was writing, of course, not about “sex” but about gender — and the effect of gender on knee pain. Supposedly, women get more kneecap pain (patellar pain) than men. I’ve written about this extensively in my advanced patellofemoral pain syndrome tutorial. (This article is an excerpt.)
This is often attributed to structural differences … an allegedly scientific argument which can sound suspiciously sexist and old-fashioned when it comes from male experts, almost like they are arguing that the feminine knee is designed to be pretty and not functional (sexism is still a problem in health care, and sports medicine in particular). So I like the fact that Dr. Arendt is a woman talking about the issue, and she makes a number of excellent points.
But Dr. Arendt also contradicts herself a little. She starts out, quite correctly, by saying that there is not adequate science to support the idea that women get more kneecap pain. She then presents a bunch of that inadequate evidence — not really a single compelling study showing significant pain differences between the kneecaps of men’s and women’s kneecaps — but then, somewhat bizarrely, concludes that “clinical data do support that [kneecap] problems are more common in females.”
What’s going on here? Is Dr. Arendt confused? Or is this just semantics?
It’s more semantics. I think Arendt brings up a number of interesting studies that do indeed show that there are more “problems” with women’s knees … but not necessarily more painful problems, and that’s the odd, newsy thing that makes writing about this so interesting. (Hopefully reading about it is interesting, too!)
The only studies Dr. Arendt brings up (which were new to me) which really do show clear gender differences do not actually indicate a difference in levels of pain and suffering, but simply in the presence of problems which are not necessarily painful. Here are the clear differences:
Difference #1: Women really do have a lot more degeneration of the cartilage under their kneecap (see McAlindon and Dejour), a condition called “chondromalacia patellae.”
Difference #2: Women really do tend to have looser kneecaps … although only after the first incident of a subluxation or dislocation (see Fithian). Yes, that’s right: the first time, this type of injury occurs at the same rate in men and women, but women have a harder time getting that kneecap to stay put afterwards, and will tend to have many re-injuries over the years compared to men.
Now, those may sound like some pretty significant differences, and they are interesting. But the point I want to make really clear to my readers with knee pain is this:
Those conditions are not necessarily pain-causing. And neither of them is closely correlated with typical patellefemoral pain.
Kneecap pain is notoriously not closely associated with arthritis (chondromalacia patellae). Many people have pitted, cruddy looking cartilage under their kneecaps … and no pain whatsoever. And many people have nice smooth cartilage … and lots of pain. So the fact that women get chondromalacia patellae significantly more often than men is probably not particularly significant! At least, not so far as patellar pain is concerned.
As for the way women’s kneecaps tend to try to “escape” the knee more frequently after the first attempt than they do in men … well, we’re talking about the aftermath of an injury here, not standard aching kneecap pain. Indeed, standard aching kneecap pain is more likely after you dislocate your knee (that’s both logical, and supported by the evidence). But — and it’s a big “but” — we’re talking about an equal number of men and women. There is no difference in the rate of initial injury, just the rate of re-injury.
And the frequency of re-injury is relatively trivial as far as patellar pain is concerned. Standard aching knee pain is extremely common, while kneecap dislocations are quite rare by comparison. More frequent post-injury kneecap slippage has very little to do with overall rates of the standard aching kneecap problem … which happens to a huge number of people who’ve never dislocated anything.
So, Dr. Arendt points out a couple of interesting differences in kneecap problems between men and women, but these differences are not especially important as far as patellofemoral pain is concerned. The case is not exactly “closed,” but I stand by my unconventional opinion that how women are built has not very much to do with kneecap pain. So let’s all stop talking about kneecap pain like it’s particularly a problem for the ladies until the evidence actually supports that theory. To date, that evidence just can’t be found — if anything, the evidence actually is pretty persuasive that there is not any such difference, as discussed in detail in the full tutorial.
About Paul Ingraham
I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of ScienceBasedMedicine.org for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter.
This article is a free chapter from PainScience.com’s huge patellofemoral pain syndrome (PFPS) tutorial, one of 100 chapters in all. There are also several other articles on PainScience.com about patellofemoral pain and related topics:
- Patellofemoral Pain Diagnosis with Bone Scan — If you have anterior knee pain, should you bother x-ray, MRI, CT scan, or bone scan?
- Patellofemoral Pain & the Vastus Medialis Myth — Can just one quarter of the quadriceps be the key to anterior knee pain?
- Patellofemoral Tracking Syndrome — The beating heart of the conventional wisdom about patellofemoral pain is mostly nonsense
- Diagnosing Runner’s Knee — It usually starts with lateral knee pain during and after runs, but there are two major types
- Massage Therapy for Your Quads — Perfect Spot No. 8, another one for runners, the distal vastus lateralis of the quadriceps group
- Should You Get A Lube Job for Your Arthritic Knee? — Reviewing the science of injecting artificial synovial fluid, especially for patellofemoral pain
- What Can a Runner With Knee Pain Do at the Gym? — Some training options and considerations for runners (and others) with overuse injuries of the knee
- Does Hip Strengthening Work for IT Band Syndrome? — The popular “weak hips” theory is itself weak
- IT Band & Patellofemoral Pain Defy Common Sense — The science shows that you can’t blame runner’s knee on structural quirks that seem like “obvious” problems