This morning I decided to start a series on what I call Orthopedic Urban Myths. What I’ll concentrate on are things that seem true because they’re widely believed by physicians and consequently patients, but when you dig into the medical research, turn out to be false. I’ll start with a big whopper that’s widely believed: lost cartilage = pain.
Cartilage is a cushion for a joint that lives on both ends of the bone. When you lose cartilage from a joint, this means you’re getting arthritis. Almost every physician and patient I’ve ever met believes that cartilage loss is directly related to pain – meaning if you lose more cartilage you have more pain. This is why patients are generally so fixated on cartilage – is it good, is it bad, how much is there, is there a hole in it? However, what if the research of the last 5 years actually showed that this concept was an urban myth? How would this change orthopedic care?
Two very large, ongoing studies that are tracking patients with knee arthritis with many different modalities such as x-ray, MRI, exams, blood work, questionnaires and biomarkers are the Osteoarthritis Initiative (OI) and the Framingham Osteoarthritis Study. Both are sponsored by the National Institutes of Health and these ongoing studies have felled many orthopedic urban myths to date, not the least of which is the idea that cartilage loss = pain.
So what do these huge studies say about knee cartilage loss and pain? Are they associated? Does lost cartilage = pain? An analysis of the Framingham study data showed that among more than 700 patients, the loss of cartilage on MRI was not associated with pain. The full text from that same data set showed that not only was cartilage loss not associated with pain, but almost all of the “abnormalities” on a knee MRI that would prompt surgeons to operate were also not associated with pain. From the Osteoarthritis Initiative, despite looking at cartilage loss in almost 500 patients, the amount of lost knee cartilage on x-ray and MRI wasn’t strongly associated with pain. Let me put the conclusions of these large studies in capital and in bold:
LOST CARTILAGE IN THE KNEE IS NOT ASSOCIATED WITH PAIN OR LOST FUNCTION.
The upshot? So, when your doctor glances at your knee x-ray and/or your MRI and sees lost cartilage and tells you that this is the cause of your pain, he’s relying on an urban myth, not science. Knee pain is caused by a complex interplay of things, only a handful of which can be seen on MRI and less cartilage is not one of those things.