Do Bad Bugs in an Obese Gut Cause Knee Pain?

So just when I thought I had formulated the authoritative take on why obesity causes knee pain (namely, that the excess weight places too much force on vulnerable knees), along comes this study:

The gut microbiome could be the culprit behind arthritis and joint pain that plagues people who are obese, according to a new study.

Hmm. Interesting.

The study appeared in a relatively new publication called JCI Insight. You can find it here. The subjects were mice (so, possible objection number one: mice aren’t humans).

One group of mice ate high-fat foods similar to a “cheeseburger and milkshake” diet for a few months. The other group consumed low-fat, healthy meals. After 12 weeks, the chubby mice were carrying nearly twice the body fat of their lean counterparts.

Researchers noted:

Pro-inflammatory bacteria dominated their colons, which almost completely lacked certain beneficial, probiotic bacteria, like the common yogurt additive bifidobacteria.

Here’s the money paragraph of the article:

Changes in the gut microbiomes of the mice coincided with signs of body-wide inflammation, including in their knees where the researchers induced osteoarthritis with a meniscal tear ... compared to lean mice, osteoarthritis progressed much more quickly in the obese mice, with nearly all of their cartilage disappearing within 12 weeks of the tear.

The researchers discovered they could prevent the destructive effects of obesity on gut bacteria, inflammation and osteoarthritis by adding oligofructose to the diet of the fat mice. Interestingly, the mice didn’t lose weight – they remained obese – but this additive preserved their knee cartilage, so it looked the same as that of the skinnier mice.

Before my heavier readers make a dash to the store, hunting for foods containing oligofructose, a word of caution:

The bacteria that protected mice from obesity-related osteoarthritis may differ from the bacteria that could help humans.

Apparently, studies using people will be forthcoming. The future studies are worth keeping an eye on. I still think the mechanical effect of obesity on knee cartilage is significant, but this at least introduces the possibility that another mechanism may be an equally big – or bigger – culprit.

Musings on Complex Systems

No, not primarily my own musings. I’m linking to this essay, which someone pointed out recently. The title is “A Systems Perspective on Chronic Pain.” The piece is nicely done, with cool visuals and some observations that will make you stop and think.

A few parts I liked:

Some pains are more simple and local while others are more global and complex.

This is very true. But there’s a deeper truth here too.

I think a lot of knee pain starts simple, then becomes complex over time. This leads to much frustration. Often knee pain sufferers wonder if they have an immune system disorder, such as rheumatoid arthritis, as chronic knee pain seems to “wander” around their body, afflicting other joints.

Unless you do have a verifiable immune system problem, doctors tend to scoff at such theories (mine did anyway). But after I developed issues with multiple joints, and I heard story after story of similar problems on this blog, I’m convinced this is really a thing.

Because complex systems often change in a non-linear fashion, we can expect progress to be non-linear as well. That means getting better is often a question of moving two steps forward and one step back. In the short term, this makes it difficult to discern positive change. But over a larger timeframe, a pattern of progress may become clear.

 Ha! This almost feels like it could be a direct quote from my book (or blog). Yes, healing is definitely nonlinear, with little steps forward, then little steps backward, then repeat. It can drive you crazy. That’s why it’s best to take the long view. Once into your recovery program, ask if you’re better this month than a month ago, or two months ago. Try not to get too hung up on the day-to-day details.

Changes are often nonlinear, which means that small perturbations to the system can produce large changes, or that large perturbations might produce very small changes. A significant non-linear change is called a phase shift.

This is also an interesting point. As an example of a phase shift, he cites water suddenly turning from a liquid to a solid at 32 degrees Fahrenheit.

I discussed a similar kind of thing in two posts: one on breakdown points, and the other mending points. These remain two of my favorite posts, though I’m not sure they got much attention.

To me, a sort of phase shift may occur between pain and no pain. On a continuum, there may be a point where these two states lie very close to each other. In other words, you can have pain but be very close to a non-painful state. Or the converse could be true.

So let’s say you’re not in knee pain, but you have subjected your joints to repeated stress and are close to being hurt. It may take only a small stressor to nudge you over the edge. That, to me, is the idea of a “breakdown point.”

The example I give in the post involves a ceramic cup. You drop it from x inches, and it makes a loud thud, but doesn’t break. Yet if you drop it from two inches higher, suddenly you’ve got pieces of a cup. You’ve broken it.

Hurting yourself may involve sudden, catastrophic breakdown points. Sometimes, it’s clear what precipitated an injury. But other times you may lurch into a painful state despite not being able to pinpoint an obvious cause.

Similarly – and this is a good thing to know when trying to heal – there may be analogous mending points. You work for months on getting better, with seemingly disappointing results, then suddenly experience a big gain almost overnight.

Above are some of my thoughts on this essay, but I invite you all to read it for yourself and leave comments below.