An interesting paper illustrates how chronic joint inflammation can lead to problems with cartilage. In a normal joint your local stem cells constantly replace damaged cartilage by differentiating into more cartilage cells. In a chronically inflamed joint, this normal repair cycle is bad because of the chemicals associated with chronic inflammation.
The article is very dense, so I took the liberty of creating the illustration above to make it easier to understand. Click on the image to see a bigger illustration. Basically, one of the cytokines (chemicals) that accumulates in a joint that’s chronically inflamed is IL-1 alpha. This is represented by the fire icon above. While in acute injuries (like a sprain), these inflammatory cytokines stoke up the flames of healing that quickly die down once the repair job is done, in chronic inflammation they stick around because the body isn’t able to complete the repair. This paper showed that IL-1-alpha was disrupting cartilage manufacture by hurting normal cartilage cells so they became “hypertrophic” (read bad cartilage). So in a normal joint, dead cartilage gets replaced by stem cells in the joint that turn into cartilage cells. In a chronically inflamed joint, these cartilage cells pick up modifications controlled by IL-1-alpha which turn them into bad hypertrophic cartilage cells.
What’s important about this paper is not the detailed biochemistry of cartilage synthesis, but the concept that chronic joint inflammation impacts stem cell based repair and is just as bad for joints as mechanical injury. Most patients simply don’t understand that those extra pounds they carry are not only placing more stress on their knees, but are also indicative of a metabolic syndrome caused by aging, a sugar laden starchy diet, and lack of exercise. This metabolic syndrome (extra weight, high triglycerides, and high blood pressure) causes chronic inflammation in joints which in turn turns good cartilage into bad cartilage, facilitating arthritis.
The upshot? So if you have a new year’s resolution to save your joints, consider cleaning up your diet and getting rid of those extra pounds by shedding the sugar and upping your exercise. In addition, adding in fish oils may help as well.