[jdmcnugent]

Orthopedic surgeon here. Articular cartilage regeneration is definitely the holy grail of my field, but for all of the promises of biologics (growth factors, stem cells, collagen matrices) it always seems to be “another five years away”.

The part of this article that I find most interesting was identifying a marker that can differentiate ankle cartilage vs the hip. This is certainly a phenomenon that we all observe clinically, hip and knee arthritis is vastly more common than ankle arthritis despite the weight bearing surface of the ankle being significantly smaller (meaning more force per square area). When we do encounter ankle arthritis, it is almost always the result of prior intra-articular fractures or instability from chronic ligamenous injuries, not the normal osteoarthritic age related degeneration we see in hips and knees.

Let’s find out what makes ankle articular cartilage so special and sprinkle it in our hips and knees.

[BurningFrog]

> it always seems to be “another five years away”.

I'm old enough that maybe I can supply some hope.

For about 15-20 years, the same thing was said about flat screen monitors. They were "always 5 years away".

And then, quite suddenly as I remember it, they were everywhere!

[warent]

The way you wrote this was really fascinating an informative. Was disappointed not to see a link to a personal blog or anything on your profile. I could read a lot more of your stuff.

[jdmcnugent]

Thanks for the compliment, I just lurk here on HN and I finally came across something in my wheelhouse. Happy to contribute. With private practice and a house full of kids I imagine my blog should be ready by 2029.

[ubertoop]

My guess? It's actually the consistent use of the cartilage that keeps it healthy. Just like how weight bearing exercises can promote deposition of calcium in bone, I'd imagine there's a similar mechanism for cartilage?

Hip joints (especially in modern era) get far less weight bearing on them - especially as a force / area, since we're sitting all the time.

[jdmcnugent]

Motion and loading is definitely integral to cartilage preservation. Unlike most tissues in the body, articular cartilage does not receive oxygen and nutrients from blood vessels, but rather directly from the oil-like synovial fluid that helps lubricate the joint surfaces. I imagine the thin squishy layer of cartilage behaves like a sponge, deforming compressive forces drive synovial fluid out and removing the load (taking weight off the joint) sucks synovial fluid back in, sort of like inhaling / exhaling.

Here is a pretty good basic science review article about articular cartilage:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445147/

[drak0n1c]

Good point about ankle cartilage, here is a detailed study about how ankle cartilage is different:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5154419/