A Goldilocks Theory of Cartilage Damage

Here’s a study I can’t access (without paying for), but I found the main conclusions interesting. The researchers decided to look at the following:

Knee cartilage damage is often linked to mechanical overloading. However, cartilage requires mechanical load to remain healthy, suggesting that underloading may be detrimental.

So there you have it. Essentially, they’re testing what we’ve talked about repeatedly here: trying to find a motion “sweet spot,” if you will. If you subject your knees to too much load, they will get worse. If you don’t subject your knees to any load, they will get worse too.

The key is finding that elusive “sweet spot” where they can handle the proper amount of load, which can be gradually increased over time. However, of course, this is no simple thing.

So what did the study consist of?

The researchers looked at how the load on a person’s knees correlated with worsening cartilage damage over a two-year period. There were 964 subjects, including 62% women. The average age was 66.9 years old, and the average BMI 29.7 (this borders on obese and roughly equates to weighing 220 lbs. for someone who is six feet tall).

People who walked a moderate or high number of steps each day (at least 6,000) and who had a high BMI (more than 31) had a greater risk of worsening damage of the cartilage in the medial part of their tibiofemoral joint, compared with those who were thinner.

But people who walked less than 6,000 steps a day and who had a low BMI were at higher risk of worse damage in both the medial part of the tibiofemoral joint and lateral (outside) part of their patellofemoral joint (where the kneecap meets the femur). They were compared to a group that also had a low BMI but walked more steps.

Clearly, one takeaway is that weight has a big influence on how much walking you can safely do.

But the results also do suggest that there is an optimal level of motion: too much will cause further damage, and not enough is harmful too.

The trick is finding that proper balance. What’s scary for people with bad knees is that finding that balance becomes a really hard task when your knees don’t seem to like to move much at all.

It will frustrate you endlessly, I guarantee. But when you do figure out the right balance, you are suddenly in a position to get better, slowly but surely.

And that's a great feeling, when you realize you're starting to make progress toward healing.