Why you don’t want to wait to regain knee extension range of motion

Posted on September 3, 2015

(Last Updated On: March 27, 2016)

This is a precursor to my manual “Regaining Knee Extension.”

You can pick a copy up here: Add to Cart

Or find out more about it here.

This isn’t a completely understood topic. I’m going to illustrate one theory, but there are others out there. (If you feel you have a good one, let me know!) More than likely, different people fit different theories. If you’re someone who has not had a knee replacement, I think the theory I’m going to cover is pretty solid. If you’ve had a knee replacement, then the list of possibilities grows considerably.

Ok, so say you don’t have full knee extension. When standing, you’re always loading your leg like this (the knee is a bit bent):

Knee flexion somewhat bent

Screen shots from this video: https://www.youtube.com/watch?v=io40SFvb0gA

Where if you had full knee extension it would be more like this:

Knee nearly fully extended

Notice as the knee bends the femoral condyles are further back on the tibia.

Knee flexion more bent

Knee flexion more bent with text

Knee extension to flexion side by side 1 cut

As the knee bends, the width of the yellow decreases.

The posterior tibial plateau ends up getting loaded more than it typically would. Rather than the stress be nice and evenly distributed across the plateau, it’s now become more concentrated posteriorly.

Knee extension to flexion side by side 2

Reconstructed image from this video: https://www.youtube.com/watch?v=H3YgbJLbIXk

Knee extension to flexion side by side with outline 2

Bone is quite complex, but simple at the same time. It grows in response to increased loading, and it grows exactly where that increased loading is. Our posterior tibial plateau may very well hypertrophy. Or gain an osteophyte or two from getting banged on more than its used to. Think of these as extra bits of bone that wouldn’t normally be there.

Stress concentration side by side with osteophyte

Before and after.

Normal extension:

Extension with increased height, or an osteophyte, in posterior tibial plateau:

Knee flexion somewhat bent with osteo

We end up blocked. The femoral condyle can’t slide back like it would.

Knee extension osteophyte blocking GIF

Now, bone can atrophy as well. To atrophy it, you don’t load it as much. But how are you going to load your posterior tibial plateau less, once it’s hypertrophied? You can’t get the knee into full extension to load the other areas and more evenly distribute the stress.

From this point, the options are,

  1. Get on crutches to deload the leg. This way you get off of walking on a bent knee, and you hopefully atrophy some of the bone. (This is theoretical though. No guarantee.) Then, try to regain extension and hope for the best. Where you don’t load the leg again until full extension is accomplished. I’ve been surprised before, and have seen some who after a couple years of walking on a bent knee, were able to make some good progress. Maybe not to where their good leg was, but pretty damn close. (These ones didn’t even go back to crutches, but I think that would have only helped them.)
  2. Back into surgery.

For a step by step process on how to regain knee extension, with exercises, and even a hour by hour example routine, check this out: Add to Cart

(Or find out more about it here.)

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