These are some common terms relating to the SI joint which, unfortunately, can be very confusing to a lot of people. Let’s clear them up!
The words hypermobile and hypomobile can be used in a few different ways to describe the SI joint, or any joint in the body.
Let’s start by talking about what these words actually mean.
Hypomobility refers to a joint that’s moving less than a healthy joint would. (The prefix hypo- means “less”).
Hypermobility refers to a joint that’s moving more than a healthy joint would. (The prefix hyper- means “more”).
I experienced both hypo- and hypermobility in my SI joints over the course of my saga. And while it’s important to know exactly why your SI joints are causing pain (are they moving too much or too little?) these issues can best be thought of as two sides of the same coin.
When an SI joint locks up, it means that the hip bone has moved out of alignment relative to the sacrum and gotten wedged in a non-optimal location. For me, the most common pattern that would occur is called a posterior rotation, as I explain in this video:
Technically, a posterior rotation like this is an example of hypomobility— if the hip bone is stuck, it’s no longer moving as much as it’s supposed to.
But, to take a step back for moment… how did things get this way? How did the hip bone move so far out of its normal range of motion that it is now wedged abnormally against another bone?
Hypermobility is what allowed that to happen in the first place– the ligaments that were supposed to hold the hip bone in place weren’t doing their job.
Two sides of the same coin
So, you can see how in cases of ligament instability like I experienced, the terms hypo- and hypermobility can simply refer to the same problem at different moments in time. Both terms simply refer to how much the hip bone is moving in relation to the sacrum.
According to my PT mentors, it’s pretty common to find that when one SI joint is hypomobile (stuck), the other is hypermobile. It’s the body’s attempt to compensate– when motion is restricted on one side of the body, the body will find a way to increase motion on the other side.
I use the word hypermobile in another way on this blog as well.
So, what I just explained to you above is how hypo- and hypermobile can be used to explain the amount of motion in a given joint.
Technically, this term simply means a joint is moving too much– it doesn’t tell you why that’s happening.
The term hypermobile can also be used to describe a genetic condition where your body doesn’t make connective tissue properly. This means your ligaments will be “stretchier” than they were meant to be, allowing a greater range of motion in your joints.
People with hypermobility conditions are at increased risk for chronic pain and potential injuries, such as SI joint dysfunction.
I was finally diagnosed with this type of genetic hypermobility condition in my 30’s, and came to learn that it played a big role in my saga. (And I now often find it plays a big role for my clients, as well).
However, once you know you’re hypermobile, there’s so much you can do! For more info on this genetic condition, check out my Hypermobility page.
What do you think of these terms? Has your doctor or PT used the words hypomobile and hypermobile when describing your issues? Let me know in the comments below!