The Scoliotic Prominence and Muscle Length-Tension Relationship

If I had a buck for every patient that came to see us stating that the muscles on one side of their back was larger, or more developed……I’d have a lot of bucks!

This is one of the most misunderstood occurrences in scoliosis.

What these patients, and sometimes personal trainers, and sometimes even general physical therapists are observing, feeling, and mis-categorizing is called the prominence in scoliosis lingo. It occurs wherever there is a scoliotic curve, and as its name suggests, it’s prominent: it feels and looks like a bump on one side of the spine. 

(Sidenote: The outdated terminology for a prominence in the thoracic spine is “rib hump”, which is arguably more descriptive than “prominence”, but we stopped using that term because it doesn’t sound nice to say someone has a rib hump – I think - Feel free to fact-check me on that one.)

Ok, so if it’s not hypertrophied muscles, what is it?

What creates the prominence is structural, bony rotation of the vertebra and the ribcage. 

Thoracic Prominence as seen during Adams Forward Bend Test

Let’s visualize this with one of the most common patterns of adolescent idiopathic scoliosis: a right thoracic curve and a left lumbar curve. As the thoracic spine (upper and mid-back) curves to the right, the vertebra also twist or rotate backwards on the right side, causing the entire ribcage to rotate backward in a clockwise direction. Therefore, what I would call the Right Thoracic Prominence as a Schroth therapist is quite literally the right ribcage rotated backward.

Lumbar Prominence as seen during Adams Forward Bend Test

What really trips people up is the lumbar prominence. We don’t have any ribs down there, so what the heck is that bump?! With a left lumbar scoliosis, the same scenario as above is happening, but in the opposite direction: as the lumbar spine (low back) curves to the left, the lumbar vertebra also twist/rotate backward on the left.

Lumbar Vertebra Anatomy

The bump or bulge is actually the transverse processes of the lumbar vertebra (check out the lumbar vertebra anatomy photo if you’re not familiar with what a transverse process is: it’s the long, finger-like projection coming off each side of the vertebra.)

This rotational component of scoliosis pushes the spinal muscles on the side of the scoliosis closer to the surface of the skin, making them appear more prominent, but they are not in fact larger that the opposite side. They’re just more prominent.

Why does this distinction matter?

Understanding this component of scoliosis is essential if you’re a healthcare professional treating this condition, and equally as important if you’re living with this condition, because you want to do the correct exercises, right?!

If the assumption has been made that a patient with left lumbar scoliosis has larger, more developed muscles on the left side of the lumbar spine, that patient and their physical therapist, massage therapist, personal trainer, etc. will be focused on releasing and relaxing those muscles, and maybe even stretching them (eek – you’ll find out in the next paragraph why I’m saying eek). The focus will also likely be to strengthen the opposite side, the right side, to “re-balance the strength” in that region.

Here’s the reality: those left lumbar muscles are anatomically in an overly-stretched-out position due to the bony rotation of the vertebra. Thus the “eek” above. Please, please, please, don’t stretch the muscles where the prominence is. Shorten them and strengthen them.

Like a rubber band that has been stretched out for too long, those muscles will have a difficult time contracting, or shortening. This is defined by The Length-Tension Relationship in the world of biomechanics: This principle states that the greatest amount of muscle contraction occurs at intermediate muscle length, whereas very little muscle contraction is generated at very short or very long muscle lengths.

Shortening the muscles that reside on top of the prominences is achieved through positioning and props during the Schroth method, creating a more optimal length for the muscles to be able to contract efficiently. 

Once these muscles start shortening, contracting, and getting stronger, they are much “happier”. The aberrant electrical activity measured in overly-stretched muscles is much greater than what is measured in muscles that are in an anatomically shortened position – this is likely why so many people with scoliosis have muscular pain where their prominences are. When the muscles start contracting well, as happens in the Schroth method, many patients find relief of those once-pesky prominence symptoms.

Scoliosis is a complex, 3-dimensional alteration of spinal alignment. Eric and I have taken many courses focusing exclusively on scoliosis in order to fully understand the condition. We’ll be the first to say “it’s complicated”, but we’re here to break it down into what hopefully feels like more manageable chunks of digestible information.

If you’d like to learn more about your scoliosis, which exercises are best for you, and find relief from scoliosis symptoms, we’d love to work with you. Our doors are open.