Spine Rotation in Scoliosis (part 3): How we correct spine malrotation and rib prominence during spine fusions

In the last 2 posts I showed how scoliosis is a 3-dimensional problem, with the spine rotating around itself as it bends to the side.  The way to visualize this is to imagine a water slide, as it turns to the side, it also rotates…just like the spine in scoliosis and how the spine twists the ribs around.

This post will show how we can improve the spine and rib position during a spine fusion surgery.
The case example is a 14 year old young lady with a 58 degree right thoracic idiopathic curve, and 35 degree proximal thoracic and 24 degree lumbar curves.

The supine side bending radiographs demonstrate the flexibility of the spine.  So only the main thoracic curve of 58 degrees is what we call “structural” and the other two curves, due to the fact they bend out to be below 25 degrees, we call “nonstructural” or “compensatory”.

In order to maximize 3-dimensional correction and long-term outcome, while minimizing need for any additional surgeries the plan was to do a T3 to L1 posterior spinal fusion.  T7-T8 and T8-T9 PCOs, or posterior column osteotomies were also performed.  These osteotomies (PCOs) are done at the time of surgery to increase spine flexibility in all 3 planes, to maximize spinal deformity correction to as close to “normal” as we can safely achieve.

Pedicle screw are the optimal method of spine fixation.  They allow rigid fixation to the spine, and permits the spine to be moved 3-dimensionally.  Not every vertebra needs to have 2 screws.  Strategically placing screws to optimize immediate correction and assure long-term outcome is preferred, so about 1.5 screws per level is common.
By placing the screws at certain locations, specifically at the apex, the spine can be derotated back more toward normal.

The silver towers or rods are attached to the screws (picture on left), and then these towers are connected together to improve strength of the spine fixation (middle picture).  This connection process, for this patient, make 3 groups, one for each curve.  These 3 groups of towers/screws are then rotated back toward normal (picture on right).  You can see the different position of the middle group, relative to the other two groups, between the middle and right-sided pictures.  Once rotated to the improved position (right picture) the screws are then tightened down, and much more work is done in surgery to 3-dimensionally improve and balance the spine.

These postoperative radiographs are one year after surgery.  The patient is nicely balanced 3-dimensionally and has nicely improved.

Spine Rotation in Scoliosis (part 2)

In the last post I showed how scoliosis is a 3-dimensional problem, with the spine rotating around itself as it bends to the side.  The way to visualize this is to imagine a water slide, as it turns to the side, it also rotates…just like the spine in scoliosis.

What is interesting is that each patient is unique in the amount of rotation of scoliosis, some have more rotation, and some have less for the exact same amount of scoliosis.  While the rotation of the spine has not yet been shown to impact the long-term functional outcome of the spine, it DOES impact the physical shape of the body.  The rib prominence in the back causes the shoulder blade to be prominent.  The rotation of the ribs also impacts the body in the front, by making the ribs stick out more on one side and can cause breast asymmetry.  So the greater the rotation of the spine, the more physical deformity of the body.

When the scoliosis is smaller, somewhere between 20 and 45 degrees, bracing is typically a treatment option.  When a scoliosis brace is applied to the body it is molded to push against the rib prominence, to try to prevent the scoliosis to continue to progress and rotate more.

 

When the scoliosis gets to more than 45 degrees, bracing is not very effective because it cannot exert enough force on the ribs to prevent the spine from progressing.  Surgery can be an option for curves >/= 45 degrees.  If surgery is an option, the amount of rotation in the scoliosis is important to determine, and is usually done using a scoliometer (see below).

This is a measurement from horizontal; similar to an inclinometer. 

As mentioned in a previous post on vertebral body tethering, rotation of more than 20 degrees is a relative contra-indication to a tether procedure.  This is because a tether does not significantly alter the rotation of the spine, so if the spine is corrected with a tether, there still may be permanent physical deformity due to the residual rotation of the spine.  In these circumstances, specifically a curve 45+ degrees with more than 20 degrees of rotation, a spine fusion may be a better option.

A successful surgery depends on quantifying the spinal deformity, identifying what are the major (and lesser) cosmetic/aesthetic/physical body concerns, and then developing a strategy to maximize correction safely.

In the next post the surgical correction of pediatric scoliosis will be demonstrated, mainly focusing on correction of the rotation.  So if you don’t like surgical photos, and a little blood, then don’t view the next post!

Spine Rotation in Scoliosis

I have scoliosis….

So why do I have a rib hump?

Why does my shoulder blade sticks out more on one side?

Why are my ribs in the front different?

These are common questions I hear from patients with scoliosis and their parents and caregivers.  So why do these changes to the chest happen? Well it’s the ribs which are causing the rib hump, shoulder blades to stick out on one side and the ribs in the front to be uneven.  Why?  Well, first we need to understand what happens to the spine in scoliosis.  If you look at the radiographs (x-rays) below,

from the top to the bottom, the spine moves to the right, then the left and back to the right.  In this sense it looks like a lazy river ride at your local water park.

The lazy river moves right, then left, then right…..just like the scoliosis.  However, we are only looking in two planes…and scoliosis is actually a 3-d spine problem.  So when the spine curves, it also rotates.  So this makes scoliosis more like a water slide than a lazy river. As it curves, it also banks

So if the spine is banking as the spine curves left and right….why does that impact the ribs?  Well the ribs are attached to the spine with strong ligaments

Which means if the spine banks or twists, it will also bank or twist the ribs, both in the back and in the front of the chest. 

On the convex, or outside part of the curve, the ribs will be pulled backwards, and on the concave side (inside) of the curve, the ribs are pushed forward.  Since most scoliosis has a curve to the right on the upper curve, the ribs on the right side stick out more, and makes the shoulder blade wing out more, as in the above two pictures.

Also, if the right ribs are pulled back and the left ribs are pushed forward (pictures above) then the patients will see the ribs on the left side, just below the breast be more prominent (stick out more).

In the next blog post I will show how we improve the rib prominence or deformity during surgery.

Be Safe…