These are not related, are they? Well, not as a syndrome. But the mechanics are entangled enough to discuss them together.
Kyphosis is the spinal curve as seen from the side that protrudes. The thorax has kyphosis. Convex..
Lordosis is the curve seen from the side as hollow, arcing forward. Concave.
Just like plus and minus 10 - 5 is less than 10 but still positive. So a kyphosis that is lordosing (a process) may still have some kyphosis but not as much as before. We see this as the RULE in adolescent scoliosis. The very first inkling may be simply less kyphosis in the thorax than was there before.
Lordosis gets a bad rap. On girls it looks good. But the excess is what crunches the spinal posterior elements together and causes those facets to howl in discomfort. So there is a whole bunch of exercises to “get rid” of lordosis. Get rid of lordosis - get rid of pain. Now really! What in life is that simple?
OK, lordosis is excessive when it simply looks horrible, or is actually causing malfunction or pain. But train backward bending from very early years and facets can shape themselves to allow that - those folks you see in the circus or gymnasts who can back bend to the extreme. You can’t decide you want to be one of them at age 25. We have learned from older surgeries that “nice and straight” is problematic. Having no lordosis makes it hard to stand erect. Leaning forward with nonstop muscle exertion, aside from being fatigue causing, begins to hurt.
So you can get flat back two ways. Lordose the normally kyphotic thoracic spine (less kyphosis) or kyphose the lumbar spine (less lordosis). Flat back is nice and straight and is trouble.
There are many odd topics that could be discussed as adult, or revision surgery or kyphosis. Flat back is a problem to itself which has implications in several areas.
Kyphosis is the contour, seen from the side of the spine itself (not rib prominence) such that it bulges out backward. Between the shoulders the chest area is normally somewhat kyphotic. Forward bending it increases a bit.
Above the chest the neck is normally lordotic, meaning it goes the other way, hollow-ish. The lower back (lumbar) also called the small of the back is naturally lordotic.
As with scoliosis, the mere presence of a curve, including kyphosis, is not an issue unless it has prospects for trouble. So progressing kyphosis - a verb rather than a noun - gets our attention as does severe kyphosis.
Here is the hard part. What if, the lordotic area, the small of the back, does not go out but isn’t lordotic enough? Is there such a thing? Not enough lordosis? Yes. And it is trouble.
Let’s look at the flip side. In idiopathic scoliosis the thoracic curve sideways is often preceded by loss of kyphosis. Typical scoliosis is relatively flat in the thoracic area. The ribs stick backward on one side but that “hump” is ribs, not spine. Flattening of the spine is trouble in scoliosis. It is also trouble period.
The spine, seen from the side ( “saggital view” ) can be measured the same way as scoliosis, except that from the side we expect to see angles between the lines that mark the transition from lordosis to kyphosis and then lordosis. No matter what it is, somebody measures it...
See? But this one is easier:
Ranges are fine, but it must balance. Head centered over pelvis - nature’s impending slam dunk.
Kind of obvious once you think about it. Without a big tail, we need to be in balance from head down or have really big feet and back muscles that don’t quit.
The Harrington rod was a great idea. It allowed the modern treatment of scoliosis. Full years hospitalized in flip beds with tall body casts to follow are still seen in horror movies. But that was real. The Harrington rod ended that. But - SOME - of those curves didn’t just straighten as seen from the back (scoliosis). They also straightened as seen from the SIDE!
It was subtle, but over time the inability to get the head centered over the pelvis without pitching the hips and knees (which is nonstop effort) just wore some folks out. Modern rods are not straight. But that is now. For those who are flat back from old scoliosis surgery, some get revised to put the saggital (side view) contour back to normal.
But there are other ways the low back gets flat or the upper back gets too slumped.
Imagine the work that the hips and knees have to do as they can never go straight without the individual falling over.
In addition, these spines are rigid, like stone. We see calcification where soft stuff belongs. Not good.
Sometimes spondylolysis happens in the same person as scoliosis. Yeah. Crummy luck. But, it happens. And when it does the spine below the fusion can decompensate badly and tilt off into kyphosis where lordosis belongs --- even though the fusion was done with enough lordosis in the rods.
Fixing Flat Back
Flat back theoretically could just be pulled back with metal as scoliosis is corrected. Right? No. All those joints on the back side open up and then hypertrophy (thicken) and act like rust on an old weathered hinge. Often to decrease the kyphosis or put in lordosis you have to get bone out of the way.
That means using a burr or even nastier tools to clear out bone that impedes correction. A surgeon, whose name is on many surgeries as a pioneer in orthopaedics back in them old days has another one with his name for this - flat back.
The Smith-Peterson surgery allows correction by taking a wedge of bone out of the posterior elements centered on an arc point near the back of a disc.
This exposes the spinal canal which is left in its soft coverings.
This leaves an empty wedge - empty of bone to close by the movement of the disc. So, the disc has to be capable of moving and moving enough.
Today we have screws that transfix the pedicles and attach a rod. So the old operation gets a face lift with better metal stabilization than Smith-Peterson had. Progress.
Here is a flat back after Harrington rod fusion, revised by a Smith-Peterson like wedge resection technique and held with vertebral screws.
Better. Here is a case where the flattening happened below the Harrington as the rod pulled out of the hook. On the right we see the revision looking much better.
But what if the disc spaces don’t have flexibility? Or the cure exceeds what disc spaces can do?
If the discs don’t move or the angle of correction gets high, then the wedge has to be moved forward and take out bone. One method, includes the pedicles in the wedge of removed bone. Like this:
The before is on the right and the after on the left. Here is an example:
In the example, wedges of bone were placed in disc spaces from the front to help create lordosis. But not enough for complete balance.
Studies of what is what test how much further this problem requires.
Making corrections on x-ray copies shows the requirements for the next stage.
In some very severe conditions, removal of ribs and one whole vertebra is performed. Do not try this at home!
Pretty gross, huh? But this is our world of medicine and surgery. We draw on every possible skill and capability of materials to get at disease. There is some logic to it, though that logic changes as new materials and tools allow.
we do keep score. We’re always keeping score. It is our belief that things today are never completely as they should be. We always look for better.