When students talk to me about their Scoliosis, I often find they are not really sure about their own condition. In part this could be due because doctors often discuss the subject in technical terms. I will try to simplify some of the terms used to describe the condition.
The direction of the curve is identified by the convexity of the curve. So if we say someone has a right thoracic curve, the convexity of the curve will be on the person’s right, the concavity of the curve on the person’s left.
The major curve, or primary curve, is the most significant curve in the spine. Often a compensatory curve develops above or below the major curve in the opposite direction of the major curve.
Apex of the curve is at the vertebrae which is the furthest away from the midline of the body.
Curves are described according to their shape, and the location in the body.
C-curves, or thoraco-lumbar curves occur along the length of the thoracic and lumbar spine. Most C-curves are right convexity.
S-curves are specified by their location in the body:
Right thoracic-left lumbar curves are the most common type of curves is in idiopathic Scoliosis. The major curve is in the thoracic spine between T4 and T12, and usually there are structural changes in the vertebrae of this major curve. There is also a less compensatory curve in the lumbar spine.
In left lumbar Scoliosis the major curve is to the left in the lumbar spine. There may be a less severe compensatory curve in the right thoracic spine.
Double major curve describes the presence of two major curves of equal severity. Usually both curves are structural.
In my own experience, a lot of people with Scoliosis actually have three, or sometimes even four curves, but there are no technical terms used to describe these, as they are usually considered compensatory curves.