Type 5 curves have structural thoracolumbar/lumbar curve while the main thoracic and the proximal thoracic curves are non-structural.
Due to the morphology of type 5 curves lumbar modifiers A and B do not exist.
A minor curve is defined as structural if at least one of the two below criteria are met:
The left X-rays show a 15 year old female with Lenke 5C curve consisting of a:
The MT curves is non-structural.
The lumbar modifier is determined by drawing a vertical line from the center of the sacrum.
The sagittal modifiers are determined from the lateral radiograph from T5-T12. A measurement less than 10° is designated as "-".
Measurements between 10°-40° is designated as "N".
A measurement larger than 40° is designated as "+".