Classification and Treatment of Spinal Curve Deformities
Flatback syndrome, also known as lumbar degenerative kyphosis (LDK) is a common problem after surgery for scoliosis. It is also the most common cause of spinal deformity in the adult Asian population. Changes include narrowing of the discs, collapsed vertebral bones, or wasting of the extensor muscles in the lumbar spine.

In this study, X-rays are used to classify or group patients with LDK. The X-rays were taken of the entire spine from the side with the patients standing. Spinal curves, sacral slope, angles, and the sagittal vertical axis were measured.

Seventy-eight women with LDK were put into two groups based on X-ray findings. The main focus was on the thoraco-lumbar (TL) junction. This is where the thoracic curve of the mid-spine meets the lumbar (lower) spine. Based on the T-L junction angle, the spinal curve deformities were either flat or lordotic.

Group 1 was classified as sagittal thoracic compensated. Compensated refers to the fact that the spine develops a second curve to offset the first one. This is a more flexible type of LDK. Group one was further divided by location and shape of the curve. The three types of lumbar kyphosis were lower lumbar, middle lumbar, and flat type.

Group two was labeled as sagittal thoracic decompensated. Decompensated means the deformity was structural and extended through the entire spine. Decompensated LDK is rigid and more difficult to correct.

They all had trouble walking and standing because of back and buttock pain. A stooped posture was common. Even those patients who compensated by extending the upper back stooped when tired.

Patients with LDK may need surgery. The authors point out that the type of surgery will differ based on whether the patient is in the compensated or decompensated group. Fusion levels are determined based on whether or not there is a compensatory thoracic curve.
Jee-Soo Jang, MD, PhD, et al. Lumbar Degenerative Kyphosis. Radiologic Analysis and Classifications. In Spine. November 15, 2007. Vol. 32. No. 24. Pp. 2694-2699.