Flatback syndrome is a condition where the lower spine loses its natural curvature, leading to a type of sagittal imbalance or front-to-back imbalance in the spine. Normally, the spine has several gentle curves front-to-back, with the lumbar (lower) spine displaying a lordosis, or inward curve. Lordosis is a spinal curve where the normal inward curve of the lower back is exaggerated, often giving a “swayback” appearance and making the buttocks more prominent. When viewed from behind, a normal spine appears straight.
There are multiple pain generators in the lumbar spine, and detecting degenerative changes and their extent is crucial in clinical management. The normal lumbar spine features a lordotic curvature, where the anterior and posterior cortices of the vertebral bodies should align with adjacent bodies. Lordosis is the natural backward curve of the spine in the neck and lower back when viewed from the side. Most patients exhibit lordosis in the neck and low back, which is normal and typically does not require treatment or surgery. However, excessive lordosis or reduced lordosis can occur in some patients.
Excessive curvature of the back, resulting in a “swayback” appearance, is known as lordosis. Some lordosis is normal in the spine at the neck and low back areas. It’s the excessive curvature that can cause problems. Symptoms of lordosis include prominent buttocks and typically painless discomfort. Lordosis, occasionally termed hyperlordosis, is a rare spinal deformity where the lower back curves excessively inward, often to compensate for hyperkyphosis elsewhere.
During a low back exam, the first step is inspecting the contour of the spine, appreciating the normal posterior curvature (kyphosis) of the upper spine and the normal anterior curvature (lordosis) of the lower spine. A lack of lumbar lordosis, i.e., a flat lower spine, is often associated with low back pain.
The normal thoracolumbar spine is relatively straight in the sagittal plane and exhibits a double curve in the coronal plane. The thoracic spine is convex posteriorly (kyphosis), and the lumbar spine is convex anteriorly (lordosis). Normally, there should be no lateral curvature of the spine.
For further details on Flatback syndrome and lordosis, visit Columbia University Neurosurgery, Children’s Hospital of Philadelphia, University of Utah Radiology, UConn Health Spine, Washington University Orthopedics, Columbia University Spinal Deformities, Stanford Medicine 25, and University of Washington Musculoskeletal Radiology.
