An LS spine lateral flexion X‑ray is a side‑bending radiograph of the lumbosacral (lower back) spine taken while the patient bends laterally. It visualizes vertebral alignment and intersegmental motion, helping detect instability, abnormal lateral translation, scoliosis progression or failed fusion after surgery. It’s usually requested when back pain, suspected spondylolisthesis or post‑operative assessment require dynamic evaluation of spinal motion.

The four standard lumbar spine radiographic views are: anteroposterior (AP) — a frontal view of vertebral bodies and disc spaces; lateral — a side view showing alignment, disc height, and canal; right oblique and left oblique — angled views to visualize facet joints and the pars interarticularis, useful for detecting spondylolysis, fractures, degeneration, and instability.

The lateral flexion of the lumbar spine is side‑bending of the lower back in the frontal plane, typically about 20° to each side. It uses the quadratus lumborum, ipsilateral erector spinae and obliques, with opposite‑side lengthening. Motion is limited by facet joint orientation, intervertebral discs and soft tissues; reduced or painful lateral flexion may indicate muscle strain, disc or facet joint problems.

Lumbar flexion is forward bending of the lower spine that reduces the lumbar curve, stretches posterior ligaments and the back of discs, and increases pressure on anterior disc surfaces. Lumbar extension is backward bending that increases the curve, compresses posterior spinal elements and facet joints, and can narrow nerve openings. Both allow trunk movement but may worsen some back conditions, so use caution with pain.

The LAT (lateral) view in an LS (lumbosacral) spine X‑ray is a side projection showing lumbar vertebrae and sacrum. It assesses vertebral body heights, intervertebral disc spaces, posterior elements and sagittal alignment, aiding detection of fractures, spondylolisthesis, degenerative changes and abnormal curvatures. Images are obtained with the patient standing or supine and the X‑ray beam directed laterally.

Lateral flexion of the spine is side‑bending: the head and trunk tilt toward one shoulder so the ear moves closer to it while the opposite side lengthens. Vertebrae and ribs approximate on the bent side and separate on the other. It is produced by obliques, quadratus lumborum and paraspinal muscles, with limited lumbar but greater cervical side‑bending.