An X‑ray of the lumbosacral (LS) spine with lateral flexion are side‑bending radiographs taken while the patient bends left and right. They assess spinal alignment and mobility, reveal abnormal movement or instability (e.g., spondylolisthesis), evaluate fusion or degenerative changes, and help plan treatment. Images compare vertebral positions in flexed and extended postures to detect pathological translation or angular motion.

The four standard lumbar spine radiographic views are anteroposterior (AP), lateral, and right and left oblique views. AP shows overall alignment and vertebral bodies; lateral demonstrates disc spaces, vertebral heights, and sagittal alignment; oblique views visualize facet joints and the pars interarticularis for spondylolysis or facet arthropathy. Often an L5–S1 spot or flexion–extension views are added when indicated.

Normal active lumbar flexion is roughly 40–60°, while active lumbar extension is about 20–35°. These approximate values refer to the lumbar spine alone measured from standing/neutral; total trunk motion also includes pelvic and thoracic contribution. Individual ranges vary with age, fitness, and measurement method; persistent limitations or pain warrant clinical assessment.

A dynamic flexion–extension view is a pair of lateral X‑rays taken while the patient bends forward (flexion) and backward (extension) to assess spinal mobility and stability. It evaluates segmental motion, spondylolisthesis, ligamentous injury, and postoperative alignment by measuring abnormal translation or angulation between vertebrae. It's commonly used for cervical and lumbar spine assessment when instability is suspected.

Patient in a true lateral position (standing or lateral recumbent) with the side of interest against the image receptor. Knees flexed, arms elevated, shoulders and pelvis superimposed; support under the waist to maintain neutral lumbar curvature. Align the mid‑coronal plane perpendicular to the IR and center the beam at the lumbosacral junction (approx. L3–L4 or L5–S1 for targeted views). Suspend respiration on expiration.

Lumbar flexion is forward bending of the lower back that decreases the lumbar lordosis, causing anterior disc compression and stretching of posterior ligaments and muscles; typical flexion is about 40–60°. Lumbar extension is backward bending that increases lordosis, compresses posterior spinal elements and facet joints, and stretches anterior tissues; typical extension is about 20–35°. Both involve coordinated spinal, pelvic, and hip motion.