LS spine flexion and extension views are dynamic X‑ray images of the lumbosacral spine taken while a patient bends forward (flexion) and backward (extension). They assess vertebral alignment, segmental motion, abnormal translation or angulation, and spinal instability (e.g., spondylolisthesis) not seen on static films. Typically obtained standing, they aid diagnosis and management of degenerative, traumatic, or postoperative conditions.

A flexion lumbar spine X-ray is a lateral radiograph taken while the patient actively bends forward (maximal comfortable forward flexion), usually standing. It assesses intervertebral alignment and posterior element separation to detect dynamic instability or spondylolisthesis. The patient bends at the hips, often reaching downward, keeping knees as straight as possible, and holds the flexed position during the exposure.

A flexion-extension X‑ray obtains lateral images of the spine in maximum forward (flexion) and backward (extension) bending to assess dynamic alignment and stability. It reveals abnormal vertebral translation or angulation, occult spondylolisthesis, ligamentous injury or fusion failure, and helps evaluate postoperative or trauma-related instability. It supplements static imaging when motion-dependent pathology is suspected.

The four standard radiographic views of the lumbar spine are: anteroposterior (AP) view, lateral view, oblique views (right and left to visualize facets and pars interarticularis), and an L5–S1 “spot” view to better show the lumbosacral junction. These views together assess alignment, fractures, degenerative change, and instability.

Lateral flexion is side‑bending of the spine or neck toward a shoulder, occurring in the frontal plane and decreasing the angle between adjacent vertebrae on that side. Extension is backward movement or straightening in the sagittal plane, increasing the angle between body segments (e.g., arching the back). Lateral flexion moves side‑to‑side; extension moves front‑to‑back.

Normal lumbar spine range of motion is about 40–60° of flexion (forward bending) and 20–35° of extension (backward bending). Measurements vary by age, body habitus and the assessment method (goniometer, inclinometer or tape-based tests). Values tend to decrease with age and may differ by sex and fitness; significant deviation suggests stiffness, injury or pathology and warrants clinical assessment.