In OA/DDD, which level is most severely affected?

In OA/DDD, which level is most severely affected?

• A. Cervical spine.
• B. Thoracic spine.
• C. Lumbar L3/L4.
• D. Most severe at L5/S1 and progresses upward.

Answer: (D)

Degenerative changes in the spine accumulate where loading and motion are greatest, and the lumbosacral junction bears the heaviest load. L5-S1 transfers the body's weight to the pelvis and experiences substantial flexion–extension and shear forces, so the disc there degenerates most severely first. This leads to disc height loss, facet joint osteoarthritis, and possible nerve compression at that level. As degeneration progresses, the altered mechanics place more stress on the levels above, causing the disease to ascend the lumbar spine. The thoracic region is shielded by the rib cage and has less motion, and while the cervical spine can develop OA/DDD, the most severe level overall is the L5–S1 junction with upward progression.

Degenerative changes in the spine accumulate where loading and motion are greatest, and the lumbosacral junction bears the heaviest load. L5-S1 transfers the body's weight to the pelvis and experiences substantial flexion–extension and shear forces, so the disc there degenerates most severely first. This leads to disc height loss, facet joint osteoarthritis, and possible nerve compression at that level. As degeneration progresses, the altered mechanics place more stress on the levels above, causing the disease to ascend the lumbar spine. The thoracic region is shielded by the rib cage and has less motion, and while the cervical spine can develop OA/DDD, the most severe level overall is the L5–S1 junction with upward progression.