Intolerable Low Back Pain Due to Ossification of the Ligamentum Flavum at the L5–S1 Level

Intolerable Low Back Pain Due to Ossification of the Ligamentum Flavum at the L5–S1 Level

A 37-year-old man presented with low back pain and leg pain. A CT scan identified ossification of ligamentum flavum (OLF) at the L5–S1, causing foraminal stenosis. AnL5 nerve root block resolved his low back pain and leg pain completely. However, the symptoms recurred after the effect of the local anesthetic wore off. Because of persistent and intolerable low back pain, he underwent surgery, partial facetectomy and removal of the ossified ligaments followed by posterior instrumented fusion at L5–S1. Histopathology of the specimen revealed no apparent degenerative changes in the ligament. The patient’s symptoms had disappeared completely at the final follow-up. This case is different from previously reported cases: the chief complaint was intolerable low back pain; the patient was a young adult; it did not involve degeneration of the spinal elements; and did not involve coexisting ossification of other spinal ligaments. Although the pathogenesis of OLF remains still unclear, it is possible that OLF of the lower lumbar spine causes severe low back pain and is treatable by surgery.