The role of calcium deposition in the ligamentum flavum causing a cauda equina syndrome and lumbar radiculopathy.

Our report concerns five patients who underwent lumbar decompressive surgery for cauda equina syndrome and radiculopathy secondary to degenerative stenosis associated with calcium deposition in the ligamentum flavum. The resected ligamentum flavum showed diffuse to massive calcium crystal deposition with a histologically marked degeneration in the elastic fibres. Energy dispensive radiographic microanalysis confirmed the crystal to be calcium pyrophosphate dihydrate in all patients, hydroxyapatite mixed in three and calcium orthophosphate mixed in one. The deposition appeared to be a change that is associated with the degenerative process in the ligament and, in some cases having marked deposition in a localised event, it causes or aggravates the neurological symptoms.