Unilateral lumbar facet joint hypertrophy causing nerve root irritation.

We present four cases of massive unilateral lumbar facet joint hypertrophy in an otherwise morphologically normal spine. All presented with a combination of low back pain and symptoms of entrapment of a single lumbar nerve root. The abnormality is best visualised by CT scanning and the results of surgical decompression by partial undercutting facetectomy are favourable.