Table 2.

Exclusion criteria

Evidence of a large contained or sequestered herniation (small contained herniation was allowed)

Loss of more than 50% disc height at the target level

Severely disrupted disc (sufficient annular tissue required for safe catheter placement)

Neurogenic claudication due to spinal stenosis

Four or more symptomatic lumbar disc levels

Previous back surgery at any level of the lumbar spine

Spondylolisthesis at a symptomatic disc level

Psychological disorders that may impact treatment outcome