We reviewed two comparable groups of patients who had been treated for lumbar disc herniation by chymopapain chemonucleolysis (145) or conventional surgical discectomy (91). They were reviewed 10 years after treatment by questionnaire, followed by a personal interview by an independent observer. The results of the surgically treated groups were slightly better than those treated with chymopapain. In particular, there was significantly better early relief of leg and low back pain, and fewer patients needed a second procedure. Complications were few in both groups.

Clinical localisation of a disc prolapse required dependable knowledge of the muscles supplied by the lumbosacral nerve roots. Localisation is most difficult in the 10 per cent of patients who have lumbosacral bony segmental anomalies. The lumbosacral plexus has been dissected in 11 cadavers with such anomalies and electrical stimulation studies carried out in 15 patients similarly afflicted. It is suggested that whatever the anomaly the "last fully mobile level" should be identified as the lowest level with a fully formed disc space, bilateral facet joints and two free transverse processes which do not articulate with the sacrum or pelvis. In three out of four patients with bony segmental anomalies the fifth lumbar root emerges at the last fully mobile level.

A prospective study of 480 patients who underwent enzymatic dissolution of the nucleus pulposus with chymopapain is reported. Seventy per cent of patients with the clincial criteria for a disc herniation had a favourable response to chemonucleolysis. The commonest cause of failure was persistent back pain. In patients with sequestered discs or lateral recess stenosis surgical intervention was not made more difficult by chemonucleolysis. Those with a previous operation, spinal stenosis or psychogenic components to the disability had very poor results. Complications were few and easily managed.