Quantitative measurement of disc space area before and after chemonucleolysis and nucleotomy.

Measurements of the area of the intervertebral disc space were made, over a period of 400 days or more, in 16 patients who underwent chemonucleolysis and 20 patients after nucleotomy. The superimpositioning method of measurement used is based on a determination of fixed points and it has a high level of reproducibility. We have measured areas which differ from volumes in only a single dimension, but which show good correlation compared with measurement of intervertebral disc space heights alone. After both chemonucleolysis and nucleotomy, narrowing of the intervertebral disc space occurs up to the 50th day, after which there is a highly significant difference: the intervertebral disc space height increases after chemonucleolysis, and continues to decrease after nucleotomy. It is concluded that the enzymatic effect of chymopapain on the nucleus pulposus produces a gain in disc substance after chemonucleolysis, whereas nucleotomy is associated with a loss of substance.