Morphological alterations of the degenerated lumbar disc following chemonucleolysis with chymopapain.

Lumbar disc tissue from 10 patients who had previously undergone chemonucleolysis without success was studied by light and scanning electron microscopy. Seven patients had a sequestrated disc; three had large protrusions. As a control, material from 10 patients subjected to disc surgery without previous chemonucleolysis was studied in the same way. The control discs revealed the characteristic signs of degeneration: alteration of the collagen, microcystic areas, and giant chondromas. Changes following chemonucleolysis were restricted exclusively to the ground substance and characterized by a marked loss of basophilia in the cartilage matrix. There was no involvement of the anulus fibrosus, cartilage plate, or bone. Following chymopapain administration, scanning electron microscopy showed a naked collagen network devoid of ground substance.