Complications following chemonucleolysis with collagenase.

Lumbar disc tissue from eight patients previously submitted to unsuccessful chemonucleolysis with collagenase was studied by light and scanning electron microscopy (SEM). Similar material from eight patients subjected to primary disc surgery served as control. The control discs revealed the characteristic signs of degeneration of collagen tissue, microcystic areas, and giant chondromas. However, the anulus fibrosus and the end-plates remained intact. Following chemonucleolysis with collagenase, "digestion" of the nucleus pulposus, the anulus fibrosus, and extensive damage to the end-plates, bone, ligaments, and epidural fat were seen.