Healing potential of the anulus fibrosus.

The purpose of this study was to investigate the healing of surgically created defects in the anulus fibrosus in an effort to determine the healing potential of this structure. Four identical lesions were made in the anulus fibrosus of ten dogs at levels L2-L5. Two dogs were killed at 3, 6, and 9 weeks. Four dogs were killed at 12 weeks. The spines were harvested during a 3- to 12-week period and evaluated grossly and microscopically. Our study demonstrated that a stab wound of the anulus has a limited healing potential and the persisting defect could provide a pathway for irritating nuclear fluid escape onto perineural tissue, possibly resulting in persistent low-back pain.