1996 Volume 45 Issue 1 Pages 123-126
We investigated the pathological changes and alterations in intradiscal pressure after an experimental intradiscal injection in the mature rabbit. Thirty intervertebral discs in 6 rabbits were used as controls, and normal pressures were measured. Chymopapain, 10% sodium chloride, or betamethasone were injected separately into 5 intervertebral discs of 9 rabbits. Rabbits were sacrificed at 1 week, 4 weeks, and at 12 weeks after the intradiscal drug injection. The intradiscal pressure changed depending on the degree of disc degeneration and if there was any regeneration. The chymopapain-injected intradiscal pressure decreased significantly at 4 weeks compared with the pressure at 1 week and at 12 weeks (p<0.05, p<0.01 respectively). The intradiscal pressure of the 10% sodium chloride-injected discs decreased at 4 weeks, but by 12 weeks the pressure had recovered to the same level as fourd in the cotrols. Necrotic nucleus pulposus was seen histopathologically at 1 week after chymopapain injection, and at 1 week after the 10% sodium chloride injection. At 12 weeks, there intervertebral discs had regenerated with chondrocytes different from in the normal nucleus pulposus.
The pressure of the betamethasone-injected discs was unchanged throughout the 12 weeks with only slight histological changes.
