Allografting intervertebral discs in dogs: a possible clinical application.

STUDY DESIGN

A lumbar disc is a tissue that is often a cause of low back pain. We conducted experimental allografting of intervertebral discs in dogs.

OBJECTIVES

To evaluate the clinical potential for allografting of intervertebral disc.

SUMMARY OF BACKGROUND DATA

There have been few reports on the allografting of intervertebral discs. The allografting of discs frozen at -196 C has never been documented. In the present experiments, we studied the effect of freezing at -80 C and -196 C on disc allografts to 25 hybrid adult dogs.

METHODS

A vertebral disc was obtained from donor dogs with parts of the adjoining vertebral bodies to serve as the allograft disc unit. After soaking in 10% dimethyl sulfoxide at 4 C, the allograft discs were frozen and stored at either -80 C or -196 C. After storage for approximately 4 weeks, they were transplanted peritoneally into the recipient lumbar vertebrae and fixed using plates and screws to preserve mobility of the grafted disc. At the same time, cells from allograft discs were incubated to examine their ability to synthesize proteoglycan and collagen. Radiologic examination of the changes after surgery in the intervertebral space was followed serially.

RESULTS

Radiographs revealed a complete bone union of the vertebral bodies at 5 months and gradual narrowing of the intervertebral space beginning at 6 months. Histologically, the anulus fibrosus was well preserved, especially in disc units stored at -196 C. Cellular synthetic activity was seriously diminished.

CONCLUSIONS

Our results indicate that allograft of intervertebral discs has clinical potential because it can serve as a dynamic disc spacer for a certain period of time, but its long-term merits and demerits have to be established.