IS LUMBAR DISC DEGENERATION REALLY DUE TO “WEAR & TEAR” A multidisciplinary, multinational research project, called the Twin Spine Study, was started in 1991. Collaborators, primarily in Canada, Finland and the United States, investigated determinants of disc degeneration, including occupational exposures, driving and whole-body vibration exposure, smoking exposure, anthropomorphic factors, heritability, and the identification of genotypes associated with disc degeneration. The methods and findings of the Twin Spine Study project were reviewed in a recent article in The Spine Journal 9 (2009) 47-59, entitled “The Twin Spine Study: Contributions To A Changing View of Disc Degeneration.” The results of the study were summarized in the abstract of the article as follows: Among the most significant findings were a substantial influence of heredity on lumbar disc degeneration and the identification of the first gene forms associated with disc degeneration. Conversely, despite extraordinary discordance between twin siblings in occupational and leisure-time physical loading conditions throughout adulthood, surprisingly little effect on disc degeneration was observed. Studies on the effects of smoking on twins with the large discordance in smoking exposure demonstrated an increase in disc degeneration associated with smoking, but this effect was small. No evidence was found to suggest that exposure to whole-body vibration through motorized vehicles leads to accelerated disc degeneration in these well-controlled studies. More recent results indicate that the effect of anthropometric factors, such as body weight and muscle strength on disc degeneration, although modest, appear in this work to be greater than those of occupational physical demands. In fact, some indications were found that routine loading may actually have some benefits to the disc. In summary, this study seems to suggest that the “wear and tear” of exertional activity, including work, has less of an influence on degenerative disc disease than heredity. Hickey Combs PLC has been using this and similar research to the advantage of our clients in cross-examining plaintiffs’ expert medical witnesses in degenerative disc disease cases. 11/06/09