Injured workers facing surgery often ask, does back fusion surgery at one level affect the disc levels above or below the surgery. For any particular individual, this question should be directed to one’s surgeon and independent, reliable research. At McCormick Law Office, we are interested in the issue because many of our cases involve causally connecting these additional disc levels to a prior work-related injury or condition years after an original surgery.
There is medical research, readily available through the National Institutes of Health PubMed search engine, indicating that the answer is probably yes, especially if certain factors are present. First, nonmedical engineers will note that by taking away a functioning disc (carrying weight and providing motion) and fusing together the two vertebrae above and below it into one large vertebrae, it necessarily requires the adjacent discs above and below to carry more of the load in terms of weightbearing and supplying flexibility. The medical experts call this phenomenom “adjacent segment disease” or ASD.
One study of fusion patients found the interval between the first and revision surgery as ranging from 5.2 to 7.1 years. It has been reported in several studies that distal (farther away and lower) ASD is less common than proximal ASD. For example, surgery at L4-5 is more likely to affect L3-4 as opposed to L5-S1. Not surprisingly, smoking and facet degeneration seems to be a factor contributing to ASD, but the question remains, would these factors have contributed to the damage even if there was no prior adjacent surgery.
In the workers’ compensation case, if the worker has returned to his physically demanding job after the first back fusion surgery, we avoid the ASD issue because the surgeon may say it is more likely that the job duties which caused the original disc to be damaged have now contributed to the damage at the additional disc levels.