Good question and one that medical financial analysts have also asked. Research shows that the trend for spinal surgery is on the rise. This includes all spine problems from disc to stenosis.

Older adults are more likely to have spinal surgery than ever before. In fact the number of patients who have had spinal fusion for stenosis increased four times (quadrupled) since the 1980s. This may be because Americans are living longer. And problems that come with aging like stenosis are causing pain and disability. Improved technology and better surgical methods make it possible to operate on older adults.

But studies so far don't show that the added operations really make a difference. Your parents are probably a good example. Some patients show improvement but others don't. More research is needed to find out who would benefit from each type of treatment.