Ever wonder if that time you hurt your back will come back to haunt you? Disc degeneration is a common problem as we get older. Adding a back injury or trauma to the mix could speed up that degenerative process.

To find out if this might be so, researchers studied 37 pairs of twins (all men) who were part of an ongoing Twin Spine Study in Finland. They interviewed the men about past back problems and history of injuries on every job they had ever had. The same questions were asked regarding back injuries during any exercise, sporting, or leisure activity.

Normally, there are 157 pairs of (identical) twins in the Twin Spine Study. The only pairs included in this study were those who had one twin with a history of back injury (or injuries) and the other twin with no recall of any back problems.

The main measure of disc health was MRI study. The height of the disc and disc signal intensity on MRI were used to assess current disc status. Everyone in the study had an MRI of the lumbar spine (L1 to S1) done.

Various factors that might affect disc degeneration were considered. These variables included type of work (occupation) and load placed on the spine during labor, amount and type of exercise (sports or leisure), and any weight training the men had participated in over the years.

They did not find any significant differences in disc height or signal between the twins who had a previous back injury and the twin who didn't. This was true for all 37 pairs. Twin members who lifted more weight at work were more likely to injure their backs but this did not seem to translate into faster or greater disc degeneration later.

Conducting a twin study like this with identical twins of the same sex and age helps control for these factors that might otherwise influence the results. By itself, this study doesn't prove (or disprove) the theory that back injuries or trauma lead to disc degeneration. But it does add evidence to previous studies with similar results to suggest that back trauma or injury is not a risk factor for accelerated disc degeneration.

The authors do point out three important features of their study. First, the participants did not have X-rays showing specific tissue damage or pathologic changes in the spine due to their injuries. They based the history of back injury on patient recall.

Second, it is possible that twins who didn't remember injuring their backs did, indeed, have a previous back injury. And third, time between injury and subsequent disc degeneration may be a factor. No one really knows how much time is required before measurable changes might be seen on an MRI. Only long-term studies will be able to answer that.

Reference: Mark J. Hancock, PhD, et al. The Role of Back Injury or Trauma in Lumbar Disc Degeneration. In Spine. October 1, 2010. Vol. 34. No. 21. Pp. 1925-1929.