I had my L4-5 fused about three years ago. Never felt better until last week. New X-rays show degeneration at L3-4 now. I was warned that the lack of motion at the fused level might take its toll on the next level above. I just didn’t think it would happen to me. Should I have L3-4 fused? Or will I just end up with more problems?

Adjacent segment degeneration (ASD) has been reported after spinal fusion in many studies. Scientists are trying to sort out the cause from the effect. Is ASD the result of decreased motion at one segment putting increased stress and load on the next level?

Would the next level have worn out anyway? Is ASD caused by the number of levels fused? What about position of the fusion? If there’s too much curve in the lower spinal curve does it transfer increased load to the next level?

Right now there are more questions than answers. A recent study from Spain may help us understand what’s going on. Researchers used computer analysis of X-rays taken before and after lumbar spinal fusion. Patients were followed up to seven and a half years later.

What they found was a uniform narrowing of the disc spaces in all the vetebral segments. It wasn’t just at the level next to the fusion. It’s looking more and more like widespread changes occur because of the natural aging process.

If this is true, fusion won’t make the next segment any better or worse. In other words, having a second fusion may help your symptoms but won’t keep the next level from developing problems later.