Herniated discs in the lower spine are less likely to be caused by a rupture than a separation of the tissue connection between the disc and spinal bone, new research shows.
 

The study, published in the journal Spine, questions long-held medical assumptions about how herniated discs happen, and how they are best treated.
 

The results suggest surgeons may need to pay more attention to problems with the attachment between the spinal bone and discs as the main cause of herniated lumbar discs.
 

The study — led by S. Rajasekaran, M.D., and colleagues from Hanga Hospital, Tamil Nadu, India — involved 181 patients undergoing surgery for herniated lumbar discs.

Sometimes called ruptured or "slipped" discs, herniated discs are a major cause of low back pain and occur when the soft material inside the disc leaks through the tough outer covering of the disc.
 

Dr. Rajasekaran's team assessed each patient, using x-rays, CT, MRI scans, and other techniques to identify the causes of the herniated discs. The results suggested only 11 percent of the cases were due to a rupture of the disc, but in 65 percent of cases, a piece of the bone and/or cartilage connecting the disc to the vertebra had actually broken off.
 

In some cases, the break healed in the time between initial injury and surgery to repair the herniated disc. This was sometimes accompanied by narrowing of the spinal canal —called spinal stenosis.
 

The results should lead spinal surgeons to rethink the causes of herniated lumbar discs, which have long been believed to be caused by ruptures, the researchers said.
 

"Our study shows that the incidence of [connective tissue] failure has been grossly underrated, probably because of the difficulty of documentation," they added. "The evidence of … failure opens up opportunities for prevention, repair, and biological strategies that may prevent progression of lumbar disc herniation."