Degenerative Disc Disease and Pre-existing Spinal Pain

Apportioning pain and disability after an auto accident or work related injury can be difficult.  Many physicians who undertake this task often state that since an x-ray or MRI soon after the injury showed degenerative disc disease (DDD), some or all of the patient's spinal pain and disability must be pre-existing.  This interpretation of imaging is a classic case of Junk Science.

In order for this statement to be true, there would need to be a strong connection between MRI or x-ray evidence of DDD and pain/disability.  If we look at this concept and compare it to the peer reviewed medical literature, we see that DDD as seen on imaging, taken by itself, is not a painful condition.  

Several studies have been done, the oldest of which is a study published in the journal of Neuroimaging in 1991.  In this study patients without low back pain underwent an MRI.  39% of this normal group had evidence of DDD.(1)  A New England Journal of Medicine Article in 1994 found similar results.  It demonstrated that of 98 subjects without low back pain, 52% had DDD on MRI. (2)  Similar findings were discovered in the thoracic spine (upper back) by Wood in the Journal of Bone and Joint Surgery in 1995.  Thoracic MRI's were performed in 90 asymptomatic adults.  73% of these patients had DDD at least one level. (3)  Similar findings have been found in radiographic analysis of asymptomatic cervical spines with the prevalence of DDD increasing with age.  In addition, MRI has been found to have high false negative and positive rates for predicting painful discs in this area. (4)  In summary, there has not been a single study published to date that convincingly shows that DDD seen on MRI or x-ray is a painful condition. 

If DDD is not painful, then why do MRI's and x-rays of people with spinal pain often show DDD?  The reason is likely that DDD can predispose a patient to a painful spinal condition.  Important clues can be gleaned from recent research showing that painful discs have nerve in-growth. (5) Additional research has shown that degenerated discs move abnormally and this property may predispose them to injury in a traumatic event.(6)  Finally, we have much to learn about the cause of axial spinal pain, but it seems clear that MRI and x-ray are not sensitive enough to show us the cause.  

In summary, DDD as seen on x-rays and MRI's is not a painful condition, therefore evidence of this "disorder" prior to an accident or injury does not mean that the patient had a painful pre-existing condition.  While it's true that some patients with DDD have pain, it's also true that many patients without DDD have pain.  Further, high percentages of the normal, pain-free population have DDD.  Based on the peer reviewed research in this area, DDD appears to be a normal part of the aging process and not "smoking gun" evidence of a pre-existing problem.

Christopher J. Centeno, M.D.

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