Patterns of disc degeneration play a role in incidence of low back pain

Investigators found no differences in the functional disability scores of patients they studied with either consecutive or skipped level lumbar disc degeneration.

Dino Samartzis

Individuals with consecutive multilevel lumbar disc degeneration were more likely to develop low back pain than individuals with skipped level disc degeneration, where healthy discs occur between degenerative discs, according to research conducted by investigators from Hong Kong and Finland.

“In individuals with [a] similar amount of disc degeneration, we noted a 40% increased likelihood of having low back pain if you had CMDD [consecutive multilevel lumbar disc degeneration],” Dino Samartzis, DSc, said at the International Society for the Study of the Lumbar Spine Annual Meeting 2011. “In fact, these individuals also had significant higher pain severity compared to the skipped level cases,” he said.

Large-scale study

In their large-scale study, Samartzis and colleagues evaluated which type of lumbar disc degeneration was most associated with low back pain by assessing MRI findings in 1,457 Chinese patients and dividing them into two groups. The first group consisted of individuals with CMDD affecting two or more lumbar levels (79% of patients) and the second group consisted of individuals with skipped level disc degeneration or SLDD (21% of patients).

“For many years, the assessment of lumbar disc degeneration on MRI in relation to low back pain was one-dimensional. Our large-scale population study has shown us that we must think of the lumbar spine as a ‘global entity’ that may develop various patterns of degeneration, which may play a role in low back pain development,” Samartzis, in the Department of Orthopaedics and Traumatology at the University of Hong Kong, told Orthopaedics Today Europe.

Historical low back pain

During his presentation, Samartzis said, “We noted that individuals with CMDD had a significantly increased prevalence of historical back pain, as well as back pain that occurred in the past year.”

Consecutive, multilevel disc degeneration, shown here, causes a historically higher incidence of back pain in patients according to study results.

Researchers classified skipped level disc degeneration, pictured here, into five different types based on the severity of pain and location of healthy discs. Images: Samartzis D

SLDD cases were further divided into five classifications according to the location of the healthy discs. SLDD type V was associated with the highest severity of pain and the highest incidence of low back pain in study patients, according to Samartzis.

Researchers found no differences in functional disability scores in either group or within the SLDD classification groups, according to the abstract.

Determining the clinical relevance of patterns of disc degeneration poses an interesting question of whether patients could have specific or unique biomechanical or biochemical components that predispose them to back pain, Samartzis told Orthopaedics Today Europe.

“SLDD, noted in approximately 20% of the population, cannot be explained by traditional age and abnormal physical loading effects, but may possess a developmental or genetic etiology that needs further exploration,” he said. – by Jeff Craven

Reference:

• Samartzis D, Karppinen J, Luk K, Cheung KMC. Are patterns of lumbar disc degeneration associated with low back pain? New insights based on skipped level disc pathology. Paper #P29. Presented at the International Society for the Study of the Lumbar Spine Annual Meeting 2011. June 14-18. Gothenburg, Sweden.

• Dino Samartzis, DSc, can be reached at the Division of Spine Surgery, Department of Orthopaedics & Traumatology, University of Hong Kong, Pokfulam Road, Hong Kong, SAR, China; +852-9584-2395; e-mail: dspine@hku.hk.
• Disclosure: Samartzis has no relevant financial disclosures.

Contrasting patterns of disc degeneration may eventually contribute to a better understanding of mechanisms of degeneration and possibly related symptoms. However, we will have to await a more detailed report by Samartzis and colleagues and further research to clarify how SLDD fits into the larger picture of the etiology and effects of disc degeneration and to discern its clinical implications. The basis for the classification of SLDD into five types is unclear from the abstract and the size of the odds ratios suggests a modest amount of variation in back pain may be explained by pattern of disc degeneration. Also, important confounding may still exist to account for the finding of less pronounced back pain in those with SLDD as compared to CMDD. Nevertheless, it will be interesting to follow developments in this line of research.

— Michele C. Battié, PhD
Faculty of Rehabilitation Medicine
University of Alberta
Edmonton, Canada
Disclosure: Battié has no relevant financial disclosures.