Contrary to the results of previous studies, a new study has found that asymptomatic patients with evidence of disc degeneration on baseline MRI have an increased risk of developing low back pain. It also showed that the risk of low back pain increases with increasing disc degeneration score or rather specific severity and patterns of degenerative changes.
According to study’s lead author Dino Samartzis (Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong), who presented the study at the North American Spine Society annual meeting (NASS; 9–12 October, New Orleans, USA), previous studies suggest that degenerative changes in the lumbar spine (on MRI) in asymptomatic patients are not predictive of low back pain. However, he added that these studies presented: “Small sample sizes, did not thoroughly assess various imaging and environmental/lifestyle phenotypes related to pain, and were heterogeneous.”
The aim of Samartzis et al’s study therefore was to prospectively assess, in a population-based cohort of Southern Chinese patients, if baseline MRI findings in asymptomatic individuals were predictive of future first-time episodes of low back pain and pain severity. Sagittal MRI assessment of the lumbar spine was performed in 248 participants who had no history of low back pain and the Schneiderman et al radiographic criteria was used to determine the stage of disc degeneration. They used the grading process to obtain a summated disc degeneration profile of the lumbar spine that would represent the global severity of disc changes. The authors also noted the presence and extent of other spinal phenotypes, such as disc bulge/extrusion, Schmorl’s nodes, and Modic changes. After a mean of over four years follow-up, participants were assessed for the presence of low back pain using the Visual Analogue Scale score and the Oswestry Disability Index
Samartzis reported that, at baseline, 60.5% of participants had evidence of disc degeneration, 19% had evidence of disc space narrowing, and 34.3% had evidence of disc bulge/extension. By the end of the study, 34.7% of participants had had a first episode of low back pain. He commented that in the overall presence of disc degeneration and disc bulge/extrusion presented with a two-fold increase risk of developing low back pain. More specifically, moderate-to-severe forms of such degenerative changes were the greatest predictors of low back pain, greater functional disability and pain severity, and increased frequency of future episodes of low back pain. The study further noted that increased workload is a predictive risk factor associated with the development of low back pain; whereas, engaging in physical activity was protective.
Based on the results of his study, Samartzis stated that assessing specific patterns and phenotypes of disc degeneration was clinically relevant for determining biological treatment to regenerate the disc, designing measures towards more personalised spine care, preventing as well as treating episodes of low back pain, and identifying protective factors of disc spinal degeneration and pain. He added: “Defining clinically-relevant phenotypes of degenerative spinal changes is a must and needs to be standardised across borders.”
This study was also co-authored by Kenneth Cheung and Keith Luk from Hong Kong (Department of Orthopaedics and Traumatology, The University of Hong Kong) and Jaro Karppinen from Finland (Institute of Clinical Sciences, University of Oulu).