'Skipped' level disc degeneration of the lumbar spine

Abstract

To challenge the traditional belief that age and biomechanics are key in the development of disc degeneration, this study addressed the prevalence and risk factors associated with a unique pattern of disc degeneration of the lumbar spine - ‘skipped’ level (non-consecutive) disc degeneration (SLDD). As part of a large population-based study in Southern Chinese (N=1,989), subjects exhibiting upon MRI assessment disc degeneration of more than two levels (n=838) were grouped into SLDD (n=174) and non-SLDD (contiguous, multilevel; n=664). Additional radiographic abnormalities and subject demographics were also assessed. SLDD was present in 8.7% and 20.8% of the overall (N=1,989) and multilevel disc degeneration (n=838) populations, respectively, and more prevalent in males (adjusted OR: 1.48; 95% CI: 1.04 to 2.10; p=0.028). SLDD was significantly associated with the presence of Schmorl’s nodes (adjusted OR: 2.72; 95% CI: 1.78 to 4.15; p<0.001), which also presented in levels with no disc degeneration. Disc bulge/extrusion and back injury history were significantly associated with non-SLDD (p<0.05). A greater degree of overall disc degeneration severity was associated with non-SLDD. Other demographics and MRI findings did not significantly differ between groups (p>0.05). To our knowledge, this is the first study to describe the prevalence and risk factors associated with SLDD. Our study challenges the ‘traditional’ paradigm for the development of disc degeneration. Although age and biomechanical factors may play a role in the manifestation of disc degeneration, our novel findings of SLDD patterns raise further awareness and support that additional etiological factors may play a role in the development of disc degeneration. Such factors warrant further investigation to shed light into the cause of disc degeneration.