MRI evaluation of lumbar spine flexion and extension in asymptomatic individuals

Flexion and extension movements or positions have been advocated in the treatment of various forms of low back dysfunction due to the potential pain relieving effects attributed to displacements of the intervertebral disc (IVD). Objective in vivo determination of the segmental behaviour of the disc to contrasting positions has until recently been difficult. Magnetic resonance imaging (MRI) was used in this study to evaluate the influence of sagittal plane positions on lumbar IVD height and nucleus displacement in a small asymptomatic population.T2-weighted sagittal plane images from L1 to S1 were obtained from 10 subjects (mean age: 30+/-5 years) positioned supine in lumbar flexion, followed by extension. Changes in disc height and localization of nucleus position (determined by peak MRI signal intensity) between the two positions were calculated. Discs were classified for degenerative changes using a semi-quantitative grading scale. The mean range of lumbar sagittal movement achieved in the MRI was 44 degrees (range: 22-77 degrees ). Between flexion and extension, a significant increase in measured anterior disc height of 1.1 mm (P