Evaluation of Water Content in Lumbar Intervertebral Discs and Facet Joints Before and After Physiological Loading Using T2 Mapping MRI

STUDY DESIGN.T2 mapping was used to quantify the water content of lumbar spine intervertebral discs (IVD) and facet joints before and after physiological loading. OBJECTIVE.To clarify the interaction between lumbar spine IVD and facet joints as load-bearing structures by measuring the water content of their matrix after physiological loading using T2 mapping magnetic resonance imaging (MRI). SUMMARY OF BACKGROUND DATA.To date, few reports have functionally evaluated lumbar spine IVD and facet joints, and their interaction in vivo. T2 mapping may help detect changes in the water content of IVD and articular cartilage of facet joints before and after physiological loading, thereby enabling the evaluation of changes in interacted water retention between IVD and facet joints. METHODS.Twenty asymptomatic volunteers (10 female and 10 male volunteers; mean age, 19.3 years; age range, 19–20 years) underwent MRI before and after physiological loading such as lumbar flexion, extension, and rotation. Each IVD from L1/2 to L5/S1 was sliced at center of the disc space, and the T2 value was measured at the nucleus pulposus (NP), anterior annulus fibrosus (AF), posterior AF, and bilateral facet joints. RESULTS.In the NP, T2 values significantly decreased after exercise at every lumbar spinal level. In the anterior AF, there were no significant differences in T2 values at any level. In the posterior AF, T2 values significantly increased only at L4/5. In the bilateral facet joints, T2 values significantly decreased after exercise at every level. CONCLUSION.There was significant decrease in the water content of facet joints and the NP at every lumbar spinal level after dynamic loading by physical lumbar exercise. These changes appear to play an important and interactional role in the maintenance of the interstitial matrix in the IVD NP and cartilage in the facet joint.Level of Evidence3