Extraforaminal with or without foraminal disk herniation: reliable MRI findings.

AJR Am J Roentgenol. 2009 May; 192(5): 1392-6Lee IS, Kim HJ, Lee JS, Moon TY, Jeon UBOBJECTIVE: The purpose of our study was to evaluate spinal MR images for extraforaminal disk herniation with or without foraminal disk herniation to determine the reliable MRI findings. MATERIALS AND METHODS: Thirty-five patients with extraforaminal with or without foraminal disk herniation confirmed at radiculography or surgery between March 2005 and July 2007 underwent spinal MRI. We assessed the morphologic features of the disk, changes in nerve root thickness, epidural fat obliteration surrounding the nerve root, and displacement of the nerve root in the foraminal and extraforaminal zones. RESULTS: Mixed disk herniation was found in 23 patients, and purely extraforaminal herniation was found in 12 patients. Focal eccentricity of the disk contour was identified in 32 patients (91%). Change in the nerve root thickness was found in 30 patients (86%). The nerve roots were displaced in 22 patients (63%), and the original location was maintained in nine patients (26%). Differentiation between the disk and the nerve root was poor in four of the 35 patients (11%). Obliteration of the epidural fat surrounding the nerve root was present in all patients. CONCLUSION: The presence of extraforaminal with or without foraminal disk herniation should be ascertained on the basis of the following MRI findings: focal eccentricity of the disk contour, obliteration of epidural fat surrounding the nerve root, change in the thickness of the nerve root, and displacement of the nerve root.

A cervical spine model to predict injury scenarios and clinical instability.

Sports Biomech. 2009 Mar; 8(1): 78-95Tchako A, Sadegh AA complete and detailed three-dimensional finite element model of the human cervical spine (C1-C7), including soft and hard tissues, was created using a digitized geometric measurement tool. The model was validated against existing experimental studies in flexion, extension, lateral bending, and axial rotation. The aims of this study were to use the model to simulate the mechanisms of injury scenarios, such as diving and football accidents, and to correlate the external and internal responses of the spinal components to disc herniation and clinical instability. It was determined that a shear-generated flexion moment of about 10 Nm or a compression-flexion load of 450 N would generate significant stresses and strains in the discs, together with sufficient posterior-anterior displacement and rotational angulation of the vertebrae, to place the mid and lower cervical spine at risk of clinical instability or disc herniation. The results revealed that the location of the maximum stresses in the discs could not be directly correlated with the type of loads. In addition, for the loadings considered, the maximum displacement of the spine could be reduced by as much as 50% when the restraint of the cervical spine is changed from a C7-T1 to C7-T1 and C1-C2 fixed conditions.