MRI characterisation of the lumbar spine in lower trunk rotation

Statistical data indicates that the percentage of prevalence of spine-related pain is considered to be high, and even up to 84%. The spinal manipulation technique, which is based on applying external forces to the shoulder and pelvis to twist the human spine can decrease lower back pain. Better understanding of the biomechanical behaviour of the normal lumbar spine during each rotational position of the lower trunk will provide valuable translational information to guide better physiotherapy in the future. It will also provide normal variant data that will help healthcare professionals and specialist in artificial spine implants to understand certain aspects of spinal pain. Therefore, this study proposes an MRI study of the lumbar spine during different lower-trunk rotational positions to investigate their effect on the normal spine structures with consideration of the shoulder and pelvis girdles’ motion. To control the angle of the lower-trunk rotation, an MRI holder and an adaptive goniometer have been developed to position the subject and obtain accurate pelvis angle of rotation during the scan. Before starting the MRI scan, the position of the subject on the MRI holder was checked by calculating specific parameters. Standard supine and four lower-trunk rotational positions with unrestricted left and right shoulder movements were performed. T2 Sagittal, T2 coronal and T2 Axial 3D acquisition cuts were performed for the lumbar spine with a 1.5-T MRI scanner. The MR images were collected from volunteers and analysed using Image J software depending on the determination of particular anatomical landmarks and image processing techniques. The results show that there is a significant difference between the position of the right and left scapula during lower trunk rotation, while there is no significant relation between the angle of rotation of L5 and the rotational angle of the posterior superior iliac spines relative to the horizontal plane in three tested sections of the sacroiliac joints. In addition, there is no significant difference in the angle of rotation of the examined sections of the sacroiliac joints during different rotational positions of the lower trunk. The effect of different lower trunk rotational positions on the angle of rotation of the lower lumbar segment and spinal canal depth was measured and it was found that the second rotational lower trunk rotational position caused the highest relative motion of the lower lumbar vertebra, while the first lower trunk rotational position caused the highest rotational torque between L5 and L3. In addition, the mean iii difference in the spinal canal depth increased significantly following the degree of the applied lower trunk rotational position. Lower trunk rotation caused morphologic changes in the intervertebral discs and intervertebral foramens at L3-L4, L4-L5, and L5-S1 levels. However, the significant change in the area, width and height of the intervertebral foramen and disc depended on the rotational positions of the lower trunk. A strong anatomical relationship was indicated between the posterior height of the intervertebral disc at both sides and the foraminal height. Finally, the degree of the lateral bending was the greatest at the L4-L5 level. The mean differences between the left and right superior articular processes according to their orientation angle and gapping distance at the L3-L4 level were higher than those of the other tested levels, while the L5 level recorded the lowest values. However, the mean differences did not achieve significant effects. These results may provide baseline information to enable the development of artificial implants of the right and left lumbar facet joints according to changes in lower trunk rotational positions. They can also help to explain the treatment benefits of manipulation therapy in spinal conditions