In Vivo Lumbar Intervertebral Disc Deformation During Lateral Bending Motion Under Different Load-Bearing Conditions

Abstract Background Lumbar Intervertebral Disc Degeneration (LDD) is one of the largest health worldwide problems, based on lost working time and associated costs. Inappropriate mechanical loading is considered to be an important factor in the development of LDD. L3-4 and L4-L5 were the commonly affected levels. Recent studies have measured geometric deformation of lumbar intervertebral discs during an in vivo functional weightbearing of the lumbar. The purpose of the present study was to determine the lumbar disc deformation in living human subjects during lateral bending motion under different load-bearing conditions. Methods 11 healthy subjects, 6 males and 5 females, aged 21 ≤ 39 years, with an average age of 30 ± 5 years, were recruited for the present study. Using the combination of dual fluoroscopic imaging system(DFIS)and CT, the sagittal images of L3-5 segments scanned by CT were transformed into three-dimensional reconstruction models and then matched to the instantaneous images of lumbar spine motion taken by a double fluorescent X-ray system under different loads. Motions were reproduced with the use of the combined imaging technique during left and right bending movements. Then, the kinematics data of the height, tension and compression deformation, and shear deformation of the lumbar intervertebral disc were obtained by using computer-related software. Result The data indicated that the tendency of tensile deformation during left and right bending was approximately symmetric. During the functional bending of the body, there was a greater compression deformation behind the same side of the movement and a higher tension deformation in front of the contralateral movement. The magnitude changed along the diagonal towards the posterolateral direction. During left bending, the upper vertebrae had a larger deformation range and tension deformation than the lower vertebrae. Meanwhile, it was not found that the small load had a significant effect on the tensile deformation of the intervertebral disc. Conclusion Lumbar disc deformation showed direction-specific and level-specific changes during lateral bending motion. These results could help understand the physiological motion characters of the lumbar spine and provide data support for other biomechanical studies.