Three-dimensional finite element analysis of traction under different lumbar physiological curvatures / 中国组织工程研究

ABSTRACT

BACKGROUND: In recent years, the finite element analysis of lumbar biomechanics has become a hot topic. Lumbar lordosis is considered to reduce the pressure load on the lumbar intervertebral disc and protect the lumbar spine. OBJECTIVE: To study the biomechanical effects of lumbar traction on L1-L5 lumbar segments in normal physiological curvature, flexion position and maximum overextension position, and to evaluate the optimal physiological curvature of lumbar traction. METHODS: A healthy male volunteer, aged 26 years, with a height of 174 cm and a weight of 60 kg, was selected, who had no history of lumbar spine diseases. With the L3 segment as the traction site, a finite element model of the whole lumbar spine was established based on lateral radiographs of the lumbar spine at the initiation site and during the maximal overextension as photographed by a DR machine. Based on the three-dimensional finite element model of the lumbar spine, the stress values and distributions of the lumbar vertebrae, the intervertebral joints, the intervertebral discs and the anterior longitudinal ligaments of the whole lumbar spine under different physiological curvatures were calculated. The patient was fully informed of the study protocol and signed an informed consent. The study protocol was approved by the Ethics Committee of Rehabilitation Hospital Affiliated to Fujian University of Traditional Chinese Medicine. RESULTS AND CONCLUSION: (1) Under six kinds of simulated working conditions, the range of motion of L1-L2 was 9.31° for flexion and extension, 9.84° for right and left bending, and 4.43° for right and left rotation; the range of motion of L2-L3 was 10.22° for flexion and extension, 12.35° for left and right bending, and 4.57° for left and right rotation; the range of motion of L3-L4 was 11.20° for flexion and extension, 11.63° for left and right bending, and 5.32° for left and right rotation; the range of motion of L4-L5 was 13.16° for flexion and extension, 11.58° for left and right bending, and 5.05° for left and right rotation. Under the normal physiological curvature of the lumbar vertebrae, the stress value of different lumbar spine structures was much greater than the stress value of hyperextension traction. The normal curvature of the anterior longitudinal ligament was 2.47 MPa, and the curvature of hyperextension traction value was 21.20 MPa. The stress value of L3 was the highest, which was four times that of the hyperextension traction. The stress value of the intervertebral joints at L2-L3 and intervertebral disc was highest than that of any other segment of the lumbar spine. These findings indicate that the pressure of lumbar vertebrae, intervertebral joints and intervertebral discs in hyperextension position is less than that in normal physiological curvature traction, and the pressure of anterior longitudinal ligament is always within the safe range. Lumbar traction may have better clinical efficacy and definite security in hyperextension position.