[Finite element analysis of intervention effect of Wuqinxi() Huju() on adolescent idiopathic cervical kyphosis].

Objective: To explore the changes of stress and displacement of intervertebral discs and vertebral bodies in adolescent idiopathic cervical kyphosis models caused by Wuqinxi () Huju() and extension movement after torque loading by finite element analysis.

Methods: One healthy male volunteer aged 24-year-old (heighted 178 cm and weighted 65 kg) was selected, software such as Mimics 21.0, Geomagic wrap 2017, SolidWorks 2017, and Ansys Workbench 17.0 were used to simulate adolescent idiopathic cervical spine model, an axial compressive load of 266 N was applied to the center of the end plate on C₂ for head physical gravity simulation, the lower part of C₇ vertebral body was set as the point of freedom constraint, a torque of 1.5 N·m was applied with C₂ as the reference point to simulate the stress on intervertebral discs and vertebral bodies after 45° movement of Wuqinxi () Huju ().

Results: The normal C₂-C₇ cervical spine model and adolescent idiopathic cervical kyphosis model were successfully constructed. The maximum stress value of intervertebral disc when the Huju()was raised and extended at 45° and loaded with torque occurred in C_3,4 intervertebral disc (3.588 1) MPa. The maximum stress values of each intervertebral disc were C_3,4(3.588 1 MPa)>C_2,3 (3.467 5 MPa) >C_4,5(2.597 7 MPa) >C_5,6 (2.378 8 MPa) >C_6,7 (1.404 9 MPa), respectively. The maximum stress of C6 vertebral body was 5.842 9 MPa, while the stresses of C₂, C₃, C₄, and C₅ vertebral bodies was 4.184 8, 4.437 8, 4.148 7, and 2.852 4 MPa respectively. The overall stress of vertebral body was mainly concentrated in the front of vertebral body.

Conclusion: After long-term practice of Huju()movement, the stress concentration in intervertebral discs and the front of vertebral body changes the stress load state of intervertebral discs and vertebral body. As time goes by, intervertebral discs may change, forming a shape that is higher in the front and lower in the back. The vertebral body may also undergo remodeling, resulting in a relative increase in the height of the anterior edge of vertebral body and promoting the recovery of cervical kyphosis to a physiological lordosis state.