[Finite element analysis of a combined manipulation technique involving pressing, traction-pressing, and oblique-...

To establish a lumbar spine model using the three-dimensional finite element method, simulate the pressing manipulation and the traction-pressing-oblique-pulling complex manipulation through mechanical simulation, to analyze the mechanical effects of these two manipulations, and compare and discuss their biomechanical mechanisms and the differences in mechanical effects.

A typical lumbar disc herniation(LDH) patient was selected. Based on the patient's lumbar CT image data, a three-dimensional finite element model of the L₄-L₅ segment was constructed, focusing on in-depth analysis of a single sample. The reliability of the model was verified through mesh convergence analysis and comparison with literature. The stress and strain distribution in various tissue units of the L₄-L₅ segment, as well as the relative displacement distance between the intervertebral disc and the nerve roots, were observed during the application of the pressing manipulation and the traction-pressing-oblique-pulling manipulation.

A three-dimensional finite element model of the L₄-L₅ segment based on imaging data from a patient with lumbar disc herniation was successfully constructed, and mechanical simulation analysis of the two manipulations was conducted. After applying the pressing manipulation, the stress was maximum at the anterior part of the intervertebral disc and minimum at the herniated site;the strain was maximum at the herniated site and smaller anteriorly. The intervertebral disc exhibited overall forward strain, but backward strain also occurred at the anterior edge. The strain values were 0.097 for the annulus fibrosus and 0.153 for the nucleus pulposus. The intervertebral disc exhibited overall forward displacement:5.531 mm to the right on the X-axis, 3.707 mm forward for the herniated disc on the Y-axis, and 2.031 mm upward for the herniated disc on the Z-axis. The left nerve root moved forward by 2.453 mm, while the right nerve root moved backward by 0.760 mm. After applying the traction-pressing-oblique-pulling complex manipulation, similar to the pressing manipulation, the stress was maximum at the anterior part of the intervertebral disc and minimum at the herniated site. Regarding disc strain, the posterior part exhibited the maximum strain, with smaller strain anteriorly. The intervertebral disc exhibited overall rightward strain and partial forward strain, with values of 0.751 for the annulus fibrosus and 0.587 for the nucleus pulposus. The intervertebral disc exhibited overall forward and rightward displacement:8.594 mm to the right on the X-axis, 5.409 mm forward for the left side on the Y-axis, while the right side (healthy side) moved backward, and 2.735 mm upward for the herniated part on the Z-axis. The left nerve root moved forward by 2.932 mm, while the right nerve root moved backward by 1.971 mm.

Both manipulations can enlarge the space between the intervertebral disc and the nerve roots, with the complex manipulation demonstrating superior biomechanical decompression effects. This study not only verifies the biomechanical mechanisms of the two Traditional Chinese Medicine manipulations but also provides a reproducible and extensible three-dimensional finite element model for subsequent related clinical and mechanical research, possessing certain promotional value and practical guiding significance.