Biomechanical Comparison of Lumbar Fixed-Point Oblique Pulling Manipulation and Traditional Oblique Pulling Manipulation in Treating Lumbar Intervertebral Disk Protrusion

Objective: To compare the biomechanical effect of lumbar fixed-point oblique pulling manipulation and traditional oblique pulling manipulation in the treatment of protrusion of lumbar intervertebral disk, and investigate the influence of disk degeneration on the 2 manipulations. Methods: Three finite element models including 1 normal model, 1 mild degeneration, and 1 moderate degeneration model of L3-S1 were developed to simulate 2 oblique pulling manipulations. The disk protrusion was assumed to be in the left central and subarticular zone of the L4-L5 disk, and manipulations were carried out on the right. A 15-Nm right axial rotation moment and 150-N compressive loading were imposed on the upper endplate of L3 to simulate a traditional oblique pulling manipulation. To simulate lumbar fixed-point oblique pulling manipulation, in addition to a 15-Nm moment and 150-N compressive loading imposed on the L3 upper endplate, a 50-N force was imposed on the right lateral area of the L4 spinous process in a left front direction. The displacement and stress in the left central and subarticular zone of the L4-L5 disk were calculated and compared in the 3 models. Results: The average displacement and stress in the left central and subarticular zone of L4-L5 disk were higher in fixed-point oblique pulling manipulation than those in traditional oblique pulling manipulation (P < .05). In addition, the values of average stress and displacement decreased significantly with the increase of lumbar disk degeneration (P < .05). Conclusion: Lumbar fixed-point oblique pulling manipulation showed a better biomechanical effect than traditional oblique pulling manipulation, and lumbar disk degeneration affected the 2 manipulations adversely in the virtual treatment of protrusion of the lumbar intervertebral disk using finite element models.