Lumbar oblique manipulation (LOM) has a well-established immediate analgesic effect in the treatment of lumbar disc herniation (LDH). However, its target and biomechanical mechanism remain unclear. Based on individualized finite element models, this study investigated the immediate effect of LOM on the disc–nerve root mechanical environment and its potential kinematic mechanism.

Using CT data from two patients with LDH, normal and pathological L4–S1 segment models were constructed. Under six typical physiological loading conditions, including flexion, extension, lateral bending, and axial rotation, the von Mises stress and strain distributions of the vertebrae, intervertebral discs, nerve roots, and spinal canal were analyzed. In addition, the manipulation kinematic data collected by the Miiglove system were incorporated into the finite element model to simulate the dynamic loading process of LOM, and the displacement changes and spatial relationship reconstruction between the intervertebral disc and the compressed nerve root were analyzed before and after manual intervention at time scales of 0.1 s and 1 s.

In the state of LDH, the stress and strain increased in the posterior annulus and nerve root region, accompanied by altered load distribution. Among different motion patterns, lateral bending and axial rotation had a more pronounced effect on the nerve root structures. After the intervention of LOM, the displacements of both the intervertebral disc and nerve root increased, with a greater magnitude of change observed in the nerve root. Meanwhile, the contact area between the two structures decreased, their spatial relationship was altered, and local stress was redistributed.

LOM may achieve a decompressive effect on the lumbosacral nerve roots by inducing coordinated displacement between the intervertebral disc and nerve root, reducing structural contact, and remodeling the local biomechanical environment, which provided kinematic and biomechanical basis for elucidating the mechanisms and targets of spinal manipulation.