Biomechanical analysis of lumbar oblique manipulation for lumbar disc herniation with different protrusion subtypes

Lumbar oblique manipulation (LOM) is one of the commonly used conservative treatments for lumbar disc herniation (LDH). Compared with surgical interventions, its non - invasive nature provides patients with greater comfort and reduces treatment resistance, resulting in its widespread clinical application. However, manual techniques may vary according to the type of disc herniation and could potentially lead to adverse outcomes. For which LDH patients is LOM truly suitable? This question deserves further consideration. To investigate the specific characteristics of LOM for different LDH types, this study constructed six representative finite element models of LDH and analyzed the biomechanical effects of LOM on each model. The findings suggest that for patients with herniations at the same level as the affected nerve root, LOM is safer when performed in the healthy lateral position, regardless of the presence of significant compression symptoms. Conversely, for patients with pronounced neurological compression symptoms, especially those with disc protrusions extending beyond the nerve root level, the technique may worsen disc and nerve root compression. This study provides the first bilateral LOM biomechanical evidence across six LDH subtypes, which can be used as a guide for safer clinical positioning.