In vivo biomechanical quantification and individual factor analysis of lever positioning manipulation under different thrust modes：a cross-sectional study

Background Lever Positioning Manipulation (LPM), an innovative manual therapy derived from traditional lumbar extension manipulation in Traditional Chinese Medicine, has been clinically proven to be effective in treating Lumbar Disc Herniation (LDH). However, clinical observations indicate significant individual variations in patients' responses to LPM treatment, with therapeutic outcomes closely related to the applied manipulation force and individual patient characteristics. Therefore, conducting quantitative research on the mechanical parameters of different LPM manipulation modes and analyzing individual factors hold significant clinical importance. Methods A total of 107 volunteers were recruited from the Department of Tuina, The Third Affiliated Hospital of Zhejiang Chinese Medical University. Biomechanical data of unilateral and bilateral LPM were collected using wearable gloves and elbow sleeves, including hand preload force (HPF), hand maximum pulling force (HMPF), hand instantaneous pulling force (HIPF), elbow preload force (EPF), elbow maximum pressing force (EMPF), and elbow instantaneous pressing force (EIPF). Individual characteristic parameters recorded included waist circumference (WC), femur length (FL), lumbosacral angle (LA), lumbar curvature (LC), and lumbar lordosis angle (LLA). Quantitative and correlation analyses were conducted. Results No significant differences were found between left- and right-sided unilateral manipulations (p > 0.05). Compared with LDH patients, healthy participants showed significant differences in EPF-A (p < 0.05), but not in other parameters. In unilateral LPM, EMPF-U correlated strongly with EIPF-U (p < 0.01), HMPF-U with both HIPF-U and HPF-U (p < 0.01), and EPF-U with EMPF-U (p < 0.05). In bilateral LPM, HMPF-A correlated with HIPF-A (p < 0.01); EPF-A correlated positively with EMPF-A (p < 0.05) but negatively with EIPF-A (p < 0.05). EMPF-A and EIPF-A were positively correlated (p < 0.01). Regarding individual characteristics, EPF-U negatively correlated with LC (p < 0.05); in bilateral LPM, HMPF-A correlated positively with WC (p < 0.05), and EPF-A negatively with FL (p < 0.05). Conclusion This study quantitatively defined biomechanical profiles of unilateral and bilateral LPM and clarified inter-parameter correlations and their associations with individual characteristic parameters. Findings support tailoring manipulation strategies based on lumbar curvature, waist circumference, and femur length to optimize individualized, precision treatment for LDH. Trial registration The study protocol was registered at ClinicalTrials.gov (ClinicalTrials.gov Registration Number and Date: NCT06872918, Initial Release: 10/03/2025).