Kinematic quantification of lever positioning manipulation under different working conditions and analysis of related individual factors: an observational cross-sectional study

Lever positioning manipulation (LPM) is an innovative traditional Chinese medicine (TCM) spine manipulation developed from the conventional lumbar extension manipulation, and its clinical efficacy has been validated. Currently, patients exhibit significant individualized characteristics, and the effectiveness of the manipulation is closely related to the direction, angle, duration, and individual factors during its application. Therefore, it is imperative to conduct quantitative research on the operational parameters of LPM under different working conditions and analyze relevant individual factors to meet personalized patient needs. Objective: To quantify the kinematic parameters of LPM, explore correlations among various kinematic parameters, and investigate the influence of individual characteristics on the kinematic parameters of the manipulation. Methods: Kinematic data were captured from 107 volunteers using an optical motion system during bilateral and unilateral LPM. Parameters included retroflexion preload angle (RPA), adduction preload angle (APA), retroflexion force-applied instant angle (RFIA), adduction force-applied instant angle (AFIA), rotation instant loading angle (RILA), instant adjustment time (IAT), maximum velocity (Vmax), and maximum acceleration (Amax). Individual characteristics including age, sex, height, weight, waist circumference (WC), lumbar curvature (LC), lumbar lordosis angle (LLA), lumbosacral angle (LA), and femur length (FL) were also measured. Correlation analyses were conducted between kinematic parameters and subject characteristics. Results: In the unilateral LPM group of healthy volunteers, no significant differences were observed between the left and right sides of the operator’s manipulations (p > 0.05). The RILA-U differed between healthy volunteers and LDH patients (p < 0.05), while other parameters showed no significant differences (p > 0.05). No differences were found in RPA between the two LPM modes (p > 0.05). However, significant differences were observed in RFIA, IAT, Vmax, and Amax between the two modes (p < 0.05). In unilateral LPM, the mean values of RPA-U, APA-U, RFIA-U, AFIA-U, RILA-U, IAT-U, Vmax-U, and Amax-U were 32.915°, 7.53°, 8.415°, 6.245°, 22.02°, 0.385 s, 0.53 m/s, and 1.03 m/s 2 , respectively. In bilateral LPM, the mean values of RPA-B, RFIA-B, IAT-B, Vmax-B, and Amax-B were 34.27°, 7.125°, 0.53 s, 0.215 m/s, and 0.55 m/s 2 , respectively. Correlation analysis of LPM kinematic parameters revealed that in unilateral LPM, RPA-U was positively correlated with APA-U and AFIA-U (p < 0.05), while APA-U was negatively correlated with RFIA-U (p < 0.05). RoPA-U showed negative correlations with RFIA-U, Vmax-U, and Amax-U, particularly with Vmax-U and Amax-U. RFIA-U was positively correlated with AFIA-U (p < 0.05). Amax-U exhibited significant positive correlations with RILA-U and Vmax-U (p < 0.01). In bilateral LPM, IAT-B was positively correlated with Vmax-B and Amax-B (p < 0.01), and Vmax-B was significantly correlated with Amax-B (p < 0.01). Analysis of correlations between LPM kinematic parameters and individual characteristics indicated that both manipulation modes were closely related to WC, with multiple unilateral LPM parameters showing significant correlations (p < 0.01), including RoPA-U, Vmax-U, and Amax-U. In unilateral LPM, RoPA-U was negatively correlated with FL (p < 0.05), while RILA-U was negatively correlated with LC (p < 0.05). Vmax-U was positively correlated with LA and WC (p < 0.01), and Amax-U was positively correlated with WC. In bilateral LPM, IAT-B was positively correlated with FL and WC (p < 0.05). No significant correlations were observed among other parameters. Conclusion: This study quantitatively analyzed the kinematic characteristics of two LPM working modes using an optical motion capture system. The results indicated that LPM operators demonstrated good consistency in bilateral manipulation. Unilateral LPM showed superior instantaneous kinematic properties and operational efficiency compared to bilateral LPM. Both modes facilitated coordinated lumbar-pelvic-hip regulation with complex parameter interactions. Key kinematic parameters correlated with WC and FL in both modes, while unilateral LPM was further associated with LA and LC. These findings reveal intricate parameter–phenotype couplings and provide empirical support for personalized LPM optimization, underscoring the need for patient-specific manipulation strategies.