Kinematic quantification of LPM under unilateral and bilateral working modes

Recently, the research paper by Professor Lü Lijiang's team from the Department of Tuina, The Third Affiliated Hospital of Zhejiang Chinese Medical University, titled "Kinematic quantification of lever positioning manipulation under different working conditions and analysis of related individual factors: an observational cross-sectional study," was published as an original research article in the international surgery journal International Journal of Surgery. Based on a  high-precision optical motion capture system , this study systematically quantified the kinematic characteristics of lever positioning manipulation (LPM) under unilateral and bilateral working modes, and revealed the significant influence of individual morphological parameters on manipulation kinematic parameters, providing a scientific basis for individualized Tuina treatment of lumbar disc herniation.

I. Protocol

The study was based on the Chingmu MC1300 optical motion capture system (8 cameras, 210 FPS, sub-millimeter accuracy of ±0.10 mm), and conducted high-precision acquisition and analysis of kinematic parameters from 107 volunteers (57 LDH patients + 50 healthy controls) during unilateral (LPM-U) and bilateral (LPM-B) lever positioning manipulation. Measured parameters included retroflexion preload angle (RPA), adduction preload angle (APA), rotation preload angle (RoPA), force-applied instant angles (RFIA, AFIA, RILA), instant adjustment time (IAT), maximum velocity (Vmax), and maximum acceleration (Amax). In addition, individual characteristics such as lumbar curvature (LC), lumbosacral angle (LA), femur length (FL), and waist circumference (WC) were collected through CT imaging and surface anthropometric measurements for correlation analysis.

Key Innovations and Advantages

1. Precise quantification of LPM kinematics under both modes: The study revealed that the unilateral mode exhibits a "dual-peak single-trough" instantaneous dynamic curve, while the bilateral mode presents a "broad single-peak" pattern, clarifying the mechanical differences and clinical applicability of the two operational modes.

2. Superior instantaneous kinematic performance of unilateral LPM: Compared with bilateral LPM, unilateral LPM demonstrated shorter IAT and higher Vmax and Amax (P < 0.05), providing a biomechanically optimized strategy for paracentral disc herniation.

3. Significant correlations between individual morphological parameters and manipulation kinematics: Waist circumference (WC) was negatively correlated with RoPA-U and positively correlated with Vmax-U/Amax-U (P < 0.01); femur length (FL) was negatively correlated with RoPA-U and positively correlated with IAT-B; lumbar curvature (LC) was negatively correlated with RILA-U, while lumbosacral angle (LA) was positively correlated with Vmax-U. These findings provide an objective quantitative basis for "tailoring manipulation to the individual."

II.Validation

The experiment was conducted in an area of approximately 6 m × 8 m. The experimental setup consisted of the Chingmu MC1300 optical motion capture system, reflective markers, and customized data acquisition and analysis software (CMprocess + Visual 3D). A total of 107 volunteers wore motion capture suits and, after reflective markers were attached to key anatomical landmarks including the iliac crest, greater trochanter of the femur, and medial and lateral femoral condyles, received LPM manipulation performed by a physician with 33 years of clinical experience. Leveraging CHINGMU's sub-millimeter positioning and 210 FPS high-frame-rate capture, the system recorded in real time the three-dimensional motion trajectories, angle changes, velocity, and acceleration curves of the lower limbs and pelvis throughout the entire manipulation process, providing precise data references for algorithm validation and ensuring the authenticity and validity of the experiment.

Figure 1: Schematic diagram of the LPM data acquisition process.

Figure 2: Loading curves of unilateral and bilateral LPM modes.

Figure 3: Comparative results of LPM kinematic parameters between healthy volunteers and LDH patients.

Figure 4: Correlations among LPM kinematic parameters.

Figure 5: Comparative results of LPM kinematic parameters between healthy volunteers and LDH patients.

III. Result

This study achieved in vivo kinematic quantification of LPM, clarified the fundamental mechanical differences between unilateral and bilateral modes, and established correlations between individual morphological parameters and manipulation kinematic parameters. These findings not only provide a scientific basis for individualized treatment based on LDH subtype, but also establish an objective gold standard for standardized teaching and skill assessment of Tuina manipulation. In the future, the team will further expand the age range of samples, introduce multi-operator comparisons, and conduct correlation analyses with clinical outcomes, advancing TCM Tuina from experience-based medicine toward data-driven precision medicine.

References:

[1] Zhang AS, Xu A, Ansari K, et al. Lumbar disc herniation: diagnosis and management. Am J Med 2023;136:645–51.

[2] Wu X, Ma Y, Ding R, Xiao X, Yang D. Should adjacent asymptomatic lumbar disc herniation be simultaneously rectified? A retrospective cohort study of 371 cases that received an open fusion or endoscopic discectomy only on symptomatic segments. Spine J 2021;21:411–17.

[3] Dunsmuir RA, Nisar S, Cruickshank JA, Loughenbury PR. No correlation identified between the proportional size of a prolapsed intravertebral disc with disability or leg pain. Bone Joint J 2022;104-B(6):715–20.

...