Uncertainty-Informed Structural Evaluation of a Halo-Gravity Traction Mobility System

Halo-gravity traction (HGT) is widely used as a preoperative treatment for severe pediatric spinal deformities by gradually applying traction forces through a cranial fixation system. While the clinical effectiveness of HGT has been extensively documented, the uncertainty associated with the structural performance and operational reliability of mobile HGT systems has received comparatively little attention. This study presents a coupled clinical–structural uncertainty quantification framework for the evaluation of a mobile halo-gravity traction wheelchair. Reduced-order structural and clinical response models are combined with Monte Carlo simulation, Latin Hypercube Sampling, bounded beta-distributed input variables, Polynomial Chaos Expansion, and Sobol sensitivity analysis to propagate uncertainty from patient, operational, and design parameters to structural response metrics. The framework evaluates structural integrity, stability, halo-pin loading, traction delivery, factors of safety, and representative clinical response measures. The probabilistic analysis demonstrates that the proposed design maintains substantial structural safety margins throughout the investigated uncertainty space, with no sampled realization producing a governing factor of safety below unity. The proposed framework provides an efficient methodology for uncertainty-informed design and evaluation of pediatric halo-gravity traction systems.