Johnson LG, Wilson DR, Mulpuri K. International Journal of Computer Assisted Radiology and Surgery. 2026;21(4):735–745. DOI: 10.1007/s11548-025-03553-4
Abstract
Background:
Little is known about how hip joint stress changes in Legg–Calvé–Perthes disease (LCPD), which makes treatment planning harder. The study built and tested a patient-specific biomechanical “digital twin” to predict shear stress in the cartilage and labrum.
Methods:
The team modelled both hips of one patient with unilateral LCPD from MRI, using the ArtiSynth platform. They tested how sensitive the model was to material properties and joint angles across a gait cycle. They then checked its stress and femoral-position predictions against upright open MRI in high-flexion postures.
Results:
Peak shear stress during gait was 22–93% higher in the LCPD hip than in the unaffected hip. Peak stress occurred at different points in the gait cycle for each hip, so a static snapshot can miss it. Stress was more sensitive to cartilage stiffness than to joint-angle error. The model matched the impingement areas and femoral position seen on upright MRI.
Conclusions:
Both motion and joint shape drive stress in very aspherical hips. Digital twins look promising for studying long-term LCPD outcomes and may eventually support planning. The study had one patient, used literature gait data, and couldn’t be validated against measured stress.
