Influence of Loading Modalities on Remodeling-Based Bone Formation in Severe OVCF Patients

Osteoporotic vertebral compression fracture (OVCF) is a common degenerative disease in the elderly. Biomechanical stimulation plays a key role in regulating bone remodeling and healing. In this study, a solid-liquid two-phase poroelastic finite element model was used to simulate bone remodeling in severely osteoporotic vertebrae under five functional loading modes: standing, flexion, extension, lateral bending, and axial rotation. Changes in tissue differentiation, mean elastic modulus, and interstitial fluid velocity in cortical and cancellous bone were quantitatively analyzed over the 77-day healing period. The results showed that standing and axial rotation significantly increased the elastic modulus of cortical bone and promoted osteogenic maturation, whereas flexion exhibited the weakest osteogenic effect. Cancellous bone regeneration was driven mainly by mesenchymal stem cell diffusion and was less affected by loading patterns. Biophysical stimuli (deviatoric strain and fluid flow) gradually decreased with tissue maturation, and the tissue differentiation follows a typical sequence: fibrous tissue, cartilage, immature bone, mature bone. This study reveals the biomechanical mechanism of bone remodeling under different rehabilitation loads and provides in silico theoretical reference for exploring personalized rehabilitation strategies, and cannot be directly applied as clinical treatment guideline.