Optimal Dosage and Distribution of Bone Cement in Vertebroplasty

STUDY DESIGN: This is a finite element biomechanical analysis. OBJECTIVE: To evaluate the optimal injection dose and distribution of bone cement in vertebroplasty using the finite element method. SUMMARY OF BACKGROUND DATA: In the treatment of osteoporotic lumbar compression fractures, PVP (percutaneous vertebroplasty) is widely used. Although this surgical method can effectively relieve pain and improve the quality of life of patients in many cases, there are still some patients who have unsatisfactory results. This may be related to factors such as the distribution of bone cement. MATERIALS AND METHODS: CT data of 1 patient with an L1 fracture were extracted to construct the thoracolumbar (T12-L2) fracture model. The 4, 6, and 8 mL bone cement filling models were constructed, and the 4 and 6 mL models were further divided into lump and discrete types to form 5 different bone cement filling models. All models fully restrained the L2 vertebral base, while 500 N axial loads were applied to the T12 endplate to simulate body weight, and 10 Nm torque was applied to simulate the 4 spinal movements of left bend, right rotation, flexion, and extension. The stress values of 5 models under different motion conditions were analyzed and compared with those without bone cement. RESULTS: Five finite element models of osteoporotic vertebral compression fractures with different amounts and distributions of bone cement were successfully established. It was found that the Von Mises stress in all parts of the 8 mL lump bone cement model group was the minimum value in the upright + left bending state. In addition, at the same volume of bone cement, there was no significant difference in stress levels between the lump and discrete bone cement models. CONCLUSIONS: A 4 mL of bone cement in percutaneous vertebroplasty does not improve the biomechanical microenvironment of the spine during lumbar arthroplasty. We need to inject as much bone cement as possible, and if there are signs of leakage, the injection should be stopped immediately.