Biomechanical changes following bone cement injection by unilateral approach needle withdrawal versus bilateral fixation point during vertebroplasty: Finite element analysis / 中国组织工程研究

ABSTRACT

BACKGROUND: The puncture approach and injection method of unilateral approach should be improved to obtain mechanical distribution of bilateral approach.Preliminary studies designed three-dimensional puncture guider and utilized withdrawal injection of bone cement,which improved clinical effect.However,the mechanical distribution of unilateral approach versus bilateral approach remains unclear.OBJECTIVE: To analyze biomechanical changes during vertebroplasty with unilateral approach and withdrawal injection using a finite element analysis and compare with bilateral approach.METHODS: The primary image was from a male patient,76 years old,with L1 osteoporosis and pain.The patient was subjected to operation in the injured vertebrae by unilateral approach,and the needle entrance point was at the left center of pedicle,with an oblique angle of 24.5°.The needle was inserted into the front one third of vertebrae body and 3 mL bone cement was injected.The needle was withdrawn to the middle of the vertebrae,maintained for 3 minutes,and 2 mL bone cement was injected.The needle was withdrawn to the posterior 1/3 of the vertebrae body,followed by injection of 1 mL bone cement.Bilateral approach was simulated,and each side was injected with 3 mL bone cement.L1-2 fault image was obtained and finite element model was established.Vertebral biomechanics was compared under loads of 500,1 000,1 500,2 000,and 2 500 N on the supine surface.RESULT AND CONCLUSION: The strain and stress were increased with increasing load.The vertebral bodies showed property of elasticity,and nearly linear minor deformity.There were no differences in stress distribution and deformity between bilateral fixation point and withdrawl injection of bone cement(P > 0.05).Results show that unilateral approach withdrawl injection of bone cement displayed similar biomechanics as bilateral fixation point during vertebroplasty.