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needle was inserted into the front one third of vertebrae body and 3 mL bone cement was injected.The needle was withdrawn to the middle of the vertebrae,maintained for 3 minutes,and 2 mL bone cement was injected.The needle was withdrawn to the posterior 1/3 of the vertebrae body,followed by injection of 1 mL bone cement.Bilateral approach was simulated,and each side was injected with 3 mL bone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.
ABSTRACT
The primary imagine is from a seventy-old man and his L_1 is osteoporosisand painful. The patient is given operation in the injured vertebrae by onelateral, the needing point is in the left central of lateral mass of vertebrae, introversion angle is 24.5°, using withdraw way. First puncture the needle to the front one third, and inject 3 mL bone cement in, and withdraw the needle to the middle of the vertebrae, staying 3 minutes, and then inject 2 mL bone cement, and then withdraw the needle to the hind 1/3 of the body, injecting 1 mL in it. Contrasting with the way inject the all 6 mL bone cement one time in the front 1/3, which is the tradition way (simulate) and get L_(1-2) fault image, getting a validated finite element mordel, exerting the load of 500, 1 000, 1 500, 2 000, 2 500 N on the supine surface of the vertebra respectively and evaluate the stress distribution of the vertebro bodies. With the increasing load, the deformity and the strain increase with it. The vertebral bodies show the property of elasticcity, nearly linear minor deformity is. The way using withdrawal way injecting bone cement has more stress distribution and deformity than the way by tradition. The way using withdrawal way injecting bone cement has better stress distribution than the way by tradition.