Effect of cement volume and placement on mechanical-property restoration resulting from vertebroplasty.

BACKGROUND AND PURPOSE Concern exists that vertebral bodies augmented with cement placed laterally may be at risk of collapse on the nonaugmented side. The purpose of the current study was to determine if placing the cement laterally rather than centrally resulted in risk of collapse on the nonaugmented side. METHODS Vertebral bodies (L2-L5) were harvested from eight osteoporotic female cadaver spines. Simulated vertebral-body compression fractures were created and stabilized by injecting 3.5 or 7.0 mL of cement centrally or laterally. Vertebral bodies were recrushed to measure their augmented strength and stiffness. Anterior, posterior, left, and right lateral heights were measured initially, after augmentation, and after recompression. RESULTS Lateral and central 3.5-mL injections of cement restored strength, whereas 7.0-mL injections significantly increased strength compared with initial values. The stiffness of vertebral bodies receiving central 3.5-mL injections was significantly less than it was initially, although the stiffness of bodies receiving 3.5-mL laterally was not significantly different from initial values. Initial and posttreatment stiffness values did not significantly differ in vertebral bodies receiving 7.0-mL, lateral or central injections. Vertebral heights did not significantly differ between the augmented and the final compression states in any location. Height loss between central and lateral injections did not differ significantly. CONCLUSION Vertebral bodies in which cement is placed laterally do not appear to be at risk for collapse on the unaugmented side.