A biomechanical comparison of lateral and posterior approaches to sacroplasty

Study Design.: Biomechanical cadaveric bench study. Objective.: To measure the augmentation effect and extravasation risk of posterior and lateral approaches to sacroplasty. Summary of Background Data.: The biomechanical stabilizing effect of sacroplasty is unknown. Methods.: Using a sacral insufficiency fracture model, we performed sacroplasty in 15 osteoporotic cadaveric pelves. Five served as controls, and 10 were each injected with 4 mL of a polymethylmethacrylate cement (5 via a posterior approach, 5 via a lateral approach). Cement extravasation was assessed using computed tomography. Restored strength and stiffness were defined as the ratios of treatment to initial strength and to stiffness, respectively. Between-group differences in restoration parameters were checked for significance (P < 0.05) using an analysis of variance followed by Tukey's test. Results.: We found no significant differences between groups in terms of restored strength (∼61%) and stiffness (∼77%). Both injection methods produced extravasation into the anterior sacrum, the posterior sacrum, the sacroiliac joint, and the neural foramens. Conclusion.: Sacroplasty with 4 mL of cement does not restore the strength or stiffness of the sacrum in a cadaveric model, regardless of the approach used.