A, C-ring and compression device. B, Pedicle screw and C-ring in a Sawbones model. (From Vaidya R, Colen R, Vigdorchik J, et al: Treatment of unstable pelvic ring injuries with an internal anterior fixator and posterior fixation: initial clinical series, J Orthop Trauma 26:1, 2012.) SEE TECHNIQUE 56.6.