Twenty-four cases of massive periacetabular bone loss (Paprosky Type 3B) were reconstructed using custom triflanged acetabular components (CTAC). Fixation is obtained by the creation of a triflanged component that is anchored to the ilium, ishium, and pubis with multiple fixation screws. Acetabular defects are grafted with large amounts of cancellous allograft. Modular polyethylene liners are then locked into the CTAC. Twenty-one of 24 cases (87.5%) were considered clinically successful at short-term follow-up (average, 48 months; maximum, 78 months), with stable fixation and reconstruction of periacetabular bone. Three failures occurred from loss of fixation in patients with a preoperative dissociation of the hemipelvis and severe osteopenia. Presently, these devices should be used with caution in cases with a preoperative dissociation of the hemipelvis, unless additional column plating is performed.