Midface hypoplasia in a 5-year-old boy with Crouzon syndrome was treated using a rigid external distraction device. Seven months prior to this surgery, a bone allograft was used during frontal-orbital bar advancement. Three weeks after the Le Fort III distraction a depression fracture was diagnosed, associated with an intracerebral screw penetration of 3.5 cm. This case report cautions against the use of distraction osteogenesis in patients when previous allografts were used for calvarial reconstruction. We suggest that a preoperative computed tomography scan is mandatory to accurately delineate the location for placement of the pins.