[Bone Flap Resorption after Cranioplasty in Pediatric Patients:Report of 2 Cases]

Aseptic bone flap resorption, a rare complication after cranioplasty following decompressive craniectomy, is more likely to develop in children. We experienced two cases of aseptic bone flap resorption and identified potential pathophysiological mechanisms through histological findings. In the first case, an 11-year-old girl underwent decompressive craniectomy due to brain swelling with contusion. An autologous bone flap was cryopreserved for four months. Twenty-five months after cranioplasty with autologous bone flap, aseptic bone flap resorption was observed, and cranioplasty was performed with ceramic bone. Most of the histological findings in this case showed mature osseous tissue, while some showed osteoclasts and new bone formation due to endochondral ossification. In the second case, a 10-year-old girl underwent frontal craniectomy and removal of contusional hematoma. Fourteen months after cranioplasty with autologous bone flap, aseptic bone flap resorption was observed, and cranioplasty was performed with ceramic bone paste. The progression of bone flap resorption was not recognized for 12 months. In these cases, new bone formation was not necessarily linked to pathological bone flap resorption. It is supposed that the balance between bone destruction and new bone formation was disrupted by unknown factors.