Cranioplasty with autogenous autoclaved calvarial bone flap in the cases of tumoural invasion.

When a bone flap is raised in the course of a craniotomy, the ideal is to replace it at the end of the procedure. When it is invaded by tumoural cells, it cannot be replaced due to the risk of tumoural recurrence. In these cases we have autoclaved the bone flap to be able to replace it with no fear of tumoural recurrence. Between October 1989 and October 1995 sixty-two patients required autoclaving of the bone flap in the course of a craniotomy due to tumoural invasion (thirty-five meningiomas, sixteen bone tumours, five metastases, and eight scalp tumours). The infiltrated bone flaps were removed, cleaned, autoclaved for 20 minutes at 134 degrees C and 1 kg/cm2 and re-implanted. Patients were followed-up for 10 to 58 months (average 41 months). At every follow-up visit skull x-ray studies, clinical examination, and photographs were done. When needed a CT scan was performed to assess the thickness of the bone flap. On follow-up roentgenograms partial resorption was observed in twelve cases (19.3%). CT scan studies showed loss of thickness in another thirty-five cases (56.4%). Meanwhile the external aspect remained unchanged. In six cases (3.2%) biopsies of the bone flaps were taken at a second surgical procedure. They showed newly formed bone partly re-populated by osteocytes but retaining areas of sequestered bone. We conclude that autoclaved bone, if replaced with direct contact with living bone, it is gradually repopulated with osteocytes. Cranial vault autoclaved autologous bone flap is a good alternative when the original bone flap is invaded but not destroyed by tumoural cells.