Calcium Phosphate Cement Cranioplasty: Clinical and Radiographic Follow-up

Abstract

The use of hydroxyapatite cements to replace bone deficits has entered widespread practice in craniofacial surgery. Although these substances have been shown to be at least partially replaced by bone in some experimental models, their long-term outcome in human cranial replacement or augmentation is not known. This study evaluated eight patients who had undergone cranioplasty using a hydroxyapatite cement. The cement was used in both inlay and onlay fashion. The mean follow-up interval was nineteen months and ranged from eight months to twenty-seven months. All patients underwent repeat CT scanning at the time of latest follow-up. Only one significant complication was noted, consisting of a postoperative persistent seroma that was resistant to repeat needle aspiration and required open drainage and removal of the material. CT scans revealed variable resorption of the cement in three cases. In the two cases in which the material was used primarily as an inlay, significant fragmentation of the material was seen. The appearance of the junction of the cement and the native bone was variable. While in some cases this interface could not be distinguished, in other areas it was seen as a distinct lucency. Although clinically minor asymmetries were noted in the appearance of the cranial vault and forehead, no patient was felt to be in need of revisional surgery. Even in areas of fragmentation, the reconstructions felt solid without evidence of mobility. No patient developed an infection or extruded the material. This study, though not providing histologic evidence, does seem to indicate that bone cements are well tolerated but are not always successfully firmly incorporated into the host bone.