FRONTO-ORBİTAL İLERLETME SEGMENTİNE NON-VASKÜLERİZE KEMİK GREFTİ OLARAK DİSTRAKSİYON OSTEOGENEZİ UYGULANAN KRANİOSİNOSTOZ HASTALARININ GEÇ DÖNEM KEMİK KALİTESİNİN MORFOLOJİK, RADYOGRAFİK VE DANSİTOMETRİK YÖNTEMLERLE DEĞERLENDİRİLMESİ

Abstract

Craniosynostosis can be defined as an early fusion of one or more cranial sutures, which results in abnormal cranial shape and restricted skull growth. In treatment, conventional fronto-orbital advancement has remained mainstream treatment technique; however, successful results have been shown using distraction osteogenesis in patients who require more than 10 mm advancement in the fronto-orbital region. As a general acceptance in the distraction osteogenesis concept, maintenance of the vascularization of the bony segments or the transport segment was considered essential for successful distraction. In classical fronto-orbital distraction techniques, it is applied as an en-bloc distraction of the frontal bone and supraorbital bar without separating from its dural connections. However, using these techniques, it is impossible to correct the supraorbital bar and reconstruct a new forehead. In our technique, the fronto-orbital complex is separated from the dural attachments, reshaped if necessary, and distracted until desired results are obtained. As a result, the benefits of both conventional fronto-orbital advancement and distraction osteogenesis are combined into one procedure. Detaching the bone from the underlying dura and distraction as a bone graft may raise concerns such as epidural dead space resulting in infection, resorption and demineralization of the frontal bone graft, and bony defects due to a decrease in the power of distraction. The purpose of this study is to present our long-term and quantitative results for the distraction of non-vascularized bone graft in the management of craniosynostosis. Medical information and computed tomography images of patients diagnosed with craniosynostosis and operated on with fronto-orbital reshaping and distraction technique were examined in our clinic. Bone density measurements were performed on late-term computed tomography images to evaluate whether bone resorption occurred in the frontal bone that was reshaped and distracted as a non-vascularized bone graft. Measurements were made separately from the cortex and medulla at five different points, and the average of the values was used. The occipital bone was chosen as a site of control measurements because no surgical attempts were made at the posterior calvaria. Frontal bone and control measurements were compared statistically. The total bone defect area and the total number of defects were calculated by performing three dimensional modeling on the latest computed tomography images of the patients. The cephalic index was calculated from computed tomography images, and measurements at each time point were compared to normative cephalic index ranges depending on their age and categorized as normal or above normal. None of the patients developed serious infections, such as intracranial infections or frontal bone osteomyelitis. No significant difference was found between the frontal bone density and native bone density in both cortex and medulla. The mean number of bone defects was 4,8 ± 2,2, and the mean total area of bone defects was measured 4,79 ± 4,43 cm2. There were no bony defects in the frontal bone, and all the defects were located in the distraction zone. In patients who underwent secondary surgery due to cerebrospinal fluid leakage, higher values of mean bone defect area were observed. The mean preoperative cephalic index was found to be 98.56 ± 6.39, and the mean late-term cephalic index was calculated as 87.63 ± 4.54. Pre-operatively, all 27 (100%) patients were outside the normal range; however, 16 (59.3%) patients reached the normal range in the late period. Serious complications such as bone resorption and necrosis are not seen in the reshaped and advanced frontal bone. Moreover the small amount of bone defect area and the low rate of intracranial infection indicate that distraction of transport segment as a non-vascularized bone graft is a safe technique. In addition, the changes in the cephalic index show that significant improvements in head shape can be achieved with this technique. As a result, fronto-orbital reshaping and distraction appear to be safe and effective approach in the management of severe craniosynostosis, especially in patients with abnormally shaped frontal bones.