Experiment Research Of The Occipitocervical Fusion

Background and objectivecraniocervical malformation(CCM) is a common neurosurgical disease. Diagnosis becomes easier as the medical knowledge accumulating and imaging techniques developing. The aim of the treatment of CCM is to perform decompression, recuperate or rebuild the stability of the craniocervical junction. Bone grafting for occipitocervical fusion is a common but important method. However, there are no affirmative conclusion yet known about the effect and influence of the fusion state. Animal model was created by mimicing the clinic decompression. Two ways of fusion was used, one is by bone block ,the other debris. The influencing factors were considered. The fusion states and time courses were observed. The aim is to provide evidence for how to choose the fusion stuffs and cautions of the operation.Methods20 rabbits were equally divided into two groups in random. First, the decompression models was established. In group A, a skull block was cut off and fixed from posterior occiput to C2 spinous. The debris was paved in the upper of the block. In group B, the occipitocervial area was just covered by debris(D=1-2mm). The bone blocks and debris were observed by orthophoric and lateral position X-ray photos in different weeks after operation and repeated operation. ResultsThe density of the contract surface increased gradually.Group A: one rabbit died suddenly in the sixth week. The grafting bone was absorbed except some fusion remnant on the C2 spinous; one case obtained bone exodus because of infection; orthophoric and lateral position radioactive photos were taken in the other 8 cases during the different time after operation. The density of the contract surface increased gradually. The mean time that the superior extremity got bone healing is about 16 weeks, however, the inferior extremity is about 10 weeks. Meanwhile, we found that the occipitocervical junction became rigid in those cases. In the repeated operation, although the edges of grafting bone had been absorbed some, the contract surface had got bone healing. The healing rate is 80%.Group B: one died two days later; the diet and spirit of two died in a week was bad; the bone drips were linked with soft tissue in 4 cases; only one obtained bone healing between 16 and 18 weeks, the healing rate is 10%.The healing rate of group A and group B have a significant difference in statistics. The mean times of superior extremity getting bone healing with inferior extremity also have a significant difference in statistics.Conclusions1. Autologous skull bone grafting can get good bone healing.2. The effect and time course of the bone healing have a significant relationship with the stability of planted bone.3. It is necessary to graft bone after the decompression because that the unstable factors exist.4. The bone block would be chosen as the stuff because that it is easier to get bone healing than debris.5. Decorticated the contract surface ,as well as paved the debris around the potential unstable position, is help to bone healing.