The evaluation of the bone graft survival status in titanium cervical cages by radionuclide bone CT scan

To find a better way to evaluate the bone graft survival status in cervical cages, forty-one patients suffering from one-level cervical spondylosis were enrolled in this study. All underwent anterior cervical decompression and fusion with titanium cage and plate. When followed up, another 21 patients were confirmed as one-level cervical spondylosis without operation and were enrolled as control group. "Bolus" injection of radioactive 99(m)Tc methylene diphosphonate (99(m)Tc-MDP) with a dose of 25 similar to 30 mCi was performed through cubital vein, and radionuclide distribution images of cervical spine were obtained by single photon emission computed tomography/computed tomography (SPECT/CT). In sagittal view, bone graft was positioned accurately. By "region of interest" (ROI) technique, the same regions in bone graft and thoracic vertebra with the same level of suprasternal fossa were selected. Radioactive count ratio was then obtained. In the control group, "bone graft" was chosen on the inferior vertebra of the lesion segment, and the ratio was similarly gotten. Statistical difference was shown between bone graft group and control group by t test (t = 2.713, P < 0.05). The bone graft survival rate was 100% by SPECT/CT and bony fusion rate was 92.7% by CT scan. It indicated that in all bony fusion cases, bone graft survived; however, the bone survival was not surely together with bony fusion.