Skull Reconstruction Using Parietal Flaps – Case Study 5
Following a fall, the patient had a huge defect involving the orbital roof.
Based on the high-resolution CT scan of the patient (0.5mm slice thickness), we reconstructed the anatomy in 3D. This first step is called segmentation and is performed by selecting the Hounsfield units (level of grey) corresponding to bone on the CT scan.
During this step, we simulated the surgery virtually using a software. A mirror of the anatomy is first created (in red) – this helps determine the ideal anatomy needed by mirroring the normal side. The osteotomy of the superior orbital rim (in orange) is simulated virtually and the mirror is used to reposition the superior orbital rim. The symmetry is then restored. The defect will be filled by the patient’s own bone which will be taken from the back of the skull. During the virtual simulation, the biomedical engineer finds the most suitable bone part to recreate the frontal skull.
Design Of Patient Specific Devices
Two patient specific guides were designed based on the virtual simulation. The two guides have a complimentary shape to facilitate their positioning. The anterior guide shows the bone to be removed so that the defect edges are clearly defined, whereas, the posterior guide indicates where to take the bone from. For this reconstruction, there are two parts: a small part to reconstruct the orbital roof (in pink) and a bigger part to reconstruct the frontal skull (in yellow). In order to maintain all the parts in the new position, some patient specific plates were designed. Their positioning is guided thanks to some pre-drilled holes that were made using a the guide.
By aligning the patient-specific plates to the previously drilled holes, the flaps are positioned as virtually planned.
No adaptation is needed.