Orbital Floor Implant and Drilling Guide – Case Study 4

CMF Case Study 4 - Orbital floor implant and drilling guide 1

Overview

In this case, the patient came to the hospital suffering from double vision which appeared after a traumatic shock while playing sports. A CT scan was performed and the surgeon confirmed that the orbital floor had dropped which made the right eye lower than the left one. The decision to create a patient specific implant to replace the defect was made.

Segmentation

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. Extra efforts were made to segment the sinus cavity and the contralateral orbital floor, in order to create some references for the design of the implant.

CMF Case Study 4 - Orbital floor implant and drilling guide 2
CMF Case Study 4 - Orbital floor implant and drilling guide 3

Virtual Simulation

The design requirements, such as thickness and size of the implant, were determined by the surgeon, Mr Komath. Surgical approach and clinical obstacles were taken into account for the design of the implant.

Using some mirroring tools and CAD software, 3D LifePrints’ biomedical engineer designed a patient-specific orbital floor implant which would sit on the defect to recreate a healthy orbital floor. The implant was designed with a 0.8mm thickness and the screws positioned on the orbital rim so that the implant could not be felt through the skin by the patient.

Design of Patient Specific Devices

To improve the accuracy of the implant positioning, the engineer designed a patient-specific drilling guide. This guide allows to pre-drill the position of the screws which will stabilise the implant

CMF Case Study 4 - Orbital floor implant and drilling guide 4
CMF Case Study 4 - Orbital floor implant and drilling guide 5

Outcome

The outcome of this surgery was excellent: there was no diplopia (double vision) and the eyelid was in great position. No post-operative scan was made as it was judged unnecessary due to patient’s excellent recovery.