Development of 3D printed patient-specific skull implants based on 3d surface scans.

Sometimes cranioplasty is necessary to reconstruct skull bone defects after a neurosurgical operation. If an autologous bone is unavailable, alloplastic materials are used. The standard technical approach for the fabrication of cranial implants is based on 3D imaging by computed tomography using the defect and the contralateral site. A new approach uses 3D surface scans, which accurately replicate the curvature of the removed bone flap. For this purpose, the removed bone flap is scanned intraoperatively and digitized accordingly. When using a design procedure developed for this purpose creating a patient-specific implant for each bone flap shape in short time is possible. The designed skull implants have complex free-form surfaces analogous to the curvature of the skull, which is why additive manufacturing is the ideal manufacturing technology here. In this study, we will describe the intraoperative procedure for the acquisition of scanned data and its further processing up to the creation of the implant.

Development of a 3D-printed, patient-specific stereotactic system for bihemispheric deep brain stimulation.

The aim of the project was to develop a patient-specific stereotactic system that allows simultaneous and thus time-saving treatment of both cerebral hemispheres and that contains all spatial axes and can be used as a disposable product. Furthermore, the goal was to reduce the size and weight of the stereotactic system compared to conventional systems to keep the strain on the patient, who is awake during the operation, to a minimum. In addition, the currently mandatory computed tomography should be avoided in order not to expose the patient to harmful X-ray radiation as well as to eliminate errors in the fusion of CT and MRI data.3D printing best meets the requirements in terms of size and weight: on the one hand, the use of plastic has considerable potential for weight reduction. On the other hand, the free choice of the individual components offers the possibility to optimize the size and shape of the stereotactic system and to adapt it to the individual circumstances while maintaining the same precision. The all-in-one stereotactic system was produced by means of the Multi Jet Fusion process. As a result, the components are highly precise, stable in use, lightweight and sterilizable. The number of individual components and interfaces, which in their interaction are potential sources of error, was significantly reduced. In addition, on-site manufacturing leads to faster availability of the system.Within the project, a patient-specific stereotaxy system was developed, printed, and assembled, which enables the execution of deep brain stimulation via only three bone anchors located on the skull. Pre-developed MRI markers, which can be screwed directly onto the bone anchors via the sleeves, eliminate the need for a CT scan completely. The fusion of the data, which is no longer required, suggests an improvement in target accuracy.