[Additive technologies in neurosurgery]

[Features of modeling a polymer implant for closing a defect after decompressive craniotomy]

BACKGROUND

Individual polymer implants are widespread for bone reconstruction after decompressive craniectomy. Despite the availability of customized titanium products, various specialists and hospitals prefer polymer implants.

OBJECTIVE

To compare the methods of modeling and manufacturing the polymethylmethacrylate implants and identify the features affecting the quality of reconstruction.

MATERIAL AND METHODS

We analyzed 14 patients with extensive skull defects after installation of polymethyl methacrylate implants. Software used for modeling of individual implants by different specialists was compared.

RESULTS

Satisfactory reconstruction result was obtained in all cases. There were no infectious complications. The authors outlined certain important aspects for modeling of individual polymer products: local use of anatomical thickness of the implant, leaving safe spaces, prevention of temporal retraction, template-based resection before reconstruction.

CONCLUSION

To date, skull defect closure with polymeric materials remains relevant, and even has certain advantages over customized titanium products.

[Skull defect repair in children using a 3D-printing technology]

Currently, 3D-printing technologies are increasingly used in neurosurgery. Active development of this approach is valuable to improve preoperative planning, intraoperative navigation, and manufacturing of realistic training models. In this manuscript, the authors report an experience of the pediatric neurosurgical department of the Almazov National Medical Research Center regarding 3D-printing technologies in manufacturing of individual implants for skull defect closure. The main aspects of this technology, advantages and disadvantages are considered. Moreover, the authors describe several cases of creating individual implants for children with skull defects of various origins, dimensions and complexity.

[Assessment of the safety and accuracy of implantation of screws into the C2 vertebra using individual 3D-navigation matrices]

Introduction

Individual 3D-navigation matrices are valuable to increase the safety of screw implantation into the axis.

Objective

To analyze safety and accuracy of screw deployment into the axis using individual 3D-navigation matrices compared to free hand technique.

Material and methods

A retrospective analysis included 23 patients (group 1) who underwent implantation of 44 screws into the axis using the «free hand» technique. The screws were installed along the transpedicular or pars trajectory. A prospective analysis enrolled 17 patients (group 2) who underwent installation of 34 screws using individual navigation matrices. 3D-printing technology was applied for manufacturing these matrices. Implantation results were evaluated considering postoperative CT data and SGT (Screw Guide Template) system.

Results

In the 1st group («free hand»), grade 0 and 1 (no malposition or less than 50% of screw diameter) were recorded for 29 (65.91%) screws, grade 2 - for 13 (29.55%) screws, grade 3 - for 2 (4.45%) screws. Intraoperative injury of the vertebral artery without postoperative neurological deficit occurred in 4 (8.89%) patients. In the 2nd group, 97% of screws were implanted in accordance with grades 1 and 2. Deviation grade 2 was registered in 11 cases (32.35%). Mean deviation was 1.8 ± 1.0 mm. In the 2nd group, 28 (82.35%) out of 34 screws were completely within the bone structures (grade 0), 4 (11.76%) screws perforated pedicles for less than 50% of their diameter (grade 1). There were 2 cases of malposition grade 2 and 3 without vertebral artery injury.

Conclusion

Individual 3D navigation matrix is an effective method for screw installation into the axis. This approach exceeds fluoroscopy-assisted "free hand" technique in terms of safety of implantation.

[Individual preoperative 3D modeling of vascular brain pathology]

The possibility of segmenting three-dimensional objects by DICOM-series is well known and available both on specialized workstations and on personal computers. The technique, however, is relatively rarely used in clinical practice, and we believe that the benefits of preoperative preparation using segmented 3D models are underestimated. The article is devoted to our experience in using segmentation of anatomical structures based on CT and MRI for preoperative preparation for surgical operations performed in neurosurgical departments on patients with vascular pathology. The paper discusses the types and possibilities of segmentation, provides some examples describing the clinical use of the technique.