Design and basic research on accuracy of a novel individualized three-dimensional printed navigation template in atlantoaxial pedicle screw placement

Operative Effect Comparison of Flexible Drill Guiding vs. Traditional Drill Guiding Template for Lower Cervical Pedicle Screw Insertion: A Retrospective Analysis

OBJECTIVE

Accurately inserting pedicle screws is the key point of posterior pedicle screw fixation for lower cervical spine (C3-C7) instability. 3D printing technology can improve the accuracy of screw placement. This study compared the safety of 3D-printed flexible drill guiding template vs. traditional rigid drill guiding template for lower cervical pedicle screw insertion.

METHODS

This was a retrospective study. A total of 34 patients who underwent lower cervical pedicle screw fixation from March 2018 to May 2021 were enrolled in this study, and they were divided into the flexible drill flexible drill group and the traditional drill group. A total of 18 patients in the flexible drill flexible drill group underwent pedicle screw fixation assisted by 3D printed flexible drill guiding templates for the lower cervix, and 16 patients in the traditional drill group underwent pedicle screw fixation assisted by 3D printed regular drill guiding templates for the lower cervix. The length of the incision and intraoperative blood loss during surgery were recorded and compared for the two groups. The grade, deviation of the screw entry point, deviation of the screw medial angle and screw length were measured and compared after surgery for the two groups by independent-sample tests.

RESULTS

There was a significant difference in the length of the incision and blood loss between the two groups (P < 0.05). There was a significant difference between the two groups for grade (P = 0.016). The deviation of the screw entry point was 0.65 ± 0.50 mm in the flexible drill group and 0.78 ± 0.83 mm in the traditional drill group. The deviation of the screw medial angle was 2.14 ± 1.78 in the flexible drill group and 4.23 ± 2.51 in the traditional drill group, with a significant difference between the two groups (P < 0.05).

CONCLUSION

Compared with regular guiding techniques, lower cervical pedicle screw placement assisted by multistep navigation templates and flexible K-wires results in less trauma and better safety.

Clinical applications and prospects of 3D printing guide templates in orthopaedics

Background

With increasing requirements for medical effects, and huge differences among individuals, traditional surgical instruments are difficult to meet the patients' growing medical demands. 3D printing is increasingly mature, which connects to medical services critically as well. The patient specific surgical guide plate provides the condition for precision medicine in orthopaedics.

Methods

In this paper, a systematic review of the orthopedic guide template is presented, where the history of 3D-printing-guided technology, the process of guides, and basic clinical applications of orthopedic guide templates are described. Finally, the limitations of the template and possible future directions are discussed.

Results

The technology of 3D printing surgical templates is increasingly mature, standard, and intelligent. With the help of guide templates, the surgeon can easily determine the direction and depth of the screw path, and choose the angle and range of osteotomy, increasing the precision, safety, and reliability of the procedure in various types of surgeries. It simplifies the difficult surgical steps and accelerates the growth of young and mid-career physicians. But some problems such as cost, materials, and equipment limit its development.

Conclusions

In different fields of orthopedics, the use of guide templates can significantly improve surgical accuracy, shorten the surgical time, and reduce intraoperative bleeding and radiation. With the development of 3D printing, the guide template will be standardized and simplified from design to production and use. 3D printing guides will be further sublimated in the application of orthopedics and better serve the patients.

The translational potential of this paper

Precision, intelligence, and individuation are the future development direction of orthopedics. It is more and more popular as the price of printers falls and materials are developed. In addition, the technology of meta-universe, digital twin, and artificial intelligence have made revolutionary effects on template guides. We aim to summarize recent developments and applications of 3D printing guide templates for engineers and surgeons to develop more accurate and efficient templates.

The feasibility of creating Image-Based Patient-Specific Drill Guides for the Atlantoaxial Instabilities using open-source CAD software and desktop 3D printers

OBJECTIVE

C1/2 cervical pedicle screw fixation is a well-known procedure for treating severely damaged and unstable C1/2 fractures. On the other hand, C1/C2 screw fixation is not safe and can lead to potentially disastrous consequences. The importance of personalized 3D printed navigational guides in avoiding these consequences cannot be overstated.

MATERIALS AND METHODS

We retrospectively reviewed the neuroimaging data of 16 patients who had undergone fixation for treatment of C1/2 diseases. We created patient-specific C1/2 models and drill guide models using open-source 3D editing software and a desktop 3D printer. The drill guides were then placed over the respective vertebrae models and fixated with 3.5 mm screws. Following fixation, the parts were scanned with a thin-slice (01 mm) CT scan, and the screw trajectories in the transverse and sagittal planes were measured at each level.

RESULTS

Of the total of 62 screws, 58 were type I (93.54%), 4 were type II (6.45%), and no screws were type III (Tab 2). The results showed that there was no significant deviation in the screw trajectories and the accuracy of the drill guides was 93.54% (Table 3). In our study, type I and type II screws were deemed acceptable, and the acceptable rates of C1/2 screw fixation were 100%.

CONCLUSIONS

In this preclinical study, we demonstrated that it is possible to create patient-specific pedicle drill guides using open source editing software and a commercially available desktop PLA printer, resulting in high accuracy rates in pedicle screw placement in C1/2 patient models.

Spiral CT measurement for atlantoaxial pedicle screw trajectory and its clinical application

OBJECTIVE

This study aimed to focus on the atlantoaxial pedicle screw placement and evaluate the effects of anatomical data and degree of surgical exposure of the atlantoaxial pedicle screw trajectory determined using spiral CT on the reference sites for pedicle screw insertion and various parameters in clinical application.

METHOD

The data of CT scan of cervical spine from individuals treated in our hospital were selected. Various anatomical parameters of the atlantoaxial pedicle screw trajectory were measured through multiplanar reconstruction (MPR) technology. Anatomical data and degree of surgical exposure of the atlantoaxial pedicle screw trajectory were obtained through spiral CT. Vernier calipers with least count of 0.01 mm was selected and the least count of the protractor was 0.2°. Prism 8.0 was adopted for graphical data analysis. The anatomical data of atlas of the local population were established. The measurement technique for pedicle screw trajectory and the method for pedicle screw insertion were mastered.

RESULTS

The results indicated that the intraoperative blood loss was between 30-280 ml with no case of excessive blood loss. Follow-up studies 10-18 months after the operations indicated stability of upper cervical spine without adverse conditions. The width of the pedicle screw was 13-24 mm, and the maximal inclination angle of the horizontal for the insertion was 17-21°.

CONCLUSION

The atlantoaxial pedicle screw placement was an effective surgical treatment for stabilizing the upper cervical spine. The measurement data of the atlantoaxial pedicle screw path was obtained through spiral CT and the surgical placement of pedicle screw was guided through individual data. Postoperative CT scan was adopted to evaluate the accuracy of pedicle screw placement, record the occurrence of secondary injuries, improve the stability of clinical applications, and reduce the risks for patients.

Surgical treatment for upper cervical deformity with atlantoaxial joint dislocation using individualized 3D printing occipitocervical fusion instrument: A case report and literature review

To introduce a novel technique of using individualized 3D printing occipitocervical fusion instrument (3D-OCF) for the treatment of upper cervical deformity with atlantoaxial joint dislocation.The surgery for deformity of the craniocervical junction area is a challenge in the field of spine. If the surgical deviation is too large to injure the spinal cord or vertebral artery, it will cause catastrophic damage to the patient. Therefore, it is controversial whether these patients should undergo surgical treatment. We provide a novel surgical approach for the challenging upper cervical surgery through 3D-OCF and a typical patient.We present a 54-year-old female patient, who suffered from dizziness and numbness in her limbs for 8 months. After the patient was admitted, we performed the three-dimensional CT scan, modeled using Mimics software 17.0, and designed customized occipitocervical fusion instrument. Besides, we repeatedly perform simulated surgery based on 3D-printed models before surgery.The operative time was 142 minutes and the intraoperative blood loss was 700 mL. X-ray showed reduction of atlantoaxial dislocation and accurate position of internal fixation. The patient's symptoms were significantly relieved: the sensation of dizziness and numbness of limbs was obviously relieved, and the sense of banding in chest, abdomen, and ankle was disappeared. At the last follow-up, imaging showed that 3D-OCF had bone-integration and Syringomyelia was disappeared. The patient's cervical JOA (Japanese Orthopaedic Association) score increased from 10 points to 17 points.Individualized 3D-OCF can improve the safety and accuracy of upper cervical surgery, reduce the operative time and the number of fluoroscopy. Our study provides a novel surgical approach for the challenging upper cervical surgery.

The Accuracy of 3D Printing Assistance in the Spinal Deformity Surgery

BACKGROUND

The pedicle screw is one of the main tools used in spinal deformity correction surgery. Robotic and navigated surgeries are usually used, and they provide superior accuracy in pedicle screw placement than free-hand and fluoroscopy-guided techniques. However, their high cost and space limitation are problematic. We provide a new solution using 3D printing technology to facilitate spinal deformity surgery.

METHODS

A workflow was developed to assist spinal deformity surgery using 3D printing technology. The trajectory and profile of pedicle screws were determined on the image system by the surgical team. The engineering team designed drill templates based on the bony surface anatomy and the trajectory of pedicle screws. Their effectiveness and safety were evaluated during a preoperative simulation surgery. The surgery consisted in making a pilot hole through the drill template on a computed tomography- (CT-) based, full-scale 3D spine model for every planned segment. Somatosensory evoke potential (SSEP) and motor evoke potential (MEP) were used for intraoperative neurophysiological monitoring. Postoperative CT was obtained 6 months after the correction surgery to confirm the screw accuracy.

RESULTS

From July 2015 to November 2016, we performed 10 spinal deformity surgeries with 3D printing technology assistance. In total, 173 pedicle screws were implanted using drill templates. No notable change in SSEP and MEP or neurologic deficit was noted. Based on postoperative CT scans, the acceptable rate was 97.1% (168/173). We recorded twelve pedicle screws with medial breach, six with lateral breach, and five with inferior breach. Medial breach (12/23) was the main type of penetration. Lateral breach occurred mostly in the concave side (5/6). Most penetrations occurred above the T8 level (69.6%, 16/23).

CONCLUSION

3D printing technology provides an effective alternative for spinal deformity surgery when expensive medical equipment, such as intraoperative navigation and robotic systems, is unavailable.