Three-Dimensional-Printed Model-Assisted Management of Craniovertebral Junction Abnormalities: An Institutional Experience with Literature Review

Abstract

Study design: Prospective study.

Purpose: To evaluate the utility and limitations of using three-dimensional (3D)-printed models for the management of craniovertebral (CV) junction abnormalities.

Overview of literature: In comparison to other bony and vascular anomalies, CV junction abnormalities are difficult to treat. For cases of irreducible atlantoaxial dislocation (AAD), posterior reduction and stabilization have replaced anterior decompression as the standard management protocol. The use of 3D models, such as those described herein, can provide surgeons with in-depth knowledge of the vertebral artery course and bony anomalies associated with CV junction abnormalities.

Methods: Clinical and radiological features of 18 patients with CV junction abnormalities were analyzed between March 2017 and February 2019 at Sawai Man Singh Medical College, Jaipur, India. Dynamic computed tomography (CT) of the CV junction and CT angiographies of the neck with respect to the vertebral artery course at the C1-C2 joints were obtained and studied. Customized 3D models of the CV junction were then made based on the CT data, and rehearsal of the surgical procedure was performed using the 3D model one day prior to performing the actual procedure.

Results: Seventeen patients had congenital-type AAD, whereas one patient had posttraumatic AAD. Improvements in neck pain and myelopathy were seen in all patients at the follow-up, as analyzed using the Visual Analog Scale and the Japanese Orthopedic Association Scale score, respectively. There were no cases of malpositioning of screws or any direct vertebral artery injury, although in one patient, the distal flow in the dominant vertebral artery was cut off as it got compressed between the bony arch and the screw head.

Conclusions: Compared to computer-generated images, 3D-printed models are a more practical approach for dealing with complex CV junction abnormalities. They provide surgeons with deep insights into the complex bony anomalies as well as variations in the vertebral artery courses, thereby improving surgical outcomes.

Keywords: C1–C2; Craniovertebral; Irreducible; Occiput–C2; Three-dimensional-printed model.

Fig. 1.

(A) A three-dimensional-printed model of a patient with occipitalized atlas. (B) Lateral view of the model. (C) Practice using the model. (D) Model with occiput–C2 screws.

Fig. 2.

(A) An intraoperative picture showing occiput–C2 fixation. (B) Another patient with C1–C2 fixation.

Fig. 3.

Improvement in the JOAS score. JOAS, Japanese Orthopedic Association Scale.

Fig. 4.

(A) Preoperative magnetic resonance imaging image showing cord compression at craniovertebral junction. (B) Preoperative CT im- Preoperative CT image showing type 1 odontoid fracture with Atlantoaxial dislocation. (C) Postoperative CT sagittal view showing good reduction. (D) Perfect alignment of C2 pedicle screws. CT, computed tomography.