Upper cervical spine reconstruction using customized 3D-printed vertebral body in 9 patients with primary tumors involving C2

Abstract

Background: Reconstruction following resection of the primary tumors of the upper cervical spine is challenging, and conventional internal implants develop complications in this region. 3D printing, also known as additive manufacturing, can produce patient-specific porous implants in a particular shape for bone defect reconstruction. This study aimed to describe the clinical outcomes of upper cervical spine reconstruction using customized 3D-printed vertebral body in 9 patients with primary tumors involving C2.

Methods: Patients with primary tumors involving C2 who were treated in our institution between July 2014 and November 2018 were enrolled. A two-stage intralesional spondylectomy was performed using the posterior-anterior approach. Anterior reconstruction was accomplished using a customized 3D-printed vertebral body, which was fabricated by successive layering of melted titanium alloy powder using electron beam melting. No bone graft was used.

Results: Nine patients (2 males and 7 females) were included in the study with a mean age of 31.4 years (12 to 59 years). Seven patients demonstrated tumors located in C2 and 2 showed involvement of C2 and C3. During a mean follow-up of 28.6 months (range, 12-42 months), 1 patient died of systemic metastasis and 1 had local tumor recurrence, the other 7 patients were alive and functional in their daily living until the last follow-up without evidence of disease. The 3D-printed vertebral bodies were all stable with no sign of displacement or subsidence, evidence of implant osseointegration was observed on the imaging studies. For the posterior instrumentation systems, no screw loosening or rod breakage was found.

Conclusions: Spinal reconstruction in the upper cervical region using customized 3D-printed vertebral body is reliable. The tailored shape matching with the contact surfaces and the porous structure conductive to osseointegration provide both short- and long-term stability to the implant.

Keywords: 3D printing; Patient-specific implant; primary spine tumor; spinal reconstruction; total spondylectomy.

Conflict of interest statement

Conflicts of Interest: NX serves as an unpaid section editor member of Annals of Translational Medicine from Oct 2019 to Sep 2020. The other authors have no conflicts of interest to declare.

2020 Annals of Translational Medicine. All rights reserved.

Figures

Figure 1

Imaging studies for patient #3. The achievement of osseointegration was defined when new bone formation was observed around the bone-implant interface on X-ray (B) and CT (D) during the follow-up compared to that of immediately postoperative (A,C). The postoperative segment vertebral height was measured on the midsagittal reconstruction CT from atlas anterior tubercle to the midpoint of the adjacent lower endplate (C).

Figure 2

The 3D-printed artificial vertebral body with porous metal scaffold fabricated by successive layering of melted titanium alloy powder.

Figure 3

Imaging studies for patient #3. The achievement of osseointegration was defined when new bone formation was observed around the bone-implant interface on X-ray (B) and CT (D) during the follow-up compared to that of immediately postoperative (A,C). The postoperative segment vertebral height was measured on the midsagittal reconstruction CT from atlas anterior tubercle to the midpoint of the adjacent lower endplate (C).

Figure 4

Imaging studies for patient #6 showing the process of fusion. Compared to the immediate postoperative X-ray (A) and CT (D), regenerated osseous tissue can be seen to gradually grew along the implant 12 months (B,E) and 24 months (C,F) after the surgery (arrow).