504 - Radiological Outcomes of Novel a 3D Printed Cervical Interbody Cage Fo...

General Session: Cervical Degenerative

Presented by: F. Cammisa - View Audio/Video Presentation (Members Only)


S. Grinberg(1), B. Walker(1), B.V. Yoon(1), C. Abjornson(1), F. Cammisa(1)

(1) Hospital for Special Surgery, Integrated Spine Research Program, New York, NY, United States


Background: Historically, titanium interbody spacers have yielded high fusion rates accompanied by high subsidence rates. Implant subsidence is often associated with a loss of sagittal alignment, focal kyphosis, and acceleration of degenerative change. A novel 3-dimensional (3D) printed titanium alloy (Ti6Al4V) interbody spacer with an internal truss system was developed to harness the benefits and minimize the shortfalls of titanium interbody spacers.

Purpose: The purpose of this study is to perform an initial radiographic review of patients treated clinically with this novel interbody spacer.

Methods: A retrospective chart review was performed at our institution from December 2014 to April 2015 to assess the radiological outcomes of a novel 3D printed cervical interbody cage following an ACDF procedure. All patients with symptomatic cervical degenerative disc disease at up to three vertebral levels between C3-7 and without prior cervical fusions were included in the study. Plain lateral radiographs and computed tomographic (CT) were reviewed to determine fusion and subsidence (>3mm) rates, changes in segmental height and cervical lordosis (CL), and incidence of cage migration. Fusion was assessed using plain lateral flexion/extension radiographs and CT images at last follow-up (LFU). A segment was considered fused if there was obvious bridging bone in or on the interbody spacer on CT scans, and if there was < 2˚ of segmental motion on flexion/extension radiographs.

Results: Thirty patients (20 males, 10 females) underwent a 1-, 2-, or 3-level ACDF with supplemental anterior plate fixation (n=7, 11, 12, respectively). The mean age and BMI at surgery was 54.07 ± 9.90 years and 28.72 ± 6.22 kg/m2, respectively. Segmental motion was significantly decreased from baseline to LFU across all groups (p=0.021, =0.001, and =0.0012). Segmental height was significantly increased from baseline to immediate postoperative (IPO) across all groups (p=0.044, =0.0025, < 0.001). Segmental height was significantly decreased from IPO to LFU for 1-, 2-, and 3- level procedures (p=0.030, < 0.001, =0.030). Cervical lordosis was significantly increased from baseline to LFU for 2- and 3-level procedures (p=0.031 and =0.0074; Table 1). One-level procedures demonstrated a fusion, subsidence, and migration rate of 100% (7:7), 0% (0:7), and 0% (0:7), respectively. Two-level procedures demonstrated a 100% (11:11) fusion rate, 0% (0:11) subsidence rate, and 0% (0:11) migration rate. Three-level procedures demonstrated a fusion, subsidence, and migration rate of 91.67% (11:12), 0% (0:12), and 0% (0:12), respectively.

Discussion: As a whole, the novel 3-D printed interbody cage inspired a fusion, subsidence, and migration rate of 96.67%, 0%, and 0%, respectively. Additionally, the device demonstrated significant improvements in segmental motion, height, and cervical lordosis. The device experienced some settling into the vertebral endplates; however, the settling failed to reach the clinically relevant 3mm subsidence threshold in any of the patients. Overall, we feel the device successfully reduced clinically relevant subsidence while promoting solid fusion.