P135. Radiological outcomes of a novel 3-dimensional printed titanium cervical interbody cage following single and multilevel anterior cervical discectomy and fusion: a case series of 108 operated levels

Abstract

BACKGROUND CONTEXT Titanium implants are widely used in orthopedic procedures due to their favorable osseointegrative properties. However, despite inherent advantages, titanium has a high Young's modulus in relation to that of the bone it interfaces and, therefore, can potentiate subsidence. Recent advancements in 3D printing technology have allowed for the printing of open architecture interbody cages in titanium alloy (Ti-6Al-4V), thus harnessing osseointegrative properties while fostering bone in-growth and on-growth. PURPOSE The purpose of this study is to assess the radiological outcomes of patients who underwent one, two, and three-level ACDF surgery using a novel 3D printed titanium interbody cage. STUDY DESIGN/SETTING Retrospective, single center consecutive series by a single senior surgeon PATIENT SAMPLE All patients underwent a one, two, or three-level ACDF surgery with a 3D printed cervical interbody cage and supplemental anterior plate fixation. OUTCOME MEASURES The primary outcome measures were fusion rates, subsidence rates, change in cervical lordosis, and incidence of gross cage migration at one-year follow-up (minimum 10 months). Additionally, the incidence of device-related complications, surgical site infections and revision procedures was recorded. METHODS A retrospective analysis of 50 consecutive patients who underwent ACDF surgery between November 2014 and August 2017 with a novel 3D printed cervical interbody cage, nano-structured hydroxyapatite bone graft, and supplemental anterior plate fixation. Radiographic imaging was analyzed at baseline, immediately postoperative, and at 1-year follow up to assess for fusion status, subsidence rates and global cervical lordosis. Dynamic radiographs at 1-year follow up were reviewed to determine fusion status, defined as 3mm of segmental height loss, for any given segment when comparing 1-year follow-up to immediately postoperative. Changes in cervical lordosis were assessed using the C2-7 tangent line method. RESULTS A total of 50 patients (32 male, 18 female) underwent ACDF surgery (108 total operated levels) in the defined study period. Radiological outcomes were reviewed at 1-year follow up (minimum 10 months). Based on the criteria, an overall fusion rate of 95.37% (103/108 levels fused) was reported. One-level procedures demonstrated a 100% (11/11) fusion rate. Two-level procedures demonstrated a fusion rate of 90% (36/40). Three-level procedures demonstrated a fusion rate of 98.25% (56/57). Cervical lordosis was significantly increased from baseline to 1-year follow-up in one and three-level cases. No incidence of subsidence or cage migration were reported. CONCLUSIONS This study provides early evidence that load-sharing, 3D printed titanium cervical interbody cages provided stabilization and clinically successful fusion rates at 12-month follow-up. Recent advancements in 3D printing technology have allowed for the manufacturing of titanium with design features that harness its inherent biocompatibility while decreasing its Young's modulus and limiting radiographic imaging artifact. Many of the disadvantages of historical titanium cages were able to be overcome by 3D printing designs. However, the limitations of our study include a small sample size and retrospective analysis, thus necessitating further prospective investigation with longer follow-up. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.