A Comparative Study Of 3D-printed Artificial Vertebral Body And Titanium Mesh Cage Used To Realign Cervical Spine

Objective:To compare the effectiveness of three-dimension printed artificial vertebral body(3D-printed AVB)and titanium mesh cage(TMC)to realign the sagittal cervical spine in the surgery of anterior cervical corpectomy and fusion(ACCF).Methods:Seventy-seven patients who underwent single-segment ACCF surgery at this hospital from January 2019 to January 2021 were divided into two groups.According to whether the implants were three dimensions printed artificial vertebral body or titanium mesh cage,the patients were divided into 3D-printed artificial vertebral body group and titanium mesh cage group.Surgery-related information data were recorded,including operation time,blood loss,levels of surgical segments and postoperative hospital stay.Japanese Orthopedics Association(JOA)score and Neck Disability Index(NDI)were assessed at the preoperative,3-month postoperative and final follow-up.Patients were radiographically evaluated preoperatively,immediately postoperatively,3 months postoperatively and at the last follow-up.The measured cervical sagittal alignment parameters included C1-2 Cobb,C2-7 Cobb,segmental angle(SA),C2-7 sagittal vertical axis(c SVA),neck tilt angle(NT),T1 slope(T1S),and thoracic inlet angle(TIA).Results:General data: Seventy-four patients were finally followed up in this study,with a mean follow-up time of 24-36 months(28.8±2.7)months.Thirty-eight patients(20males and 18 females)(age 56.4±7.9 years,range 41-71 years)were in 3D-printed AVB group and thirty-six patients(19 males and 17 females)(age 53.2±9.0 years,range 41-71)were in TMC group.There were no significant differences in age(P=0.253),gender(P=0.737),level of surgical segment(P=0.649),intraoperative blood loss(101.1±14.6 vs 109.8±12.2,P=0.056)and length of postoperative hospital stay(3.3±1.0 days vs 3.6±1.4 days,P=0.545)between the two groups.In contrast,the surgical time was significantly shorter in 3D-printed AVB group(67.4 ± 8.3 minutes)than that in TMC group(85.1 ± 7.4 minutes)(P < 0.05).Clinical outcome:JOA and NDI were no statistically different between the two groups in preoperative and postoperative(P > 0.05),but both JOA scores and NDI were significantly improved at the final follow-up compared with preoperative(P <0.05)in each group.Radiography data: The C1-2 Cobb Angle,C2-7 Cobb Angle,SA,c SVA,NT and T1 S in each group were significantly improved immediately after operation,3months after operation and at the last follow-up when compared with those before operation.There was no significant difference in preoperative sagittal parameters between the two groups(P>0.05).But there were significant differences in C1-2Cobb Angle,C2-7 Cobb Angle,SA,c SVA,NT and T1 S between 3D-printed AVB group and TMC group immediately after operation,3 months after surgery and at the last follow-up(P<0.05).Bone fusion was achieved in both groups at the final follow-up.The preoperative intervertebral height in 3D-printed AVB group increased from(24.8±3.7mm)preoperatively to(30.1±3.9mm)immediately postoperatively and(28.7±3.6mm)at the last follow-up.The preoperative intervertebral height in TMC group increased from(24.4±3.1mm)preoperatively to(27.6±3.5mm)immediately postoperatively and(25.4±3.3mm)at the last follow-up.There was no statistically significant difference in preoperative intervertebral height between the two groups(P>0.05),while in 3D-printed AVB group,there was a significant higher intervertebral height than that in TMC group immediately after surgery and at the last follow-up(P<0.05).At the final follow-up,subsidence occurred less in 3D-printed AVB group(10.5%,4/38)than that in TMC group(33.3%,12/36).Complications: There were no common complications such as hematoma compression,hoarseness,incision infection,and cerebrospinal fluid leakage in the two groups.Conclusions:Compared with conventional TMC implantation,the 3D-printed AVB implantation showed better performance in maintaining intervertebral height and cervical sagittal alignment at the 2-year follow-up.Three dimensional printed AVB is a good substitute for TMC as the implant in ACCF surgery.