Artificial Vertebral Body Research Articles

Preliminary Application of Bilateral Submandibular Horizontal Incision in the Treatment of Upper Cervical Tumors.

The upper cervical spine has a complex anatomical structure, making anterior surgical approaches challenging and prone to complications. This study aims to explore the use of bilateral submandibular incisions to provide safer and more convenient exposure of the upper cervical spine and to assess the feasibility of this approach for anterior surgical treatment of complex upper cervical diseases. From November 2019 to August 2021, three patients with malignant tumors of the upper cervical spine were subjected to an anterior-posterior combined approach for cervical tumor resection. The cohort consisted of one male and two females, aged between 41 and 51 years. The anterior approach began with a submandibular incision, followed by blunt dissection through the prevertebral muscles to expose the diseased vertebra. Subsequently, the diseased vertebra was excised, and either a titanium cage or a pre-customized 3D-printed artificial vertebral body was implanted anteriorly. Then, posterior fixation of the cervical spine was performed using pedicle screws to provide additional stability. Follow-up ranged from 8 to 34 months. All patients experienced varying degrees of pain relief within 24 hours post-operation. Frankel grading showed improvement by at least one grade in all three cases. Regular X-ray and magnetic resonance imaging examinations revealed no tumor recurrence or involvement of adjacent vertebrae in the surgical area. The anterior bilateral submandibular horizontal incision approach offers comprehensive exposure of the anatomical structures of the upper cervical spine. This approach introduces a new option for the anterior treatment of upper cervical spine diseases.

Clinical Application of 3D-Printed Artificial Vertebral Body (3DP AVB): A Review.

Introduction: The choice of prosthesis for vertebral body reconstruction (VBR) remains a controversial issue due to the lack of a reliable solution. The subsidence rate of the most commonly used titanium mesh cages (TMC) ranges from 42.5% to 79.7%. This problem is primarily caused by the differences in the elastic modulus between the TMC and bone. This review aims to summarize the clinical and radiological outcomes of new 3D-printed artificial vertebral bodies (3DP AVB). Methods: A literature search of PubMed, Scopus and Google Scholar was conducted to extract relevant studies. After screening the titles and abstracts, a total of 50 articles were selected for full-text analysis. Results: Preliminary data suggest fewer implant-related complications with 3DP AVB. Most comparative studies indicate significantly lower subsidence rates, reduced operation times and decreased intraoperative blood loss. However, the scarcity of randomized clinical trials and the high variability of the results warrant caution. Conclusion: Most literature data show an advantage of 3DP AVB in terms of the operation time, intraoperative blood loss and subsidence rate. However, long manufacturing times, high costs and regulatory issues are this technology's main drawbacks.

Dual-graded lattice with mechanical bionics to enhance fatigue performance

Additive manufacturing (AM) is revolutionizing the design and fabrication of orthopedic implants, enabling the creation of complex graded structures to enhance biomechanical bionics. This study aims to enhance fatigue life and reduce stress shielding for a long-term stability by using functionally graded lattice. Various lattice with minimal surface, including uniform array, Z-axis graded, and dual-graded Gyroid, were designed and fabricated by selective laser melting (SLM), followed by mechanical and fatigue tests for validation of design objectives. With a novel Sigmoid-Boltzmann fusion algorithm, the dual-graded lattice enhances the artificial vertebral body (AVB) with an 11 % increase in strength, >200 % improvement in fatigue life and reduced stress shielding on the contact surface, benefiting long-term implant stability and biomechanical fidelity. It displayed outstanding resistance to fatigue crack propagation due to superior load-bearing capacity and energy absorption capabilities contributed by the graded central region. The findings highlight the significance of biomimetic design principles and offer insights into the optimization of orthopedic implants using dual-graded lattice.

Treatment of cervical ossification of posterior longitudinal ligament with titanium alloy trabecular bone three-dimensional printed artificial vertebral body

To evaluate the effectiveness of using titanium alloy trabecular bone three-dimensional (3D) printed artificial vertebral body in treating cervical ossification of the posterior longitudinal ligament (OPLL). A retrospective analysis was conducted on clinical data from 45 patients with cervical OPLL admitted between September 2019 and August 2021 and meeting the selection criteria. All patients underwent anterior cervical corpectomy and decompression, interbody bone graft fusion, and titanium plate internal fixation. During operation, 21 patients in the study group received titanium alloy trabecular bone 3D printed artificial vertebral bodies, while 24 patients in the control group received titanium cages. There was no significant difference in baseline data such as gender, age, disease duration, affected segments, or preoperative pain visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), vertebral height, and C 2-7Cobb angle ( P>0.05). Operation time, intraoperative blood loss, and occurrence of complications were recorded for both groups. Preoperatively and at 3 and 12 months postoperatively, the functionality and symptom relief were assessed using JOA scores, VAS scores, and NDI evaluations. The vertebral height and C 2-7 Cobb angle were detected by imaging examinations and the implant subsidence and intervertebral fusion were observed. The operation time and incidence of complications were significantly lower in the study group than in the control group ( P<0.05), while the difference in intraoperative blood loss between the two groups was not significant ( P>0.05). All patients were followed up 12-18 months, with the follow-up time of (14.28±4.34) months in the study group and (15.23±3.54) months in the control group, showing no significant difference ( t=0.809, P=0.423). The JOA score, VAS score, and NDI of the two groups improved after operation, and further improved at 12 months compared to 3 months, with significant differences ( P<0.05). At each time point, the study group exhibited significantly higher JOA scores and improvement rate compared to the control group ( P<0.05); but there was no significantly difference in VAS score and NDI between the two groups ( P>0.05). Imaging re-examination showed that the vertebral height and C 2-7Cobb angle of the two groups significantly increased at 3 and 12 months after operation ( P<0.05), and there was no significant difference between 3 and 12 months after operation ( P>0.05). At each time point, the vertebral height and C 2-7Cobb angle of the study group were significantly higher than those of the control group ( P<0.05), and the implant subsidence rate was significantly lower than that of the control group ( P<0.05). However, there was no significant difference in intervertebral fusion rate between the two groups ( P>0.05). Compared to traditional titanium cages, the use of titanium alloy trabecular bone 3D-printed artificial vertebral bodies for treating cervical OPLL results in shorter operative time, fewer postoperative complications, and lower implant subsidence rates, making it superior in vertebral reconstruction.

Numerical evaluation of spinal reconstruction using a 3D printed vertebral body replacement implant: effects of material anisotropy.

Artificial vertebral implants have been widely used for functional reconstruction of vertebral defects caused by tumors or trauma. However, the evaluation of their biomechanical properties often neglects the influence of material anisotropy derived from the host bone and implant's microstructures. Hence, this study aims to investigate the effect of material anisotropy on the safety and stability of vertebral reconstruction. Two finite element models were developed to reflect the difference of material properties between linear elastic isotropy and nonlinear anisotropy. Their biomechanical evaluation was carried out under different load conditions including flexion, extension, lateral bending and axial rotation. These performances of two models with respect to safety and stability were analyzed and compared quantitatively based on the predicted von Mises stress, displacement and effective strain. The maximum von Mises stress of each component in both models was lower than the yield strength of respective material, while the predicted results of nonlinear anisotropic model were generally below to those of the linear elastic isotropic model. Furthermore, the maximum von Mises stress of natural vertebra and reconstructed system was decreased by 2-37MPa and 20-61MPa, respectively. The maximum reductions for the translation displacement of the artificial vertebral body implant and motion range of whole model were reached to 0.26mm and 0.77°. The percentage of effective strain elements on the superior and inferior endplates adjacent to implant was diminished by up to 19.7% and 23.1%, respectively. After comprehensive comparison, these results indicated that the finite element model with the assumption of linear elastic isotropy may underestimate the safety of the reconstruction system, while misdiagnose higher stability by overestimating the range of motion and bone growth capability.

Surgical outcomes and risk factors for surgical complications after en bloc resection following reconstruction with 3D-printed artificial vertebral body for thoracolumbar tumors

BackgroundThe outcomes of patients with tumors of the thoracolumbar spine treated with en bloc resection (EBR) using three-dimensional (3D)-printed endoprostheses are underreported.MethodsWe retrospectively evaluated patients with thoracolumbar tumors who underwent surgery at our institution. Logistic regression analysis was performed to identify the potential risk factors for surgical complications. Nomograms to predict complications were constructed and validated.ResultsA total of 53 patients with spinal tumors underwent EBR at our hospital; of these, 2 were lost to follow-up, 45 underwent total en bloc spondylectomy, and 6 were treated with sagittal en bloc spondylectomy. The anterior reconstruction materials included a customized 3D-printed artificial vertebral body (AVB) in 10 cases and an off-the-shelf 3D-printed AVB in 41 cases, and prosthesis mismatch occurred in 2 patients reconstructed with the off-the-shelf 3D-printed AVB. The median follow-up period was 21 months (range, 7–57 months). Three patients experienced local recurrence, and 5 patients died at the final follow-up. A total of 50 perioperative complications were encountered in 29 patients, including 25 major and 25 minor complications. Instrumentation failure occurred in 1 patient, and no prosthesis subsidence was observed. Using a combined surgical approach was a dependent predictor of overall complications, while Karnofsky performance status score, lumbar spine lesion, and intraoperative blood loss ≥ 2000 mL were predictors of major complications. Nomograms for the overall and major complications were constructed using these factors, with C-indices of 0.850 and 0.891, respectively.ConclusionsEBR is essential for the management of thoracolumbar tumors; however, EBR has a steep learning curve and a high complication rate. A 3D-printed AVB is an effective and feasible reconstruction option for patients treated with EBR.

The application of 3D-printed auto-stable artificial vertebral body in en bloc resection and reconstruction of thoracolumbar metastases

BackgroundNerve compression symptoms and spinal instability, resulting from spinal metastases, significantly impact the quality of life for patients. A 3D-printed vertebral body is considered an effective approach to reconstruct bone defects following en bloc resection of spinal tumors. The advantage of this method lies in its customized shape and innermost porous structure, which promotes bone ingrowth and leads to reduced postoperative complications.ObjectiveThe purpose of this study is to assess the effectiveness of 3D-printed auto-stable artificial vertebrae in the en bloc resection and reconstruction of thoracolumbar metastases.MethodsThis study included patients who underwent en bloc resection of thoracolumbar metastases based on the Weinstein-Boriani-Biagini surgical staging system, between January 2019 and April 2021. The patients were divided into two groups: the observation group, which was reconstructed using 3D-printed auto-stable vertebral bodies, and the control group, treated with titanium cages and allograft bone. Evaluation criteria for the patients included assessment of implant subsidence, instrumentation-related complications, VAS score, and Frankel grading of spinal cord injury.ResultsThe median follow-up period was 21.8 months (range 12–38 months). Among the patients, 10 received a customized 3D-printed artificial vertebral body, while the remaining 10 received a titanium cage. The observation group showed significantly lower operation time, intraoperative blood loss, and postoperative drainage compared to the control group (P < 0.05). At the final follow-up, the average implant subsidence was 1.8 ± 2.1 mm for the observation group and 5.2 ± 5.1 mm for the control group (P < 0.05). The visual analog scale (VAS) scores were not statistically different between the two groups at preoperative, 24 h, 3 months, and 1 year after the operation (P < 0.05). There were no statistically significant differences in the improvements of spinal cord functions between the two groups.ConclusionThe utilization of a 3D-printed auto-stable artificial vertebra for reconstruction following en bloc resection of thoracolumbar metastases appears to be a viable and dependable choice. The low occurrence of prosthesis subsidence with 3D-printed prostheses can offer immediate and robust stability.

Analysis of surgical treatment of severe angular kyphosis with keeping the spinal cord length constant in osteotomy area

Objective: To explore the surgical methods and clinical outcomes of severe angular kyphosis with the length of the spinal cord constant in the osteotomy area. Methods: Clinical data from 20 patients with severe angular kyphosis who underwent surgical treatment from January 2017 to December 2020 in the Department of Spinal Surgery,Hangzhou Xiaoshan District Hospital of Traditional Chinese Medicine were retrospectively analyzed. There were 11 males and 9 females, aged (28.5±8.9) years (range:17 to 46 years).There were 15 cases with congenital angular kyphosis,5 cases with tuberculous angular kyphosis.The angle of kyphosis was (107.1±12.9)° (range:93.2° to 131.4°).Frankel classification:2 cases with grade B,4 cases with grade C,3 cases with grade D.The kyphotic vertex is located at the T9 to T12 segments.Pedicle screws were placed in 3 or 4 adjacent segments at the proximal and distal kyphosis apex of the patients using a surgical navigation system.Piezosurgery combined with a grinding drill was used to complete the osteotomy in the apical vertebral region.Titanium mesh or artificial vertebral body was implanted,and the osteotomy surface was closed using this as the fulcrum to complete osteotomy.Spinal X-ray examination was performed before surgery,immediately after surgery and at the last follow-up,and sagittal and coronal Cobb angle,sagittal and coronary balance parameters,anterior vertebral height,posterior vertebral height,and spinal cord length were measured.Pulmonary function,visual analogue scale (VAS),and Oswestry's disability index (ODI) were collected and estimated before and after treatment.The analysis of variance of repeated measurement data was used for each evaluation index before and after treatment,and the t test was used for pairwise comparison. Results: All patients successfully completed surgery,with artificial vertebral body in 11 cases and double titanium mesh in 9 cases.The follow-up time was (28.2±2.3) months (range:26 to 31 months).Sagittal vertical axis improved from (46.9±13.7)mm(range:21.7 to 75.7 mm) before surgery to (10.7±5.5)mm (range:3.6 to 28.1 mm) after surgery,and (11.0±5.7)mm(range:3.6 to 29.3 mm) at the last follow-up,the differences were statistically significant compared to before surgery (all P<0.01).The mean kyphotic Cobb angle was corrected from (107.1±12.9) ° (range:93.2 ° to 131.4°) before surgery to (30.6±8.5) ° (range:20.0 ° to 47.8 °) after surgery (all P<0.01),and (32.1±8.7) ° (range:18.2 ° to 50.8°) at the last follow-up,the differences were statistically significant compared to before surgery(all P<0.01).The anterior vertebral height improved from (14.2±2.9)mm(range:11.04 to 23.6 mm) before surgery to (45.3±7.5)mm(range:29.4 to 56.5 mm) after surgery,and (44.3±6.8)mm(range:29.6 to 56.0 mm) at the last follow-up,the differences were statistically significant compared to before surgery (all P<0.01).The posterior vertebral height was improved from (51.8±5.3)mm (range:43.1 to 61.4 mm)before surgery to (57.6±4.7)mm (range:45.7 to 64.1 mm)after surgery,and (56.3±5.0) mm (range:49.7 to 68.5 mm) at the last follow-up,the differences were statistically significant compared to before surgery (all P<0.01).The spinal cord length of the osteotomy segment was (73.1±12.0)mm (range:56.8 to 98.4 mm) before surgery and (74.8±12.8)mm (range:53.5 to 100.2 mm) after surgery and (75.2±13.7)mm (range:53.9 to 102.4 mm) at the last follow-up,the difference was not statistically significant among them(F=0.144,P=0.866).The ODI and VAS scores improved significantly after surgery and at the last follow-up,and the differences were statistically significant (all P<0.01). Conclusion: The posterior vertebral column resection technique combined with titanium mesh or an artificial vertebral body implant for the treatment of severe angular kyphosis can significantly improve the kyphosis,neurological function,and life quality of patients without affecting the length of the spinal cord.

Comparison of radiological and clinical outcomes of 3D-printed artificial vertebral body with Titanium mesh cage in single-level anterior cervical corpectomy and fusion: A meta-analysis.

This meta-analysis aimed to determine whether 3D-printed artificial vertebral body have superior clinical and radiographic outcome than Titanium Mesh Cage(TMC) in single-level anterior cervical corpectomy and fusion. A comprehensive search of the PubMed, Embase, Cochrane Library, Web of Science, and CNKI (China National Knowledge Infrastructure) databases was conducted to find randomized control trials (RCTs) or cohort studies that compared 3D-printed artificial vertebral body with conventional Titanium Mesh Cage (TMC) in single-level anterior cervical corpectomy and fusion (SL-ACCF). Operation time; intraoperative blood loss; subsidence of vertebral body; preoperative, and final follow-up C2-C7 Cobb angle, Japanese Orthopedic Association (JOA) scores, and Visual Analog Scale(VAS) scores were collected from eligible studies for meta-analysis. We included 6 cohort studies with 341 patients. The results of the meta-analysis showed that the 3D group has a shorter operation time than the traditional TMC group(p = 0.04) and the TMC group had more severe subsidence(≥3 mm) of vertebral body than the 3D group(p < 0.0001). And the cervical C2-C7 Cobb angle in the 3D group was larger than that in the TMC group at the final follow-up. This meta-analysis demonstrates that 3D-printed artificial vertebral body is superior to traditional TMC in reducing the operation time and maintaining the postoperative vertebral height and restoring sagittal balance to the cervical spine in single-level anterior cervical corpectomy and fusion.

Stand-alone artificial vertebral body in cervical corpectomy surgeries: A new option of zero-profile fixation

Stand-alone artificial vertebral body in cervical corpectomy surgeries: A new option of zero-profile fixation

Effect of different fixation methods on biomechanical property of cervical vertebral body replacement and fusion

BackgroundThe main purpose of this study was to examine the effect of different fixation methods (anterior fixation, self-stabilizing fixation and anterior-posterior fixation) on biomechanical property of vertebral body replacement and fusion. MethodsThree finite element models of cervical vertebral body replacement and fusion were established. The implanted models included artificial vertebral body and fixation system, and the loads imposed on the models included 75 N compression load and 1 Nm moment load. FindingsFor anterior-posterior fixation, the cervical load was mainly transmitted by the posterior pedicle screw and rod (more than 50%), and the stress shielding problem was the most significant than the self-stabilizing and anterior fixation. Self-stabilizing fixation was more helpful to the fusion of implant and vertebrae, but the higher risk of vertebral body collapse was worthy of attention if the cervical spine with osteoporosis. The stress of bone was mainly concentrated around the screw hole. The maximum stress (20.03 MPa) was lower than the yield stress of cortical bone and the possibility of fracture around the fixation device of cervical spine was low. The anterior fixation could meet the requirement of vertebral body replacement and fusion, and the addition of posterior pedicle screws and rods might obtain better treatment in cases of severe spine injury or osteoporosis. InterpretationThe findings of this study may provide guidance on clinical treatments for choosing more appropriate fixation methods for different patients.

3D-printed vertebral body for anterior spinal reconstruction in patients with thoracolumbar spinal tumors.

A 3D-printed vertebral prosthesis can be used to reconstruct a bone defect more precisely because of its tailored shape, with its innermost porous structure inducing bone ingrowth. The aim of this study was to evaluate the clinical outcomes of using a 3D-printed artificial vertebral body for spinal reconstruction after en bloc resection of thoracolumbar tumors. This was a retrospective analysis of 23 consecutive patients who underwent surgical treatment for thoracolumbar tumors at our hospital. En bloc resection was performed in all cases, based on the Weinstein-Boriani-Biagini surgical staging system, and anterior reconstruction was performed using a 3D-printed artificial vertebral body. Prosthesis subsidence, fusion status, and instrumentation-related complications were evaluated. Stability of the anterior reconstruction method was evaluated by CT, and CT Hounsfield unit (HU) values were measured to evaluate fusion status. The median follow-up was 37 (range 24-58) months. A customized 3D-printed artificial vertebral body was used in 10 patients, with an off-the-shelf 3D-printed artificial vertebral body used in the other 13 patients. The artificial vertebral body was implanted anteriorly in 5 patients and posteriorly in 18 patients. The overall fusion rate was 87.0%. The average prosthesis subsidence at the final follow-up was 1.60 ± 1.79 mm. Instrument failure occurred in 2 patients, both of whom had substantial subsidence (8.47 and 3.69 mm, respectively). At 3 months, 6 months, and 1 year postoperatively, the mean CT HU values within the artificial vertebral body were 1930 ± 294, 1997 ± 336, and 1994 ± 257, respectively, with each of these values being significantly higher than the immediate postoperative value of 1744 ± 321 (p < 0.05). The use of a 3D-printed artificial vertebral body for anterior reconstruction after en bloc resection of the thoracolumbar spinal tumor may be a feasible and reliable option. The low incidence of prosthesis subsidence of 3D-printed endoprostheses can provide good stability instantly. Measurement of HU values with CT is a valuable method to evaluate the osseointegration at the bone-metal interface of a 3D-printed vertebral prosthesis.

Customized Multilevel 3D Printing Implant for Reconstructing Spine Tumor: A Retrospective Case Series Study in a Single Center.

ObjectiveTo investigate the clinical efficacy and safety of 3D printed artificial vertebral body for patients who underwent multilevel total en bloc spondylectomy (TES) and analyze whether it could reduce the incidence of implant subsidence.MethodsThis is a retrospective study. From January 2017 to May 2018, eight consecutive cases with spine tumor undergoing multilevel TES were analyzed. All patients underwent X‐ray and CT examinations to evaluate the stability of internal fixation during the postoperative follow‐up. Demographic, surgical details, clinical data, and perioperative complications was collected. Visual analog scale, Frankel score, and spinal instability neoplastic score (SINS) classification were also recorded.ResultsThere were six cases of primary spinal tumor and two cases of metastatic spinal tumor. All patients achieved remarkable pain relief and improvement in neurological function. Five patients underwent operation through the posterior approach, one patient underwent operation through the anterior approach and the remaining two patients through a combined anterior and posterior approach. At the last follow‐up period, X‐rays showed that the 3D printed artificial vertebral body of all cases matched well, and the fixation was reliable. Hardware failure such as loosening, sinking, breaking, and displacement wasn't observed during the follow‐up period.Conclusion3D printed customized artificial vertebral body can provide satisfying good clinical and radiological outcomes for patients who have undergone multilevel TES.

Research on application of new nanomaterials in repairing ligament injury of Wushu athletes

Objective: The paper explored the application value of nanohydroxyapatite/polyamide 66 composite bioactive artificial vertebral body in anterior surgery of thoracolumbar ligament injury in martial arts athletes. Methods: In the experiment, 81 patients with thoracolumbar ligament injury who were treated by anterior menstrual route from January 2016 to September 2019 and were followed up divided into titanium mesh group and artificial vertebral body group according to different intervertebral bone graft support materials. Results: All 81 cases were followed up for more than 12 months. There was no significant difference in the Cobb angle and the height of adjacent intervertebral space between the two groups at 1 week and 3 months after surgery (P > 0.05). Conclusion: Thoracolumbar ligament injury anterior decompression is thorough, the reconstruction method conforms to the principle of spine biomechanical distribution, and the spinal cord function recovery is better.

Effectiveness of three-dimensional printing artificial vertebral body and interbody fusion Cage in anterior cervical surgery

To evaluate the effectiveness of three-dimensional (3D) printing artificial vertebral body and interbody fusion Cage in anterior cervical disectomy and fusion (ACCF) combined with anterior cervical corpectomy and fusion (ACDF). The clinical data of 29 patients with multilevel cervical spondylotic myelopathy who underwent ACCF combined with ACDF between May 2018 and December 2019 were retrospectively analyzed. Among them, 13 patients were treated with 3D printing artificial vertebral body and 3D printing Cage as 3D printing group and 16 patients with ordinary titanium mesh Cage (TMC) and Cage as TMC group. There was no significant difference in gender, age, surgical segment, Nurick grade, disease duration, and preoperative Japanese Orthopaedic Association (JOA) score, visual analogue scale (VAS) score, and Cobb angle of fusion segment between the two groups ( P>0.05). The operation time, intraoperative blood loss, hospitalization stay, complications, and implant fusion at last follow-up were recorded and compared between the two groups; JOA score was used to evaluate neurological function before operation, immediately after operation, at 6 months after operation, and at last follow-up; VAS score was used to evaluate upper limb and neck pain. Cobb angle of fusion segment was measured and the difference between the last follow-up and the immediate after operation was calculated. The height of the anterior border (HAB) and the height of the posterior border (HPB) were measured immediately after operation, at 6 months after operation, and at last follow-up, and the subsidence of implant was calculated. The operation time of 3D printing group was significantly less than that of TMC group ( t=3.336, P=0.002); there was no significant difference in hospitalization stay and intraoperative blood loss between the two groups ( P>0.05). All patients were followed up 12-19 months (mean, 16 months). There was no obvious complication in both groups. There were significant differences in JOA score, VAS score, and Cobb angle at each time point between the two groups ( P<0.05). There was an interaction between time and group in the JOA score ( F=3.705, P=0.025). With time, the increase in JOA score was different between the 3D printing group and the TMC group, and the increase in the 3D printing group was greater. There was no interaction between time and group in the VAS score ( F=3.038, P=0.065), and there was no significant difference in the score at each time point between the two groups ( F=0.173, P=0.681). The time of the Cobb angle interacted with the group ( F=15.581, P=0.000). With time, the Cobb angle of the 3D printing group and the TMC group changed differently. Among them, the 3D printing group increased more and the TMC group decreased more. At last follow-up, there was no significant difference in the improvement rate of JOA score between the two groups ( t=0.681, P=0.502), but the Cobb angle difference of the 3D printing group was significantly smaller than that of the TMC group ( t=5.754, P=0.000). At last follow-up, the implant fusion rate of the 3D printing group and TMC group were 92.3% (12/13) and 87.5% (14/16), respectively, and the difference was not significant ( P=1.000). The incidence of implant settlement in the 3D printing group and TMC group at 6 months after operation was 15.4% (2/13) and 18.8% (3/16), respectively, and at last follow-up were 30.8% (4/13) and 56.3% (9/16), respectively, the differences were not significant ( P=1.000; P=0.264). The difference of HAB and the difference of HPB in the 3D printing group at 6 months after operation and last follow-up were significantly lower than those in the TMC group ( P<0.05). For patients with multilevel cervical spondylotic myelopathy undergoing ACCF combined with ACDF, compared with TMC and Cage, 3D printing artificial vertebrae body and 3D printing Cage have the advantages of shorter operation time, better reduction of height loss of fusion vertebral body, and maintenance of cervical physiological curvature, the early effectiveness is better.

Comparative Analysis of 3D-Printed Artificial Vertebral Body Versus Titanium Mesh Cage in Repairing Bone Defects Following Single-Level Anterior Cervical Corpectomy and Fusion.

BackgroundThe aim of this study was to compare the clinical and radiological outcomes of the 3D-printed artificial vertebral body vs the titanium mesh cage in repairing bone defects for single-level anterior cervical corpectomy and fusion (ACCF).Material/MethodsA total of 51 consecutive patients who underwent single-level ACCF in Huai’an Second People’s Hospital from July 2017 to August 2020 were retrospectively reviewed. According to the implant materials used, patients were divided into a 3D-printed artificial vertebral body group (3D-printed group) (n=20; 12 males, 8 females) and a titanium mesh cage group (TMC group) (n=31; 15 males, 16 females). General data, radiological parameters, and clinical outcomes were recorded.ResultsThe rate of subsidence in the 3D-printed group (0.01, 2/20) was lower than in the TMC group (0.29, 9/31) (P<0.05). HAE and HPE of the patients in the 3D-printed group were significantly higher than those in the TMC group (P<0.05). C2–C7 Cobb angle and SA of the patients in the 3D-printed group were significantly larger than those in the TMC group (P<0.05). All patients in the 2 groups showed significant improvement in VAS, JOA, and NDI scores at 3 months and 1 year after surgery.Conclusions3D-printed artificial vertebral body helps maintain intervertebral height and cervical physiological curvature and is a good candidate for ACCF.

Biomechanical properties of a novel nonfusion artificial vertebral body for anterior lumbar vertebra resection and internal fixation

The aim of the study was to evaluate the biomechanical properties of a novel nonfused artificial vertebral body in treating lumbar diseases and to compare with those of the fusion artificial vertebral body. An intact finite element model of the L1–L5 lumbar spine was constructed and validated. Then, the finite element models of the fusion group and nonfusion group were constructed by replacing the L3 vertebral body and adjacent intervertebral discs with prostheses. For all finite element models, an axial preload of 500 N and another 10 N m imposed on the superior surface of L1. The range of motion and stress peaks in the adjacent discs, endplates, and facet joints were compared among the three groups. The ranges of motion of the L1–2 and L4–5 discs in flexion, extension, left lateral bending, right lateral bending, left rotation and right rotation were greater in the fusion group than those in the intact group and nonfusion group. The fusion group induced the greatest stress peaks in the adjacent discs and adjacent facet joints compared to the intact group and nonfusion group. The nonfused artificial vertebral body could better retain mobility of the surgical site after implantation (3.6°–8.7°), avoid increased mobility and stress of the adjacent discs and facet joints.

A prospective randomized cohort study on 3D-printed artificial vertebral body in single-level anterior cervical corpectomy for cervical spondylotic myelopathy.

BackgroundThis was a prospective randomized cohort study aiming at examining the safety and efficacy of artificial vertebral body (AVB) fabricated by electron beam melting (EBM) in comparison to conventional titanium mesh cage (TMC) used in single-level anterior cervical corpectomy and fusion (SL-ACCF).MethodsForty patients with cervical spondylotic myelopathy (CSM) underwent SL-ACCF using either the EBM-AVB or the TMC. Patients were evaluated for their demographics, radiological characteristics, neurologic function [using the Japanese Orthopaedic Association (JOA) scale], and health-related quality-of-life (HRQoL) aspects [using the Short Form 36 (SF-36)] before and after the surgery and comparison was made between the two groups both at baseline and the last follow-up. The Student t-text, paired-sample t-text, and Fisher’s exact test were used when appropriate to detect any statistical significance at the level of α=0.05.ResultsPost-operative recovery was uneventful for all patients and no revision surgery was required. There were no significant differences between the EBM-AVB group and the TMC group at baseline. Patients in both groups demonstrated significant improvement in cervical alignment, JOA score, and SF-36 score after the surgery. Six months post-operatively, patients in the EBM-AVB group were found to have significantly less loss of fusion height and lower incidence for severe implant subsidence compared with the TMC group. Patients in the two groups were comparable at the last follow-up regarding their rate of fusion, cervical alignment, JOA recovery rate, SF-36 score, and by Odom’s criteria.ConclusionsFor CSM patients undergoing SL-ACCF, the EBM-AVB group demonstrated comparable outcomes regarding patient cervical alignment, neurologic function, and HRQoL in comparison with the TMC group. Furthermore, the use of EBM-AVB was associated with decreased loss of the height of the fusion mass and a lower rate for severe implant subsidence.

A finite element analysis on comparing the stability of different posterior fixation methods for thoracic total en bloc spondylectomy

ObjectiveTo compare the spinal stability with different fixation methods after thoracic TES using finite element analysisMethodsThe spinal finite element model was established from a healthy volunteer, and the validity was verified. The models of T8 thoracic total en bloc spondylectomy (TES) with and without artificial vertebral body were established combination with different fixation methods: the first was long segment fixation with fixed segments T5–7, T9–11; the second was short segment fixation with fixed segments T6–7, T9–10; the third was modified short segment with a pair of vertebral body screws on T7 and T9 added on the basis of short segment fixation. The motions of each model in standing state were simulated in software. The range of motion (ROM) and internal fixation stress changes were analyzed.ResultsWhen anterior support was effective, the three fixation methods could effectively maintain the stability of the spine. However, when anterior support failed, the ROM of the long segment fixation group and the short segment fixation group in the flexion-extension directions was significantly higher than that of when the anterior support existed, while the modified short segment fixation group had no significant changes. Meanwhile, the stress of internal fixation in the long segment fixation group and the short segment fixation group were greatly increased. However, there were no significant changes in modified short segment fixation group.ConclusionAfter TES, the presence of the thoracic cage gives partial anterior stabilization. When the anterior support failed, the modified short segment fixation method can provide better stability.

Preliminary study on the a novel individualized 3D printing artificial vertebral body in spine reconstruction

Objective To explore the advantages of the novel individualized 3D printing artificial vertebral body in spine reconstruction and to evaluate its clinical effect. Methods From January 2017 to December 2018, the 15 patients who underwent total vertebrectomy and spine reconstruction with individualized 3D printing artificial vertebral body were analyzed retrospectively. There were 8 males and 7 females, with the mean age 39.5 years (range: 20-57), including 12 primary tumors and 3 metastatic tumors. According to tumor location and surrounding soft tissue invasion range, simple posterior or combined anterior and posterior approach were used for total vertebral resection, and the defection was reconstructed by 3D printing artificial vertebral body. The operation time, intraoperative bleeding volume, postoperative stability of artificial vertebral body and bone ingrowth of adjacent vertebral body, preoperative and postoperative neurological changes, preoperative and postoperative VAS score, local control and survival of patients were analyzed. Results The mean operation time was 412.0 min (range: 135-740 min), and the mean blood loss was 4 140.0ml (range: 100-14 000 ml). The mean follow-up time was 23.2 months (range: 12-35 months), and no one loss to follow-up. One case had pleural rupture, one case had cerebrospinal fluid leakage and one case had L5 nerve root palsy. All patients recovered after active symptomatic treatment. Compare with the preoperative VAS score (4.7±1.1), the differences of VAS score at 7 d postoperative and last follow-up (1.6±0.6 and 1.0±0.5) were significantly reduced (P<0.001). Three patients with Frankel grade C gradually recovered to grade D, and no change were found in grade D and Grade E patients, there was no significant improved at last follow-up. Preliminary bone growth was found between the artificial vertebral body and the adjacent vertebral body 3 months after operation. The bone growth was more obvious at 12 months post-operation, and the artificial vertebral body fused with the adjacent vertebral bodies to form bone integration. At 24 months post-operation, the integration of the artificial vertebral body was more accurate. During the follow-up period, there was no loosening or displacement of the artificial vertebral body and no failure of internal fixation. A case of hemangioendothelioma and a case of epithelioid angiosarcoma died at 33 months and 35 months postoperatively. One patient with chondrosarcoma had local recurrence at16 months post-operation. After treated with arotinib, the tumor did not progress. The other 12 patients had no tumor recurrence or distant metastasis. Conclusion After spinal tumor resection, individualized 3D printing artificial vertebral body can be used to accurate restoration of spinal continuity, and provide nice interface matching and bone growth between artificial vertebral body and the adjacent vertebral endplates. Moreover, the immediate and long-term stability of the artificial vertebral body can meet the needs of spinal reconstruction. Key words: Imaging, three-dimensional; Spinal neoplasms; Individualized medicine; Bone remodeling