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

3D-Printed Laminae for Kyphosis in Ankylosing Spondylitis During Pedicle Subtraction Osteotomy

OBJECTIVE

Ankylosing spondylitis (AS) often presents with spinal kyphosis, and pedicle subtraction osteotomy (PSO) is a common surgical technique for correcting AS-related kyphosis. However, after PSO, the posterior column lacks rigid bone support, potentially leading to intervertebral disc mobility and loss of correction. This study aims to introduce a novel 3D-printed laminae for the treatment of AS-related kyphosis.

METHODS

This is a retrospective cohort study. A total of 48 patients receiving posterior correction surgeries between December 2021 and January 2022 were included and divided into two groups according to whether they accepted the 3D-printed laminae. We propose a novel approach using 3D-printed laminae to enhance posterior column stability and reduce deformity loss. Sixteen patients receiving 3D-printed laminae and 32 patients who did not receive that device. We collected preoperative and postoperative radiographic parameters, perioperative data, and patient-reported clinical scores. Statistical analysis involved independent sample t tests or randomization tests for continuous variables and chi-square tests for categorical variables.

RESULTS

In the implanted group, kyphosis was corrected from 75.88° preoperatively to 27.06° postoperatively, and in the unimplanted group, from 70.98° to 28.42°. At the last follow-up, the ΔGK (global kyphosis) was 1.76° in the implanted group and 2.50° in the unimplanted group. PJA was 9.77° in the implanted group and 15.45° in the unimplanted group, showing significant differences. Two patients in the unimplanted group experienced sagittal reconstruction failure. Health-related quality of life (HRQoL) scores improved in the implanted group, with back pain scores of 2.63 and Oswestry Disability Index (ODI) scores of 13.50.

CONCLUSIONS

Our study introduces a novel 3D-printed laminae technique for AS-related kyphosis, aiding in maintaining sagittal balance. Patients reported improved subjective outcomes, including reduced pain and better HRQoL.

Patient-specific 3D-Printed PEEK implants for spinal tumor surgery

Aims & objectives

This study evaluates the feasibility and clinical outcomes of using 3D-printed polyetheretherketone (PEEK) patient-specific implants (PSI) for vertebral body replacement (VBR) in patients with spinal tumors. The research question focuses on postoperative results, implant integration, and complications over a 12-month period.

Methods

A single-center, retrospective case series analyzed five patients who underwent spinal reconstruction after tumor resection using PEEK 3D VBR between April 2022 and June 2023. Inclusion criteria were thoracic/lumbar spinal tumors, tumor resection with PEEK 3D VBR reconstruction, and follow-up exceeding 12 months. PEEK implants were created using fused filament fabrication from medical-grade PEEK. Patient data included demographics, medical history, tumor characteristics, and surgical outcomes. Radiological evaluations assessed bony fusion, local angle changes, and segment height stability. Descriptive statistical analyses were performed using R software.

Results

The mean follow-up duration was 19.2 months. All patients remained alive, with one experiencing local recurrence. Postoperative imaging showed a decrease in local angle with no significant changes during follow-up. Segment heights remained stable, and no PEEK 3D VBR subsidence or hardware failure was observed. Bony fusion was observed in all patients.

Conclusions

The use of PEEK 3D printed PSI for VBR in spinal tumor patients demonstrates promising feasibility and clinical outcomes, with stable implant integration and minimal complications over a 12-month period. Further studies with larger cohorts are recommended to validate these findings.

The rational design, biofunctionalization and biological properties of orthopedic porous titanium implants: a review

Porous titanium implants are becoming an important tool in orthopedic clinical applications. This review provides a comprehensive survey of recent advances in porous titanium implants for orthopedic use. First, the review briefly describes the characteristics of bone and the design requirements of orthopedic implants. Subsequently, the pore size and structural design of porous titanium alloy materials are presented, then we introduce the application of porous titanium alloy implants in orthopedic clinical practice, including spine surgery, joint surgery, and the treatment of bone tumors. Following that, we describe the surface modifications applied to porous titanium implants to obtain better biological functions. Finally, we discuss incorporating environmental responsive mechanisms into porous titanium alloy materials to achieve additional functionalities.

Rapid Manufacturing, Regulatory Approval, and Utilization of Patient-specific 3D-Printed Titanium Implants for Complex Multistage Spinal Surgeries

STUDY DESIGN

Technical note and case series.

OBJECTIVES

3D-printed implants (3DPI) for spinal surgery are a relatively recent development. We report on our experience with the rapid creation and regulatory approval of patient-specific 3DPI for use in complex spinal reconstruction, including a novel expedited turnaround time for implant creation.

METHODS

Four patients underwent placement of 3DPI to replace osseous anatomy during complex spinal reconstructions. These implants were created and used to replace patient-specific anatomy created by either en bloc tumor resection or by severe neurogenic spinal arthropathy. The surgical planning, implant creation, and postoperative outcomes are outlined.

RESULTS

All patients underwent successful implantation of 3DPI, which was confirmed on postoperative imaging at most recent follow-up. The time to plan, create, obtain regulatory approval, and use the first 3DPI was 28 days. Subsequent 3DPI could be planned, approved, and used in surgery in as little as 4-5 days, which is faster than previously-published reports. Thus, a 3DPI could be generated based on osseous defects created during stage 1 of a multistage surgical plan and implanted during a subsequent stage in an especially expedited manner.

CONCLUSIONS

3DPI may be used to effectively replace patient-specific anatomy during complex spinal reconstructions, including for osseous defects that are generated after the initial surgical procedure. These 3DPI may be created, approved, and used in surgery over much faster timelines than have been previously reported. Additional cases utilizing these custom 3DPI will further elucidate their utility during complex reconstructions.

Using additive manufacturing for craniocervical reconstruction in traditionally challenging cases

Retrospective case series. The aim of this study was to evaluate the clinical outcomes and effectiveness of using 3D printed implants in upper cervical spine and occipitocervical junction surgery. C2 primary tumor patients who required axial en bloc resection and other patients who required partial bone decompression using customized 3D printed implants or fixation devices for surgery were included. Evaluate the stability and surgical outcomes of 3D printed implants through perioperative and follow-up period. Five tumor patients underwent reconstruction using customized 3D printed artificial vertebral bodies, while another five patients with atlantoaxial joint dislocation underwent reduction and decompression using customized 3D printed internal fixation devices. The postoperative imaging results showed that the 3D printed structures had good immediate stability and had no signs of displacement or subsidence. Follow up showed that all five cases of vertebral body reconstruction had achieved fusion. Only one patient died one month after surgery due to infection and respiratory difficulties. Other patients showed excellent improvement in neurological function in follow up. The use of 3D printed implants in surgery involving the occipitocervical area is a feasible and reliable alternative choice. It is a valuable attempt for complex atlantoaxial dislocation that cannot be treated with conventional instruments. 3D printed implants can improve the safety and accuracy of surgery, provide good immediate stability, have a low incidence of subsidence, fewer related complications during the follow-up period.

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.

Applying 3D-printed prostheses to reconstruct critical-sized bone defects of tibial diaphysis (> 10 cm) caused by osteomyelitis and aseptic non-union

BACKGROUND

Clinical repair of critical-sized bone defects (CBDs) in the tibial diaphysis presents numerous challenges, including inadequate soft tissue coverage, limited blood supply, high load-bearing demands, and potential deformities. This study aimed to investigate the clinical feasibility and efficacy of employing 3D-printed prostheses for repairing CBDs exceeding 10 cm in the tibial diaphysis.

METHODS

This retrospective study included 14 patients (11 males and 3 females) with an average age of 46.0 years. The etiologies of CBDs comprised chronic osteomyelitis (10 cases) and aseptic non-union (4 cases), with an average defect length of 16.9 cm. All patients underwent a two-stage surgical approach: (1) debridement, osteotomy, and cement spacer implantation; and (2) insertion of 3D-printed prostheses. The interval between the two stages ranged from 8 to 12 weeks, during which the 3D-printed prostheses and induced membranes were meticulously prepared. Subsequent to surgery, patients engaged in weight-bearing and functional exercises under specialized supervision. Follow-up assessments, including gross observation, imaging examinations, and administration of the Lower Extremity Functional Scale (LEFS), were conducted at 3, 6, and 12 months postoperatively, followed by annual evaluations thereafter.

RESULTS

The mean postoperative follow-up duration was 28.4 months, with an average waiting period between prosthesis implantation and weight-bearing of 10.4 days. At the latest follow-up, all patients demonstrated autonomous ambulation without assistance, and their LEFS scores exhibited a significant improvement compared to preoperative values (30.7 vs. 53.1, P < 0.001). Imaging assessments revealed progressive bone regeneration at the defect site, with new bone formation extending along the prosthesis. Complications included interlocking screw breakage in two patients, interlocking screw loosening in one patient, and nail breakage in another.

CONCLUSIONS

Utilization of 3D-printed prostheses facilitates prompt restoration of CBDs in the tibial diaphysis, enabling early initiation of weight-bearing activities and recovery of ambulatory function. This efficacious surgical approach holds promise for practical application.

Comparison of En Bloc Resection and Intralesional Excision for Re-resection of Giant Cell Tumors of the Spine

OBJECTIVE

Re-resection of spinal giant cell tumors is an exceedingly difficult procedure. Moreover, the prognosis of patients with en bloc resection or intralesional excision for re-resection has rarely been reported. This study aimed to compare the prognostic value of en bloc resection with that of intralesional excision in patients undergoing re-resection for giant cell tumors of the spine.

METHODS

This retrospective analysis evaluated patients who underwent revision surgeries for relapse of giant cell tumors of the spine at our center between January 2005 and January 2021. Local progression-free survival represents the duration between en bloc resection or intralesional excision and tumor recurrence. Neurological recovery, survival rates, local control, and complications were evaluated. The Kaplan-Meier estimator was used for survival analysis.

RESULTS

A total of 22 patients (nine men and 13 women) with a mean age of 34.1 (range 19-63) years were included. Significant statistical differences were found in the local tumor recurrence rate between patients treated with en bloc resection and those treated with intralesional excision (p < 0.05). The 5- and 10-year local progression-free survival rates were both 90% in the en bloc resection group, while in the intralesional excision group, the 5-year local progression-free survival rate was 80% with a 10-year rate of 45.7%. The en bloc resection group had a lower local tumor recurrence rate than that of the intralesional excision group (p < 0.05), but the former had a higher rate of complications (p = 0.015).

CONCLUSIONS

This study revealed a low local recurrence rate in patients who underwent en bloc resection for giant cell tumors, while the perioperative complication rate was high.

Simvastatin/hydrogel-loaded 3D-printed titanium alloy scaffolds suppress osteosarcoma via TF/NOX2-associated ferroptosis while repairing bone defects

Postoperative anatomical reconstruction and prevention of local recurrence after tumor resection are two vital clinical challenges in osteosarcoma treatment. A three-dimensional (3D)-printed porous Ti6Al4V scaffold (3DTi) is an ideal material for reconstructing critical bone defects with numerous advantages over traditional implants, including a lower elasticity modulus, stronger bone-implant interlock, and larger drug-loading space. Simvastatin is a multitarget drug with anti-tumor and osteogenic potential; however, its efficiency is unsatisfactory when delivered systematically. Here, simvastatin was loaded into a 3DTi using a thermosensitive poly (lactic-co-glycolic) acid (PLGA)-polyethylene glycol (PEG)-PLGA hydrogel as a carrier to exert anti-osteosarcoma and osteogenic effects. Newly constructed simvastatin/hydrogel-loaded 3DTi (Sim-3DTi) was comprehensively appraised, and its newfound anti-osteosarcoma mechanism was explained. Specifically, in a bone defect model of rabbit condyles, Sim-3DTi exhibited enhanced osteogenesis, bone in-growth, and osseointegration compared with 3DTi alone, with greater bone morphogenetic protein 2 expression. In our nude mice model, simvastatin loading reduced tumor volume by 59%-77 % without organic damage, implying good anti-osteosarcoma activity and biosafety. Furthermore, Sim-3DTi induced ferroptosis by upregulating transferrin and nicotinamide adenine dinucleotide phosphate oxidase 2 levels in osteosarcoma both in vivo and in vitro. Sim-3DTi is a promising osteogenic bone substitute for osteosarcoma-related bone defects, with a ferroptosis-mediated anti-osteosarcoma effect.

Comparison of clinical efficacy of 3D-printed artificial vertebral body and conventional titanium mesh cage in spinal reconstruction after total en bloc spondylectomy for spinal tumors: a systematic review and meta-analysis

Propose

This meta-analysis aimed to determine whether 3D-printed artificial vertebral bodies (AVBs) have superior clinical efficacy compared to conventional titanium mesh cages (TMCs) for spinal reconstruction after total en bloc spondylectomy (TES) for spinal tumors.

Methods

Electronic databases, including PubMed, OVID, ScienceDirect, Embase, CINAHL, Web of Science, Cochrane Library, WANFANG, and CNKI, were searched to identify clinical trials investigating 3D-printed AVB versus conventional TMC from inception to August 2023. Data on the operation time, intraoperative blood loss, preoperative and postoperative visual analogue scale (VAS) scores, preoperative and postoperative Frankel classification of spinal cord injury, vertebral body subsidence, and early complications were collected from eligible studies for a meta-analysis. Data were analyzed using Review Manager 5.4 and Stata 14.0.

Results

Nine studies assessing 374 patients were included. The results revealed significant differences between the 3D-printed AVB and conventional TMC groups with regard to operation time (P = 0.04), intraoperative blood loss (P = 0.004), postoperative VAS score (P = 0.02), vertebral body subsidence (P < 0.0001), and early complications (P = 0.02). Conversely, the remaining preoperative VAS score and Frankel classifications (pre-and postoperative) did not differ significantly between the groups.

Conclusion

The 3D-printed AVB in spinal reconstruction after TES for spinal tumors has the advantages of a short operative time, little intraoperative blood loss, weak postoperative pain, low occurrence of vertebral body subsidence and early complications, and a significant curative effect. This could provide a strong basis for physicians to make clinical decisions.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023441521, identifier CRD42023441521.

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

BACKGROUND

The outcomes of patients with tumors of the thoracolumbar spine treated with en bloc resection (EBR) using three-dimensional (3D)-printed endoprostheses are underreported.

METHODS

We 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.

RESULTS

A 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.

CONCLUSIONS

EBR 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.

Reconstruction after resection of C2 vertebral tumors: A comparative study of 3D-printed vertebral body versus titanium mesh

Background

Surgical resection of C2 vertebral tumors is challenging owing to the complex anatomy of C2 vertebrae and the challenges to surgical exposure. Various surgical approaches are available, but some are associated with excessively high risks of complications. An additional challenge is reconstruction of the upper cervical spine following surgery. In the last decade, additive-manufacturing personalized artificial vertebral bodies (AVBs) have been introduced for the repair of large, irregular bony defects; however, their use and efficacy in upper cervical surgery have not been well addressed. Therefore, in this study, we compared instrumented fixation status between patients who underwent conventional titanium mesh reconstruction and those who underwent the same resection but with personalized AVBs.

Methods

We performed a retrospective comparative study and recruited a single-institution cohort of patients with C2 vertebral tumors. Clinical data and imaging findings were reviewed. Through data processing and comparative analysis, we described and discussed the feasibility and safety of surgical resection and the outcomes of hardware implants. The primary outcome of this study was instrumented fixation status.

Results

The 31 recruited patients were divided into two groups. There were 13 patients in group A who underwent conventional titanium mesh reconstruction and 18 group B patients who underwent personalized AVBs. All patients underwent staged posterior and anterior surgical procedures. In the cohort, 9.7% achieved total en bloc resection of the tumor, while gross total resection was achieved in the remaining 90.3%. The perioperative complication and mortality rates were 45.2% and 6.5%, respectively. The occurrence of perioperative complications was related to the choice of anterior approach (p < 0.05). Group A had a higher complication rate than group B (p < 0.05). Four patients (4/13, 30.8%) developed hardware problems during the follow-up period; however, this rate was marginally higher than that of group B (1/18, 5.6%).

Conclusions

Total resection of C2 vertebral tumors was associated with a high risk of perioperative complications. The staged posterior and retropharyngeal approaches are better surgical strategies for C2 tumors. Personalized AVBs can provide a reliable reconstruction outcome, yet minor pitfalls remain that call for further modification.