Application of Titanium Alloy 3D-Printed Artificial Vertebral Body for Stage III Kümmell's Disease Complicated by Neurological Deficits

Current Applications of the Three-Dimensional Printing Technology in Neurosurgery: A Review

BACKGROUND

 In the recent years, three-dimensional (3D) printing technology has emerged as a transformative tool, particularly in health care, offering unprecedented possibilities in neurosurgery. This review explores the diverse applications of 3D printing in neurosurgery, assessing its impact on precision, customization, surgical planning, and education.

METHODS

 A literature review was conducted using PubMed, Web of Science, Embase, and Scopus, identifying 84 relevant articles. These were categorized into spine applications, neurovascular applications, neuro-oncology applications, neuroendoscopy applications, cranioplasty applications, and modulation/stimulation applications.

RESULTS

 3D printing applications in spine surgery showcased advancements in guide devices, prosthetics, and neurosurgical planning, with patient-specific models enhancing precision and minimizing complications. Neurovascular applications demonstrated the utility of 3D-printed guide devices in intracranial hemorrhage and enhanced surgical planning for cerebrovascular diseases. Neuro-oncology applications highlighted the role of 3D printing in guide devices for tumor surgery and improved surgical planning through realistic models. Neuroendoscopy applications emphasized the benefits of 3D-printed guide devices, anatomical models, and educational tools. Cranioplasty applications showed promising outcomes in patient-specific implants, addressing biomechanical considerations.

DISCUSSION

 The integration of 3D printing into neurosurgery has significantly advanced precision, customization, and surgical planning. Challenges include standardization, material considerations, and ethical issues. Future directions involve integrating artificial intelligence, multimodal imaging fusion, biofabrication, and global collaboration.

CONCLUSION

 3D printing has revolutionized neurosurgery, offering tailored solutions, enhanced surgical planning, and invaluable educational tools. Addressing challenges and exploring future innovations will further solidify the transformative impact of 3D printing in neurosurgical care. This review serves as a comprehensive guide for researchers, clinicians, and policymakers navigating the dynamic landscape of 3D printing in neurosurgery.

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.

Advances in Implant Technologies for Spine Surgery

Spine implants are becoming increasingly diversified. Taking inspiration from other industries, three-dimensional modeling of the spinal column has helped meet the custom needs of individual patients as both en bloc replacements and pedicle screw designs. Intraoperative tailoring of devices, a common need in the operating room, has led to expandable versions of cages and interbody spacers.

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.

Biomechanical behaviour of a novel bone cement screw in the minimally invasive treatment of Kummell's disease: a finite element study

OBJECTIVE

To investigate and evaluate the biomechanical behaviour of a novel bone cement screw in the minimally invasive treatment of Kummell's disease (KD) by finite element (FE) analysis.

METHODS

A validated finite element model of healthy adult thoracolumbar vertebrae T12-L2 was given the osteoporotic material properties and the part of the middle bone tissue of the L1 vertebral body was removed to make it wedge-shaped. Based on these, FE model of KD was established. The FE model of KD was repaired and treated with three options: pure percutaneous vertebroplasty (Model A), novel unilateral cement screw placement (Model B), novel bilateral cement screw placement (Model C). Range of motion (ROM), maximum Von-Mises stress of T12 inferior endplate and bone cement, relative displacement of bone cement, and stress distribution of bone cement screws of three postoperative models and intact model in flexion and extension, as well as lateral bending and rotation were analyzed and compared.

RESULTS

The relative displacements of bone cement of Model B and C were similar in all actions studied, and both were smaller than that of Model A. The minimum value of relative displacement of bone cement is 0.0733 mm in the right axial rotation of Model B. The maximum Von-Mises stress in T12 lower endplate and bone cement was in Model C. The maximum Von-Mises stress of bone cement screws in Model C was less than that in Model B, and it was the most substantial in right axial rotation, which is 34%. There was no substantial difference in ROM of the three models.

CONCLUSION

The novel bone cement screw can effectively reduce the relative displacement of bone cement by improving the stability of local cement. Among them, novel unilateral cement screw placement can obtain better fixation effect, and the impact on the biomechanical environment of vertebral body is less than that of novel bilateral cement screw placement, which provides a reference for minimally invasive treatment of KD in clinical practice.

Congenital Cervical Scoliosis Treated with Concave Side Distraction with Three-Dimensional Printed Titanium Cage

STUDY DESIGN

Single-center, retrospective study.

OBJECTIVE

Hemivertebra resection is the only treatment option for congenital cervical scoliosis (CCS). However, this procedure is complex and technically demanding. It often requires a considerably long operation, and there is substantial intraoperative bleeding. Therefore, we have attempted to treat CCS with a concave side distraction comprising a three-dimensional (3D) printed titanium cage. The purpose of this study is to evaluate the safety and efficacy of this technique for the treatment of patients with CCS.

METHODS

A series of 22 patients with CCS who underwent a concave side distraction technique between 2019 and 2021 were retrospectively reviewed and analyzed. Radiological measurements included the Cobb angle of the distraction segments, the kyphosis angle, the range of movement, and the distraction correction angle. Student's t-test and Spearman correlation analysis were used for statistical analysis. p < 0.05 was considered statistically significant.

RESULTS

The study included 12 males and 10 females whose ages ranged from 6 to 14 years old (9.8 ± 2.1 years old). Follow-up times ranged from 15 to 30 months (25.8 ± 3.6 months). Among 22 patients, two patients developed a postoperative C5 nerve root palsy and recovered after being treated with conservative treatment for 6 months. The duration of surgery ranged from 229 to 756 min (389 ± 112 min), and the estimated volume of blood loss ranged from 100 to 600mL (235 ± 121 mL). The coronal Cobb angle (p < 0.001), kyphosis angle (p < 0.05), and range of movement (p < 0.001) between the last follow-up and preoperative period were significantly different. A total of 28 segments were distracted, and the Cobb angle of the distraction segment ranged from 2.4 to 14.1° (8.5 ± 3.0°). There were six upper cervical spines (8.9 ± 1.9°) and 22 lower cervical spines (8.4 ± 3.2°) with no significant difference between them (p = 0.130). In addition, there was no correlation between the angle of the concave side distraction and patients' age (r = 0.018, p = 0.315). The fusion was solid between the bone and the customized 3D-printed pore metal cage at the final follow-up.

CONCLUSION

The concave side distraction comprising a customized 3D-printed titanium cage implantation can provide satisfactory correction results and is a safe and reliable procedure for treating CCS.

Modified posterior osteotomy for osteoporotic vertebral collapse with neurological dysfunction in thoracolumbar spine: a preliminary study

OBJECTIVE

The risk of osteoporotic vertebral collapse (OVC) associated with delayed neurological dysfunction (DND) is substantial, and performing surgery for this condition in elderly patients presents challenges. The focus of the current research is on simplifying surgical procedures while maintaining their effectiveness. This study was designed to contribute clinical data supporting the use of modified posterior osteotomy for treating thoracolumbar OVC with DND. The study compares perioperative clinical parameters, imaging data characteristics, and changes in efficacy outcome indicators to provide evidence for the advancement of this technique.

METHODS

A total of 12 patients diagnosed with osteoporotic vertebral collapse and neurological dysfunction were included in the study. All patients underwent modified posterior osteotomy. Data regarding perioperative and radiological parameters as well as complications such as surgery duration, blood loss, ASIA grade, VAS, ODI, regional kyphosis angle (RKA), anterior vertebral height ratio (AVHr), and spinal canal clearance ratio (SCCr), were collected retrospectively. These parameters were then analysed to evaluate the clinical efficacy and safety of the modified posterior osteotomy technique.

RESULTS

A total of 12 patients were included in the study, with a mean age of 65.5 ± 9.7 years. The average follow-up period was 29.4 ± 5.0 months. The mean operative blood loss was 483.3 ± 142.0 ml, and the average operative time was 3.7 ± 0.7 h. The visual analogue scale (VAS) score decreased from a preoperative value of 5.8 ± 0.7 to a final follow-up value of 1.3 ± 0.8 (P < 0.05), indicating a significant improvement in pain. The ODI decreased from 65.2 ± 6.0 before surgery to 20.5 ± 7.0, indicating a decrease in disability, and the postoperative neurological function showed a significant improvement. Correction of the RKA was observed, with the angle changing from 35.8 ± 10.8° before surgery to 20.0 ± 3.5° after surgery and to 22.5 ± 3.1° at the final follow-up. Similarly, correction of the AVHr was observed, with the height changing from 39.3 ± 18.0 to 63.0 ± 14.3 after surgery and to 53.9 ± 8.9 at the final follow-up. Correction of the SCCr was also observed, with the ratio changing from 54.9 ± 5.4 to 68.1 ± 5.3 after surgery and to 68.68 ± 6.76 at the final follow-up.

CONCLUSIONS

Posterior modified osteotomy is an effective treatment for thoracolumbar osteoporotic fractures with OVC combined with DND. It can significantly preserve vertebral height, increase vertebral canal volume, correct kyphotic angle, and improve postoperative neurological function. The simplified osteotomy also offers advantages in terms of operating time, blood loss, postoperative VAS score, and improvement in lumbar function.

3D printing metal implants in orthopedic surgery: Methods, applications and future prospects

Background

Currently, metal implants are widely used in orthopedic surgeries, including fracture fixation, spinal fusion, joint replacement, and bone tumor defect repair. However, conventional implants are difficult to be customized according to the recipient's skeletal anatomy and defect characteristics, leading to difficulties in meeting the individual needs of patients. Additive manufacturing (AM) or three-dimensional (3D) printing technology, an advanced digital fabrication technique capable of producing components with complex and precise structures, offers opportunities for personalization.

Methods

We systematically reviewed the literature on 3D printing orthopedic metal implants over the past 10 years. Relevant animal, cellular, and clinical studies were searched in PubMed and Web of Science. In this paper, we introduce the 3D printing method and the characteristics of biometals and summarize the properties of 3D printing metal implants and their clinical applications in orthopedic surgery. On this basis, we discuss potential possibilities for further generalization and improvement.

Results

3D printing technology has facilitated the use of metal implants in different orthopedic procedures. By combining medical images from techniques such as CT and MRI, 3D printing technology allows the precise fabrication of complex metal implants based on the anatomy of the injured tissue. Such patient-specific implants not only reduce excessive mechanical strength and eliminate stress-shielding effects, but also improve biocompatibility and functionality, increase cell and nutrient permeability, and promote angiogenesis and bone growth. In addition, 3D printing technology has the advantages of low cost, fast manufacturing cycles, and high reproducibility, which can shorten patients' surgery and hospitalization time. Many clinical trials have been conducted using customized implants. However, the use of modeling software, the operation of printing equipment, the high demand for metal implant materials, and the lack of guidance from relevant laws and regulations have limited its further application.

Conclusions

There are advantages of 3D printing metal implants in orthopedic applications such as personalization, promotion of osseointegration, short production cycle, and high material utilization. With the continuous learning of modeling software by surgeons, the improvement of 3D printing technology, the development of metal materials that better meet clinical needs, and the improvement of laws and regulations, 3D printing metal implants can be applied to more orthopedic surgeries.

The translational potential of this paper

Precision, intelligence, and personalization are the future direction of orthopedics. It is reasonable to believe that 3D printing technology will be more deeply integrated with artificial intelligence, 4D printing, and big data to play a greater role in orthopedic metal implants and eventually become an important part of the digital economy. We aim to summarize the latest developments in 3D printing metal implants for engineers and surgeons to design implants that more closely mimic the morphology and function of native bone.

An overview of 3D printed metal implants in orthopedic applications: Present and future perspectives

With the ability to produce components with complex and precise structures, additive manufacturing or 3D printing techniques are now widely applied in both industry and consumer markets. The emergence of tissue engineering has facilitated the application of 3D printing in the field of biomedical implants. 3D printed implants with proper structural design can not only eliminate the stress shielding effect but also improve in vivo biocompatibility and functionality. By combining medical images derived from technologies such as X-ray scanning, CT, MRI, or ultrasonic scanning, 3D printing can be used to create patient-specific implants with almost the same anatomical structures as the injured tissues. Numerous clinical trials have already been conducted with customized implants. However, the limited availability of raw materials for printing and a lack of guidance from related regulations or laws may impede the development of 3D printing in medical implants. This review provides information on the current state of 3D printing techniques in orthopedic implant applications. The current challenges and future perspectives are also included.

Customized three dimensional printed prosthesis as a novel intercalary reconstruction for resection of extremity bone tumours: a retrospective cohort study

AIMS

The 3D-printed prosthesis (3DP) is a novel treatment for massive bone defect reconstruction after tumor resection. This study was aiming to explore the clinical efficacy of customized 3DP for intercalary reconstruction by comparing the clinical outcomes after implanting customized 3DP or conventional allograft in limb salvage surgery.

METHODS

A total of 28 patients with extremity bone tumors who underwent customized 3DP or conventional allograft reconstruction between 2011 and 2018 at our institution were analyzed retrospectively. Among them, 14 cases received customized 3DP reconstruction (3DP group), and 14 cases received conventional allograft reconstruction (control group). Demographics, surgical outcomes, radiographical assessments, limb functions, and post-operative complications between these two groups were collected to evaluate clinical outcomes.

RESULTS

No significant difference was observed in the demographics, mean intra-operative blood loss, MOSI scores, and MSTS scores between the two groups. Patients in 3DP group had a shorter operative time (157.9 vs 199.6 min, p = 0.03) and lesser number of fluoroscopy (4.1 vs 8.1, p < 0.001) compared to control group. The mean time to osseointegration at bone-implant interfaces in 3DP group was significantly earlier than that in control group (6.1 vs 12.2 months, p < 0.001). Moreover, the 3DP group had a significantly lower post-operative complication rate than the control group (7% vs 50%, p = 0.03).

CONCLUSIONS

The customized 3DP might provide a promising strategy for intercalary reconstruction in limb salvage surgery with more precise reconstruction, higher surgical efficiency, and comparable satisfactory clinical outcomes.

3D printing applications in spine surgery: an evidence-based assessment toward personalized patient care

PURPOSE

Spine surgery entails a wide spectrum of complicated pathologies. Over the years, numerous assistive tools have been introduced to the modern neurosurgeon's armamentarium including neuronavigation and visualization technologies. In this review, we aimed to summarize the available data on 3D printing applications in spine surgery as well as an assessment of the future implications of 3D printing.

METHODS

We performed a comprehensive review of the literature on 3D printing applications in spine surgery.

RESULTS

Over the past decade, 3D printing and additive manufacturing applications, which allow for increased precision and customizability, have gained significant traction, particularly spine surgery. 3D printing applications in spine surgery were initially limited to preoperative visualization, as 3D printing had been primarily used to produce preoperative models of patient-specific deformities or spinal tumors. More recently, 3D printing has been used intraoperatively in the form of 3D customizable implants and personalized screw guides.

CONCLUSIONS

Despite promising preliminary results, the applications of 3D printing are so recent that the available data regarding these new technologies in spine surgery remains scarce, especially data related to long-term outcomes.