Customized "Whole-Cervical-Vertebral-Body" Reconstruction After Modified Subtotal Spondylectomy of C2-C7 Spinal Tumor Via Piezoelectric Surgery

Patient-specific implants and spinal alignment outcomes

Background

Patient specific (PS) technology has become popular in the field of spine surgery, as it gives surgeons control over the manufacturing of implants based on a patient's anatomy. Patient specific surgical guides, preoperative planning software, and patient specific implants - such as rods and cages, have demonstrated promising results in the literature for helping surgeons achieve spinal alignment goals.

Methods

A review of the literature regarding PS technology in spine surgery for the correction of spinal deformity was performed and is compiled here.

Results

A description of the PS tools currently used for deformity correction and treatment of degenerative spine pathology with example cases are included in this manuscript.

Conclusions

The use of PS technology in spine surgery is an important development in the field that should continue to be studied.

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.

Advancements in Custom 3D-Printed Titanium Interbody Spinal Fusion Cages and Their Relevance in Personalized Spine Care

3D-printing technology has revolutionized spinal implant manufacturing, particularly in developing personalized and custom-fit titanium interbody fusion cages. These cages are pivotal in supporting inter-vertebral stability, promoting bone growth, and restoring spinal alignment. This article reviews the latest advancements in 3D-printed titanium interbody fusion cages, emphasizing their relevance in modern personalized surgical spine care protocols applied to common clinical scenarios. Furthermore, the authors review the various printing and post-printing processing technologies and discuss how engineering and design are deployed to tailor each type of implant to its patient-specific clinical application, highlighting how anatomical and biomechanical considerations impact their development and manufacturing processes to achieve optimum osteoinductive and osteoconductive properties. The article further examines the benefits of 3D printing, such as customizable geometry and porosity, that enhance osteointegration and mechanical compatibility, offering a leap forward in patient-specific solutions. The comparative analysis provided by the authors underscores the unique challenges and solutions in designing cervical, and lumbar spine implants, including load-bearing requirements and bioactivity with surrounding bony tissue to promote cell attachment. Additionally, the authors discuss the clinical outcomes associated with these implants, including the implications of improvements in surgical precision on patient outcomes. Lastly, they address strategies to overcome implementation challenges in healthcare facilities, which often resist new technology acquisitions due to perceived cost overruns and preconceived notions that hinder potential savings by providing customized surgical implants with the potential for lower complication and revision rates. This comprehensive review aims to provide insights into how modern 3D-printed titanium interbody fusion cages are made, explain quality standards, and how they may impact personalized surgical spine care.

Microendoscopic Tailored Spine Decompression as a Less-Invasive, Stability-Preserving Surgical Option to Instrumented Correction in Complex Spine Deformities: A Preliminary Multicenter Experience

OBJECTIVES

The aim of this study was to explore the effectiveness of a less-invasive posterior spine decompression in complex deformities. We studied the potential advantages of the microendoscopic approach, supplemented by the piezoelectric technique, to decompress both sides of the vertebral canal from a one-sided approach to preserve spine stability, ensuring adequate neural decompression.

METHODS

A series of 32 patients who underwent a tailored stability-preserving microendoscopic decompression for lumbar spine degenerative disease was retrospectively analyzed. The patients underwent selective bilateral decompression via a monolateral approach, without the skeletonization of the opposite side. For omo- and the contralateral decompression, we used a microscopic endoscopy-assisted approach, with the assistance of piezosurgery, to work safely near the exposed dura mater. Piezoelectric osteotomy is extremely effective in bone removal while sparing soft tissues.

RESULTS

In all patients, adequate decompression was achieved with a high rate of spine stability preservation. The approach was essential in minimizing the opening, therefore reducing the risk of spine instability. Piezoelectric osteotomy was useful to safely perform the undercutting of the base of the spinous process for better contralateral vision and decompression without damaging the exposed dura. In all patients, a various degree of neurologic improvement was observed, with no immediate spine decompensation.

CONCLUSIONS

In selected cases, the tailored microendoscopic monolateral approach for bilateral spine decompression with the assistance of piezosurgery is adequate and safe and shows excellent results in terms of spine decompression and stability preservation.

Technical aspects of total spondylectomy of C2

BACKGROUND

Tumorous involvement of the second cervical vertebra is an infrequent, but severe disease. Primary tumors and solitary metastases can be addressed by a radical procedure, a complete removal of the whole compartment. The second cervical vertebra has a highly complex anatomy, and its operation requires considerable surgical skills. The aim of this retrospective study is to present technical aspects of complete resection of C2 for tumor indications, clinical and radiological evaluation of our group of patients and comparison of results of recent reports on surgery in this region in the literature.

METHODS

Between 2006 and 2019 we performed 10 total resections of C2 for primary bone tumor or solitary metastasis at our department. Operation was indicated for chordoma in 4 cases and for other diagnoses (plasmacytoma, EWSA, metastases of papillary thyroid carcinoma, medullary thyroid carcinoma, lung carcinoma and sinonasal carcinoma) in one case each. The operative procedure was in all cases performed in two steps. It always started with the posterior approach. The anterior procedure was scheduled according to the patient's condition after an average interval of 16.9 days (range 7-21).

RESULTS

A stable upper cervical spine was achieved in all patients. A solid bone fusion over the whole instrumentation was present in all living patients and they returned to their preoperative activity level. By the final follow-up 6 patients died: one patient died on the 5th postop day because of diffuse uncontrollable bleeding from surgical wound, three patients died of generalization of the underlying disease and two patients due to complications associated with local recurrence of the disease. In addition to regular follow-ups, the surviving patients (N.=4) were also examined upon completion of the study, i.e., on average 91 months (range 17-179 months) postoperatively. With exclusion of an early deceased patient, the average follow-up period of deceased patients was 34.6 months (range 9-55) (N.=5). The average follow-up of the whole group of patients was 59,7 months (N.=9).

CONCLUSIONS

Total spondylectomy of C2 is an exceptional surgical procedure associated with risk of serious complications but offers chance for a complete recovery of the patient. Defining indications accurately, especially in solitary metastases, is very difficult even with current level of imaging and other testing. The quality of life of long-term surviving patients in our study was not significantly impacted.

The efficacy and safety of ultrasonic bone scalpel for removing retrovertebral osteophytes in anterior cervical discectomy and fusion: A retrospective study

In this study, we present a novel surgical method that utilizes the ultrasonic bone scalpel (UBS) for the removal of large retrovertebral osteophytes in anterior cervical discectomy and fusion (ACDF) and evaluate its safety and efficacy in comparison to the traditional approach of using high-speed drill (HSD). A total of 56 patients who underwent ACDF for retrovertebral osteophytes were selected. We recorded patients' baseline information, operation time, intraoperative blood loss, complications, JOA and VAS scores, and other relevant data. The mean operation time and the mean intraoperative blood loss in the UBS group were less than those in the HSD group (P < 0.05). Although both groups exhibited considerable improvements in JOA and VAS scores following surgery, there was no statistically significant difference between the two groups (P > 0.05). Additionally, no significant disparities were found in bone graft fusion between the two groups at 6- and 12-months postsurgery. Notably, neither group exhibited complications such as dura tear or spinal cord injury. Our study found that the use of UBS reduced operative time, minimized surgical bleeding, and led to clinical outcomes comparable to HSD in ACDF. This technique offers an effective and safe method of removing large retrovertebral osteophytes.

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.

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

BACKGROUND

The 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.

METHODS

Three 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.

FINDINGS

For 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.

INTERPRETATION

The findings of this study may provide guidance on clinical treatments for choosing more appropriate fixation methods for different patients.

The Role of 3D-Printed Custom-Made Vertebral Body Implants in the Treatment of Spinal Tumors: A Systematic Review

In spinal surgery, 3D prothesis represents a useful instrument for spinal reconstruction after the removal of spinal tumors that require an “en bloc” resection. This represents a complex and demanding procedure, aiming to restore spinal length, alignment and weight-bearing capacity and to provide immediate stability. Thus, in this systematic review the authors searched the literature to investigate and discuss the advantages and limitations of using 3D-printed custom-made vertebral bodies in the treatment of spinal tumors. A systematic literature review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, with no limits in terms of date of publication. The collected studies were exported to Mendeley. The articles were selected according to the following inclusion criteria: availability of full articles, full articles in English, studies regarding the implant of 3D custom-made prothesis after total or partial vertebral resection, studies regarding patients with a histologically confirmed diagnosis of primary spinal tumor or solitary bone metastasis; studies evaluating the implant of 3d custom-made prothesis in the cervical, thoracic, and lumbar spine. Nineteen published studies were included in this literature review, and include a total of 87 patients, 49 males (56.3%) and 38 females (43.7%). The main tumoral location and primary tumor diagnosis were evaluated. The 3D custom-made prothesis represents a feasible tool after tumor en-bloc resection in spinal reconstruction. This procedure is still evolving, and long-term follow-ups are mandatory to assess its safeness and usefulness.

Reconstruction of the cervical lateral mass using 3D-printed prostheses

Objective

This study aimed to investigate the outcome of using 3-dimensional (3D)-printed prostheses to reconstruct a cervical lateral mass to maintain cervical stability.

Methods

We retrospectively analyzed data of 7 patients who underwent cervical lateral mass reconstruction using a 3D-printed prosthesis, comprising axial and subaxial lateral mass reconstruction in 2 and 5 patients, respectively. Bilateral mass was reconstructed in 1 patient and unilateral mass in the remaining 6 patients.

Results

Using a 3D-printed lateral mass prosthesis, internal fixation was stable for all 7 patients postoperatively. No implant-related complications such as prosthesis loosening, displacement, and compression were observed at the last follow-up.

Conclusion

Reconstruction of the lateral mass structure is beneficial in restoring load transfer in the cervical spine under physiological conditions. A 3D-printed prosthesis can be considered a good option for reconstruction of the lateral mass as fusion was achieved, with no subsequent complications observed.

3D-printed Patient-specific Spine Implants: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To review the current clinical use of 3-dimensional printed (3DP) patient-specific implants in the spine.

SUMMARY OF BACKGROUND DATA

Additive manufacturing is a transformative manufacturing method now being applied to spinal implants. Recent innovations in technology have allowed the production of medical-grade implants with unprecedented structure and customization, and the complex anatomy of the spine is ideally suited for patient-specific devices. Improvement in implant design through the process of 3DP may lead to improved osseointegration, lower subsidence rates, and faster operative times.

METHODS

A comprehensive search of the literature was conducted using Ovid MEDLINE, EMBASE, Scopus, and other sources that resulted in 1842 unique articles. All manuscripts describing the use of 3DP spinal implants in humans were included. Two independent reviewers (N.W. and N.E.S.) assessed eligibility for inclusion. The following outcomes were collected: pain score, Japanese Orthopedic Association (JOA) score, subsidence, fusion, Cobb angle, vertebral height, and complications. No conflicts of interest existed. No funding was received for this work.

RESULTS

A total of 17 studies met inclusion criteria with a total of 35 patients. Only case series and case reports were identified. Follow-up times ranged from 3 to 36 months. Implant types included vertebral body replacement cages, interbody cages, sacral reconstruction prostheses, iliolumbar rods, and a posterior cervical plate. All studies reported improvement in both clinical and radiographic outcomes. 11 of 35 cases showed subsidence >3 mm, but only 1 case required a revision procedure. No migration, loosening, or pseudarthrosis occurred in any patient on the basis of computed tomography or flexion-extension radiographs.

CONCLUSIONS

Results of the systematic review indicate that 3DP technology is a viable means to fabricate patient-matched spinal implants. The effects on clinical and radiographic outcome measures are still in question, but these devices may produce favorable subsidence and pseudoarthrosis rates. Currently, the technology is ideally suited for complex tumor pathology and atypical bone defects. Future randomized controlled trials and cost analyses are still needed.

LEVEL OF EVIDENCE

IV-systematic review.

Three-Dimensional Printed Anatomic Modeling for Surgical Planning and Real-Time Operative Guidance in Complex Primary Spinal Column Tumors: Single-Center Experience and Case Series

OBJECTIVE

Three-dimensional (3D) printing has emerged as a visualization tool for clinicians and patients. We sought to use patient-specific 3D-printed anatomic modeling for preoperative planning and live intraoperative guidance in a series of complex primary spine tumors.

METHODS

Over 9 months, patients referred to a single neurosurgical provider for complex primary spinal column tumors were included. Most recent spinal magnetic resonance and computed tomography (CT) imaging were semiautomatically segmented for relevant anatomy and models were printed using polyjet multicolor printing technology. Models were available to surgical teams before and during the operative procedure. Patients also viewed the models preoperatively during surgeon explanation of disease and surgical plan to aid in their understanding.

RESULTS

Tumor models were prepared for 9 patients, including 4 with chordomas, 2 with schwannomas, 1 with osteosarcoma, 1 with chondrosarcoma, and 1 with Ewing-like sarcoma. Mean age was 50.7 years (range, 15-82 years), including 6 males and 3 females. Mean tumor volume was 129.6 cm³ (range, 3.3-250.0 cm³). Lesions were located at cervical, thoracic, and sacral levels and were treated by various surgical approaches. Models were intraoperatively used as patient-specific anatomic references throughout 7 cases and were found to be technically useful by the surgical teams.

CONCLUSIONS

We present the largest case series of 3D-printed spine tumor models reported to date. 3D-printed models are broadly useful for operative planning and intraoperative guidance in spinal oncology surgery.

3D-printed spine surgery implants: a systematic review of the efficacy and clinical safety profile of patient-specific and off-the-shelf devices

PURPOSE

Three-dimensional printing (3DP), or additive manufacturing, is an emergent fabrication technology for surgical devices. As a production method, 3DP enables physical realisation of surgical implants from geometrically complex digital-models in computer-aided design. Spine surgery has been an innovative adopter of 3DP technology for both patient-specific (PS) and market-available 'Off-The-Shelf' (OTS) implants. The present study assessed clinical evidence for efficacy and safety of both PS and OTS 3DP spinal implants through review of the published literature. The aim was to evaluate the clinical utility of 3DP devices for spinal surgery.

METHODS

A systematic literature review of peer-reviewed papers featured on online medical databases evidencing the application of 3DP (PS and OTS) surgical spine implants was conducted in accordance with PRISMA guidelines.

RESULTS

Twenty-two peer-reviewed articles and one book-chapter were eligible for systematic review. The published literature was limited to case reports and case series, with a predominant focus on PS designs fabricated from titanium alloys for surgical reconstruction in cases where neoplasia, infection, trauma or degenerative processes of the spine have precipitated significant anatomical complexity.

CONCLUSION

PS and 3DP OTS surgical implants have demonstrated considerable utility for the surgical management of complex spine pathology. The reviewed literature indicated that 3DP spinal implants have also been used safely, with positive surgeon- and patient-reported outcomes. However, these conclusions are tentative as the follow-up periods are still relatively short and the number of high-powered studies was limited. Single case and small case series reporting would benefit greatly from more standardised reporting of clinical, radiographic and biomechanical outcomes. These slides can be retrieved under Electronic Supplementary Material.

Management of C2 Body Giant Cell Tumor by Innovatively Fashioned Iliac Crest Graft and Modified Cervical Mesh Cage Used as Plate

BACKGROUND

Locally aggressive vertebral body tumors of the axis must be treated with wide local excision for best outcome. Reconstruction of the load-bearing vertebra needs to be done after tumor resection in such a manner so as to give stable, long-term fusion in this young population.

METHODS

We describe the management strategy of a 25-year-old acutely quadriplegic patient, with respiratory distress, with a C2 giant cell tumor. The use of a novel iliac crest graft modification used for C2 reconstruction along with a modified mesh cage used as an anterior plate has been reported.

RESULTS

The patient had a good outcome at 18 months' follow-up, with neurologic improvement and a solid fusion.

CONCLUSIONS

Iliac crest autograft is inexpensive and easy to harvest and can be considered as a C2 prosthesis, especially in a resource-constrained setting. Modified iliac crest graft can be used for load transmission from C1 lateral mass to C3 body, and the mesh cage can be modified according to need as a plate with good results in an emergency.

Surgical Resection of Solitary Bone Plasmacytoma of Atlas and Reconstruction with 3-Dimensional-Printed Titanium Patient-Specific Implant

BACKGROUND

Solitary plasmacytoma of bone (SPB) is a rare malignancy of localized osseous lesion consisting of neoplastic monoclonal plasma cells. Recommended treatment of SPB includes a combination of surgery and radiation therapy. We present a rare case of SPB lesion in the atlas requiring surgical resection, followed by restoration of atlas stability with a custom 3-dimensional-printed (3DP) patient-specific implant (PSI).

CASE DESCRIPTION

A 57-year-old man presented with severe neck pain. Assessment by radiographs, computed tomography, and magnetic resonance imaging was found to harbor a single osteolytic lesion at the C1 (atlas) vertebra. Diagnostic tumor screening returned negative results. Transoral biopsy suggested solitary plasmacytoma. Spinal instability was apparent-hence the decision for surgical intervention via the retropharyngeal external approach to resect the lesion. Atlas reconstruction and stabilization were achieved using a custom 3DP titanium PSI. Subsequent pathologic findings confirmed plasma cell infiltration of the atlas. Histologic evaluations and cytogenetic risk analysis indicated a non-high-risk SPB. The patient was given localized radiation therapy at 57 Gy in 27 fractions. Her neurologic complaints were subsequently relieved, and mobility was restored 7 days postoperatively.

CONCLUSIONS

No consensus on the appropriate surgical approaches and perioperative strategies for spinal SPB exists. Surgical intervention is recommended when vertebral instability is evident, followed by radiation therapy to minimize local recurrence and/or progression to multiple myeloma. The use of 3D modeling for preoperative planning improves intraoperative accuracy and avoids iatrogenic injuries to vital anatomic structures. Customized 3DP-PSI to restore atlas stability is an effective option for the treatment of spinal SPBs.

C3-C5 Chordoma Resection and Reconstruction with a Three-Dimensional Printed Titanium Patient-Specific Implant

BACKGROUND

With this case report, we aim to add to the clinical literature on the use of three-dimensional printed patient-specific implants in spinal surgery, show the current state of the art in patient-specific implant device design, present thorough clinical and radiographic outcomes, and discuss the suitability of titanium alloy as an implant material for patients with cancer.

CASE DESCRIPTION

A 45-year-old man presented with neck and left arm pain combined with shoulder weakness. Imaging revealed significant destruction of the C3-C5 vertebrae, and chordoma diagnosis was confirmed by biopsy. Gross total tumor resection including multilevel corpectomy was performed in combination with reconstruction using a three-dimensional printed titanium custom implant. Custom-designed features aimed to reduce reconstruction time and result in good clinical and radiographic outcomes. Clinical scores improved postoperatively and remained improved at 17-month postoperative follow-up: visual analog scale score 10/10 preoperatively improved to 2-6/10 at 17 months; Neck Disability Index 46% preoperatively improved to 32% at 17 months. Neither dysphagia nor dysphonia remained after surgical soft tissue swelling subsided. The patient was successfully treated with proton beam therapy after surgery, with no tumor recurrence at 17-month follow-up. Radiographic assessment showed incomplete fusion at 3 months, with clinically insignificant implant subsidence (2.7 mm) and no implant migration or failure at 14 months.

CONCLUSIONS

Computer-aided preoperative planning with three-dimensional printed biomodels and custom implant resulted in relatively quick and simple reconstruction after tumor resection, with good clinical and radiographic outcomes at 17 and 14 months, respectively. For patients with primary tumors who may require follow-up radiotherapy or postoperative magnetic resonance imaging, metals used in the devices cause significant imaging artifact.