Novel approach for the efficient use of a full-scale, 3-dimensional model for cervical posterior fixation: a technical case report

Patient-Specific Highly Realistic Spine Surgery Phantom Trainers

A realistic phantom created from a three-dimensional (3D)-reconstructed digital patient model would enable researchers to investigate the morphological aspects of the pathological spine, thereby resolving the issue of scarce cadaveric specimens. We designed a patient-specific, human-like, reliable, and cost-effective prototype of the examined pathological spine through open-source editing software analysis, a desktop 3D printer, and alginate material. We aimed to validate that the major surgical steps and anatomy replicated the real surgery as it would be conducted in actual patients.We cover the fundamental principles and procedures involved in 3D printing, from spine imaging to phantom manufacturing. Three representative simulation cases were included in the study. All phantoms were sequentially evaluated by surgeons for fidelity. Following each surgery, participants were given a survey that included 20 questions regarding the fidelity of the training phantom.We validated this simulation model by analyzing neurosurgeons' performance on the phantom trainer. Based on a 20-item survey to test content validity and reliability, there was little variation among participants' ratings, and the feedback was consistently positive. The gross appearance of the phantom was analogous to the cadaveric specimen and the phantoms demonstrated an excellent ability to imitate the intraoperative condition. The plastic material expenditure ranged from 170 to 470 g, and the alginate expenditure was 450 g. The total cost of acrylonitrile butadiene styrene (ABS) varied from $5.1 to $17.6 ($0.03 per gram of ABS), whereas the total cost of alginate was $14.3. The average cost of our phantoms was approximately $25.7, and the 3D printer used in this study costs approximately $200.The basic properties of this phantom were similar to cadaveric tissue during manipulation. We believe our phantoms have the potential to improve skills and minimize risk for patients when integrated into trainee education.

3D Printed Patient-Specific Complex Hip Arthroplasty Models Streamline the Preoperative Surgical Workflow: A Pilot Study

Introduction: Surgical planning for complex total hip arthroplasty (THA) often presents a challenge. Definitive plans can be difficult to decide upon, requiring unnecessary equipment to be ordered and a long theatre list booked. We present a pilot study utilising patient-specific 3D printed models as a method of streamlining the pre-operative planning process. Methods: Complex patients presenting for THA were referred to the research team. Patient-specific 3D models were created from routine Computed Tomography (CT) imaging. Simulated surgery was performed to guide prosthesis selection, sizing and the surgical plan. Results: Seven patients were referred for this pilot study, presenting with complex conditions with atypical anatomy. Surgical plans provided by the 3D models were more detailed and accurate when compared to 2D CT and X ray imaging. Streamlined equipment selection was of great benefit, with augments avoided post simulation in three cases. The ability to tackle complex surgical problems outside of the operating theatre also flagged potential complications, while also providing teaching opportunities in a low risk environment. Conclusion: This study demonstrated that 3D printed models can improve the surgical plan and streamline operative logistics. Further studies investigating the optimal 3D printing material and workflow, along with cost-benefit analyses are required before this process is ready for routine use.

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 Drill Guides Versus Fluoroscopic-guided Freehand Technique for Pedicle Screw Placement: A Systematic Review and Meta-analysis of Radiographic, Operative, and Clinical Outcomes

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

The objective of this study was to compare surgical, clinical, and radiographic outcomes of 3-dimensional printed (3DP) drill guides to the fluoroscopic-guided, freehand placement of pedicle screws in the spine.

SUMMARY OF BACKGROUND DATA

3DP is a budding technology in spine surgery and has recently been applied to patient-specific drill guides for pedicle screw placement. Several authors have reported the benefits of these drill guides, but no clear consensus exists on their utility.

MATERIALS AND METHODS

A comprehensive search of the literature was conducted and independent reviewers assessed eligibility for included studies. Outcomes analyzed included: total operation time, estimated blood loss, screw accuracy, pain score, Japanese Orthopedic Association score, and postoperative complications. Weighted mean differences (WMD) and weighted risk differences were calculated using a random-effects model.

RESULTS

Six studies with a total of 205 patients were included. There were significantly lower operation times [WMD=-32.32 min, 95% confidence interval (CI)=-53.19 to -11.45] and estimated blood loss (WMD=-51.42 mL, 95% CI=-81.12 to -21.72) in procedures performed with 3DP drill guides as compared with freehand technique. The probability of "excellent" screw placement was significantly higher in 3DP guides versus freehand (weighted risk difference=-0.12, 95% CI=-0.17 to 0.07); however, no differences were observed in "poor" or "good" screw placement. There were no significant differences between groups in pain scores or Japanese Orthopedic Association scores. No difference in the rate of surgical complications was noted between the groups.

CONCLUSIONS

Pedicle screws placed with 3DP drill guides may result in shorter operative time, less blood loss, and a greater probability of excellent screw placement as compared with those placed with freehand techniques. We conclude that 3DP guides may potentially develop into an efficient and accurate option for pedicle screw placement. However, more prospective, randomized controlled trials are needed to strengthen the confidence of these conclusions.

LEVEL OF EVIDENCE

Level III.

3-Dimensional printing guide template assisted percutaneous vertebroplasty: Technical note

Percutaneous vertebroplasty (PVP) is currently considered as an effective treatment for pain caused by acute osteoporotic vertebral compression fracture. Recently, puncture-related complications are increasingly reported. It's important to find a precise technique to reduce the puncture-related complications. We report a case and discussed the novel surgical technique with step-by-step operating procedures, to introduce the precise PVP assisted by a 3-dimensional printing guide template. Based on the preoperative CT scan and infrared scan data, a well-designed individual guide template could be established in a 3-dimensional reconstruction software and printed out by a 3-dimensional printer. In real operation, by matching the guide template to patient's back skin, cement needles' insertion orientation and depth were easily established. Only 14 times C-arm fluoroscopy with HDF mode (total exposure dose was 4.5 mSv) were required during the procedure. The operation took only 17 min. Cement distribution in the vertebral body was very good without any puncture-related complications. Pain was significantly relieved after surgery. In conclusion, the novel precise 3-dimensional printing guide template system may allow (1) comprehensive visualization of the fractured vertebral body and the individual surgical planning, (2) the perfect fitting between skin and guide template to ensure the puncture stability and accuracy, and (3) increased puncture precision and decreased puncture-related complications, surgical time and radiation exposure.

Systematic review of 3D printing in spinal surgery: the current state of play

Three-dimensional printing (3DP), also known as "Additive Manufacturing", is a rapidly growing industry, particularly in the area of spinal surgery. Given the complex anatomy of the spine and delicate nature of surrounding structures, 3DP has the potential to aid surgical planning and procedural accuracy. We perform a systematic review of current literature on the applications of 3DP in spinal surgery. Six electronic databases were searched for original published studies reporting cases or outcomes for 3DP surgical models, guides or implants for spinal surgery. The findings of these studies were synthesized and summarized. These searches returned a combined 2,411 articles. Of these, 54 were included in this review. 3DP is currently used for surgical planning, intra-operative surgical guides, customised prostheses as well as "Off-the-Shelf" implants. The technology has the potential for enhanced implant properties, as well as decreased surgical time and better patient outcomes. The majority of the data thus far is from low-quality studies with inherent biases linked with the excitement of a new field. As the body of literature continues to expand, larger scale studies to evaluate advantages and disadvantages, and longer-term follow up will enhance our knowledge of the effect 3DP has in spinal surgery. In addition, issues such as financial impact, time to design and print, materials selection and bio-printing will evolve as this rapidly expanding field matures.