Improved accuracy with 3D planning and patient-specific instruments during simulated pelvic bone tumor surgery

Three-Dimensional-Printed Lesser Metatarsal Replacement: The First Case Report

Different procedures have been reported for severe and recurrent lesser toes deformity. These included DuVries metatarsophalangeal joint arthroplasty, resection arthroplasty, partial proximal phalangectomy, syndactylization, or lesser toe amputation. In the presence of a failed metatarsal head resection, the surgeon is faced with limited salvage options including Hoffman procedure or lesser toe amputation. The 3D printing technology has allowed orthopaedic surgeons to expand the therapeutic arsenal to address challenging situations. We herein present the first case of 3D-printed second lesser metatarsal replacement performed after a failed second metatarsal head resection.Level of Evidence: V.

Do patient-specific cutting guides for pelvic and sacral tumour resection provide tumour-free bone margins?

BACKGROUND

Achieving R0 margin, i.e., tumour-free margin, during conservative surgery for pelvic or sacral tumours is demanding. Small cohort studies suggest that patient-specific instrumentation (PSI) may hold promise, notably for bone margin accuracy. Objectives of this study were to determine whether PSI allowed R0 bone margins; R0 soft-tissue margins; and increased disease-free survival, without local recurrence or distant metastases, comparatively to previous studies of patients treated by free-hand or navigated surgery; and whether PSI positioning for the bone cuts was readily achieved.

HYPOTHESIS

Using PSI provides R0 bone margins in 100% patients and improves disease-free survival).

MATERIAL AND METHODS

Retrospective study including consecutively patients who underwent PSI-assisted surgical resection of a pelvic or sacral tumour between October 2011 and February 2020. Bone and soft-tissue margins were assessed according to the Union for International Cancer Control classification. Overall survival and disease-free survival were evaluated using the Kaplan-Meier method. PSI positioning was assessed by surgeons for each patient on a scale from 5 (excellent) to 1 (failed).

RESULTS

Of the 42 included patients (26 males and 16 females), 34 had primary bone malignancies, 3 had soft-tissue malignancies extended to the bone, 3 had locally aggressive benign bone tumours, and 2 had solitary bone metastases. Mean follow-up was 49 (range 4-112) mo. Bone margins were as follow: R0 in 40 (95%) patients; R1 in 1 (2.5%) and R2 in 1 (2.5%). Soft-tissue margins were as follow: R0 in 76% of patients; R1 in 21.5% of patients. At 5 years, overall disease-free survival was 63.4% (95% CI, 49.3-81.4), survival without local recurrence was 65.5% (95% CI, 47.7-90.0], and survival without distant metastases was 70.1% (95% CI, 55.4-88.5). Positioning of the 60 PSIs used was rated excellent or good in 93.3% of cases and fair or poor in 6.7% of cases; no cases of positioning failure were recorded.

DISCUSSION

PSIs provided excellent accuracy for achieving R0 bone margin. Nonetheless, local recurrence remained high similarly to free-hand surgery. This finding may be related to surgeons relying on PSI's accuracy for maximal preservation.

CONCLUSION

PSIs are technically reliable and safe for obtaining R0 margins during conservative resection surgery to treat pelvic and sacral tumours. However, PSIs do not substantially decrease the local recurrence rate.

LEVEL OF EVIDENCE

IV; retrospective observational cohort study.

Using three-dimensional virtual imaging of renal masses to improve prediction of robotic-assisted partial nephrectomy Tetrafecta with SPARE score

OBJECTIVE

To improve the predictability of outcomes in robotic-assisted partial nephrectomy, we utilized three-dimensional virtual imaging for SPARE nephrometry scoring. We compared this method with a conventional two-dimensional scoring system to determine whether 3D virtual images offer enhanced predictive accuracy for Tetrafecta outcomes.

METHODS

We retrospectively collected basic information, demographic data, and perioperative indices from patients who underwent robot-assisted partial nephrectomy for renal masses at the Department of Urology, First Affiliated Hospital of Xi'an Jiaotong University. A three-dimensional visualization system (IPS system, Yorktal) was employed to reconstruct the patients' imaging data using AI-based automatic segmentation, resulting in a three-dimensional visualization model (3DVM). This model was then imported into the virtual surgical planning software (Touch Viewer System, Yorktal) for automatic measurement of the SPARE score. Tetrafecta was defined as a warm ischemic time (WIT) of less than 25 min, negative surgical margins, absence of major perioperative complications, and no decline in postoperative renal function. The receiver operating characteristic (ROC) curve was utilized to evaluate the sensitivity and specificity of the SPARE score.

RESULTS

A total of 141 patients were included in this study, with a mean age of 55.6 ± 11.14 years and a mean tumor size of 3.5 ± 1.2 cm. All variables, except for estimated blood loss (EBL) (Coefficient = 0.056, 0.035; P = 0.514, 0.685), showed significant correlation with the SPARE score when comparing CT and 3D virtual models (Tetrafecta: Coefficient = 0.408, 0.56; P < 0.001, < 0.001; WIT: Coefficient = 0.340, 0.237; P < 0.001, 0.007; ΔeGFR: Coefficient = 0.212, 0.257; P = 0.012, 0.002). The area under the curve (AUC) values from the ROC curves indicated that the 3D virtual model group had significantly better performance than the 2D image group for the SPARE score. However, there was no significant difference in the ROC curves for the SPARE complexity category between the two imaging modalities (AUC for SPARE category with 3DVM = 0.658 vs. AUC for SPARE category with CT = 0.643, P = 0.59; AUC for SPARE score with 3DVM = 0.854 vs. AUC for SPARE score with CT = 0.755, P < 0.001).

CONCLUSIONS

The SPARE score combined with 3DVM has a more accurate predictive ability for Tetrafecta of RAPN compared to the traditional 2D SPARE score.

Clinical outcomes after extra-articular resection of hip joint tumour using a custom-made osteotomy guide and 3D-printed endoprosthesis with posterior column preserved

Aims

For rare cases when a tumour infiltrates into the hip joint, extra-articular resection is required to obtain a safe margin. Endoprosthetic reconstruction following tumour resection can effectively ensure local control and improve postoperative function. However, maximizing bone preservation without compromising surgical margin remains a challenge for surgeons due to the complexity of the procedure. The purpose of the current study was to report clinical outcomes of patients who underwent extra-articular resection of the hip joint using a custom-made osteotomy guide and 3D-printed endoprosthesis.

Methods

We reviewed 15 patients over a five-year period (January 2017 to December 2022) who had undergone extra-articular resection of the hip joint due to malignant tumour using a custom-made osteotomy guide and 3D-printed endoprosthesis. Each of the 15 patients had a single lesion, with six originating from the acetabulum side and nine from the proximal femur. All patients had their posterior column preserved according to the surgical plan.

Results

Postoperative pathological assessment revealed a negative surgical margin was achieved in all patients. At final follow-up, 13.3% (2/15) died and no recurrence occurred. The overall survival was 81.7% at five years. None of the patients showed any signs of aseptic loosening, and no wound healing issues were observed. In total, 20% (3/15) developed complications, with two cases of early hip dislocation and one case of deep infection. The cumulative incidence of mechanical and non-mechanical failure in this series was 13.7% and 9.3%, respectively, at five years. In this cohort, the mean time to full weightbearing was 5.89 (SD 0.92) weeks and the mean Musculoskeletal Tumor Society score was 24.1 (SD 4.4).

Conclusion

For patients with a hip joint tumour who met the inclusion criteria and were deemed suitable for posterior column preservation, a custom-made osteotomy guide combined with 3D-printed endoprosthesis is worth performing when treating patients who require extra-articular resection of the hip joint, as it can achieve adequate margin for local control, maximize bone preservation to maintain pelvic ring integrity, reduce the risk of complications by simplifying the surgical procedure, and allow for more precise reconstruction for better function.

Patient-specific guides for consistently achieving R0 bone margins after resection of primary malignant bone tumors of the pelvis

AIMS

Primary malignant bone tumor of the pelvis is an uncommon lesion, the resection of which via freehand osteotomy is subject to inaccuracy due to its three-dimensional anatomy. Patient-Specific Guides (PSG), also called Patient-Specific Instruments (PSI) are essential to ensure surgical planning and resection adequacy. Our aim was to assess their use and effectiveness.

METHODS

A monocentric retrospective study was conducted on 42 adult patients who underwent PSG-based resection of a primary malignant bone tumor of the pelvis. The primary outcome was the proportion of R0 bone margins. The secondary outcomes were the proportion of overall R0 margins, considering soft-tissue resection, the cumulative incidence of local recurrence, and the time of production for the guides. A comparison to a previous series at our institution was performed regarding histological margins.

RESULTS

Using PSGs, 100% R0 safe bone margin was achieved, and 88% overall R0 margin due to soft-tissue resection being contaminated, while the comparison to the previous series showed only 80% of R0 safe bone margin. The cumulative incidences of local recurrence were 10% (95% CI: 4-20%) at one year, 15% (95% CI: 6-27%) at two years, and 19% (95% CI: 8-33%) at five years. The median overall duration of the fabrication process of the guide was 35 days (Q1-Q3: 26-47) from the first contact to the surgery date.

CONCLUSIONS

Patient-Specific Guides can provide a reproducible safe bony margin.

Fluoroscopically calibrated 3D-printed patient-specific instruments improve the accuracy of osteotomy during bone tumor resection adjacent to joints

BACKGROUND

Inadequate surface matching, variation in the guide design, and soft tissue on the skeletal surface may make it difficult to accurately place the 3D-printed patient-specific instrument (PSI) exactly to the designated site, leading to decreased accuracy, or even errors. Consequently, we developed a novel 3D-printed PSI with fluoroscopy-guided positioning markers to enhance the accuracy of osteotomies in joint-preserving surgery. The current study was to compare whether the fluoroscopically calibrated PSI (FCPSI) can achieve better accuracy compared with freehand resection and conventional PSI (CPSI) resection.

METHODS

Simulated joint-preserving surgery was conducted using nine synthetic left knee bone models. Osteotomies adjacent to the knee joint were designed to evaluate the accuracy at the epiphysis side. The experiment was divided into three groups: free-hand, conventional PSI (CPSI), and fluoroscopically Calibrated PSI (FCPSI). Post-resection CT scans were quantitatively analyzed. Analysis of variance (ANOVA) was used.

RESULT

FCPSI improved the resection accuracy significantly. The mean location accuracy is 2.66 mm for FCPSI compared to 6.36 mm (P < 0.001) for freehand resection and 4.58 mm (P = 0.012) for CPSI. The mean average distance is 1.27 mm compared to 2.99 mm (p < 0.001) and 2.11 mm (p = 0.049). The mean absolute angle is 2.16° compared to 8.50° (p < 0.001) and 5.54° (p = 0.021). The mean depth angle is 1.41° compared to 8.10° (p < 0.001) and 5.32° (p = 0.012). However, there were no significant differences in the front angle compared to the freehand resection group (P = 0.055) and CPSI (P = 0.599) group. The location accuracy observed with FCPSI was maintained at 4 mm, while CPSI and freehand resection exhibited a maximum deviation of 8 mm.

CONCLUSION

The fluoroscopically calibrated 3D-printed patient-specific instruments improve the accuracy of osteotomy during bone tumor resection adjacent to joint joints compared to conventional PSI and freehand resection. In conclusion, this novel 3D-printed PSI offers significant accuracy improvement in joint preserving surgery with a minimal increase in time and design costs.

How Does Customized Cutting Guide Design Affect Accuracy and Ergonomics in Pelvic Tumor Resection? A Study in Cadavers

BACKGROUND

Customized cutting guides are technical aids that make primary pelvic bone tumor resection safer and more reliable. Although the effectiveness of such devices appears to be widely accepted, their conception and design remain varied. Two main designs have been reported: the heavier block-type customized cutting guides and the lighter patch-type customized cutting guides. As recent tools, there must be more evidence regarding the impact of design on their accuracy and ergonomics. Thus, an evaluation of their respective performances appears warranted.

QUESTIONS/PURPOSES

In a cadaver model, we assessed whether (1) a thinner, patch-type customized cutting guide design results in resections that are closer to the planned resections than the heavier block-type customized cutting guides, and (2) the patch-type customized cutting guide design is more ergonomic than the block-type customized cutting guide with improved usability in surgery (in terms of bulkiness, ease of placement, primary and secondary stability, and stability during cutting).

METHODS

We conducted an experimental study involving five fresh whole-body anatomic specimens (three women and two men with a median age of 79 years and median weight of 66 kg) by simulating six virtual tumors in three areas according to the Enneking classification (Zones I: iliac wing, II: periacetabular area, and I and IV: sacroiliac joint area). We compared the impact of the customized cutting guide's design on performance in terms of the resection margin accuracy using CT scan analysis (deviation from the planned margin at the closest point and the maximum deviation from the planned margin) and the intraoperative ergonomic score under conditions simulating those of an oncologic resection of a bone tumor (with a range of 0 to 100, with 100 being best).

RESULTS

The patch customized cutting guides performed slightly better than the block customized cutting guides regarding deviation from the planned margin at the closest point, with median values of 1 mm versus 2 mm (difference of medians 1 mm; p = 0.02) and maximum deviation from the planned margin of 3 versus 4 mm (difference of medians 1 mm; p = 0.002). In addition, the patch design was perceived to be slightly more ergonomic than the block design, with a 92% median score versus 84% for the block design (difference of medians 8%; p = 0.03).

CONCLUSION

We observed an equivalence in performance regarding accuracy and ergonomics, with slight advantages for patch customized cutting guides, especially in complex zones (Zone I and IV). Owing to a small cohort in a cadaver study, these results need independent replication.

CLINICAL RELEVANCE

The patch-type customized cutting guide with thinner contact spots to the bone in specific areas and less soft tissue dissection might offer an advantage over a larger block design for achieving negative oncologic bony margins, but it does not address issues of soft tissue margins.

Midfoot Tarsectomy in Cavovarus: Why PSI Makes a Difference?

The cavovarus foot is a complex deformity that can be treated using multiple surgical procedures, ranging from soft tissue surgery to triple arthrodesis. Among these options, anterior midfoot tarsectomy is a three-dimensional closed-wedge osteotomy, traditionally performed slowly and progressively in a blind fashion, and remaining a challenge for unexperimented surgeons with variable outcomes. As such, we investigated and discussed the use of patient-specific cutting guides (PSCGs) in computer-assisted anterior midfoot tarsectomy in terms of accuracy, reproducibility, and safety.

Database of segmentations and surface models of bones of the entire lower body created from cadaver CT scans

The range of applications of digital surface models of the bones in science and industry is wide. Three-dimensional reconstructions of bones are used in biomechanics, biomedical engineering, medical image processing, orthopedics, traumatology, radiology, patient education, anatomy, anthropometry, forensic anthropology, ergonomics, usability and human factors engineering, or accident and injury analysis and prevention. No open access database or repository of skeletal surface models of the full lower extremities exists. Therefore, the objective of this publication was to provide access to consistent complete bone models of the pelvis and lower limbs of multiple subjects, including biometric data. Segmentations and surface models of the bones of the lower extremities of more than twenty subjects were created from open access postmortem whole-body computed tomography scans. The database provides a broad range of applications by giving access to the data of the complete process chain, from the raw medical imaging data through the segmentations to the surface models.

Pelvic bone sarcomas, prognostic factors, and treatment: A narrative review of the literature

Primary sarcomas of bone are rare malignant mesenchymal tumors. The most common bone sarcomas are osteosarcoma, Ewing's sarcoma, and chondrosarcoma. The prognosis has improved over the years, but bone sarcomas are still life-threatening tumors that need a multidisciplinary approach for diagnosis and treatment. Bone sarcomas arising in the pelvis present a unique challenge to orthopedic oncologists due to the absence of natural anatomical barriers, the close proximity of vital neurovascular structures, and the high mechanical demands placed on any pelvic reconstruction following the excision of the tumor. While radiotherapy has an important role especially in Ewing's sarcoma and chemotherapy for both Ewing's sarcoma and osteosarcoma, surgery remains the main choice of treatment for all three entities. While external hemipelvectomy has remained one option, the main aim of surgery is limb salvage. After complete tumor resection, the bone defect needs to be reconstructed. Possibilities to reconstruct the defect include prosthetic or biological reconstruction. The method of reconstruction is dependent on the location of tumor and the surgery required for its removal. The aim of this article is to give an insight into pelvic bone sarcomas, their oncological and surgical outcomes, and the options for treatment based on the authors' experiences.

The Role of 3D Printing in Treatment Planning of Spine and Sacral Tumors

Three-dimensional (3D) printing technology has proven to have many advantages in spine and sacrum surgery. 3D printing allows the manufacturing of life-size patient-specific anatomic and pathologic models to improve preoperative understanding of patient anatomy and pathology. Additionally, virtual surgical planning using medical computer-aided design software has enabled surgeons to create patient-specific surgical plans and simulate procedures in a virtual environment. This has resulted in reduced operative times, decreased complications, and improved patient outcomes. Combined with new surgical techniques, 3D-printed custom medical devices and instruments using titanium and biocompatible resins and polyamides have allowed innovative reconstructions.

Insights and trends review: the role of three-dimensional technology in upper extremity surgery

The use of three-dimensional (3-D) technology in upper extremity surgery has the potential to revolutionize the way that hand and upper limb procedures are planned and performed. 3-D technology can assist in the diagnosis and treatment of conditions, allowing virtual preoperative planning and surgical templating. 3-D printing can allow the production of patient-specific jigs, instruments and implants, allowing surgeons to plan and perform complex procedures with greater precision and accuracy. Previously, cost has been a barrier to the use of 3-D technology, which is now falling rapidly. This review article will discuss the current status of 3-D technology and printing, including its applications, ethics and challenges in hand and upper limb surgery. We have provided case examples to outline how clinicians can incorporate 3-D technology in their clinical practice for congenital deformities, management of acute fracture and malunion and arthroplasty.

What are the resection accuracy and guide-fitting errors associated with 3D-printed, patient-specific resection guides for bone tumour resections?

AIMS

This study aimed to analyze the accuracy and errors associated with 3D-printed, patient-specific resection guides (3DP-PSRGs) used for bone tumour resection.

METHODS

We retrospectively reviewed 29 bone tumour resections that used 3DP-PSRGs based on 3D CT and 3D MRI. We evaluated the resection amount errors and resection margin errors relative to the preoperative plans. Guide-fitting errors and guide distortion were evaluated intraoperatively and one month postoperatively, respectively. We categorized each of these error types into three grades (grade 1, < 1 mm; grade 2, 1 to 3 mm; and grade 3, > 3 mm) to evaluate the overall accuracy.

RESULTS

The maximum resection amount error was 2 mm. Out of 29 resection amount errors, 15 (51.7%) were grade 1 errors and 14 (38.3%) were grade 2 errors. Complex resections were associated with higher-grade resection amount errors (p < 0.001). The actual resection margins correlated significantly with the planned margins; however, there were some discrepancies. The maximum guide-fitting error was 3 mm. There were 22 (75.9%), five (17.2%), and two (6.9%) grade 1, 2, and 3 guide-fitting errors, respectively. There was no significant association between complex resection and fitting error grades. The guide distortion after one month in all patients was rated as grade 1.

CONCLUSION

In terms of the accurate resection amount according to the preoperative planning, 3DP-PSRGs can be a viable option for bone tumour resection. However, 3DP-PSRG use may be associated with resection margin length discrepancies relative to the planned margins. Such discrepancies should be considered when determining surgical margins. Therefore, a thorough evaluation of the preoperative imaging and surgical planning is still required, even if 3DP-PSRGs are to be used.Cite this article: Bone Joint J 2023;105-B(2):190-197.

The application of additive manufacturing technology in pelvic surgery: A bibliometrics analysis

With the development of material science, additive manufacturing technology has been employed for pelvic surgery, addressing the challenges, such as the complex structure of the pelvis, difficulty in exposing the operative area, and poor visibility, of the traditional pelvic surgery. However, only limited studies have been done to review the research hotspots and trends of the additive manufacturing technology applied for pelvic surgery. In this study, we comprehensively analyzed the literatures related to additive manufacturing technology in pelvic surgery by a bibliometrics analysis and found that additive manufacturing technology is widely used in several aspects of preoperative diagnosis, preoperative planning, intraoperative navigation, and personalized implants for pelvic surgery. Firstly, we searched and screened 856 publications from the Web of Science Core Collection (WoSCC) with TS = (3D printing OR 3D printed OR three-dimensional printing OR additive manufacturing OR rapid prototyping) AND TS = (pelvis OR sacrum OR ilium OR pubis OR ischium OR ischia OR acetabulum OR hip) as the search strategy. Then, 565 of these were eliminated by evaluating the titles and abstracts, leaving 291 pieces of research literature whose relevant information was visually displayed using VOSviewer. Furthermore, 10 publications with high citations were selected by reading all publications extensively for carefully evaluating their Titles, Purposes, Results, Limitations, Journal of affiliation, and Citations. Our results of bibliometric analysis demonstrated that additive manufacturing technology is increasingly applied in pelvic surgery, providing readers with a valuable reference for fully comprehending the research hotspots and trends in the application of additive manufacturing technology in pelvic surgery.

Review of Enhanced Handheld Surgical Drills

The handheld drill has been used as a conventional surgical tool for centuries. Alongside the recent successes of surgical robots, the development of new and enhanced medical drills has improved surgeon ability without requiring the high cost and consuming setup times that plague medical robot systems. This work provides an overview of enhanced handheld surgical drill research focusing on systems that include some form of image guidance and do not require additional hardware that physically supports or guides drilling. Drilling is reviewed by main contribution divided into audio-, visual-, or hardware-enhanced drills. A vision for future work to enhance handheld drilling systems is also discussed.

Three-dimensional technologies in presurgical planning of bone surgeries: current evidence and future perspectives

BACKGROUND

The recent development of three-dimensional (3D) technologies introduces a novel set of opportunities to the medical field in general, and specifically to surgery. The preoperative phase has proven to be a critical factor in surgical success. Utilization of 3D technologies has the potential to improve preoperative planning and overall surgical outcomes. In this narrative review article, the authors describe existing clinical data pertaining to the current use of 3D printing, virtual reality, and augmented reality in the preoperative phase of bone surgery.

METHODS

The methodology included keyword-based literature search in PubMed and Google Scholar for original articles published between 2014 and 2022. After excluding studies performed in nonbone surgery disciplines, data from 61 studies of five different surgical disciplines were processed to be included in this narrative review.

RESULTS

Among the mentioned technologies, 3D printing is currently the most advanced in terms of clinical use, predominantly creating anatomical models and patient-specific instruments that provide high-quality operative preparation. Virtual reality allows to set a surgical plan and to further simulate the procedure via a 2D screen or head mounted display. Augmented reality is found to be useful for surgical simulation upon 3D printed anatomical models or virtual phantoms.

CONCLUSIONS

Overall, 3D technologies are gradually becoming an integral part of a surgeon's preoperative toolbox, allowing for increased surgical accuracy and reduction of operation time, mainly in complex and unique surgical cases. This may eventually lead to improved surgical outcomes, thereby optimizing the personalized surgical approach.

Internal Hemipelvectomy for primary bone sarcomas using intraoperative patient specific instruments- the next step in limb salvage concept

BACKGROUND

During pelvic Sarcoma resections, Surgeons often struggle to obtain negative margins while minimizing collateral damage and maintaining limb function. These complications are usually due to the complex anatomy of the pelvis. Here we present an accurate 3D surgical approach, including pre-operative printing of models and intraoperative patient-specific instruments (PSIs) for optimizing pelvic sarcoma resections.

METHODS

This single-center retrospective study (N = 11) presents surgical, functional, and oncological outcomes of patients (average age 14.6 +/- 7.6 years, 4 males) who underwent pelvic sarcoma resections using a 3D surgical approach between 2016 and 2021. All patients were followed up for at least 24 months (mean = 38.9 +/- 30.1 months).

RESULTS

Our results show promising surgical, oncological, and functional outcomes. Using a 3D approach, 90.9% had negative margins, and 63.6% did not require reconstruction surgery. The average estimated blood loss was 895.45 ± 540.12 cc, and the average surgery time was 3:38 ± 0.05 hours. Our results revealed no long-term complications. Three patients suffered from short-term complications of superficial wound infections. At 24 month follow up 72.7% of patients displayed no evidence of disease. The average Musculoskeletal Tumor Society (MSTS) score at 12 months was 22.81.

CONCLUSION

3D technology enables improved accuracy in tumor resections, allowing for less invasive procedures and tailored reconstruction surgeries, potentially leading to better outcomes in function and morbidity. We believe that this approach will enhance treatments and ease prognosis for patients diagnosed with pelvic sarcoma and will become the standard of care in the future.

Digital chain for pelvic tumor resection with 3D-printed surgical cutting guides

Surgical cutting guides are 3D-printed customized tools that help surgeons during complex surgeries. However, there does not seem to be any set methodology for designing these patient-specific instruments. Recent publications using pelvic surgical guides showed various designs with no clearly classified or standardized features. We, thus, developed a systematic digital chain for processing multimodal medical images (CT and MRI), designing customized surgical cutting guides, and manufacturing them using additive manufacturing. The aim of this study is to describe the steps in the conception of surgical cutting guides used in complex oncological bone tumor pelvic resection. We also analyzed the duration of the surgical cutting guide process and tested its ergonomics and usability with orthopedic surgeons using Sawbones models on simulated tumors. The original digital chain made possible a repeatable design of customized tools in short times. Preliminary testing on synthetic bones showed satisfactory results in terms of design usability. The four artificial tumors (Enneking I, Enneking II, Enneking III, and Enneking I+IV) were successfully resected from the Sawbones model using this digital chain with satisfactory ergonomic outcomes. This work validates a new digital chain conception and production of surgical cutting guides. Further works with quantitative margin assessments on anatomical subjects are needed to better assess the design implications of patient-specific surgical cutting guide instruments in pelvic tumor resections.

Quality of resection margin with patient specific instrument for bone tumor resection

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Patient-specific instruments (PSI) improve surgical orthopaedic interventions.

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Resection margins are all safe for oncologic resections in our series.

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All types of bone tumour were included.

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Planification margins can be shortened to 5 mm thanks to their accuracy.

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The correlation index between planned and obtained margins is excellent.

Background

Patient Specific Instruments (PSI) is currently a proven technique for bone tumor resection. In a previous publication, we analyzed the quality of margin resection of pelvic sarcoma resections with the use of PSI (by pathologic evaluation of the margins). In this new study, we compare preoperative resection planning and actual resection margins by MRI analysis of the resection specimens.

Methods

Between 2011 and 2020, 31 patients underwent bone tumor resection with the use of PSI. Preoperatively, the margins were planned with a software and PSI were made according to these margins. Postoperatively, the surgical resection specimens were analyzed with MRI. Resection margins were measured with the same software used in the preoperative planning.

Results

All margins were safe (free of tumor). The differences between preoperative planned margins and the obtained ones were within the range −5 to +5 mm. The correlation between planned margin and the obtained one was excellent (R² = 0.841; p < 0.0001).

Conclusions

This study demonstrates the accuracy of PSI. In our series, all resection margins were safe. A minimal 5 mm-margin has to be planned but a larger sample is needed to give recommendations.

Surgical Treatment of Bone Sarcoma

Bone sarcomas are rare primary malignant mesenchymal bone tumors. The three main entities are osteosarcoma, chondrosarcoma, and Ewing sarcoma. While prognosis has improved for affected patients over the past decades, bone sarcomas are still critical conditions that require an interdisciplinary diagnostic and therapeutic approach. While radiotherapy plays a role especially in Ewing sarcoma and chemotherapy in Ewing sarcoma and osteosarcoma, surgery remains the main pillar of treatment in all three entities. After complete tumor resection, the created bone defects need to be reconstructed. Possible strategies are implantation of allografts or autografts including vascularized bone grafts (e.g., of the fibula). Around the knee joint, rotationplasty can be performed or, as an alternative, the implantation of (expandable) megaprostheses can be performed. Challenges still associated with the implantation of foreign materials are aseptic loosening and infection. Future improvements may come with advances in 3D printing of individualized resection blades/implants, thus also securing safe tumor resection margins while at the same time shortening the required surgical time. Faster osseointegration and lower infection rates may possibly be achieved through more elaborate implant surface structures.

The feasibility of creating Image-Based Patient-Specific Drill Guides for the Atlantoaxial Instabilities using open-source CAD software and desktop 3D printers

OBJECTIVE

C1/2 cervical pedicle screw fixation is a well-known procedure for treating severely damaged and unstable C1/2 fractures. On the other hand, C1/C2 screw fixation is not safe and can lead to potentially disastrous consequences. The importance of personalized 3D printed navigational guides in avoiding these consequences cannot be overstated.

MATERIALS AND METHODS

We retrospectively reviewed the neuroimaging data of 16 patients who had undergone fixation for treatment of C1/2 diseases. We created patient-specific C1/2 models and drill guide models using open-source 3D editing software and a desktop 3D printer. The drill guides were then placed over the respective vertebrae models and fixated with 3.5 mm screws. Following fixation, the parts were scanned with a thin-slice (01 mm) CT scan, and the screw trajectories in the transverse and sagittal planes were measured at each level.

RESULTS

Of the total of 62 screws, 58 were type I (93.54%), 4 were type II (6.45%), and no screws were type III (Tab 2). The results showed that there was no significant deviation in the screw trajectories and the accuracy of the drill guides was 93.54% (Table 3). In our study, type I and type II screws were deemed acceptable, and the acceptable rates of C1/2 screw fixation were 100%.

CONCLUSIONS

In this preclinical study, we demonstrated that it is possible to create patient-specific pedicle drill guides using open source editing software and a commercially available desktop PLA printer, resulting in high accuracy rates in pedicle screw placement in C1/2 patient models.

Application of Patient-Specific Instrumentation in a Dog Model with Antebrachial Growth Deformity Using a 3-D Phantom Bone Model

One of the most frequent bone deformities in dogs is antebrachial growth deformity (AGD), which results from malunion of the distal growth plates. The objective of the present study was to re-align the limbs, which can correct the length mismatch and reset the coherence of the joint with the aid of a 3-D phantom model for surgical preplanning. A 14-month-old, intact female Golden Retriever with an angular deformity of the left radius and ulna was selected for the study. The diagnosis was confirmed by orthogonal radiographs. Moreover, computed tomography (CT) scans revealed a multiplane deformity with valgus, procurator, and external rotation of the left radius. The pre-surgical planning started with the quantification of the angular deformity, followed by a simulated virtual osteotomy, and concluded with an in vitro rehearsal surgery on 3-D printed phantom bone models. In the operating room, prefabricated patient-specific instrumentation (PSI) was attached at the planned site of the radial bone surface for a precise closing wedge osteotomy. Then two locking plates were fixed routinely. Post-operative radiographs showed accurate correction of the deformity as we had planned. At 12 weeks post-operatively, the follow-up surveys revealed improved gait, weight-bearing, and progression of bone healing. Our PSI design, based on novel surgical planning, was steady yet straightforward during the osteotomy. The osteotomy was performed without difficulty since the PSI that pre-determined the sites and angles let the surgeon perform the antebrachial malformation surgery. This method of operation reduces stress on the operator and helps to improve accuracy, repeatability, and surgery time.

Custom-made 3D-Printed Prosthesis in Periacetabular Resections Through a Novel Ileo-adductor Approach

Resection of sarcomas around the acetabulum presents major challenges. The resulting bone effect can be reconstructed with personalized custom-made prostheses. Patient-specific instruments (PSIs) have been demonstrated to be of added value for bone-cutting accuracy, and they may improve pelvic surgery. The authors describe a novel ileo-adductor approach for pelvic tumor surgery and report the preliminary results of 5 reconstructions using custom 3D-printed prostheses associated with PSI surgical guides. This combined technique allows an optimal restoration of the anatomy with reduced surgical time and reduced postoperative complications such as infections and wound healing problems. [Orthopedics. 2022;45(2):e110-e114.].

Anatomical Engineering and 3D Printing for Surgery and Medical Devices: International Review and Future Exponential Innovations

Three-dimensional printing (3DP) has recently gained importance in the medical industry, especially in surgical specialties. It uses different techniques and materials based on patients' needs, which allows bioprofessionals to design and develop unique pieces using medical imaging provided by computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, the Department of Biology and Medicine and the Department of Physics and Engineering, at the Bioastronautics and Space Mechatronics Research Group, have managed and supervised an international cooperation study, in order to present a general review of the innovative surgical applications, focused on anatomical systems, such as the nervous and craniofacial system, cardiovascular system, digestive system, genitourinary system, and musculoskeletal system. Finally, the integration with augmented, mixed, virtual reality is analyzed to show the advantages of personalized treatments, taking into account the improvements for preoperative, intraoperative planning, and medical training. Also, this article explores the creation of devices and tools for space surgery to get better outcomes under changing gravity conditions.

Patient-specific guides in orthopedic surgery

The interest of patient-specific guides (PSGs) lies in reliable intraoperative achievement of preoperative planning goals. They are a form of instrumentation optimizing intraoperative precision and thus improving the safety and reproducibility of surgical procedures. Clinical superiority, however, has not been demonstrated. The various steps from design to implementation leave room for error, which needs to be known and controlled by the surgeon who is responsible for final outcome. Instituting large-scale patient-specific surgery requires management systems for guides and innovative implants which cannot be a simple extension of current practices. We shall approach the present state of knowledge regarding PSGs via 5 questions: (1) What is a PSG? Single-use instrumentation produced after preoperative planning, aiming exclusively to optimize procedural exactness. (2) How to use and assess PSGs in orthopedic surgery? Strict rules of use must be adhered to. Any deviation from the predefined objective is, necessarily, an error that must be identified as such. (3) Do PSGs provide greater surgical exactness? The contribution of PSGs varies greatly between procedures. Exactness is enhanced in the spine, in osteotomies around the knee and in bone-tumor surgery. In the shoulder, their contribution is seen only in complex cases. Data are sparse for hip replacement, and controversial for knee replacement. (4) What are the expected benefits of PSGs? As well as improving exactness, PSGs allow a lower radiation dose and shorter operating time. They also enable junior surgeons to train in techniques otherwise reserved to hyperspecialists. (5) How to include PSGs in everyday practice? As well as their potential clinical interest, PSGs involve deep changes in organization, equipment provision and economic model. LEVEL OF EVIDENCE: V; expert opinion.

Reconstruction With 3D-Printed Prostheses After Sacroiliac Joint Tumor Resection: A Retrospective Case-Control Study

Background

Sacroiliac joint tumor is rare, and the reconstruction after tumor resection is difficult. We aimed to analyze and compare the clinical effects of three-dimensional (3D) printed prostheses and bone cement combined with screws for bone defect reconstruction after sacroiliac joint tumor resection.

Methods

Twelve patients with sacroiliac joint tumors who underwent tumor resection and received 3D-printed prostheses to reconstruct bone defects in our hospital from January 2014 to December 2020 were included in the study group Twelve matched patients who underwent sacroiliac joint tumor resection and reconstruction with bone cement and screws in the same time period were selected as the control group.

Results

In the 3D-printing group, six cases were extensively excised, and six cases were marginally excised. All patients were followed up for 6–90 months, and the median follow-up time was 21 months. Among them, nine patients had disease-free survival, two survived with tumor recurrence, and one died due to tumor metastasis. The MSTS-93 score of the surviving patients was 24.1 ± 2.8. The operation time was 120.30 ± 14.50 min, and the intraoperative bleeding was 625.50 ± 30.00 ml. In the control group, seven cases were extensively excised, and five cases were marginally excised. All patients were followed up for 6–90 months, with a median follow-up time of 20 months. Among them, nine patients had disease-free survival, one survived with tumor recurrence, and two died due to tumor metastasis. The MSTS-93 score of the patients was 18.9 ± 2.6. The operation time was 165.25 ± 15.00 min, and the intraoperative bleeding was 635.45 ± 32.00 ml. There was no significant difference in survival status, intraoperative blood loss, or complications between the two groups (P>0.05). However, there were statistically significant differences in operative time and postoperative MSTS-93 scores between the two groups (P<0.05).

Conclusions

After resection of the sacroiliac joint tumor, reconstruction using 3D printed prostheses was shorter and resulted in better movement function.

Periacetabular reconstruction following limb-salvage surgery for pelvic sarcomas

Limb-salvage surgery for pelvic sarcomas remains one of the most challenging surgical procedures for musculoskeletal oncologists. In the past several decades, various surgical techniques have been developed for periacetabular reconstruction following pelvic tumor resection. These methods include endoprosthetic reconstruction, allograft or autograft reconstruction, arthrodesis, and hip transposition. Each of these procedures has its own advantages and disadvantages, and there is no consensus or gold standard for periacetabular reconstruction. Consequently, this review provides an overview of the clinical outcomes for each of these reconstructive options following pelvic tumor resections. Overall, high complication rates are associated with the use of massive implants/grafts, and deep infection is generally the most common cause of reconstruction failure. Functional outcomes decline with the occurrence of severe complications. Further efforts to avoid complications using innovative techniques, such as antibiotic-laden devices, computer navigation, custom cutting jigs, and reduced use of implants/grafts, are crucial to improve outcomes, especially in patients at a high risk of complications.

Augmented Reality as a Tool to Guide PSI Placement in Pelvic Tumor Resections

Patient-specific instruments (PSIs) have become a valuable tool for osteotomy guidance in complex surgical scenarios such as pelvic tumor resection. They provide similar accuracy to surgical navigation systems but are generally more convenient and faster. However, their correct placement can become challenging in some anatomical regions, and it cannot be verified objectively during the intervention. Incorrect installations can result in high deviations from the planned osteotomy, increasing the risk of positive resection margins. In this work, we propose to use augmented reality (AR) to guide and verify PSIs placement. We designed an experiment to assess the accuracy provided by the system using a smartphone and the HoloLens 2 and compared the results with the conventional freehand method. The results showed significant differences, where AR guidance prevented high osteotomy deviations, reducing maximal deviation of 54.03 mm for freehand placements to less than 5 mm with AR guidance. The experiment was performed in two versions of a plastic three-dimensional (3D) printed phantom, one including a silicone layer to simulate tissue, providing more realism. We also studied how differences in shape and location of PSIs affect their accuracy, concluding that those with smaller sizes and a homogeneous target surface are more prone to errors. Our study presents promising results that prove AR's potential to overcome the present limitations of PSIs conveniently and effectively.

The application of additive manufacturing / 3D printing in ergonomic aspects of product design: A systematic review

Additive Manufacturing (AM) facilitates product personalization and iterative design, which makes it an ideal technology for ergonomic product development. In this study, a systematic review was conducted of the literature regarding the use of AM in ergonomic-product design, and methodological aspects of the studies were analyzed. A literature search was performed using the keywords "3D print*," "additive manufacturing," "ergonomic*" and "human factors". Included were studies reporting the use of AM specifically in ergonomic design of products/prototypes including the detailing of an ergonomic testing methodology used for evaluation. Forty studies were identified pertaining to the fields of medicine, assistive technology, wearable technology, hand tools, testing devices and others. The most commonly used technology was fused deposition modeling with polylactic acid, but the overall preferred material was acrylonitrile butadiene styrene. Various combinations of objective/subjective and qualitative/quantitative product evaluation methods were used. Based on the findings, recommendations were developed to facilitate the choice of most suitable AM technologies and materials for specific applications in ergonomics.

Computer Assisted Surgery and 3D Printing in Orthopaedic Oncology: A Lesson Learned by Cranio-Maxillo-Facial Surgery

Primary bone sarcomas are rare tumors and surgical resection in combination with chemo and radiation therapy is the mainstay of treatment. Some specific anatomical sites still represent a reconstructive challenge due to their complex three-dimensional anatomy. In recent years, patient specific instruments along with 3D printing technology has come to represent innovative techniques in orthopaedic oncology. We retrospectively reviewed 23 patients affected by primary bone sarcoma treated with patient-specific instruments and 3D printing custom made prostheses. At follow up after approximately two years, the infection rate was 26%, mechanical complication rate 13%, and local recurrence rate 13% (with a five-years implant survival rate of 74%). Based on our experience, patient-specific instruments and 3D custom-made prostheses represents a reliable and safe technique for improving the accuracy of resection of primary bone tumour, with a particular use in pelvic surgery ameliorating functional results.

Validation of patient-specific 3D impression models for pelvic oncological orthopedic surgery

INTRODUCTION

Pelvic ring tumors pose a challenge due to the difficulty in obtaining adequate surgical margins. Tools such as surgical navigation or 3D printing for the fabrication of patient-specific surgical positioning templates help in preoperative planning and intraoperative execution. Their correct positioning is essential in complex locations such as the pelvis, so it is necessary to identify positioning errors. The aim of this study is to demonstrate the reliability of 3D template placement for pelvic ring osteotomies.

MATERIAL AND METHODS

Experimental study in cadaver with 10 hemipelvis. CT was performed to obtain the three-dimensional model, planning of osteotomies, design of positioning templates in ischiopubic (I), iliopubic (P), supracetabular (S) and iliac crest (C) branches; and a positioning marker (rigid-body) on the C and S templates for navigation. The templates and rigid-body are 3D printed and positioned according to pre-planning. Navigation allows the final position of the inserts and osteotomies to be checked.

RESULTS

The positioning of the templates with respect to the preoperative planning varied depending on the location, being greater the error in those of the iliac crest. Using navigation the mean error of distance to the cutting plane is 3.5mm, except in pubis (5-8mm), being conditioned by the position of the rigid body.

CONCLUSION

The use of patient-specific templates printed in 3D is a reliable tool for performing osteotomies in pelvic cancer surgery.

Primary malignant bone tumours of spine and pelvis in children

PURPOSE

Axial malignant bone tumours are rare in children and adolescents, and their prognosis is still relatively poor due to non-specific symptoms, such as back or groin pain, which may result in late hospital presentation. Therefore, it is very important to raise awareness regarding this pathology.

METHODS

We performed a narrative review, including scientific publications published in English. We searched Medline and Google Scholar databases for information on the incidence and prognosis of axial malignant bone tumours in children and adolescents (< 18 years). Outcomes of different surgical management strategies and reconstruction options were assessed.

RESULTS

The incidence of primary malignant bone tumours before the age of 18 years is approximately five per one million population; around 25% of these tumours are located in the axial skeleton. With a five-year survival rate of 50%, tumours in an axial location (chest cage, spine, pelvis) are associated with a poorer prognosis than tumours in more peripheral locations. En bloc excision with clear margins has been shown to improve local control and overall survival, even though obtaining adequate surgical margins is difficult due to the close location of large neurovascular structures and other major organs. Spinal reconstruction options include instrumented fusion with allograft or expandable cage. Pelvic reconstruction is needed in internal hemipelvectomy, and the options include biological, endoprosthetic reconstructions, hip transposition, arthrodesis or creation of pseudoarthrosis and lumbopelvic instrumentation.

CONCLUSION

Early diagnosis, a timely adequate multidisciplinary management, appropriate en bloc excision, and reconstruction improve survival and quality of life in these patients.

LEVEL OF EVIDENCE

V.

Use of Three-dimensional Titanium Trusses for Arthrodesis Procedures in Foot and Ankle Surgery: A Retrospective Case Series

Periarticular osseous defects pose a challenge when considering arthrodesis. Failure to restore the cubic content of bone can result in shortening and malalignment, as well as subsequent biomechanical issues. This study reports on 12 patients treated with patient-specific 3-D printed (7) and prefabricated titanium trusses (5). Twelve consecutive patients were treated for osseous defects of the forefoot, hindfoot, and ankle with patient-specific, 3D printed or prefabricated manufacturer titanium trusses. Seven were customized, patient-specific 3D printed trusses (4WEB, Frisco, Texas) and 5 were prefabricated manufacturer titanium trusses. All patients had a minimum of 6 months of clinical and radiographic follow-up. and no patients were lost to follow-up. Seven of the 12 patients had a computed tomography (CT) scan performed following surgery. Successful limb or ray salvage was achieved in 11 of 12 patients (91.7%). Six of 7 patients (85.7%) with a postoperative CT scan, went on to complete radiographic consolidation across all arthrodesis sites. The remaining 5 patients showed complete consolidation across the arthrodesis sites on plain film radiographs. Complications included one patient with a residual midfoot deformity that required a subsequent midfoot osteotomy in order to obtain a plantigrade foot following successful tibiotalocalcaneal (TTC) arthrodesis, and a below knee amputation in one patient who underwent revision TTC arthrodesis to salvage avascular necrosis of the talus that developed following the index procedure. Eleven of 12 patients undergoing arthrodesis demonstrated successful union with both customized, patient-specific 3D printed and prefabricated manufacturer titanium trusses on CT scans or radiographs. The average follow-up was 14 months. Reports on traditional methods of addressing periarticular defects in patients requiring arthrodesis show mixed results and relatively high complication rates. Custom, 3D printed and prefabricated titanium truss technology offers an alternative to traditional methods for large, periarticular osseous defects.

3D printing innovation: New insights into upper extremity surgery planning

INTRODUCTION

Surgical planning relies on the use of images to develop an action plan prior to the actual surgical intervention. Imaging technology improvement together with the development of specific software to treat three dimensional images has increased the accuracy and capabilities of pre-surgical planning. In addition to this, 3D printing allows us to manufacture customized surgical tools to implement and aid in the success of surgeries.

MATERIAL AND METHODS

3D virtual planning together with 3D printing has been implemented through different approaches in 8 different upper extremity trauma cases. We describe these 8 cases (2 women and 6 men with ages ranging from 16 to 67 years), their specific challenges and management.

RESULTS

We show how 3D technology changes the conception, planning and execution of surgery in 8 different cases. In addition, we describe what challenges were faced as well as the various utilities of 3D technology beyond that of anatomical model printing.

CONCLUSIONS

The use of 3D technology has improved and enhanced surgical planning. It allows us to view and virtually manipulate fracture fragments prior to surgery. It also enables us to develop customized surgical tools and guides that can increase the accuracy of certain procedures, and help in the management of orthopaedic and trauma lesions. We believe that the use of this technology is beneficial to both the patient and surgeon, since it reduces surgical time and complications giving a better understanding of the injury and its treatment.

[Three dimensional nephrometry system for partial nephrectomy: Our initial exploration]

OBJECTIVE

To construct a preoperative evaluation system for partial nephrectomy using CT three-dimensional visualization technology and to explore its practical value.

METHODS

The clinical data of the patients who underwent partial nephrectomy for renal tumors in Department of Urology, Peking University First Hospital were collected retrospectively. At the same time, the homogenized standard data of patients who underwent partial nephrectomy for renal tumors were collected in 16 clinical centers in China. The CT three-dimensional visualization system was applied (IPS system, Yorktal) to evaluate tumor anatomy, blood supply, perirenal fat and other information. The parameters were summarized to build a three-dimensional nephrometry system, on the basis of which virtual surgery design and intraoperative navigation were completed.

RESULTS

A three-dimensional visualization image was established based on the enhanced CT urography. The nephrometry system included the longest diameter and volume of the tumor, proportion volume of tumor invading the parenchyma, maximum depth of the tumor invading the parenchyma, contact surface area, flatness of the tumor surface, renal segment where the tumor was located, vascular variation, and perirenal fat. The average two-dimensional diameter of the tumor was (2.78±1.43) cm, the average three-dimensional maximum diameter was (3.09±1.35) cm, and the average postoperative pathological size was (3.01±1.38) cm. The maximum tumor diameter in the three-dimensional image was significantly related to the prolonged renal artery clamping time and intra-operative blood loss (r=0.502, P=0.020; r=0.403, P=0.046). The three-dimensional and pathological tumor volume were (25.7±48.4) cm³ and (33.0±36.4) cm³, respectively (P=0.229). The tumor volume was significantly related to the intraoperative blood loss (r=0.660, P < 0.001). The proportion volume of the tumor invading into renal parenchyma was significantly related to the prolongation of renal artery clamping and the occurrence of postoperative complications (r=0.410, P=0.041; r=0.587, P=0.005). The tumor contact surface area and the presence of vascular variation did not show correlation with the perioperative data and postoperative complications. While the preoperative evaluation was completed, the reconstructed three-dimensional image could be zoomed, rotated, combined display, color adjustment, transparency, and simulated cutting on the Touch Viewer system. The process generally consisted of showing or hiding the tissue, adjusting the transparency of the interested area, rotating and zooming the image to match the position of the surgical patient. Together, these functions met the requirements of preoperative virtual surgery plan and intraoperative auxiliary navigation.

CONCLUSION

Three-dimensional images can provide a more intuitive anatomical structure. The CT three-dimensional visua-lization system clearly displays tumor anatomical parameters, blood supply and perirenal fat. The three-dimensional nephrometry system for renal tumors can help predict the difficulty of partial nephrectomy and perioperative complications. Importing the reconstructed three-dimensional visualization image into the specified program or robot operating system can complete virtual surgery and intraoperative navigation, helping the surgeon to better grasp the surgical process. The indexes included in the nephrometry system and the score weights of each index need to be confirmed and perfected by multi-center study with large samples.

Affordable Three-Dimensional Printed Heart Models

This is a 7-years single institution study on low-cost cardiac three-dimensional (3D) printing based on the use of free open-source programs and affordable printers and materials. The process of 3D printing is based on several steps (image acquisition, segmentation, mesh optimization, slicing, and three-dimensional printing). The necessary technology and the processes to set up an affordable three-dimensional printing laboratory are hereby described in detail. Their impact on surgical and interventional planning, medical training, communication with patients and relatives, patients' perception on care, and new cardiac device development was analyzed. A total of 138 low-cost heart models were designed and printed from 2013 to 2020. All of them were from different congenital heart disease patients. The average time for segmentation and design of the hearts was 136 min; the average time for printing and cleaning the models was 13.5 h. The average production cost of the models was €85.7 per model. This is the most extensive series of 3D printed cardiac models published to date. In this study, the possibility of manufacturing three-dimensional printed heart models in a low-cost facility fulfilling the highest requirements from a technical and clinical point of view is demonstrated.

Complex Bone Tumors of the Trunk-The Role of 3D Printing and Navigation in Tumor Orthopedics: A Case Series and Review of the Literature

The combination of 3D printing and navigation promises improvements in surgical procedures and outcomes for complex bone tumor resection of the trunk, but its features have rarely been described in the literature. Five patients with trunk tumors were surgically treated in our institution using a combination of 3D printing and navigation. The main process includes segmentation, virtual modeling and build preparation, as well as quality assessment. Tumor resection was performed with navigated instruments. Preoperative planning supported clear margin multiplanar resections with intraoperatively adaptable real-time visualization of navigated instruments. The follow-up ranged from 2–15 months with a good functional result. The present results and the review of the current literature reflect the trend and the diverse applications of 3D printing in the medical field. 3D printing at hospital sites is often not standardized, but regulatory aspects may serve as disincentives. However, 3D printing has an increasing impact on precision medicine, and we are convinced that our process represents a valuable contribution in the context of patient-centered individual care.

Personalized three-dimensional printed polyether-ether-ketone prosthesis for reconstruction after subtotal removal of chronic clavicle osteomyelitis: A case report

RATIONALE

Three-dimensional (3D) printing has attracted wide attention for its potential and abilities in the assistance of surgical planning and the development of personalized prostheses. We herewith report a unique case of chronic clavicle osteomyelitis treated with a two-stage subtotal clavicle reconstruction using a 3D printed polyether-ether-ketone (PEEK) prosthesis.

PATIENT CONCERNS

A 23-year-old Chinese female presented to our clinic complaining about a progressive pain of her right clavicle for about 1 year.

DIAGNOSES

Chronic clavicle osteomyelitis confirmed by percutaneous biopsy and lesion biopsy.

INTERVENTIONS

This patient accepted a long-term conservative treatment, which did not gain satisfactory outcomes. Thus, a subtotal removal and two-stage reconstruction of the right clavicle with a 3D-printed polyether-ether-ketone prosthesis stabilized by screw fixation system was performed.

OUTCOMES

At 2-year follow-up, complete pain relief and satisfactory functional recovery of her right shoulder were observed.

LESSONS

Personalized 3D printed prosthesis is an effective and feasible method for reconstruction of complex bone defects.

Pelvic Reconstruction With a Novel Three-Dimensional-Printed, Multimodality Imaging Based Endoprosthesis Following Enneking Type I + IV Resection

BACKGROUND AND PURPOSE

Pelvic tumor involving Type I + IV resections are technically challenging, along with various reconstructions methods presenting unsatisfactory outcomes and high complication rates. Since predominating studies preferred adopting pedicle screw-rod system (PRSS) to address this issue, we designed a novel three-dimensional-printed, multimodality imaging (3DMMI) based endoprosthesis with patient-specific instrument (PSI) assistance to facilitate the surgical reconstruction of pelvic tumor involving Enneking Type I + IV resection. We aimed to investigate the clinical effectiveness of this novel endoprosthesis and compare it with PRSS in Type I + IV reconstruction.

METHODS

We retrospective studied 28 patients for a median follow-up of 47 months (range, 10 to 128 months) in this study with either 3D-printed endoprosthesis reconstruction (n = 10) or PRSS reconstruction (n = 18) between January 2000 and December 2017. Preoperative 3DMMI technique was used for tumor evaluation, PSI design, virtual surgery, and endoprosthesis fabrication. Clinical, oncological outcomes, functional assessments, and complications were analyzed between the two groups.

RESULTS

Minor surgical trauma with mean operative duration of 251 ± 52.16 minutes (p = 0.034) and median intraoperative hemorrhage of 2000ml (range, 1600, 4000ml) (p = 0.032) was observed in endoprosthesis group. Wide margins were achieved in 9 patients of the endoprosthesis group compared with 10 in the PRSS group (p = 0.09). The 1993 version of the Musculoskeletal Tumor Society score (MSTS-93) was 23.9 ± 3.76 in endoprosthesis group, which was higher than PRSS group (p = 0.012). No statistical significance was found in relapse between two groups (p = 0.36). Complications were observed in two patients in endoprosthesis group compared with 12 patients in PRSS group (p = 0.046).

CONCLUSION

The novel design of this 3D-printed endoprosthesis, together with 3DMMI and PSI assisted, is technically accessible with favorable clinical outcomes compared with PRSS. Further study is essential to identify its long-term outcomes.

Three-dimensional printed implant for reconstruction of pelvic bone after removal of giant chondrosarcoma: a case report

Background

Three-dimensional (3D) reconstruction has been used for various diseases, but few reports have described its application in pelvic reconstruction after removal of giant chondrosarcoma. Case reports describing the clinical application of personalized 3D-printed titanium implants are needed for future clinical reference.

Case presentation: We herein describe a 29-year-old woman with a giant chondrosarcoma treated with a personalized 3D titanium implant. The surgery was successful, and the patient recovered with significant pain relief and good functional recovery after the surgery. No implant-related complications occurred during the 12-month follow-up. The current case represents successful application of 3D printing technology to the treatment of a massive bone defect due to the removal of a giant osteoporotic tumor.

Conclusions

Personalized 3D titanium implants can be used in the reconstruction of massive bone defects after the removal of giant pelvic sarcomas. The methodology and results described in the current case report can be a used as reference in the treatment of similar cases in future.

Three-Dimensionally-Printed Joint-Preserving Prosthetic Reconstruction of Massive Bone Defects After Malignant Tumor Resection of the Proximal Tibia

Joint-preserving prosthetic reconstruction for massive bone defects has the potential to be a new and revolutionary treatment option. In this paper, we discuss the case of a 30-year-old female patient who presented with pain and swelling around the knee for three months. The patient underwent this procedure. Postoperative patient satisfaction, pain scores, and range of motion results were found to be promising. We believe that this method has the potential to be the next stage in the quest for better treatment options for this condition.

The application of 3D-printing technology in pelvic bone tumor surgery

BACKGROUND

Three-dimensional (3D)-printing technology provides an advanced approach to pelvic bone tumor resection and reconstruction. However, only a few cases of pelvic bone tumor surgery using 3D-printing have been reported due to limited time since the introduction of the new implant. This study introduces pelvic bone tumor surgeries using 3D-printed bone-cutting guides and implants.

METHODS

This single-center retrospective review included 12 patients who underwent malignant pelvic bone tumor surgeries using a 3D-printed bone-cutting guide and/or implant. Clinical information was collected regarding patient demographics, tumor characteristics, pathologic diagnosis, surgery details, and functional recovery.

RESULTS

Type I internal hemipelvectomy was performed using 3D-printed bone-cutting guides for 4 patients that underwent cavitary bone tumor resection of the ilium. For 3 of these 4 patients, cavitary bone defects were filled with structural allobone graft precisely trimmed by the 3D-printed allograft-shaping guide (n = 1) and 3D-printed mesh-style titanium spacer (n = 2). For type II and III areas, one and two patients, respectively, underwent 3D-printing-assisted surgery. Five patients underwent type I, II, and III pelvic resection using 3D-printed cutting guides and reconstruction with 3D-printed implants. In all patients, independent gait was recovered except for a patient who underwent hindquarter amputation 4 months postoperatively because of local recurrence.

CONCLUSIONS

This study provides preliminary, short-term data on the efficacy and safety of pelvic bone tumor surgery using 3D-printing.

Computer Navigation and 3D Printing in the Surgical Management of Bone Sarcoma

The long-term outcomes of osteosarcoma have improved; however, patients with metastases, recurrence or axial disease continue to have a poor prognosis. Computer navigation in surgery is becoming ever more commonplace, and the proposed advantages, including precision during surgery, is particularly applicable to the field of orthopaedic oncology and challenging areas such as the axial skeleton. Within this article, we provide an overview of the field of computer navigation and computer-assisted tumour surgery (CATS), in particular its relevance to the surgical management of osteosarcoma.

Surgical planning of pelvic tumor using multi-view CNN with relation-context representation learning

Limb salvage surgery of malignant pelvic tumors is the most challenging procedure in musculoskeletal oncology due to the complex anatomy of the pelvic bones and soft tissues. It is crucial to accurately resect the pelvic tumors with appropriate margins in this procedure. However, there is still a lack of efficient and repetitive image planning methods for tumor identification and segmentation in many hospitals. In this paper, we present a novel deep learning-based method to accurately segment pelvic bone tumors in MRI. Our method uses a multi-view fusion network to extract pseudo-3D information from two scans in different directions and improves the feature representation by learning a relational context. In this way, it can fully utilize spatial information in thick MRI scans and reduce over-fitting when learning from a small dataset. Our proposed method was evaluated on two independent datasets collected from 90 and 15 patients, respectively. The segmentation accuracy of our method was superior to several comparing methods and comparable to the expert annotation, while the average time consumed decreased about 100 times from 1820.3 seconds to 19.2 seconds. In addition, we incorporate our method into an efficient workflow to improve the surgical planning process. Our workflow took only 15 minutes to complete surgical planning in a phantom study, which is a dramatic acceleration compared with the 2-day time span in a traditional workflow.

Patient-Specific Three-Dimensional Printing Guide for Single-Stage Skull Bone Tumor Surgery: Novel Software Workflow with Manufacturing of Prefabricated Jigs for Bone Resection and Reconstruction

OBJECTIVE

To describe a novel system workflow to design and manufacture patient-specific three-dimensional (3D) printing jigs for single-stage skull bone tumor excision and reconstruction and to present surgical outcomes of 14 patients.

METHODS

A specific computer-aided design/computer-aided manufacturing software and hardware system was set up, including a virtual surgical planning subsystem and a 3D printing-associated manufacturing subsystem. Computed tomography data of the patient's skull were used for 3D rendering of the skull and tumor. The output of patient-specific designing included a 3D printing guide for tumor resection and a 3D printing model of the bone defect after tumor excision. A polymethyl methacrylate implant was fabricated preoperatively and used for repair.

RESULTS

The specific 3D printing guide was used to design intraoperative jigs and implants for 14 patients (age range, 1-72 years) with skull bone tumors. In all cases, the cutting jig allowed precise excision of tumor and bone, and implants were exact fits for the defects created. All operative results were successful, without intraoperative or postoperative complications. Postoperative computed tomography scans were obtained for analysis. Postoperative 3D measurement of the skull symmetry index (cranial vault asymmetry index) showed significant improvement of head contour after surgery.

CONCLUSIONS

The computer-aided design/computer-aided manufacturing system described allows definitive preoperative planning and fabrication for treatment of skull bone tumors. Apparent benefits of the method include more accurate determination of surgical margins and better oncological outcomes.

Design and application of personalized surgical guides to treat complex tibial plateau malunion

Intra-articular corrective osteotomy can be used to restore the anatomic position of knee surfaces for tibial plateau malunion (TPM) but precise restoration is not easy. The personalized surgical guide (PSG) might improve the TMP outcomes. This study developed a two-staged PSG method to provide registration and drill the bone for subsequent osteotomy. The tests were performed to compare the accuracy the proposed PSG and the conventional guide (Anterior cruciate ligament guide, ACLG). The results showed that the PSG provides better accuracy (0.50 ± 0.19 mm) than the ACLG (1.58 ± 0.67 mm). The results show the PSG method is a feasible alternative to the conventional ACLG procedure.

Sacroiliac joint cut accuracy: Comparing new technologies in an idealized sawbones model

BACKGROUND AND OBJECTIVES

The anatomical complexity of the pelvis creates challenges for orthopaedic oncologists to accurately and safely resect tumors involving the sacroiliac joint. Current technology may help overcome these obstacles.

METHODS

Four fellowship-trained orthopaedic oncologists performed 22 all-posterior sacroiliac cuts using freehand, computerized navigation, and patient-specific cutting guides on a Sawbones male pelvis model. Cut accuracies to preoperative planned margins were analyzed via a high-resolution optical scanner. Soft tissue damage was determined by visually inspecting the Sawbones foam placed on the far side of the cut.

RESULTS

Within 5 mm of the margins, the freehand technique resulted in 67.0% cut accuracy, the navigation technique had 71.1%, and the patient-specific cutting guide technique had 85.6% (P = .093). Within 2 mm, the techniques showed an accuracy of 25.8%, 32.5%, and 47.5%, respectively (P = .022). Regarding soft tissue damage, the freehand technique exhibited minimal penetration damage for 16.7% of the cuts, while navigation and patient-specific guide techniques exhibited 25.0% and 75.0%, respectively (P = .046). Years of surgical experience of the operator (1-7) did not influence the cut accuracy for any method.

CONCLUSIONS

Under ideal conditions, patient-specific guide technology possesses the same or better accuracy as other cutting techniques as well as the circumvention of soft tissue damage.

Do predetermined surgical margins compromise oncological safety in computer-assisted head and neck reconstruction?

OBJECTIVES

Computer assisted head and neck reconstruction has gained popularity over the past few years. In computer assisted surgery (CAS), surgical margins are predetermined in virtual surgery and resection guides are designed to be fitted intra-operatively. However, concerns have been raised regarding the oncological safety of predetermined surgical margins. Therefore, the aim of this study was to compare surgical margins, recurrence and survival outcomes in patients underwent CAS and non-CAS in head and neck reconstruction.

METHODS

We retrospectively reviewed the patients underwent oral and maxillofacial malignancies surgical excision and free flap reconstruction from October 2014 to December 2019 by the same chief surgeon. Patients were divided into two groups depending on whether CAS and predetermined surgical margins were adopted. The primary outcome was surgical resection margin and the secondary outcomes included recurrence and survival.

RESULTS

A total of 66 subjects were recruited with 37 in the CAS group and 29 in the non-CAS group. The follow-up rate was 100%. The average follow-up time was 24.5 months. No significant difference in resection margin was identified between the groups (p = 0.387). Tumor staging, margin status, perineural invasion, lymphovascular invasion and extranodal extension were identified as significant factors influencing survival. Both before and after adjustment for these prognostic factors identified, CAS and non-CAS group showed no significant difference in survival outcome.

CONCLUSION

Predetermined surgical margins do not compromise oncological safety in terms of resection margin, disease recurrence and patient survival.