Three dimensional-printed patient-specific cutting guides for femoral varization osteotomy: Do it yourself

A systematic approach to managing complications after proximal tibial osteotomies of the knee

Proximal tibial osteotomy (PTO) is an effective procedure for active and young adult patients with symptomatic unicompartmental osteoarthritis and malalignment. They were considered technically demanding and prone to various complications related to the surgical technique, biomechanical or biological origin. Among the most important are hinge fractures and delayed or non-healing, neurovascular complications, loss of correction, implant-related problems, patellofemoral complaints, biological complications and changes in limb length. Being aware of these problems can help minimizing their prevalence and improve the results of the procedure.The aim of this narrative review is to discuss the potential complications that may occur during and after proximal tibial osteotomies, their origin and ways to prevent them.

Automatic Assessment of Lower-Limb Alignment from Computed Tomography

BACKGROUND

Preoperative planning of lower-limb realignment surgical procedures necessitates the quantification of alignment parameters by using landmarks placed on medical scans. Conventionally, alignment measurements are performed on 2-dimensional (2D) standing radiographs. To enable fast and accurate 3-dimensional (3D) planning of orthopaedic surgery, automatic calculation of the lower-limb alignment from 3D bone models is required. The goal of this study was to develop, validate, and apply a method that automatically quantifies the parameters defining lower-limb alignment from computed tomographic (CT) scans.

METHODS

CT scans of the lower extremities of 50 subjects were both manually and automatically segmented. Thirty-two manual landmarks were positioned twice on the bone segmentations to assess intraobserver reliability in a subset of 20 subjects. The landmarks were also positioned automatically using a shape-fitting algorithm. The landmarks were then used to calculate 25 angles describing the lower-limb alignment for all 50 subjects.

RESULTS

The mean absolute difference (and standard deviation) between repeat measurements using the manual method was 2.01 ± 1.64 mm for the landmark positions and 1.05° ± 1.48° for the landmark angles, whereas the mean absolute difference between the manual and fully automatic methods was 2.17 ± 1.37 mm for the landmark positions and 1.10° ± 1.16° for the landmark angles. The manual method required approximately 60 minutes of manual interaction, compared with 12 minutes of computation time for the fully automatic method. The intraclass correlation coefficient showed good to excellent reliability between the manual and automatic assessments for 23 of 25 angles, and the same was true for the intraobserver reliability in the manual method. The mean for the 50 subjects was within the expected range for 18 of the 25 automatically calculated angles.

CONCLUSIONS

We developed a method that automatically calculated a comprehensive range of 25 measurements that defined lower-limb alignment in considerably less time, and with differences relative to the manual method that were comparable to the differences between repeated manual assessments. This method could thus be used as an efficient alternative to manual assessment of alignment.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Office Three-Dimensional Printed Osteotomy Guide for Corrective Osteotomy in Fibrous Dysplasia

Fibrous dysplasia is a benign condition but can lead to severe long-bone deformities. Three-dimensional (3D) printing technology is a rapidly developing field that has now been popularized to aid surgeons in preoperative planning. We report a case of hip deformity in a 21-year-old woman who suffered from fibrous dysplasia and underwent a corrective osteotomy. We utilized open-source 3D computing software for preoperative planning before producing an osteotomy guide to aid in the operation.

Computer-Guided Osteotomy with Simultaneous Implant Placement and Immediately Loaded Full-Arch Fixed Restoration: A Case Report

Aim: This case report aims to illustrate a clinical protocol that allows for the rehabilitation of patients requiring extensive osteotomy, simultaneous implant placement, and full-arch, screwed-in prosthetics in one session. This protocol allows for the improvement of the aesthetics and functionality of the fixed implant-supported prosthesis through the preoperative planning of all surgical procedures, including osteotomy, and of the prosthesis through the application of 3D-printing technology for the creation of surgical templates and prostheses. Methods: This case report concerns a 72-year-old patient, ASA1, who, following diagnosis, the establishment of a treatment plan, and the provision of informed consent, opted for an immediate, full-arch rehabilitation of the lower arch. The digital planning stage started with the correct positioning of the fixtures. The proper bone levels were found and used to guide the creation of the provisional screwed-in prothesis. Two templates with the same supports (landmarks/pins) were then 3D-printed: a positioning template, including a slit to assist the surgeon during the osteotomy, and a surgery template to assist the surgeon during the implants’ positioning. A screwed-in prosthesis encased in resin C&B MFH (NEXTDENT®, Soesterberg, The Netherlands) was delivered. Minimal occlusal adjustments were performed. Results: In a single clinical session, through careful planning and the pre-operative 3D printing of a prosthesis, a temporary implant-supported prosthetic rehabilitation was possible in a case that required an extended osteotomy. Clinically, the correspondence between the virtual design phase and the final realization was consistent. At a functional level, the provisional prosthesis required minimal occlusal adjustments and the DVO values obtained in the immediate post-operative period were found to be comparable to those of the virtual design. By planning the final position of the bone and the implants in advance, it was possible to deliver a full-arch prothesis with proper implant emergence, occlusal vertical dimensions, and occlusal relationship. Conclusion: This fully digital protocol allows the clinician to preview and plan the osteotomy and implant surgery as well as the delivery of the temporary, immediately loaded, complete, fixed prosthesis in patients who are candidates for post-extraction surgery with the need for severe osteotomy.

Registration based assessment of femoral torsion for rotational osteotomies based on the contralateral anatomy

Background

Computer-assisted techniques for surgical treatment of femoral deformities have become increasingly important. In state-of-the-art 3D deformity assessments, the contralateral side is used as template for correction as it commonly represents normal anatomy. Contributing to this, an iterative closest point (ICP) algorithm is used for registration. However, the anatomical sections of the femur with idiosyncratic features, which allow for a consistent deformity assessment with ICP algorithms being unknown. Furthermore, if there is a side-to-side difference, this is not considered in error quantification.

The aim of this study was to analyze the influence and value of the different sections of the femur in 3D assessment of femoral deformities based on the contralateral anatomy.

Material and methods

3D triangular surface models were created from CT of 100 paired femurs (50 cadavers) without pathological anatomy. The femurs were divided into sections of eponymous anatomy of a predefined percentage of the whole femoral length. A surface registration algorithm was applied to superimpose the ipsilateral on the contralateral side. We evaluated 3D femoral contralateral registration (FCR) errors, defined as difference in 3D rotation of the respective femoral section before and after registration to the contralateral side. To compare this method, we quantified the landmark-based femoral torsion (LB FT). This was defined as the intra-individual difference in overall femoral torsion using with a landmark-based method.

Results

Contralateral rotational deviation ranged from 0° to 9.3° of the assessed femoral sections, depending on the section. Among the sections, the FCR error using the proximal diaphyseal area for registration was larger than any other sectional error. A combination of the lesser trochanter and the proximal diaphyseal area showed the smallest error. The LB FT error was significantly larger than any sectional error (p < 0.001).

Conclusion

We demonstrated that if the contralateral femur is used as reconstruction template, the built-in errors with the registration-based approach are smaller than the intraindividual difference of the femoral torsion between both sides. The errors are depending on the section and their idiosyncratic features used for registration. For rotational osteotomies a combination of the lesser trochanter and the proximal diaphyseal area sections seems to allow for a reconstruction with a minimal error.

Deformity-Correcting Ankle Fusions With Patient-Specific 3D Operative Planning and 3D-Printed Cut Guides: Report of 2 Cases

CASE

We report 2 cases of severe arthrogrypotic clubfeet presenting with multiplanar ankle deformities. Two patients (3 ankles) were treated with deformity-correcting ankle fusions using 3D preoperative planning and 3D-printed patient-specific cut guides. This technique enabled safe, accurate, and efficient surgical correction with good clinical outcomes. At 1 year, physical function and patient outcome measures improved.

CONCLUSION

In the setting of complex multiplanar deformities of the foot and ankle, the use of 3D preoperative planning and 3D-printed cut guides is a safe and accurate adjunct to ankle fusion.

Improved Accuracy of Coronal Alignment Can Be Attained Using 3D-Printed Patient-Specific Instrumentation for Knee Osteotomies: A Systematic Review of Level III and IV Studies

PURPOSE

To evaluate the accuracy and precision of postoperative coronal plane alignment using 3D-printed patient-specific instrumentation (PSI) in the setting of proximal tibial or distal femoral osteotomies.

METHODS

A systematic review evaluating the accuracy of 3D-printed PSI for coronal plane alignment correcting knee osteotomies was performed. The primary outcomes were accuracy of coronal plane limb alignment correction and number of correction outliers. Secondary variables were duration of surgery, number of intraoperative fluoroscopic images, complications, cost, and clinical outcomes (as applicable).

RESULTS

Ninety-three studies were identified, and 14 were included in the final analysis. Overall, mean postoperative deviation from target correction ranged from 0.3° to 1° for all studies using hip-knee angle measurements and 2.3% to 4.9% for all studies using weight-bearing line measurements. The incidence of correction outliers was assessed in 8 total studies and ranged from 0 to 25% (total n = 10 knees) of patients corrected with 3D-printed PSI. Osteotomies performed with 3D-printed cutting guides or wedges demonstrated significantly shorter operative times (P < .05) and fewer intraoperative fluoroscopic images (P < .05) than control groups in four case control studies.

CONCLUSION

Patients undergoing distal femoral osteotomy or proximal tibial osteotomy procedures with 3D-printed patient-specific cutting guides and wedges had highly accurate coronal plane alignment with a low rate of outliers. Patients treated with 3D printed PSI also demonstrated significantly shorter operative times and decreased intraoperative fluoroscopy when compared to conventional techniques.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III-IV studies.

3D-printed Cutting Guides for Lower Limb Deformity Correction in the Young Population

BACKGROUND

Three-dimensional (3D) virtual surgical planning technology has advanced applications in the correction of deformities of long bones by enabling the production of 3D stereolithographic models, patient-specific instruments and surgical-guiding templates. Herein, we describe the implementation of this technology in young patients who required a corrective osteotomy for a complex 3-plane (oblique plane) lower-limb deformity.

PATIENTS AND METHODS

A total of 17 patients (9 males, average age 14.7 y) participated in this retrospective study. As part of preoperative planning, the patients' computerized tomographic images were imported into a post-processing software, and virtual 3D models were created by a segmentation process. Femoral and tibial models and cutting guides with locking points were designed according to the deformity correction plan. They were used for both planning and as intraoperative guides. Clinical parameters, such as blood loss and operative time were compared with a traditional surgical approach group.

RESULTS

All osteotomies in the 3D group were executed with the use intraoperative customized cutting guides which matched the preoperative planning simulation and allowed easy fixation with prechosen plates. Surgical time was 101±6.2 minutes for the 3D group and 126.4±16.1 minutes for the control group. The respective intraoperative hemoglobin blood loss was 2.1±0.2 and 2.5+0.3 g/dL.Clinical and radiographic follow-up findings showed highly satisfactory alignment of the treated extremities in all 3D intervention cases, with an average time-to-bone union (excluding 2 neurofibromatosis 1 patients) of 10.3 weeks (range 6 to 20 wk).

CONCLUSION

The use of 3D-printed models and patient-specific cutting guides with locking points improves the clinical outcomes of osteotomies in young patients with complex bone deformities of the lower limbs.

LEVEL OF EVIDENCE

Level III.

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.

Preoperative Simulation and Three-Dimensional Model for the Operative Treatment of Forearm Double Fracture: A Randomized Controlled Clinical Trial

BACKGROUND

To assess the safety and efficacy of preoperative simulation and three-dimensional (3D) models in the treatment of ulnoradial diaphyses fracture. It was hypothesized that preoperative simulation and 3D printing might significantly shorten the mean operative time, intraoperative bleeding, and intraoperative fluoroscopy.

MATERIAL AND METHODS

Forty patients with forearm double fracture were divided into 3D printing group and conventional surgery group. Preoperative simulation and 3D printing were performed on patients in the 3D printing group to examine implant reduction and placement as well as preoperative plate/screw size. The operation time, intraoperative bleeding, and frequency of fluoroscopies were recorded.

RESULTS

In the conventional surgery group, the operative time, intraoperative bleeding, and the frequency of fluoroscopy were 106.2 ± 15.92 min, 61.45 ± 11.33 ml and 5.65 ± 1.23 times, whereas in the 3D printing group, values of all the three parameters were better than those of the conventional surgery group (91.3 ± 14.85 min, 48.6 ± 10.39 ml and 3.85 ± 1.04 times, respectively). The forearm pronation and supination of the 3D printing group improved to 79.55 ± 5.12° and 76.80 ± 3.96°, respectively. In the conventional surgery group, patients also had significant improvement in these indicators, which improved to 78.60 ± 5.18° and 75.4 ± 5.30°.

CONCLUSIONS

The results showed that preoperative simulation and 3D printing can enhance the safety as well as personalization of the surgical process during the treatment of forearm double fracture and therefore holds potential for future application in clinical practice.

TRIAL REGISTRY

Name of the registry: This study was registered in the Chinese Clinical Trial Registry; Trial registration number: ChiCTR2100045790.

Three-Dimensional Printing of Medical Devices Used Directly to Treat Patients: A Systematic Review

Until recently, three-dimensional (3D) printing/additive manufacturing has not been used extensively to create medical devices intended for actual clinical use, primarily on patient safety and regulatory grounds. However, in recent years there have been advances in materials, printers, and experience, leading to increased clinical use. The aim of this study was to perform a structured systematic review of 3D-printed medical devices used directly in patient treatment. A search of 13 databases was performed to identify studies of 3D-printed medical devices, detailing fabrication technology and materials employed, clinical application, and clinical outcome. One hundred and ten papers describing one hundred and forty medical devices were identified and analyzed. A considerable increase was identified in the use of 3D printing to produce medical devices directly for clinical use in the past 3 years. This is dominated by printing of patient-specific implants and surgical guides for use in orthopedics and orthopedic oncology, but there is a trend of increased use across other clinical specialties. The prevailing material/3D-printing technology used were titanium alloy/electron beam melting for implants, and polyamide/selective laser sintering or polylactic acid/fused deposition modeling for surgical guides and instruments. A detailed analysis across medical applications by technology and materials is provided, as well as a commentary regarding regulatory aspects. In general, there is growing familiarity with, and acceptance of, 3D printing in clinical use.

Heat Sterilization Effects on Polymeric, FDM-Optimized Orthopedic Cutting Guide for Surgical Procedures

Improvements in software for image analysis have enabled advances in both medical and engineering industries, including the use of medical analysis tools to recreate internal parts of the human body accurately. A research analysis found that FDM-sourced elements have shown viability for a customized and reliable approach in the orthopedics field. Three-dimensional printing has allowed enhanced accuracy of preoperative planning, leading to reduced surgery times, fewer unnecessary tissue perforations, and fewer healing complications. Furthermore, using custom tools chosen for each procedure has shown the best results. Bone correction-related surgeries require customized cutting guides for a greater outcome. This study aims to assess the biopolymer-based tools for surgical operations and their ability to sustain a regular heat-sterilization cycle without compromising the geometry and fit characteristics for a proper procedure. To achieve this, a DICOM and FDM methodology is proposed for fast prototyping of the cutting guide by means of 3D engineering. A sterilization test was performed on HTPLA, PLA, and nylon polymers. As a result, the unique characteristics within the regular autoclave sterilization process allowed regular supplied PLA to show there were no significant deformations, whilst annealed HTPLA proved this material’s capability of sustaining repeated heat cycles due to its crystallization properties. Both of these proved that the sterilization procedures do not compromise the reliability of the part, nor the safety of the procedure. Therefore, prototypes made with a similar process as this proposal could be safely used in actual surgery practices, while nylon performed poorly because of its hygroscopic properties.

Patient-Specific Instrument Guided Double Chevron-Cut Distal Femur Osteotomy

The risk of non-union and prolonged periods of protected weight-bearing still remain unsolved issues after distal femur osteotomy (DFO). To improve the stability, we developed the double chevron-cut technique, which is a modified medial closing-wedge DFO guided by a patient-specific instrument. The purpose of this study was to investigate the feasibility and outcome of this operative approach. Twenty-five knees in twenty-three consecutive patients with genu valgum and lateral compartment osteoarthritis that received double chevron-cut DFO were included. The target of correction was 50% on the weight-bearing line (WBL) ratio. Patient-reported outcomes included the Oxford Knee Score (OKS) and the 2011 Knee Society Score (KSS). The mean of the WBL ratio was corrected from 78.7% ± 12.0% to 48.7% ± 2.9% postoperatively. The mean time to full weight bearing was 3.7 ± 1.4 weeks. Union of the osteotomy was achieved at 11.3 ± 2.8 weeks. At a mean follow-up of 17 months, the OKS improved from a mean of 27.6 ± 11.7 to 39.1 ± 7.5 (p = 0.03), and the KSS from a mean of 92.1 ± 13.0 to 143.9 ± 10.2 (p < 0.001). Three patients developed complications, including one case of peri-implant fracture, one of loss of fixation, and one of non-union. The double chevron-cut DFO followed by immediate weight-bearing as tolerated is effective in treating genu valgum deformity and associated lateral compartment osteoarthritis.

CT based PSI blocks for osteotomies around the knee provide accurate results when intraoperative imaging is used

Purpose

Correction osteotomies around the knee are common methods for the treatment of varus or valgus malalignment of the lower extremity. In recent years, patient specific instrumentation (PSI) guides were introduced in order to enhance the accuracy of these procedures. The purpose of this study was to determine the accuracy of CT based PSI guides for correction osteotomies around the knee of low volume osteotomy surgeons and to evaluate if CT based PSI blocks deliver a high degree of accuracy without using intraoperative fluoroscopy.

Methods

Two study arms with CT based PSI cutting blocks for osteotomies around the knee were conducted. Part one: A retrospective analysis of 19 osteotomies was made in order to evaluate the accuracy in the hands of a low volume surgeon on long-leg radiographs. Part two: A cadaveric study with 8 knees was performed for the purpose of analyzing the accuracy without using intraoperative fluoroscopy on pre- and postoperative CT scans. Hip-Knee-Ankle angle (HKA), lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were analyzed. The mean absolute delta (∂) between the planned and postoperative parameters were calculated. The accuracy of both study arms were compared.

Results

Part one: The mean MPTA ∂, LDFA ∂ and HKA ∂ was 0.9°, 1.9° and 1.5°, respectively. Part two: The mean MPTA ∂ and LDFA ∂ was 3.5° and 2.2°, respectively. The mean ∂ of MPTA is significantly different between clinical patients with fluoroscopic control and cadaveric specimens without fluoroscopic control (P < 0.001). All surgeries were performed without complications such as a hinge fracture.

Conclusion

The clinical use of PSI guides for osteotomies around the knee in the hands of low volume surgeons is a safe procedure. The PSI guides deliver a reliable accuracy under fluoroscopic control whereas their non-use of intraoperative fluoroscopy leads to a lack of accuracy. The use of fluoroscopic control during PSI guided correction osteotomies is highly recommended.

Level of evidence

IV – Retrospective and experimental Study

Are the common sterilization methods completely effective for our in-house 3D printed biomodels and surgical guides?

INTRODUCTION

In-hospital 3D printing is being implemented in orthopaedic departments worldwide, being used for additive manufacturing of fracture models (or even surgical guides) which are sterilized and used in the operating room. However, to save time and material, prints are nearly hollow, while 3D printers are placed in non-sterile rooms. The aim of our study is to evaluate whether common sterilization methods can sterilize the inside of the pieces, which would be of utmost importance in case a model breaks during a surgical intervention.

MATERIAL AND METHOD

A total of 24 cylinders were designed and printed with a 3D printer in Polylactic Acid (PLA) with an infill density of 12%. Manufacturing was paused when 60% of the print was reached and 20 of the cylinders were inoculated with 0.4 mL of a suspension of S epidermidis ATTCC 1228 in saline solution at turbidity 1 McFarland. Printing was resumed, being all the pieces completely sealed with the inoculum inside. Posteriorly, 4 groups were made according to the chosen sterilization method: Ethylene Oxide (EtO), Gas Plasma, Steam Heat or non-sterilized (positive control). Each group included 5 contaminated cylinders and 1 non-contaminated cylinder as a negative control. After sterilization, the inside of the cylinders was cultured during 7 days.

RESULTS

We observed bacterial growth of just a few Forming Colony Units (FCU) in 4 out of 5 positive controls and in 2 out of 5 contaminated cylinders sterilized with Gas Plasma. We could not assess any bacterial growth in any of the EtO or Steam Heat samples or in any of the negative controls. Pieces sterilized under Steam Heat resulted completely deformed.

CONCLUSIONS

High temperatures reached during the procedure of additive manufacturing can decrease the bacterial load of the biomodels. However, there is a potential risk of contamination during the procedure. We recommend sterilization with EtO for in-hospital 3D-printed PLA hollow biomodels or guides. Otherwise, in case of using Gas Plasma, an infill of 100% should be applied.

In-House, Fast FDM Prototyping of a Custom Cutting Guide for a Lower-Risk Pediatric Femoral Osteotomy

Three-dimensional printed custom cutting guides (CCGs) are becoming more and more investigated in medical literature, as a patient-specific approach is often desired and very much needed in today’s surgical practice. Three-dimensional printing applications and computer-aided surgical simulations (CASS) allow for meticulous preoperatory planning and substantial reductions of operating time and risk of human error. However, several limitations seem to slow the large-scale adoption of 3D printed CCGs. CAD designing and 3D printing skills are inevitably needed to develop workflow and address the study; therefore, hospitals are pushed to include third-party collaboration, from highly specialized medical centers to industrial engineering companies, thus increasing the time and cost of labor. The aim of this study was to move towards the feasibility of an in-house, low-cost CCG 3D printing methodology for pediatric orthopedic (PO) surgery. The prototype of a femoral cutting guide was developed for its application at the IOR—Rizzoli Orthopedic Institute of Bologna. The element was printed with an entry-level 3D printer with a high-temperature PLA fiber, whose thermomechanical properties can withstand common steam heat sterilization without bending or losing the original geometry. This methodology allowed for extensive preoperatory planning that would likewise reduce the overall surgery time, whilst reducing the risks related to the intervention.

Point-of-care manufacturing: a single university hospital's initial experience

Background

The integration of 3D printing technology in hospitals is evolving toward production models such as point-of-care manufacturing. This study aims to present the results of the integration of 3D printing technology in a manufacturing university hospital.

Methods

Observational, descriptive, retrospective, and monocentric study of 907 instances of 3D printing from November 2015 to March 2020. Variables such as product type, utility, time, or manufacturing materials were analyzed.

Results

Orthopedic Surgery and Traumatology, Oral and Maxillofacial Surgery, and Gynecology and Obstetrics are the medical specialties that have manufactured the largest number of processes. Working and printing time, as well as the amount of printing material, is different for different types of products and input data. The most common printing material was polylactic acid, although biocompatible resin was introduced to produce surgical guides. In addition, the hospital has worked on the co-design of custom-made implants with manufacturing companies and has also participated in tissue bio-printing projects.

Conclusions

The integration of 3D printing in a university hospital allows identifying the conceptual evolution to “point-of-care manufacturing.”

Conceptual evolution of 3D printing in orthopedic surgery and traumatology: from "do it yourself" to "point of care manufacturing"

BACKGROUND

3D printing technology in hospitals facilitates production models such as point-of-care manufacturing. Orthopedic Surgery and Traumatology is the specialty that can most benefit from the advantages of these tools. The purpose of this study is to present the results of the integration of 3D printing technology in a Department of Orthopedic Surgery and Traumatology and to identify the productive model of the point-of-care manufacturing as a paradigm of personalized medicine.

METHODS

Observational, descriptive, retrospective and monocentric study of a total of 623 additive manufacturing processes carried out in a Department of Orthopedic Surgery and Traumatology from November 2015 to March 2020. Variables such as product type, utility, time or materials for manufacture were analyzed.

RESULTS

The areas of expertise that have performed more processes are Traumatology, Reconstructive and Orthopedic Oncology. Pre-operative planning is their primary use. Working and 3D printing hours, as well as the amount of 3D printing material used, vary according to the type of product or material delivered to perform the process. The most commonly used 3D printing material for manufacturing is polylactic acid, although biocompatible resin has been used to produce surgical guides. In addition, the hospital has worked on the co-design of customized implants with manufacturing companies.

CONCLUSIONS

The integration of 3D printing in a Department of Orthopedic Surgery and Traumatology allows identifying the conceptual evolution from "Do-It-Yourself" to "POC manufacturing".

Combining Augmented Reality and 3D Printing to Improve Surgical Workflows in Orthopedic Oncology: Smartphone Application and Clinical Evaluation

During the last decade, orthopedic oncology has experienced the benefits of computerized medical imaging to reduce human dependency, improving accuracy and clinical outcomes. However, traditional surgical navigation systems do not always adapt properly to this kind of interventions. Augmented reality (AR) and three-dimensional (3D) printing are technologies lately introduced in the surgical environment with promising results. Here we present an innovative solution combining 3D printing and AR in orthopedic oncological surgery. A new surgical workflow is proposed, including 3D printed models and a novel AR-based smartphone application (app). This app can display the patient’s anatomy and the tumor’s location. A 3D-printed reference marker, designed to fit in a unique position of the affected bone tissue, enables automatic registration. The system has been evaluated in terms of visualization accuracy and usability during the whole surgical workflow. Experiments on six realistic phantoms provided a visualization error below 3 mm. The AR system was tested in two clinical cases during surgical planning, patient communication, and surgical intervention. These results and the positive feedback obtained from surgeons and patients suggest that the combination of AR and 3D printing can improve efficacy, accuracy, and patients’ experience.

Patient-specific high-tibial osteotomy's 'cutting-guides' decrease operating time and the number of fluoroscopic images taken after a Brief Learning Curve

PURPOSE

Patient-specific cutting guides (PSCGs) have been advocated to improve the accuracy of deformity correction in opening-wedge high-tibial osteotomies (HTO). It was hypothesized that PSCGs for HTO would have a short learning curve. Therefore, the goals of this study were to determine the surgeons learning curve for PSCGs used for opening-wedge HTO assessing: the operating time, surgeons comfort levels, number of fluoroscopic images, accuracy of post-operative limb alignment and functional outcomes.

METHODS

This prospective cohort study included 71 consecutive opening-wedge HTO with PSCGs performed by three different surgeons with different experiences. The operating time, the surgeon's anxiety levels evaluated using the Spielberger State-Trait Anxiety Inventory (STAI), the number of fluoroscopic images was systematically and prospectively collected. The accuracy of the postoperative alignment was defined by the difference between the preoperative targeted correction and the final post-operative correction both measured on standardized CT-scans using the same protocol (ΔHKA, ΔMPTA, ΔPPTA). Functional outcomes were evaluated at 1 year using the different sub-scores of the KOOS. Cumulative summation (CUSUM) analyses were used to assess learning curves.

RESULTS

The use of PSCGs in HTO surgery was associated with a learning curve of 10 cases to optimize operative time (mean operative time 26.3 min ± 8.8), 8 cases to lessen surgeon anxiety levels, and 9 cases to decrease the number of fluoroscopic images to an average of 4.3 ± 1.2. Cumulative PSCGs experience did not affect accuracy of post-operative limb alignment with a mean: ΔHKA = 1.0° ± 1.0°, ΔMPTA = 0.5° ± 0.6° and ΔPPTA = 0.4° ± 0.8°. No significant difference was observed between the three surgeons for these three parameters. There was no statistical correlation between the number of procedures performed and the patient's functional outcomes.

CONCLUSION

The use of PSCGs requires a short learning curve to optimize operating time, reduce the use of fluoroscopy and lessen surgeon's anxiety levels. Additionally, this learning phase does not affect the accuracy of the postoperative correction and the functional results at 1 year.

LEVEL OF EVIDENCE

II: prospective observational study.

Finding NEEMO: towards organizing smart digital solutions in orthopaedic trauma surgery

There are many digital solutions which assist the orthopaedic trauma surgeon. This already broad field is rapidly expanding, making a complete overview of the existing solutions difficult.The AO Foundation has established a task force to address the need for an overview of digital solutions in the field of orthopaedic trauma surgery.Areas of new technology which will help the surgeon gain a greater understanding of these possible solutions are reviewed.We propose a categorization of the current needs in orthopaedic trauma surgery matched with available or potential digital solutions, and provide a narrative overview of this broad topic, including the needs, solutions and basic rules to ensure adequate use in orthopaedic trauma surgery. We seek to make this field more accessible, allowing for technological solutions to be clearly matched to trauma surgeons' needs. Cite this article: EFORT Open Rev 2020;5:408-420. DOI: 10.1302/2058-5241.5.200021.

Contralateral preoperative templating of lower limbs' mechanical angles is a reasonable option

PURPOSE

In cases where the femur or tibia exhibits abnormal mechanical angulation due to degenerative changes or fracture, the contralateral leg is often used to complete preoperative templating. The aim of this study was to determine the degree of asymmetry between knee joints in healthy individuals and to determine whether it is affected by differing demographic parameters.

METHODS

A CT scan-based modelling and analysis system was used to examine the lower limb of 233 patients (102 males, 131 women; mean age 61.2 ± 15.2 years, mean body mass index 24.9 ± 4.4 kg/m²) The hip-knee angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), posterior proximal tibial angle (ppta) and posterior distal femoral angle (PDFA) were then calculated for each patient. Results were then analysed to calculate femoral symmetry based on absolute differences (AD) and percentage asymmetry (%AS) using a previously validated method.

RESULTS

Our results do not demonstrate any considerable asymmetry (percentage of asymmetry > 2%) for all the anatomical parameters analysed: HKA (mean AD = 1.5°; mean AS % = 0.8, n.s), MPTA (AD = 1.1°; AS % = 1.3, n.s), PPTA (AD = 1.4°; AS % = 1.0, n.s), LDFA (AD = 1.2 mm; AS % = 1.4, n.s) and PDFA (AD = 0.9°; AS % = 1.0, n.s). Gender and ethnicity were not associated with significantly higher AD asymmetry. A significant correlation of AD asymmetry was observed between BMI and HKA, BMI and MPTA, and between patients' age and the MPTA.

CONCLUSION

This data demonstrate that there is a non-statistically significant mechanical angle asymmetry between the two lower limbs. In cases where contralateral templating is used, such asymmetry will induce minimal (if any) clinical differences.

LEVEL OF EVIDENCE

IV.

Three-dimensional assessment of lower limb alignment: Reference values and sex-related differences

BACKGROUND

Three-dimensional (3D) preoperative planning and assisted surgery is increasingly popular in deformity surgery and arthroplasty. Reference ranges for 3D lower limb alignment are needed as a prerequisite for standardized analysis of alignment and preoperative planning in 3D, but are not yet established.

METHODS

On 60 3D bone models of the lower limbs based on computed tomography data, fifteen parameters per leg were assessed by standardized validated 3D analysis. Distribution parameters and differences between sexes were evaluated. Reference values were generated by adding/subtracting one standard deviation from the mean.

RESULTS

Women had a significantly lower mean mechanical lateral distal femoral angle compared with men (86.4 ± 2.1° vs. 87.8 ± 2.0°; P < .05) and significantly lower mean joint line convergence angle (-2.5 ± 1.4° vs. -1.3 ± 1.2; P < .01), but higher mean hip knee ankle angle (178.9 ± 1.9° vs. 177.8 ± 2.3°; P < .05) and mean femoral torsion (18.2 ± 9.5° vs. 13.2 ± 6.4°; P < .05), resulting in a tendency towards valgus alignment and vice versa for men. Differences in mean medial proximal tibial angle were not significant. The mean mechanical axis deviation from the tibial knee joint center was 6.9 ± 7.3 mm medial and 1.4 ± 16.1 mm ventral without significant differences between sexes.

CONCLUSIONS

We describe total and sex-related reference ranges for all alignment relevant axes and joint angles of the lower limb. There are sex-related differences in certain alignment parameters, which should be considered in analysis and surgical planning.

Application of 3D printed osteotomy guide plate-assisted total knee arthroplasty in treatment of valgus knee deformity

INTRODUCTION

To analyze the application of 3D printed osteotomy guide plate-assisted total knee arthroplasty (TKA) for valgus knee deformity.

METHODS

The clinical data of 20 patients with valgus knee deformity admitted to our hospital from April 2012 to April 2017 were collected and analyzed. According to the treatment method, these patients were divided into two groups: 3D printed osteotomy guide plate-assisted TKA (combined treatment group, n = 10) and TKA (treatment group, n = 10). The operation time, intraoperative bleeding volume, postoperative mean femorotibial angle (MFTA), and Knee Society Score (KSS) of the two groups were statistically analyzed.

RESULTS

Compared with the treatment group, the operation time was significantly shorter (P < 0.05), the intraoperative blood loss and postoperative MFTA were significantly decreased (P < 0.05), and the clinical and functional scores were significantly increased (P < 0.05) in the combined treatment group.

CONCLUSION

3D printed osteotomy guide plate-assisted TKA for valgus knee deformity is more effective than TKA alone.

[Current concepts and new developments of 3D printing in trauma surgery]

The use of 3D printing (synonyms "rapid prototyping" and "additive manufacturing") has played an increasing role in the industry for many years and finds more and more interest and application in musculoskeletal surgery, especially orthopedic trauma surgery.In this article the current literature is systematically reviewed, presented and evaluated in a condensed and comprehensive way according to anatomical (upper and lower extremities) and functional aspects. As many of the publications analyzed were feasibility studies, the degree of evidence is low and methodological weaknesses are obvious and numerous; however, this pioneering work is extremely stimulating and important for further development because the technical, medical and economic potential of this technology is huge and interesting for all those involved in the treatment of musculoskeletal problems.

3D printing in experimental orthopaedic surgery: do it yourself

INTRODUCTION

Periprosthetic infection is considered an increasing incidence pathology whose therapeutic strategies can be defined as unsatisfactory. Currently, animal models are employed to study its physiopathology and strategic therapies, but non-species-specific materials are implanted as foreign bodies. The use of these implants implies intrinsic instability, which hinders the development of a biofilm on their surfaces and complicates the post-operative recovery of the animal. The objective of the present study is the design of a species-specific implant for the New Zealand white (NZW) rabbit by means of 3D printing.

MATERIALS AND METHODS

A CT scan of the knee of a NZW rabbit was performed, and the tibial surface was reconstructed in order to fabricate a species-specific tibial plateau using Horos^® and Autodesk^® Meshmixer™ software. This implant was inserted in fifteen NZW rabbits, and the assessment of its stability was based on the position of the limb at rest and the animal weight-bearing capacity. Biofilm formation on the surface was demonstrated by crystal violet staining.

RESULTS

A 1.81 cm × 1 cm × 1.24 cm stainless steel implant was designed. It consisted of a 4-mm-thick tibial plate with a rough surface and an eccentric metaphyseal anchoring. All of the animals exhibited hyperflexion of the operated limb immediately post-operative, and 100% could apply full weight bearing from day 5 after surgery.

CONCLUSIONS

The species-specific design of implants in experimental surgery encourages rapid recovery of the animal and the development of a biofilm on their surfaces, making them ideal for the study of the physiopathology and for establishing possible therapeutic targets for prosthetic infection.

Three-dimensional assessment of lower limb alignment: Accuracy and reliability

INTRODUCTION

Three-dimensional (3D) surgical planning and patient-specific implants are becoming increasingly popular in orthopedics and trauma surgery. In contrast to the established and standardized alignment assessment on two-dimensional (2D) long standing radiographs (LSRs) there is neither a standardized nor a validated protocol for the analysis of 3D bone models of the lower limb. This study aimed to create a prerequisite for pre-operative planning.

METHODS

According to 2D analysis and after meticulous research, 24 landmarks were defined on 3D bone models obtained from computed axial tomography (CT) scans for a 3D alignment assessment. Three observers with different experience levels performed the test three different times on three specimens. Intraobserver and interobserver variability of the landmarks and the intraclass correlation coefficient (ICC) of the resulting axes and joint angles were evaluated.

RESULTS

Overall, the intraobserver and interobserver variability was low, with a mean deviation <5 mm for all landmarks. The ICC of all joint angles and axis deviations was >0.8, except for tibial torsion (ICC = 0.69). All knee joint angles showed excellent ICC (>0.95).

CONCLUSIONS

Using the defined landmarks, a standardized 3D alignment assessment with low intraobserver and interobserver variability and high ICC values for the knee joint angles can be performed regardless of examiner's experience. The described method serves as a reliable standardized protocol for a 3D malalignment test of the lower limb. Three-dimensional pre-operative analysis might enhance understanding of deformities and lead to a new focus in surgical planning.

"More accurate correction using "patient-specific" cutting guides in opening wedge distal femur varization osteotomies

PURPOSE

The distal femoral varization osteotomy (DFVO) by a lateral opening wedge osteotomy is an established intervention for patients suffering from lateral femoro-tibial osteoarthritis on a genu valgum deformity. In order to improve the accuracy of this correction, the use of a customized cutting guide (PSI) has been proposed as an alternative to conventional technique. The objective of our study was to compare the accuracy of post-operative alignment following DFVO in the coronal and sagittal plane using either a conventional abacus technique or PSI guide.

METHOD

Twenty-one patients that underwent lateral opening wedge osteotomy from a technique using PSI based on 3D CT-scans were matched 1:1 to 21 patients operated on using a conventional technique (pre-operative planning performed on standard radiographs). The accuracy of the correction was analyzed, comparing coronal and sagittal mechanical post-operative angles with pre-operative planning.

RESULTS

With regard to alignment in the coronal plane (HKA correction), our study demonstrated a significant improvement in the accuracy of the correction obtained in the PSI group compared to the conventional group (0.43 ± 0.50 vs 3.95 ± 1.64 p < 0.001). In the sagittal plane (PDFA correction), we also found a significant improvement in correction accuracy in the PSI group (0.52 ± 0.60 vs 3.10 ± 1.83 p < 0.001). There was a significant decrease in operating time (delta 7.7 ± 3.07 (1.5-13.9) (p = 0.0.161) and fluoroscopic images taken (6.9 ± 0.54 (5.8-8) p < 0.001).

CONCLUSION

Our results suggest that the use of PSI in DFVO improves the accuracy of correction in both the coronal and sagittal planes compared to conventional techniques.

Augmented reality in computer-assisted interventions based on patient-specific 3D printed reference

Augmented reality (AR) can be an interesting technology for clinical scenarios as an alternative to conventional surgical navigation. However, the registration between augmented data and real-world spaces is a limiting factor. In this study, the authors propose a method based on desktop three-dimensional (3D) printing to create patient-specific tools containing a visual pattern that enables automatic registration. This specific tool fits on the patient only in the location it was designed for, avoiding placement errors. This solution has been developed as a software application running on Microsoft HoloLens. The workflow was validated on a 3D printed phantom replicating the anatomy of a patient presenting an extraosseous Ewing's sarcoma, and then tested during the actual surgical intervention. The application allowed physicians to visualise the skin, bone and tumour location overlaid on the phantom and patient. This workflow could be extended to many clinical applications in the surgical field and also for training and simulation, in cases where hard body structures are involved. Although the authors have tested their workflow on AR head mounted display, they believe that a similar approach can be applied to other devices such as tablets or smartphones.

3D printing and its applications in orthopaedic trauma: A technological marvel

BACKGROUND

With rapid emergence of 3D printing technology, surgeons have recently started to apply this for nearly all areas of orthopaedic trauma surgery. Computed tomography or magnetic resonance images of trauma patients can be utilized for making graspable objects from 3D reconstructed images. Patient specific anatomical models can thereby be created. They enhance surgeon's knowledge of their patients' precise patho-anatomy, regarding both traumatized bones and soft tissue as well as normal areas, and therefore help in accurate preoperative planning. 3D printed patient specific instrumentation can help to achieve precise implant placement, and better surgical results. Most importantly, customized implants, casts, orthoses and prosthetics can be manufactured to match an individual's anatomy. Three dimensional (3D) printing, also called as 'additive manufacturing' and 'rapid prototyping' is considered as the "second industrial revolution", and this appears to be especially true for orthopaedic trauma surgery.

METHODS

A literature search was performed for extracting all papers related to 3D Printing applications in orthopaedics and allied sciences on the Pubmed, and SCOPUS; using suitable key terms and Boolean operators ("3D Printing" OR "3 dimensional printing" OR "3D printed" OR "additive manufacturing" OR "rapid prototyping") AND (''Orthopaedics" OR "Orthopaedics'') AND ("Trauma" OR "Injury")in June 2018. Search was also performed in Web of Science, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews. No limits were set on the time period or evidence level, as 3D printing in orthopaedics is relatively recent and mainly low level evidence is available. Titles and abstracts were screened and all duplicate and unrelated papers were excluded. Papers related to orthopaedic trauma were manually selected for this review.

RESULTS

The search on Pubmed retrieved 144 Papers and similar search on SCOPUS retrieved 94 papers. Additional searches did not reveal more relevant papers. After excluding duplicates and unrelated papers, and on screening of titles and abstracts, 59 papers were considered for review. Papers related to spine fractures only were not included, as they have been covered in another paper in this journal issue.

CONCLUSION

All over the world, orthopaedic Surgeon's and allied professionals and scientists are enthusiastically using 3D printing technology for designing patient specific models, instrumentation, implants, orthosis and prosthesis, besides 3D bioprinting of bone and cartilage scaffolding, and the same has been applied for nearly all areas of orthopaedic trauma surgery, from head to foot.

Three dimensional patient-specific printed cutting guides for closing-wedge distal femoral osteotomy

PURPOSE

Medial closing-wedge distal femoral osteotomy (MCWDFO) was used to treat valgus knee malalignment combined with lateral compartment disease. The clinical outcome of the osteotomy depends on the accurate correction of valgus malalignment. The aim of this study was to evaluate the accuracy of a MCWDFO assisted by three-dimensional (3D)-printed cutting guides and locking guides.

PATIENTS AND METHODS

Thirty-three consecutive patients (33 knees) were operated on using the same MCWDFO. 3D-printed cutting guides and locking guides were used to locate the osteotomy cut plane and to facilitate closing the wedge in 12 patients (3D-guide group). Another 21 patients (conventional group) underwent MCWDFO following the conventional technique. The desired correction was defined as a weight-bearing line (WBL) coordinate 50% of the width of the tibial plateau from the medial tibial margin. The deviation between the planned and executed WBL coordinate, surgical time and fluoroscopic time were compared.

RESULTS

The mean deviation between the planned and executed WBL coordinate was 4.9% in the 3D-guide group and 7.6% in the conventional group (P = 0.024). Shorter surgical time was found in the 3D-guide group (mean, 77.7 minutes vs. mean, 96.5 minutes; P < 0.001), while the mean number of intra-operative fluoroscopic images was 6.1, compared with 34.7 in the conventional group (P < 0.001).

CONCLUSION

The use of 3D-printed cutting guides and locking guides can increase the precision of the MCWDFO in patients with lateral compartment disease and valgus deformity, making our surgery more efficiency and occupying less fluoroscopic time.