3D Printed Bone Models Research Articles

Minimally invasive plate osteosynthesis of femoral fractures with 3D-printed bone models and custom surgical guides: A cadaveric study in dogs.

Assess the accuracy and efficiency of reduction provided by application of plates precontoured to 3-dimensional (3D)-printed femoral bone models using a custom fracture reduction system (FRS) or intramedullary pin (IMP) to facilitate femoral minimally invasive plate osteosynthesis (MIPO) in dogs. Experimental cadaveric study. Seven dog cadavers. Virtual 3D femoral models were created using computed tomographic images. Simulated, virtual mid-diaphyseal femoral fractures were created and reduced. Reduced femoral models were 3D-printed and a plate was contoured. Custom drill guides for plate screw placement were designed and 3D-printed for the FRS. Mid-diaphyseal simulated comminuted fractures were created in cadavers, and fractures were aligned using FRS or IMP and stabilized with the precontoured plates. Number of fluoroscopic images acquired per procedure and surgical duration were recorded. Computed tomographic scans were repeated to assess femoral length and alignment. Compared to the preoperative virtual plan, median change in femoral length and frontal, sagittal, and axial alignment was less than 3 mm, 2°, 3°, and 3° postoperatively, respectively, in both reduction groups. There was no difference in length or alignment between reduction groups (P > .05). During FRS, fewer fluoroscopic images were taken (P=.001), however, surgical duration was longer than IMP procedures (P=.011). Femoral alignment was accurate when using plates precontoured to 3D printed models, regardless of reduction method. Accurate plate contouring using anatomically accurate models may improve fracture reduction accuracy during MIPO applications. Custom surgical guides may reduce fluoroscopy use associated with MIPO.

Mapping of Orthopaedic Fractures for Optimal Surgical Guidance.

Orthopaedic fractures may be difficult to treat surgically if accurate information on the fracture propagation and its exit points are not known. Even with two-dimensional (2D) radiographic images, it is difficult to be completely certain of the exact location of the fracture site, the fracture propagation pattern and the exit points of the fracture. Three-dimensional (3D) computerised tomographic models are better in providing surgeons with the extent of bone fractures, but they may still not be sufficient to allow surgeons to plan open reduction and internal fixation (ORIF) surgery.Fracture patterns and fracture maps are developed to be visual tools in 2D and 3D. These tools can be developed using fractured bones either before or after fracture reduction. Aside from being beneficial to surgeons during pre-surgical planning, these maps aid bioengineers who design fracture fixation plates and implants for these fractures, as well as represent fracture classifications.Fracture maps can be either created ex silico or in silico. Ex silico models are created using 3D printed bone models, onto which fracture patterns are marked. In silico fracture models are created by tracing the fracture lines from a fractured bone to a healthy bone template on a computer. The points of interest in both of these representations are the path of fracture propagation on the bone's surface and exit zones, which eventually determine the surgeon's choice of plate and fracture reduction. Both ex silico and in silico fracture maps are used for pre-surgical planning by the surgeons where they can plan the best way to reduce the fracture as well as template various implants in a low-risk environment before performing the surgery.Recently, fracture maps have been further digitised into heat maps. These heat maps provide visual representations of critical regions of fractures propagating through the bone and identify the weaker zones in the bone structure. These heat maps can allow engineers to develop optimal surgical plates to fix an array of fracture patterns propagating through the bone. Correlation of fractured regions with the mechanisms of injury, age, gender, etc. may improve fracture predictability in the future and optimise the intervention, along with making sure that surgeons do not miss fractures of the bone that may otherwise be hidden from plain sight.

Design and topographic evaluation of a canine humeral anatomic plating system (CHAPS) for humeral condylar fracture repair in spaniels.

To design a precontoured plating system for humeral condylar fracture repair in spaniels with humeral intracondylar fissure (HIF) and quantify accuracy of fit of the system on 3D printed bone models. Experimental on 3D printed models. The plating system was based on morphometric data obtained from CT. Plates were applied to models and impression material was measured under the plates at points of interest to define plate bone gap (PBG). Data on locking screw interference on plate application were also obtained. Eleven elbows models were plated. Statistical analysis to assess for any difference in PBG measurements between left and right humuri revealed two loci (3 and 17) under the lateral plate and two loci (3 and 17) under the medial plate. On cumulate portion analysis, 67% of lateral plate loci and 80% of medial plate loci had a PBG of ≤2 mm respectively. An incidence of 2.1% (3/143) screw interference occurred. Design of a contoured plating system for application to humeral models from spaniels with HIF and its application with objective measurement of PBG is described. The majority of the loci measured under both lateral and medial plates had a BPG of ≤2 mm and the incidence of locking screw interference on plate application was low. This novel system may have application for the stabilization of humeral condylar fractures in spaniels avoiding the need for plate contouring and minimizing the incidence of locking screw interference.

Corrective osteotomy for complex tibial deformity in a patient with hereditary vitamin D-resistant hypophosphatemic rickets (HVDRR) using CT-based navigation system and 3D printed osteotomy model

Planning a three-dimensional (3D) osteotomy using computed tomography (CT) data is useful especially in cases with complex deformities. Furthermore, CT-based navigation system allows the preoperative virtual planning to be replicated in actual surgery. However, one disadvantage when using navigation systems is that when osteotomies are performed on tracker-attached bone, the bone fragments on the side that were cut away cannot be tracked. This is especially problematic when performing multiple osteotomies on bones with complex deformities. We solved this problem by creating a 3D printed bone model that can be referenced intraoperatively and used in combination with the navigation system. We applied these techniques to perform segmental corrective osteotomy for a complex tibial deformity with intramedullary nail (IMN) fixation case of hereditary vitamin D-resistant hypophosphatemic rickets (HVDRR) in an adult man. Due to the patient’s history of multiple surgeries, the affected tibia had a narrow and partially closed medullary canal. Therefore, we planned to use an IMN for correction and fixation of tibial deformity to protect the thin and stretched skin around the deformed tibia. With the assistance of CT-based navigation, we could perform an accurate three-dimensional tibial osteotomy. Moreover, we could perform accurate preparation of closed medullary canal for the IMN placement by referring to the 3D printed bone models. Six months after the operation, the bone union at the osteotomy sites was confirmed and the patient was able to return to his normal life and work.

Virtual Reality, Autostereoscopy, and Physical Models for Learning Anatomy: Performance Comparisons

IntroductionTraditional anatomical education relies on textbooks, physical models, and cadaveric specimens. Advances in technology have provided other display modalities including virtual reality (VR), and autostereoscopic displays. VR uses head‐mounted displays (HMDs) for an interactive experience and autostereoscopic screens, like AlioscopyTM, offer a stereoscopic but HMD‐free environment. Current research shows contradictory results on the efficacy of VR compared to physical models, and there appears to be no data on the efficacy of autostereoscopic displays in learning anatomy. The purpose of this study is to determine whether VR, AlioscopyTM, or physical models yield the best performance for anatomical education.MethodsStudents at McMaster University without prior anatomy training will learn nominal skeletal anatomy in three different modalities: VR (Oculus Quest 2TM), AlioscopyTM, or a physical 3D‐printed bone model. Each of the environments will be as identical as possible (i.e, the VR environment is a rendering of the exact room and set‐up used for testing the physical bone models). Participants will be randomized to one of three interventions where they will study ten bony landmarks on either the human hemipelvis, zygomatic bone, or calcaneus in a distinct modality. Participants will be seated and use an XboxTM controller to rotate the bone along the vertical axis of rotation. After four minutes, an untimed, recognition‐based test will be administered, where participants will be given a 3D‐printed bone identical to the one used in the learning phase, with randomized landmarks and word bank of landmarks learnt. Performance will be evaluated based on landmarks correctly identified on the recognition‐based test.ResultsBased on the current literature, we hypothesize that the physical models will be a superior learning environment compared to the VR environment. However, significant improvements in the HMD of the Oculus Quest 2 may have ameliorated previous issues with the VR environment. There is no data available on the efficacy of AlioscopyTM and while the absence of an HMD is appealing, its narrow viewing angle compared to the immersive VR environment may be problematic.ConclusionWith the push to increase accessibility and decrease costs associated with anatomical education with the help of digital modalities, the findings from this study are critical to informing teaching practices, and technology use in anatomy education.

Comparison of Summative Temporal Bone Dissection Scales Demonstrate Equivalence.

Introduction Temporal bone surgery is a unique and complicated surgical skill that requires extensive training. There is an educational requirement to maximize trainee experience and provide effective feedback. Objective We evaluate three temporal bone dissection scales for efficacy, reliability, and accuracy in identifying resident skill during temporal bone surgery. Methods Residents of various skill levels performed a mastoidectomy with posterior tympanotomy on identic 3D-printed temporal bone models. Four blinded otologic surgeons evaluated each specimen at two separate intervals using three separate dissection scales: the Welling Scale (WS), the Iowa Temporal Bone Assessment Tool (ITBAT), and the CanadaWest Scale (CWS). Scores from each scale were compared in their ability to accurately separate residents by skill level, inter- and intrarater reliability, and efficiency in application. Results Nineteen residents from 9 postgraduate programs participated. Assessment was clustered into junior (postgraduate year or PGY 1, 2), intermediate (PGY 3) and senior resident (PGY 4, 5) cohorts. Analysis of variance (ANOVA) found significant differences between cohort performance ( p < 0.05) for all 3 scales considering the PGY level and the subjective account of temporal bone surgical experience. The inter-rater reliability was consistent across each scale. The intrarater reliability was comparable between the CWS (0.711) and the WS (0.713), but not the ITBAT (0.289). Time (in seconds) to complete scoring for each scale was also comparable between the CWS (42.7 ± 16.8), the WS (76.6 ± 14.5), and the ITBAT (105.6 ± 38.9). Conclusion All three scales demonstrated construct validity and consistency in performance, and consideration should be given to judicious use in training.

Development of a Novel X-ray Compatible 3D-Printed Bone Model to Characterize Different K-Wire Fixation Methods in Support of the Treatment of Pediatric Radius Fractures.

Additive manufacturing technologies are essential in biomedical modeling and prototyping. Polymer-based bone models are widely used in simulating surgical interventions and procedures. Distal forearm fractures are the most common pediatric fractures, in which the Kirschner wire fixation is the most widely used operative method. However, there is still lingering controversy throughout the published literature regarding the number of wires and sites of insertion. This study aims to critically compare the biomechanical stability of different K-wire fixation techniques. Different osteosyntheses were reconstructed on 189 novel standardized bone models, which were created using 3D printing and molding techniques, using PLA and polyurethane materials, and it has been characterized in terms of mechanical behavior and structure. X-ray imaging has also been performed. The validation of the model was successful: the relative standard deviations (RSD = 100 × SD × mean−1, where RSD is relative standard deviation, SD is the standard deviation) of the mechanical parameters varied between 1.1% (10° torsion; 6.52 Nm ± 0.07 Nm) and 5.3% (5° torsion; 4.33 Nm ± 0.23 Nm). The simulated fractures were fixed using two K-wires inserted from radial and dorsal directions (crossed wire fixation) or both from the radial direction, in parallel (parallel wire fixation). Single-wire fixations with shifted exit points were also included. Additionally, three-point bending tests with dorsal and radial load and torsion tests were performed. We measured the maximum force required for a 5 mm displacement of the probe under dorsal and radial loads (means for crossed wire fixation: 249.5 N and 355.9 N; parallel wire fixation: 246.4 N and 308.3 N; single wire fixation: 115.9 N and 166.5 N). We also measured the torque required for 5° and 10° torsion (which varied between 0.15 Nm for 5° and 0.36 Nm for 10° torsion). The crossed wire fixation provided the most stability during the three-point bending tests. Against torsion, both the crossed and parallel wire fixation were superior to the single-wire fixations. The 3D printed model is found to be a reliable, cost-effective tool that can be used to characterize the different fixation methods, and it can be used in further pre-clinical investigations.

Arthroscopic Debridement of Elbow Osteoarthritis Using CT-Based Computer-Aided Navigation Systems Is Accurate

PurposeTo evaluate whether the bony impingement lesion in elbow osteoarthritis can be removed accurately, as planned during arthroscopy, by using the computer-aided navigation system and performing mock surgery using 3-dimensional (3D)-printed bone models for clinical applications.MethodsWe performed mock surgery using 3D-printed plaster bone models of the humerus of 15 actual patients with elbow osteoarthritis. Two types of experiments were conducted to evaluate the surgical accuracy. Three surgeons performed the mock surgery, each with 15 bone models (total, 45 trials). Surgical accuracy was based on the mean of 45 trials. The differences in surgical accuracy among the 3 surgeons were also evaluated (mean 15 trials). The same surgeon performed 30 trials, and the difference in surgical accuracy between the first and the second halves was also evaluated (mean 15 trials).ResultsThe spatial error in the entire elbow joint was 1.13 mm. In terms of resection volume, a mean of 8% more volume was resected than was planned, and 85% of the planned area was resected. In our experiments, the surgical accuracy was significantly lower in the anterior than in the posterior joint. Intrarater reliability was intraclass correlation (ICC)2,1 0.81 and inter-rater reliability was ICC1,1 0.87.ConclusionsSurgery using computer-aided navigation systems for arthroscopic debridement of the elbow provided accuracy comparable to that in other joints.Clinical RelevanceArthroscopic debridement of elbow osteoarthritis requires advanced surgical skills because accurate identification of the bony impingement legion is difficult during surgery. Surgery using computer-aided navigation systems for arthroscopic debridement of the elbow will provide real-time tracking of both the surgical instruments and bony impingement lesions as well as solve the technical difficulties of arthroscopic surgery of the elbow joint.

A method for finding high accuracy surface zones on 3D printed bone models

The use of three-dimensional (3D) printing for surgical applications is steadily increasing. Errors in the printed models can lead to complications, especially when the model is used for surgery planning or diagnostics. In patient care, the validation of printed models should therefore be performed routinely. However, there currently is no standard method to determine whether the printed model meets the necessary quality requirements. In this work, we present a method that not only finds surface deviations of a printed model, but also shows high accuracy zones of a potentially corrupted model, that are safe to be used for surgery planning.Our method was tested on printed patient bone models with acetabular fractures and was compared to two common methods in orthopedics, simple landmark registration as well as landmark plus subsequent iterative closest point registration.In order to find suitable parameters and to evaluate the performance of our method, 15 digital acetabular bone models were artificially deformed, imitating four typical 3D printing errors. A sensitivity of over 95% and a specificity of over 99% was observed in finding these surface deformations. Then, the method was applied to 32 printed models that had been re-digitized using a computed tomography scanner. It was found that only 25% of these printed models were free of significant deformations. However, focussing on two common implant locations, our method revealed that 72% of the models were within the acceptable error tolerance. In comparison, simple landmark registration resulted in a 9% acceptance rate and landmark registration followed by iterative closest point registration resulted in a 41% acceptance rate.This outcome shows that our method, named Similarity Subgroups Registration, allows clinicians to safely use partially corrupted 3D printed models for surgery planning. This improves efficiency and reduces time to treatment by avoiding reprints. The similarity subgroups registration is applicable in further clinical domains as well as non-medical applications that share the requirement of local high accuracy zones on the surface of a 3D model.

Predictions of the elastic modulus of trabecular bone in the femoral head and the intertrochanter: a solitary wave-based approach.

This paper deals with the numerical prediction of the elastic modulus of trabecular bone in the femoral head (FH) and the intertrochanteric (IT) region via site-specific bone quality assessment using solitary waves in a one-dimensional granular chain. For accurate evaluation of bone quality, high-resolution finite element models of bone microstructures in both FH and IT are generated using a topology optimization-based bone microstructure reconstruction scheme. A hybrid discrete element/finite element (DE/FE) model is then developed to study the interaction of highly nonlinear solitary waves in a granular chain with the generated bone microstructures. For more robust and reliable prediction of the bone's mechanical properties, a face sheet is placed at the interface between the last chain particle and thebone microstructure, allowing more bone volume to be engaged in the dynamic deformation during interaction with the solitary wave. The hybrid DE/FE model was used to predict the elastic modulus of the IT and FH by analysing the characteristic features of the two primary reflected solitary waves. It was found that the solitary wave interaction is highly sensitive to the elastic modulus of the bone microstructure and can be used to identify differences in bone density. Moreover, it was found that the use of a relatively stiff face sheet significantly reduces the sensitivity of the wave interaction to local stiffness variations across the test surface of the bone, thereby enhancing the robustness and reliability of the proposed method. We also studied the effect of the face sheet thickness on the characteristics of the reflected solitary waves and found that the optimal thickness that minimizes the error in the modulus predictions is 4mm for the FH and 2mm for the IT, if the primary reflected solitary wave is considered in the evaluation process. We envisage that the proposed diagnostic scheme, in conjunction with 3D-printed high-resolution bone models of an actual patient, could provide a viable solution to current limitations in site-specific bone quality assessment.

Validation of a 3D-printed human temporal bone model for otology surgical skill training.

HypothesisThree-dimensional (3D) printed temporal bones are comparable to cadaveric temporal bones as a training tool for otologic surgery.BackgroundCadaveric temporal bone dissection is an integral part of otology surgical training. Unfortunately, availability of cadaveric temporal bones is becoming much more limited and concern regarding chemical and biological risks persist. In this study, we examine the validity of 3D-printed temporal bone model as an alternative training tool for otologic surgery.MethodsSeventeen otolaryngology trainees participated in the study. They were asked to complete a series of otologic procedures using 3D-printed temporal bones. A semi-structured questionnaire was used to evaluate their dissection experience on the 3D-printed temporal bones.ResultsParticipants found that the 3D-printed temporal bones were anatomically realistic compared to cadaveric temporal bones. They found that the 3D-printed temporal bones were useful as a surgical training tool in general and also for specific otologic procedures. Overall, participants were enthusiastic about incorporation of 3D-printed temporal bones in temporal bone dissection training courses and would recommend them to other trainees.Conclusion3D-printed temporal bone model is a viable alternative to human cadaveric temporal bones as a teaching tool for otologic surgery.

Comparison between Novice and Experienced Surgeons Performing Corrective Osteotomy with Patient-Specific Guides in Dogs Based on Resulting Position Accuracy.

Corrective osteotomy has been applied to realign and stabilize the bones of dogs with lameness. However, corrective osteotomy for angular deformities requires substantial surgical experience for planning and performing accurate osteotomy. Three-dimensional printed patient-specific guides (3D-PSGs) were developed to overcome perioperative difficulties. In addition, novices can easily use these guides for performing accurate corrective osteotomy. We compared the postoperative results of corrective osteotomy accuracy when using 3D-PSGs in dogs between novice and experienced surgeons. We included eight dogs who underwent corrective osteotomy: three angular deformities of the radius and ulna, three distal femoral osteotomies, one center of rotational angle-based leveling osteotomy, and one corrective osteotomy with stifle arthrodesis. All processes, including 3D bone modeling, production of PSGs, and rehearsal surgery were carried out with computer-aided design software and a 3D-printed bone model. Pre- and postoperative positions following 3D reconstruction were evaluated by radiographs using the 2D/3D registration technique. All patients showed clinical improvement with satisfactory alignment and position. Postoperative accuracy evaluation revealed no significant difference between novice and experienced surgeons. PSGs are thought to be useful for novice surgeons to accurately perform corrective osteotomy in dogs without complications.

Selective Laser Melting of Patient Individualized Osteosynthesis Plates-Digital to Physical Process Chain.

We report on the exemplified realization of a digital to physical process chain for a patient individualized osteosynthesis plate for the tarsal bone area. Anonymized patient-specific data of the right feet were captured by computer tomography, which were then digitally processed to generate a surface file format (standard tessellation language, STL) ready for additive manufacturing. Physical realization by selective laser melting in titanium using optimized parameter settings and post-processing by stress relief annealing results in a customized osteosynthesis plate with superior properties fulfilling medical demands. High fitting accuracy was demonstrated by applying the osteosynthesis plate to an equally good 3D printed bone model, which likewise was generated using the patient-specific computer tomography (CT) data employing selective laser sintering and polyamid 12. Proper fixation has been achieved without any further manipulation of the plate using standard screws, proving that based on CT data, individualized implants well adapted to the anatomical conditions can be accomplished without the need for additional steps, such as bending, cutting and shape trimming of precast bone plates during the surgical intervention. Beyond parameter optimization for selective laser melting, this exemplified digital to physical process chain highlights the potential of additive manufacturing for individualized osteosynthesis.

Forensic 3D printing from micro-CT for court use- process validation

Forensic application of 3D scanning and printing technology is gaining momentum with 3D printed evidence starting to be produced for court. However, the processes for creating these forensic 3D models requires still rigorous assessment to ensure they adhere to the relevant legal standards. Although, previous work has examined the accuracy of 3D prints created from medical grade Computed Tomography (CT), no such assessment has been carried out for Micro Computed Tomography (micro-CT) which offers superior resolution and the ability to capture forensically relevant injuries. This study aimed to quantify the error rates associated with forensic 3D printed models and toolmarks, created using three different printing technologies, based on micro-CT data. Overall, 3D printed models, based on micro-CT scans, replicate bone surface geometry to sub-millimetre accuracy (<0.62mm for overall shape and <0.36mm for toolmarks). However, there were significant differences between the printing technology employed (mean errors of −0.3%, −0.8%, and 0.7% for shape geometry and −0.8%, 14.1%, and 0.7% for toolmark geometry for Printers 1–3 respectively). Where possible, the authors recommend micro-CT imaging for producing forensic 3D printed bone models particularly when injuries are present.

Effectiveness of circular hexapod external fixation with soft tissue reconstruction in treating severe knee dislocation due to burn scarring: a case report

BackgroundSevere varus deformity and soft tissue injury caused by a burn around a complex knee dislocation is a rare injury. Soft tissue reconstruction and deformity correction with circular hexapod external fixation of the knee and hinged total knee arthroplasty (TKA) are challenging and can lead to major complications if not performed appropriately. We present a case in which a combination of soft tissue reconstruction, circular hexapod external fixation, and TKA was used treat severe knee dislocation due to burn scarring.Case presentationWe report the case of a 58-year-old woman who presented for knee surgery with soft tissue reconstruction, deformity correction with circular hexapod external fixation, and hinged TKA for a severe complex deformity and soft tissue injury caused by a burn injury at 6 months of age. The left leg was shorter by 35 mm in terms of functional leg length discrepancy. She walked with a limp, with a marked varus deformity of the left knee during the stance phase of walking. After a 3-stage repair, the patient was able to walk without assistance, confirming improvement of mobility.ConclusionThe treatment method was an effective use of a combination of soft tissue reconstruction, circular hexapod external fixation, and rehearsal surgery using a 3D printed bone model of the modular rotating hinge component of TKA, which was successfully used to treat a severe knee dislocation due to burn scarring. This staged surgery maintained the leg length and ultimately achieved a satisfactory alignment.

Design and testing 3D printed structures for bone replacements

Purpose: 3D printing has shown enormous potential for building plastic products, including bone, organs, and body parts. The technology has progressed from visualization and preoperation training to the 3D printing of customized body parts and implants. This research aims to create 3D printed bone structure from plastics and test the mechanical properties of the cortical and trabecular bone structures if they match the real bone structure strength. Design/methodology/approach: We used Digital Imaging, and Communications in Medicine (DICOM) images from Computer Tomography (CT) scans to created external bone structures. These images' resolution did not allow the creation of fine trabecular bone structures, so we used 3D modeling software to engineer special 3D void honeycomb structures (with triangular, square, and hexagonal shapes). Another reason to design void structures is that the 3D printing of complex shapes without support materials is problematic. After designing and 3D printing of the 3D bone structures, their mechanical properties need to be tested. Findings: 3D bone models, solid (cortical), and void (trabecular) bone structures were designed, 3D printed, and then tested. Tensile, bending, and compression testing was performed. Testing the mechanical properties of the honeycomb structures (triangular, square, and hexagonal) shows that their strength and modulus are higher than those of the real trabecular bones. The results show that 3D printed honeycomb structures mechanical properties can match and some cases exceeding the properties of the actual bones trabecular structures, while the sold structures have lower mechanical properties than the bone cortical structures. Research limitations/implications: During the 3D printing experiments, we found that 3D printers, in general, have low resolution, not enough to print fine trabecular bone structures. To solve the existing 3D printing technology's insufficient resolution, we later designed and built an SLA (stereolithography) 3D printer with high printing resolution (10 micrometers). Another limitation we found is the lack of biocompatible materials for 3D printing of bone structures. Future research work is in progress formulating superior ink/resin for bone structures 3D printing. Further, clinical trials need to be performed to investigate 3D printed parts’ influence on the healing of bone structures. Practical implications: We found that the 3D void (honeycomb) structures will have an impact not only on building bone structures but also in engineering special structures for industrial applications that can reduce the weight, time, and the cost of the material, while still keep sufficient mechanical properties. Originality/value: Designing and testing 3D printed bone models, solid (cortical), and void (trabecular) bone structures could replace bones. Design and test special void honeycomb structures as a replacement for cortical bone structures.

A computed tomographic graphical approach to guide correction of femoral torsion.

To report geometric methods to assess femoral transverse bone morphology and develop a virtual method to guide the surgical correction of femoral torsional deformities. Observational study. Sixteen client-owned dogs comprising 14 normal femurs and 14 femurs with angulation-rotation bone deformities. Femoral torsion angle was measured with computed tomographic (CT) three-dimensional (3D) multiplanar reconstruction. Distal femoral transverse morphology was estimated with geometric methods and compared to direct measurements to span a target 20° angle on 3D reconstructions. A virtual correction of 20° was performed, and 3D-printed bone models were created. Femoral torsion of corrected bone models was compared to precorrection. Geometric estimates with an arc and chord of the metaphyseal area and chord of a best fit circle did not differ from direct measurement of femoral cortical length along the cranial cortex. Femoral torsion differed between normal femurs (25.8° ± 6°) and those with deformity (36.9° ± 8.4°, P < .001). Torsion that was measured on corrected 3D bone models did not differ from the expected torsion (preoperative +20°). Geometric methods provided an accurate estimate of distal femoral transverse bone morphology. Rotation of the distal femur based on geometric methods resulted in an accurate correction of torsion. Femoral bone diameter can be measured on a CT cross-section, and rotation distance can be calculated to achieve a desired correction of torsion. This approach provides a simple and accurate method to guide the correction of femoral torsion.

The role of 3D reconstruction in surgical training for the ENT young surgeon

Abstract BACKGROUND. Nose and paranasal sinus surgery requires an accurate anatomical knowledge and a fine systematic learning. Surgical practice on cadaveric specimens is very important for the ENT resident to allow for a step-by-step learning, but it is not easy in all countries to have access to this compound. MATERIAL AND METHODS. We propose 3D-printed anatomical bone model exercitations as an alternative method for anatomical study, morphological research and surgical learning RESULTS. We have achieved very satisfactory morphological results both for the colours and shapes. CONCLUSION. The use of 3D modelling simulation allows the young surgeon to improve their technical skills and to the expert surgeon to plan the preoperative strategy in complex situations.

Three-dimensional-printing Technology in Hip and Pelvic Surgery: Current Landscape.

The use of three-dimensional (3D) printing is becoming more common, including in the field of orthopaedic surgery. There are currently four primary clinical applications for 3D-printing in hip and pelvic surgeries: (i) 3D-printed anatomical models for planning and surgery simulation, (ii) patient-specific instruments (PSI), (iii) generation of prostheses with 3D-additive manufacturing, and (iv) custom 3D-printed prostheses. Simulation surgery using a 3D-printed bone model allows surgeons to develop better surgical approaches, test the feasibility of procedures and determine optimal location and size for a prosthesis. PSI will help inform accurate bone cuts and prosthesis placement during surgery. Using 3D-additive manufacturing, especially with a trabecular pattern, is possible to produce a prosthesis mechanically stable and biocompatible prosthesis capable of promoting osseointergration. Custom implants are useful in patients with massive acetabular bone loss or periacetabular malignant bone tumors as they may improve the fit between implants and patient-specific anatomy. 3D-printing technology can improve surgical efficiency, shorten operation times and reduce exposure to radiation. This technology also offers new potential for treating complex hip joint diseases. Orthopaedic surgeons should develop guidelines to outline the most effective uses of 3D-printing technology to maximize patient benefits.

Three-Dimensional Printed Models for Lateral Skull Base Surgical Training: Anatomy and Simulation of the Transtemporal Approaches.

Three-dimensional (3D) printing holds great potential for lateral skull base surgical training; however, studies evaluating the use of 3D-printed models for simulating transtemporal approaches are lacking. To develop and evaluate a 3D-printed model that accurately represents the anatomic relationships, surgical corridor, and surgical working angles achieved with increasingly aggressive temporal bone resection in lateral skull base approaches. Cadaveric temporal bones underwent thin-slice computerized tomography, and key anatomic landmarks were segmented using 3D imaging software. Corresponding 3D-printed temporal bone models were created, and 4 stages of increasingly aggressive transtemporal approaches were performed (40 total approaches). The surgical exposure and working corridor were analyzed quantitatively, and measures of face validity, content validity, and construct validity in a cohort of 14 participants were assessed. Stereotactic measurements of the surgical angle of approach to the mid-clivus, residual bone angle, and 3D-scanned infill volume demonstrated comparable changes in both the 3D temporal bone models and cadaveric specimens based on the increasing stages of transtemporal approaches (PANOVA<.003,<.007, and<.007, respectively), indicating accurate representation of the surgical corridor and working angles in the 3D-printed models. Participant assessment revealed high face validity, content validity, and construct validity. The 3D-printed temporal bone models highlighting key anatomic structures accurately simulated 4 sequential stages of transtemporal approaches with high face validity, content validity, and construct validity. This strategy may provide a useful educational resource for temporal bone anatomy and training in lateral skull base approaches.