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Page data
Part of Tibial Fracture Fixation
Type Medical course
Keywords orthopedic surgery, surgical training, tibial fracture, bicortical drilling, modular external fixation, open tibial shaft fracture, 3D printing, artificial bones
SDG Sustainable Development Goals SDG03 Good health and well-being
Authors Medical Makers
Published 2021
License CC-BY-SA-4.0
Affiliations Medical Makers
Impact Number of views to this page. Views by admins and bots are not counted. Multiple views during the same session are counted as one. 4,606

Modular External Fixation for an Open Tibial Shaft Transverse Fracture

This module allows medical officers and surgeons who are not orthopedic specialists to become confident and competent in irrigation and debridement, power and manual drilling, positioning and correctly inserting Schanz screws, and constructing the rod-to-rod modular frame as part of external fixation procedures for open tibial shaft fractures performed in regions without specialist coverage.

Overview[edit | edit source]

Global Impact[edit | edit source]

A systematic review of 204 countries estimated there were 455 million prevalent cases of acute or long-term symptoms of a fracture in 2019.[1] The 2019 global prevalence of fractures of the patella, tibia or fibula, or ankle was 300 million cases resulting in an estimated 15.5 million years lived with disability worldwide. Open tibial shaft fractures are the most common open long-bone fractures, and absolute fracture counts have been increasing substantially over the past 30 years.[1][2]

In low to middle income countries (LMICs), tibial fractures most often result from motor vehicle accidents, predominantly occur in young male adults (< 40 years, male to female ratio of 3:1), and often lead to reduced quality-of-life, loss of employment, and financial hardship for patients and their young families.[3][4][5] A 2018 Ugandan study found that only 12% of tibial fracture patients had recovered physically and economically at 24 months post-injury.

Access to high-quality orthopedic care in LMICs is limited by a lack of providers, resources, and training programs.[6] The global standard is a ratio of one orthopedic surgeon to 200,000 people.[7] In 2008, Uganda reported a ratio of 1 orthopedic surgeon for every 1.3 million people.[8] In 2020, Nigeria had an estimated population of over 206 million people.[9] According to the Nigerian Orthopaedic Association, Nigeria's ratio is 1 orthopedic surgeon to approximately 500,000 people.[7] An estimated 75% of Nigerian orthopedic surgeons are located in 4 major cities which leaves other urban areas and rural regions without coverage.[10]

The national shortages of orthopedic surgeons in LIMCs leaves patients vulnerable to traditional bone setters whose unsafe practices commonly lead to malunion, limb shortening, gangrene, limb loss, and death.[11][12][13][14][15] A 2007 study of Nigerian healthcare institutions found unacceptably high rates of amputation (57% to 77.8%) and mortality (11.1% to 26.7%) secondary to bone setter's gangrene.[11] A 2004 study on 82 Nigerian patients (median age of 27 years) found that the leading cause for limb amputation (32%) was gangrene resulting from treatment of extremity injuries by traditional bone setters.[12]

This self-assessed training module uses open source, locally reproducible, high fidelity 3D printed bone simulation models to educate and empower physicians who are not orthopedic specialists to perform modular external fixation procedures as part of the surgical management of open tibial shaft fractures to save limbs and lives. This module teaches essential irrigation and debridement, power and manual drilling, and modular external fixation skills that are transferable to the performance of other limb-saving and life-saving surgeries that require hardware stabilization and fixation.[16] These skills can be used to prevent needless suffering, disability, and deaths for the estimated 133 million patients who sustain extremity and pelvic fractures globally every year.[1]

Open-Source 3D Printing Technologies for High Fidelity Orthopedic Surgery Simulation Training[edit | edit source]

The specific psychomotor skills that will be acquired by the user of this module are:

  • Directing an assistant to perform irrigation while drilling to prevent thermal osteonecrosis
  • Listening to sound changes and paying attention to tactile feel during bicortical drilling to minimize plunge
  • Performing wound lavage of an open tibial shaft fracture
  • Properly placing widely spaced Schanz screws into fracture fragments
  • Inserting Schanz screws into the safe zones of the tibia
  • Power drilling Schanz screws through the near cortex
  • Manually advancing Schanz screws to avoid perforation of the far cortex
  • Constructing a rod-to-rod modular frame, and
  • Reducing and stabilizing an open tibial shaft fracture with a rod-to-rod modular frame[16][17][18][19]

Open-source 3D printing technology supports the local and automated reproduction of the highest fidelity bone simulation models at the lowest cost for medical officers and surgeons who are not orthopedic specialists in LMICs.

Open-source, open filament and user-friendly desktop 3D printers are currently in use at businesses, Makerspaces, universities, and hospitals in Africa.[20][21][22][23][24] Our 3D printed bone simulation models are designed to reduce simulator costs, simplify the simulator build, and minimize simulator assembly time for the learner.

This module provides an open source library of downloadable, 3D printed bone simulation models which accurately represent bone length and diameter, external contour and cross-sectional shape, bicortical anatomy, cortical hardness, cancellous bone porosity, and microstructure, and far cortex thickness for both genders at drilling sites for tibial shaft fractures.[25][26][27][28][29][30][31][32][33][34]

All of the module's 3D printed models can be locally reproduced on open source, open filament, user-friendly, fused deposition modelling, single extruder desktop 3D printers that print polylactic acid (PLA), a low-cost, biorenewable, and biodegradable plastic.[35][36][37][38][39] According to one filament manufacturer, 3D printed PLA at 100% infill has a Shore Hardness D value of 83D while independently measured Shore Hardness D values of 3D printed PLA samples range from 80D to 88D (n=12).[28][29] These Shore Hardness D values of 3D printed PLA are within the 3-sigma range for the Shore Hardness D measurements of 86.7D + 1.91D (ave. ± s.d., n=1815) for human cortical bone.[30]

To maximize the likelihood that these 3D printed models provide similar tactile feedback as human bone and do not foster the development of anti-skills, the bone simulation models are made from PLA, a plastic filament with a hardness level similar to cortical bone, which exhibits force and displacement ratios similar to artificial bone, and whose haptic feedback was rated as similar to bone during drilling by experienced maxillofacial surgeons and surgical residents.[28][29][30][35][40][41] These bone simulation models are digitally manufactured using customized settings to match age, gender, and bone site-specific cortical thickness values, and cancellous bone porosity values for the target patient population.[31][33]

To overcome the drawbacks of 3D printed plastic melting at high drilling temperatures, this module trains the learner to irrigate during bicortical drilling, which is a standard orthopedic surgical practice to reduce the risk of thermal osteonecrosis.[17][35] This provides continuous cooling to prevent melting of the 3D printed plastic bone models.

The user's learnings on high fidelity 3D printed bone simulation models will translate into the clinical performance of:

  • bicortical drilling to minimize plunge
  • irrigation and debridement of open fractures
  • external irrigation to prevent thermal osteonecrosis
  • placement of widely spaced Schanz screws into fracture fragments
  • pin insertion at drill trajectory angles within the safe zones of the tibia
  • manual advancement of Schanz screws to avoid perforation of the far cortex, and
  • construction of a rod-to-rod modular frame to reduce and stabilize an open tibial shaft fracture.

In the next phase, we plan to:

  • refine this module based on survey feedback from expert orthopedic surgeons and learners on the visual, acoustic and haptic fidelity of the 3D printed bone models and suitability for surgical simulation training
  • measure the number of procedures performed by learners and their post-operative complication rates to evaluate whether the 3D printed bone models are effective in training irrigation and debridement, power and manual drilling, and modular external fixation skills and do not foster the development of anti-skills.

Phase 1: Knowledge Review[edit | edit source]

It is highly recommended that the learner be familiar with this content before proceeding to the skill pages.

Phase 2: Simulator Build[edit | edit source]

Phase 3: Skills Practice[edit | edit source]

Phase 4: Self-Assessment[edit | edit source]

Bicortical Drilling Skills[edit | edit source]

The Tibial Shaft Simulator is designed to include mechanisms for targeted feedback which enables the user to: ensure they are practicing the appropriate skills; modify their performance to improve competence; and determine when they have practiced to a sufficient level of mastery to perform the procedure in a patient.

The Tibial Shaft Simulator has a simulated Periosteum Layer for Far Cortex Breakthrough Detection and a simulated Soft Tissue Layer for Plunge Depth Measurement for the self-assessment framework.

The Training Logbook - Bicortical Drilling Skills includes:

  • Checklist for bicortical drilling techniques to minimize plunge
  • Augmented feedback in the form of an auditory tone to alert the user if the drill bit exits the far cortex during bicortical drilling skills training
  • Measuring and recording average plunge depths on the clay backstop

Modular External Fixation for an Open Tibial Shaft Transverse Fracture[edit | edit source]

The Tibial Shaft Transverse Fracture Simulator is designed to include mechanisms for targeted feedback which enables the user to: ensure they are practicing the appropriate skills; modify their performance to improve competence; and determine when they have practiced to a sufficient level of mastery to perform the procedure in a patient.

The transparent cellophane that is wrapped around the 3D printed bone models and simulates the overlying periosteum will permit the learner to visually inspect and confirm post-fixation fracture alignment, the Schanz screws did not perforate the far cortex of the Tibial Shaft Transverse Fracture Simulator, and the Schanz screws are properly positioned medial to the tibial crest for the self-assessment framework.

Unlike conventional artificial bone fracture models, the base of the 3D printed models of the Tibial Shaft Transverse Fracture Simulator allows the proximal and distal fracture fragments to be positioned on a flat surface to permit easy, convenient, and precise measurement of the drill trajectory angles of the Schanz screws using a low-cost (20¢ USD) protractor for the self-assessment framework.[42]

The Training Logbook - Modular External Fixation for an Open Tibial Shaft Transverse Fracture includes:

  • Step-by-step procedural checklists to confirm following of the proper modular external fixation technique for open tibial shaft fractures
  • Visual inspection and taking cellphone photos ("digital X-rays") to verify post-fixation fracture alignment, no pin penetration of the far cortex, proper pin positioning in each fracture fragment, and drill trajectory angles are within the acceptable ranges for the safe zones of the tibia

Based on our user testing, we opted not to require the use of Far Cortex Breakthrough Detection and chose not to include the Plunge Depth Measurement for the Tibial Shaft Transverse Fracture Simulator. The rationale for these design choices is becauseː

  • the likelihood of perforating the far cortex and plunging is very low with the manual advancement of the Schanz screw into the far cortex
  • the transparent cellophane allows the learner to visually inspect and confirm that the self-drilling Schanz screws did not perforate the far cortex
  • plunge detection has not been shown to confer long-term learning benefits in reducing plunge
  • we want to avoid fostering learner dependence on augmented feedback ("anti-skills") since the learner will not have augmented feedback during the real procedure, and
  • this increases simulator fidelity, reduces simulator costs, simplifies the simulator build, and minimizes simulator assembly time for the learner.[19][43]

Innovative Design[edit | edit source]

This module provides data-driven, gender-specific, easy to print, labor-saving, environmentally friendly, hygienic, and cruelty-free bone simulation models that are not made with natural rubber latex, are designed with safety features to protect users, and can be locally reproduced to provide the highest fidelity, standardized orthopedic surgical simulation training at the lowest cost in LMICs to medical officers and surgeons who are not orthopedic specialists.

Safety By Design[edit | edit source]

Our team has prioritized safety in the design of our simulators.

All of the module's 3D printed bone models have a vise attachment to allow the user to secure the model inside a standard vise clamp to maximize safety during simulation training. Although using a vise clamp is more costly, it is standard training practice for bone models to be secured inside a vise clamp to maximize safety during bicortical drilling and fracture fixation simulation training.[44][45][46] Based on our clinical experience and user testing, we do not recommend having an assistant hold a bone model during drilling training because this exposes the assistant to potential injury. There is always a risk that the drill bit may slip when drilling through a tibia during Bicortical Drilling Skills training.[47]

One safety drawback of using an augmented feedback circuit for plunge detection is that it potentially exposes the learner to a live electrical circuit. To minimize the risk of the learner touching any conductive material in a live electrical circuit during simulation training:

High Fidelity[edit | edit source]

To maximize learning efficiency and minimize simulator overall costs and assembly time, we provide high fidelity, standardized bone simulation models for basic and advanced simulation training instead of having the learner progress through a range of homemade (DIY) simulators of varying and increasing fidelity.

The 3D printed bone models accurately simulate bone length and diameter, external contour, cross-sectional shape, bicortical anatomy, cortical hardness, cancellous bone porosity, and microstructure, and far cortex thickness for both genders at tibial shaft fracture drilling sites for modular external fixation.[25][26][27][28][29][30][31][32][33][34]

Cortical thickness varies depending on gender, age, and regions in the tibia.[34] In LMICs, tibial fractures predominantly occur in young adults (< 40 years) with a male to female patient ratio of 3:1.[4] The 3D printed bone models are designed to accurately simulate far cortex thickness values for young (< 50 years), healthy (BMI < 30) adult males and females at tibial diaphysis drilling sites for modular external fixation.[34]

During bicortical drilling skills training, the learner adjusts the applied drilling force to minimize plunge depth.[19] Drilling forces are influenced by cortical thickness, bone site, patient age, and bone mineral density.[48] To minimize the risk of teaching anti-skills (excessive or inadequate drilling forces), the high fidelity 3D printed bone models are made of plastic with similar hardness to human cortical bone and are designed to accurately simulate the age, gender, and bone site-specific cortical thickness values and cancellous bone porosity for the target patient population.[4][28][29][30][34]

A simulator without augmented (extrinsic) feedback is a higher fidelity simulator than a simulator with augmented feedback because this more accurately reflects real clinical scenarios. Thus, we opted to make the augmented feedback feature for plunge detection optional for the Tibial Shaft Transverse Fracture Simulator for modular external fixation skills training.

Easy to Manufacture[edit | edit source]

3D printing technology empowers local, labor-saving, and automated reproduction of high fidelity bone simulation models to permit standardized, high quality, self-assessed simulation training in LMICs. Using our high fidelity 3D printed bone models substantially simplifies the simulator build, minimizes the simulator assembly time, and accelerates the learning process for greater convenience for the learner.

All of the module's 3D printed bone simulation models are open source and can be locally reproduced on open-source, open filament, user friendly, single extruder desktop 3D printers that print polylactic acid (PLA), a low-cost and easy to print plastic.[20][21][35][36][49][50]

Unlike most 3D printed bone models, all of the module's 3D printed bone models are designed to:

  1. print without support material, rafts or brims
  2. require no cleaning, sanding, gluing, priming, painting, dipping, coating, smoothing, polishing, or any post-processing
  3. not require any non-3D printed parts, and
  4. be ready for use right out of the 3D printer.[51]

The Tibial Shaft Simulator and Tibial Shaft Transverse Fracture Simulator are easy and quick to assemble and do not require any tools, specialized equipment, technical expertise, or time-consuming preparation to build, install, operate and maintain these simulators within the intended place of use.

Lower Cost[edit | edit source]

The 3D Printed Adult Tibial Bone Models can be locally reproduced to provide the highest fidelity simulators at the lowest cost for orthopedic surgical simulation training in LMICs. The costs of the 3D Printed Adult Tibial Bone Models will vary depending on the region's 3D printing organizations, and locally available brands of filament.

In Canada, a 1.0 kg roll of white PLA costs $17.95 CAD which is equal to about 1.4¢ USD per gram.[52] The Tibial Shaft Simulator (3D Printed Adult Female Tibial Bone Model #1) weighs 138.57 grams and the total filament cost in Canada is $1.95 USD. The Tibial Shaft Transverse Fracture Simulator (3D Printed Adult Female Tibial Bone Models # 2 and # 3) weighs 332.86 grams and the total filament cost in Canada is $4.69 USD.

In Nigeria, one 750 gram roll of Ultimaker White PLA filament (Shore Hardness 83D) costs €33 Euros which is equal to about 5¢ USD per gram.[28][53] The total filament cost of the Tibial Shaft Simulator (3D Printed Adult Female Tibial Bone Model #1) in Nigeria can be $6.88 USD or less. The total filament cost of the Tibial Shaft Transverse Fracture Simulator (3D Printed Adult Female Tibial Bone Models # 2 and # 3) in Nigeria can be $16.53 USD or less.

The benefits of 3D printing the Tibial Shaft Simulator locally in Nigeria for bicortical drilling skills training are that the 3D printer filament costs are 12 times cheaper and the production time is 84 times faster than purchasing a comparable artificial bone cylinder product that is imported from abroad.[53][54] By obtaining locally made 3D printed bone models for bicortical drilling skills training, the learner also supports the local economy while saving on customs dues, processing fees, and international shipping costs that would be incurred when using artificial bone products that are not made locally.

Comparison of Tibial Shaft Simulator Locally Made in Nigeria to Commercially Available Composite Cylinder
Tibial Shaft Simulator

(3D Printed Adult Female Tibial Bone Model #1)

Sawbones Composite Cylinder

(SKU:3403-7)[54]

Bone Simulator Features Anatomic model that simulates mid-diaphyseal tibial bone for bicortical drilling skills training in preparation for modular external fixation training of an open tibial shaft transverse fracture. Cylinder that simulates mid-diaphyseal bone for fracture fixation testing.
Bone Simulator Materials 3D printed, biorenewable plastic anatomic bone models are made with a rigid plastic shell and inner cancellous material. Hollow short fiber reinforced epoxy cylinder. Customized cellular rigid polyurethane foam filling available upon request.
Vise Attachment Contains a vise attachment to safely secure the model inside a standard vise clamp. Does not contain a vise attachment.
Bone Simulator Dimensions Variable outer diameter (including 40 mm) x 6.2 mm wall thickness x 203.05 mm length. 40 mm outer diameter x 6 mm wall thickness x 500 mm length.
Unit Cost $6.88 USD per model[53] $78.78 USD (original $194.00 USD pricing adjusted for model length of 203.05 mm)[54][55]
Production Time 6 hours and 2 minutes Ready to ship in 21 days or more[54]

The benefits of 3D printing the Tibial Shaft Transverse Fracture Simulator locally in Nigeria for modular external fixation skills training are that the 3D printer filament costs are over 3 times cheaper and the production time is over 33 times faster than purchasing a comparable artificial bone product that is imported from abroad, and the 3D printer filament costs are over 9 times cheaper than acquiring a human cadaveric tibia prepared by a local university anatomy lab.[53][56][57] By obtaining locally made 3D printed bone models for modular external fixation skills training, the learner also supports the local economy while saving on customs dues, processing fees, and international shipping costs that would be incurred when using artificial bone products that are not made locally.

Comparison of Tibial Shaft Transverse Fracture Simulator Locally Made in Nigeria to Commercially Available Artificial Bone and Human Cadaveric Bone
Tibial Shaft Transverse Fracture Simulator

(3D Printed Adult Female Tibial Bone Models #2 and #3)

Sawbones Tibia, Plastic Cortical Shell, Left

(SKU:1104-9)[56]

Human Cadaveric Tibia

(Prepared by an University Anatomy Lab in Nigeria)[57]

Bone Simulator Features 3D printed, biorenewable plastic anatomic bone models are made with a rigid plastic shell and inner cancellous material. Plastic cortical shell models are made of a rigid plastic shell with inner cancellous material.
  • Human cadaveric tibial bone specimen prepared by an anatomy lab.
  • Age of donor may not be known.
  • Requires wet storage (which incurs additional fees)
Fracture Simulation Simulates a transverse mid-shaft fracture of the tibia for modular external fixation training. Requires additional preparation by user to simulate a fracture. Requires additional preparation to simulate a fracture.
Fracture Encapsulation Encapsulates transverse fracture with cellophane. Does not encapsulate or re-attach fracture. No. This would incur additional preparation and storage fees.
Vise Attachment Contains a vise attachment to safely secure the model inside a standard vise clamp. Does not contain a vise attachment. Does not contain a vise attachment.
Bone Simulator Dimensions Tibia with an overall length of 41 cm. Tibia with an overall length of 42 cm. Varies.
Unit Cost $16.53 USD[53] $53.50 USD $150.00 USD
Production Time 15 hours 8 minutes (when Adult Female Tibial Bone Models #2 and #3 are printed consecutively). Ready to ship in 21 days or more. Depends on local availability of cadaver specimens which is difficult to predict.

Noteː A product comparison was not made with the:

  • Sawbones Tibia, Solid Foam, Large ($16.00 USD) because the foam material does not simulate the hardness of cortical bone and thus, could foster anti-skills, and
  • Sawbones Cylinder with Encapsulated Oblique Fracture ($37.50 USD) because the hollow short fiber reinforced epoxy cylinder does not have anatomic features that make it suitable for modular external fixation training and does not appear to have adequate length to properly simulate an adult tibial midshaft fracture for modular external fixation training which requires the placement of widely spaced pins in each fracture fragment.[58][59][60]

Not Made With Natural Rubber Latex[edit | edit source]

Instead of using conventional rubber latex bands glued to re-attach artificial bone fracture fragments, the Tibial Shaft Transverse Fracture Simulator uses inexpensive, locally available, and easy to apply clear cellophane to encapsulate displaced fracture fragments in a simulated soft-tissue envelope. Using cellophane, a material that is not made with natural rubber latex, reduces the risk of triggering latex sensitivities and potentially life-threatening allergic reactions in healthcare workers.[61][62]

Eco-Friendly[edit | edit source]

All of the module's 3D printed bone simulation models are made from polylactic acid (PLA), a biorenewable, biodegradable, and minimally off-gassing thermoplastic.[37][38][39][63][64][65]

The 3D printed bone models of the Tibial Shaft Transverse Fracture Simulator can be recycled and indefinitely reused for training learners on the clinical diagnosis of fractures in the Management of Non-Displaced Fractures module (coming in the next phase!). The management of non-displaced fractures is one of the 44 essential surgical procedures identified by the World Bank.[16]

Cruelty-Free[edit | edit source]

Our 3D printed bone models provide a higher fidelity, hygienic, and humane training alternative to using live animal models or mammal cadaveric bones which makes them suitable for the 1.2 billion followers of Hinduism, over 520 million followers of Buddhism, 4.5 million followers of Jainism, and ethical vegans who refrain from using any animal products.[66][67][68][69]

No animal should be harmed from using this training module in accordance with the principles of ahimsa (non-violence or non-injury to all living beings), no killing of any living being under the Right Action Factor of The Eightfold Path of Buddhism, and the recognition of consciousness of all mammals outlined in The Cambridge Declaration on Consciousness.[67][68][70][71]

Equity[edit | edit source]

To make global surgical care equitable, then surgical training (including simulation models) for the Global South must be equivalent in quality to the Global North. This module gives surgical practitioners in LMICs access to open-source, affordable, high fidelity, locally reproducible 3D printed bone simulation models that are comparable to state-of-the-art, quality-tested artificial bone products that are available in high income countries.[54][56]

To advance surgical education and care in LMICs, surgical simulation training must be standardized to monitor performance and clinical outcomes. Providing standardized surgical simulation training requires using standardized, reproducible simulators. This module provides standardized, high fidelity, 3D printed bone models that can be locally reproduced in any country with an inexpensive, single extruder, fused deposition modeling desktop 3D printer with a minimum build volume Z height of 210 mm, such as the open-source Original Prusa i3 MK3S+ that costs $999 USD.[20] This Appropedia module and our open-source, high fidelity, locally reproducible 3D printed bone simulators can empower unrestricted access to standardized, self-assessed orthopedic surgical simulation training around the world.

Targeted Feedback[edit | edit source]

The Tibial Shaft Simulator has a simulated Periosteum Layer for Far Cortex Breakthrough Detection and a simulated Soft Tissue Layer for Plunge Depth Measurement to permit the measurement of plunge depth for the self-assessment framework.

The transparent cellophane that is wrapped around the Tibial Shaft Transverse Fracture Simulator and simulates the overlying periosteum will permit the learner to visually inspect and confirm that the self-drilling Schanz Screws did not perforate the far cortex for the self-assessment framework.

Unlike conventional artificial bone fracture models, the base of the 3D printed models of the Tibial Shaft Transverse Fracture Simulator allows the proximal and distal fracture fragments to be positioned on a flat surface to permit easy, convenient, and precise measurement of the drill trajectory angles of the Schanz Screws using a low-cost (20¢ USD) protractor for the self-assessment framework.[42][61]

Drawbacks of Traditional Approaches[edit | edit source]

According to the Global Surgical Training Challenge Discovery Awards: Mentoring Programme Handbook - March 2021, "anti-skills are clinically irrelevant skills that the simulator teaches that need to be unlearned when the clinician attempts to transfer what they have learned over to a real clinical scenario," and "[a]t its most fundamental level, anti-skills means incorrect or irrelevant technique, approach and methodology developed or reinforced as a result of using simulation."

During bicortical drilling, the surgeon adjusts drilling direction, speed and applied force to minimize plunge depth.[19] Drilling forces are influenced by cortical thickness, bone site, patient age, and bone mineral density.[48] Low fidelity simulators that do not accurately replicate human cortical bone hardness, and age- and gender-specific cortical thicknesses of tibial diaphyseal sites could foster anti-skills for bicortical drilling in learners. 100% of the orthopedic surgeons (n = 5) we surveyed agreed or strongly agreed that training on high fidelity simulators that accurately replicate human cortical bone hardness will translate into improved plunge depths when performing bicortical drilling on patients compared to low fidelity simulators.

Alternative approaches to orthopedic surgery simulation training include (in order of increasing fidelity): virtual reality simulators, DIY bone simulators, like the Fundamentals of Orthopedic Surgery (FORS) simulator, animal models, synthetic bones, and cadaver laboratories.[72][73]

Virtual reality simulators can be expensive and do not provide haptic or acoustic feedback for bicortical drilling skills training.

Low-cost DIY bone simulation models can be time-consuming to prepare and can vary widely in fidelity. This makes it impossible to provide standardized simulation training and to obtain objective, generalizable evaluation data to verify that the user's learnings will directly translate into the safe, clinical performance of bicortical drilling and external modular fixation procedures and will not foster the development of anti-skills.

The FORS simulator can be built from supplies purchased at a local hardware store.[73] However, the FORS Simulator uses low-fidelity polyvinyl chloride (PVC) hollow pipes which:

  1. do not recreate bone contours so the learner is unable to identify anatomic landmarks for proper positioning of external fixation pins into safe zones of the tibia or verify post-fixation fracture alignment
  2. do not simulate cancellous bone
  3. are not available in accurate cortical thicknesses or cross-sectional shapes which could foster the development of anti-skills for bicortical drilling
  4. are made from vinyl chloride, an industrial carcinogen, and contain small amounts of phthalates, which are endocrine disrupting chemicals, and
  5. do not readily biodegrade and thus, contribute to the rising global levels of plastic waste in landfills, microplastics in oceans and atmosphere, and nanoplastics in the environment.[74][75][76][77][78][79][80][81][82][83][84]

Animal models require the slaughtering of sentient beings and additional time-consuming preparation for use in simulation training.[71] Animal bones do not have realistic human cortical thicknesses or cross-sectional shapes and this could foster the development of anti-skills for bicortical drilling.[85][86] Studies have shown significantly different drilling temperature values (which correlate with drilling energy and drilling force) in animal versus human bones.[48][85][86]

Artificial bones are inaccessible in low to middle income countries due to long delivery times and high import costs from customs dues and processing fees because they are not produced locally.[54][56]

There is limited or no practitioner access to costly cadaver labs outside of training centers.

Evaluation[edit | edit source]

A description of how the original prototype design was iterated and developed with user-centered design methodology (including user testing) is outlined below:

1
Expert Input

Our team created an online survey to help initially guide the design of the module’s frugal simulators, psychomotor skills training, and targeted self-assessment frameworks. With mentorship support from the Royal College of Surgeons of Ireland, this survey received responses from 5 male orthopedic surgeons in two countries with a combined total of 85 years of practice experience. 80% of the survey respondents are orthopedic surgeons based in a LMIC.

  • 100% of survey respondents agreed or strongly agreed that training on high fidelity simulators that accurately replicate human cortical bone hardness will translate into improved plunge depths when performing bicortical drilling on patients compared to low fidelity simulators.
  • All survey respondents agreed or strongly agreed that training on powered drills reduces the risk of learners developing anti-skills for bicortical drilling on patients compared to manual drills.
  • When asked about the importance of powered drills for bicortical drilling skills training, survey respondents stated that it was "[c]ritically important to have powered drills available" and "[i]t provides for a better outcome and improves efficiency."

Based on the survey feedback, we chose to:

  • Design high-fidelity, 3D printed bone models that simulate human cortical bone hardness to better train learners to minimize plunge depths
  • Train learners to use powered drills designed for resource-constrained settings for the Bicortical Drilling Skills training module

The survey responses also helped guide the inclusion of checklist items on the Bicortical Drilling Skills Checklist for the self-assessment framework.

2
Although our team had initially planned to design a 3D printed cylinder (shown on left) for bicortical drilling skills training, we opted to provide anatomic bone models to minimize the risk of developing anti-skills from using training models that do not simulate the external contour or cross-sectional shape of a human tibial diaphysis.
Simulator Build
  • Although our team had originally proposed to design 3D printed cylinders (and even other geometric, non-organic shapes) with bicortical anatomy, realistic far cortex thickness values, and cancellous bone porosity and microstructure to train learners on bicortical drilling skills, we opted to provide anatomic bone models for bicortical drilling skills training in preparation for modular external fixation procedures.[47][87] The rationale for this design choice was based on the desire to accelerate the learning curve for users by providing high-fidelity artificial bone models and to minimize the risk of learners developing anti-skills for bicortical drilling through training on models that do not simulate the external contour or cross-sectional shape of human tibial shafts.
  • To optimize bone simulation model aesthetics and enable these models to print support-free, a base was added to the bottom of the bone models using Blender, an open-source 3D design software program.
  • During user testing in Nigeria, we reduced the height of the base and removed the fibula component from the Tibial Shaft Transverse Fracture Simulator because the fibula is not required for skills training and this would reduce filament costs for the learner.
  • To further reduce material costs in LMICs, we later re-designed the Tibial Shaft Transverse Fracture Simulator to reduce the diameter of the base.
  • To help the learner in setting up the simulators, each 3D printed bone simulation model displays the model number translated in the 6 official languages of the United Nations, and the model gender using internationally recognized graphical symbols for males and females. We received written authorization from the International Organization for Standardization to use ISO 7001 graphical symbols for males and females on our gender-specific bone simulation models.
  • We added a semi-engraved drilling direction arrow on the bottom of the Tibial Shaft Simulator to help users orient this simulator in the vise clamp.
  • The removal of the fibula from the Tibial Shaft Transverse Fracture Simulator had the unintended consequence of eliminating a key anatomic landmark for model orientation. Our user testing in Nigeria showed that our instructions need to emphasize that 3D Printed Adult Tibial Bone Model #2 is inserted into the left vise clamp and 3D Printed Adult Tibial Bone Model #3 is inserted into the right vise clamp to ensure proper orientation of the left Tibial Shaft Transverse Fracture Simulator for skills training. Based on user feedback, we added a semi-engraved drilling direction arrow on the base of 3D Printed Adult Tibial Bone Models #2 and #3 to assist with proper orientation.
  • Our user testing in Nigeria showed that all bone models require a vise attachment to allow the user to secure the model inside a standard vise clamp to maximize learner safety during simulation training. We do not recommend having an assistant hold a bone model during drilling training because it exposes the assistant to potential injury.
  • A vise attachment was added to the Tibial Shaft Simulator to allow it to be secured in a vise clamp for safe Bicortical Drilling Skills training. We increased the height of the vise attachment of the Tibial Shaft Simulator to 6.0 cm in order to maximize compatibility with different sizes of locally available vise clamps in Nigeria.
  • In LIMCs, 3D printer filament is usually imported and not locally produced. To reduce material costs in LMICs, we re-designed the Tibial Shaft Simulator to make the vise attachment with a hollow opening. Our initial user safety testing indicates that this design could compromise the mechanical strength of the Tibial Shaft Simulator for Bicortical Drilling Skills training so this cost-saving feature was not used in order to maximize safety.
  • Each 3D printed fracture fragment of the Tibial Shaft Transverse Fracture Simulator has a vise attachment so when it is placed inside a standard vise clamp, the bone model will be properly positioned to simulate a patient in the supine position.
  • We added detailed instructions on how to input the customized settings for the 3D printed bone models into a 3D slicing program in case the user was not familiar with using advanced 3D slicer settings.
  • Our user testing in Nigeria showed that manually wrapping the Tibial Shaft Transverse Fracture Simulator in cellophane can keep a displaced fracture loosely attached.
3
Skills Practice

Based on user feedback from Uganda, we explained the function of each hardware component, and listed and photographed the Surgical Hardware in order of use by the practitioner in the Modular External Fixation Kit for Simulation Training with 3D Printed Tibial Adult Bone Models knowledge page.

In the procedural steps for Modular External Fixation for an Open Tibial Shaft Transverse Fracture, we identified and highlighted the critical phases of the procedure in which only essential conversations and activities in the operating room should occur to avoid distracting the operator from their performance of his or her duties.[88]

Our user testing in Nigeria showed that a sponge can be cut out to fit over the medial aspect of each fracture fragment to simulate the soft tissue overlying the periosteum, and the sponge can be wrapped with cellophane to simulate the skin overlying the soft tissue on the Tibial Shaft Transverse Fracture Simulator. This permits the user to practice making a stab incision for the Schanz screw insertion sites.

Our user testing in Nigeria found that the sponge, if not properly retracted, gets entangled in the drill bit. Therefore, the sponge material was removed from the Tibial Shaft Transverse Fracture Simulator, and the cellophane is used to simulate the overlying skin for the stab incision for the subcutaneous medial tibia. We decided it was not necessary to simulate the various soft tissue layers with different materials for the simulator because of the superficial location of the medial tibia. This has the benefit of reducing simulator costs, simplifying the simulator build, and minimizing simulator assembly time for the learner.

Our user testing in Nigeria showed that the drill sleeve assembly should not be placed directly on the 3D printed bone model but should be held 3.0 mm above the bone model while drilling to prevent the plastic strands from getting stuck inside the drill sleeve assembly. Normally, the drill sleeve assembly is placed directly on the bone during real clinical scenarios.

Our user testing in Nigeria indicated that external irrigation would be useful during Bicortical Drilling Skills training but is not required for power drilling through the near cortex only for the Modular External Fixation for an Open Tibial Shaft Transverse Fracture skills training module.

Our user testing in Nigeria showed that the 3D printed bone simulation models would tolerate bicortical drilling with a 3.2 mm drill bit and 3.5 mm self-drilling Schanz screws but not with 4.5 mm self-drilling Schanz screws.

Our user testing in Nigeria showed that the 3D printed bone simulation models would tolerate near cortex drilling and manual advancement with a 3.5 mm self-drilling Schanz screws without the need for pre-drilled bicortical holes. It is acceptable to use smaller sized hardware for simulation skills training because the fundamental principles for modular external fixation are the same irrespective of hardware size.

We added a section to this module that educates the learner on the differences between the simulation training hardware and the hardware they would use in the operating room. In the future, we will be conducting additional testing to identify alternative 3D printed materials to permit learners to use the same sized hardware for simulation training and operating room procedures.

Our user testing in Nigeria showed that 3.5 mm diameter Schanz screws and 6.5 mm rods and clamps can be used to reduce and stabilize the simulated fracture of the Tibial Shaft Transverse Fracture Simulator.

Our subsequent user testing in Nigeria showed that:

  • the Tibial Shaft Simulator made from Ultimaker PLA (Shore Hardness 83D) was able to mechanically tolerate bicortical drilling with a 4.0 mm drill bit, and
  • the Tibial Shaft Transverse Fracture Simulator made from Ultimaker PLA (Shore Hardness 83D) and Ultimaker Tough PLA (Shore Hardness 79D) were able to mechanically tolerate power drilling of a new (unused) self-drilling 5.0 mm Schanz Screw through the near cortex and manual advancement to anchor the self-drilling 5.0 mm Schanz Screw into the far cortex.[28][89]

These findings will permit learners to use the same sized hardware for simulation training and real clinical scenarios. We hypothesize that the key differences from our prior user testing is that new (sharp) Schanz screws were used and that fresher filament was likely used.

We also observed that two other filament materials (ABS and CPE+) exhibited mechanical failure during power drilling of a new self-drilling 5.0 mm Schanz Screw through the near cortex and manual advancement to anchor the self-drilling 5.0 mm Schanz Screw into the far cortex. Although these two filaments are described as stronger materials, their Shore Hardness D values are lower than PLA and Tough PLA.[28][89][90][91][92][93]

Filament Material Testing for 3D Printed Adult Male Tibial Bone Models
Simulator Model # Filament Brand Filament Material Shore Hardness Test Observations
Tibial Shaft Simulator 1 Ultimaker PLA 83D[28] Model was able to tolerate power drilling of a 4.0 mm drill bit through both cortices.
Tibial Shaft Transverse Fracture Simulator 2 Ultimaker PLA 83D Model was able to tolerate power drilling of a self-drilling 5.0 mm Schanz Screw through the near cortex and manual advancement of the 5.0 mm Schanz Screw for anchoring into the far cortex.
Tibial Shaft Transverse Fracture Simulator 3 Ultimaker PLA 83D Model was able to tolerate power drilling of a self-drilling 5.0 mm Schanz Screw through the near cortex and manual advancement of the 5.0 mm Schanz Screw for anchoring into the far cortex.
Tibial Shaft Transverse Fracture Simulator 3 Ultimaker Tough PLA 79D[89] Model was able to tolerate power drilling of a self-drilling 5.0 mm Schanz Screw through the near cortex and manual advancement of the 5.0 mm Schanz Screw for anchoring into the far cortex.
Tibial Shaft Transverse Fracture Simulator 3 Ultimaker ABS 76D[92] Model was unable to tolerate power drilling of a self-drilling 5.0 mm Schanz Screw through the near cortex and manual advancement of the 5.0 mm Schanz Screw for anchoring into the far cortex.
Tibial Shaft Transverse Fracture Simulator 3 Ultimaker CPE+ 75D[93] Model was unable to tolerate power drilling of a self-drilling 5.0 mm Schanz Screw through the near cortex and manual advancement of the 5.0 mm Schanz Screw for anchoring into the far cortex.

Our user testing in Nigeria showed that unused (sharp) 4.5 mm diameter Schanz screws and 11.0 mm diameter rods and corresponding clamps can be used to reduce and stabilize the simulated fracture of the Tibial Shaft Transverse Fracture Simulator.

4
Self-Assessment

For plunge depth measurement on the Tibial Shaft Simulator, we switched to using modelling clay for the backstop instead of foam material because clay is reusable and can be locally obtained in Nigeria and Uganda.[44][45]

In response to the feedback we received at the August 18, 2021 Prototype Showcase, our team added a Far Cortex Breakthrough Detector to the Tibial Shaft Simulator for Bicortical Drilling Skills training that uses an electric circuit and powered orthopedic surgical drill designed for resource-constrained settings.

To maximize safety and minimize the risk of the learner touching any conductive material in a live electrical circuit during simulation training:

  • we added an extra insulated alligator clip to minimize the length of non-insulated metal wire for the Far Cortex Breakthrough Detector
  • we revised the simulator build and use instructions to re-emphasize and explain the safety rationale for the mandatory use of gloves during training.

Our user testing in Nigeria showed that wrapping the entire clay backstop in cellophane keeps the clay from covering the aluminum foil during plunge which interrupts the breakthrough detection circuit. This helps to prolong the duration of the auditory signal for far cortex breakthrough detection.

Our user testing in Nigeria showed that a depth gauge can be used to measure plunge in a clay backstop wrapped in cellophane.

Our user testing gave us significant concerns that augmented feedback for plunge detection can foster anti-skills for bicortical drilling by training the self-assessed learner to depend on extrinsic (augmented) feedback instead of intrinsic feedback (drilling by sound and feel) to adjust the applied drilling force to minimize plunge depth.

Our user testing has observed the unintended consequence of adding augmented feedback for plunge detection during bicortical drilling skills training is that it distracts the learner from paying attention to drilling by sound and feel of the drill bit to minimize plunge. This was observed in user testing sessions on two continents where users had accidentally missed the step to connect the augmented feedback circuit and exhibited significant plunge because they were dependent on augmented feedback.

In the video below, you can observe how the practitioner inadvertently missed the step to connect the plunge detector circuit and exhibited significant plunge because he was dependent on the augmented feedback circuit for plunge detection. In the second segment, the practitioner is using the augmented feedback circuit for plunge detection. Although this reduces plunge during the simulation training, this could lead to overconfidence in the learner and result in worse plunge depths in real clinical procedures where plunge detection is not available.

A literature review supports our concerns and raises questions on the utility of augmented feedback for bicortical drilling skills and other orthopedic surgical simulation skills training.

  • Studies have found the use of augmented feedback increases performance during surgical simulation skills training but has either no effect, or a detrimental effect during retention tests assessing long-term learning.[19][43][94] These findings can be attributed to learner attendance to easily available extrinsic feedback over intrinsic cues (attentional processing hypothesis) and learner dependence on augmented feedback (guidance hypothesis).[94]
  • A 2009 study found that although augmented feedback for plunge detection was beneficial to initial outcomes during the preliminary learning stages for bicortical drilling, the effect was transient and did not lead to significant long-term learning benefits.[19] Learning retention tests showed that all novice groups learned equally well on how to prevent plunging, regardless of if they received augmented feedback (in the form of an auditory tone when plunging occurred) during bicortical drilling skills training. For bicortical drilling skills training, focusing on intrinsic cues (drilling by sound and feel of the drill bit) is essential for long-term learning outcomes to minimize plunge, and should not be overridden or distracted by augmented feedback.
  • A 2007 study on computer-assisted total hip replacement simulation training found that augmented feedback improved performance during training but had no effect on long-term learning outcomes.[94] These results are consistent with prior literature that indicated that the learning benefits ascribed to extrinsic feedback are often transitory, and do not translate into better performance outcomes when evaluated on retention tests.[95]
  • A 2005 dental study that used visual augmented feedback for basic cavity preparation tasks observed that augmented feedback was beneficial to performance during training but detrimental to performance on retention tests.[43] This was attributed to feedback dependence, which can occur when feedback is provided too frequently causing the learner to perform poorly in its absence. A subsequent study found that the frequency of augmented feedback in training had no effect on learning retention.[96]
  • A 2005 dental surgical simulation training study added expert tutorial input to promote proper processing of feedback and decrease augmented feedback dependence.[97] However, this strategy requires expert mentors and thus, cannot be used in our self-assessed surgical simulation training module.
  • A 2008 study found that distracting noise impairs bicortical drilling performance and has been shown to adversely impact the plunge depths of intermediate residents and orthopedic surgeons.[18]

Based on these published scientific findings, the likely best course of action is to remove augmented feedback for plunge detection entirely from our self-assessed Bicortical Drilling Skills training module to promote learner processing of intrinsic cues to minimize plunge, prevent learner dependence on augmented feedback, and optimize long-term learning and clinical outcomes for minimizing plunge.

We will be conducting further user testing to determine if completing self-assessed bicortical drilling skills training without augmented feedback translates into similar or better plunge depth performance on long-term retention testing compared to simulators with augmented feedback. If augmented feedback for plunge detection does not confer long-term learning benefits (which is what the current research literature indicates) or if we continue to observe that augmented feedback fosters anti-skills and distracts self-assessed learners from paying attention to intrinsic cues to minimize plunge, we will remove the augmented feedback feature from the Tibial Shaft Simulator toː

  • reduce simulator costs by up to $51.47 USD, simplify the simulator build, and minimize simulator assembly time for the learner
  • increase learner safety with the removal of the live electric circuit
  • permit the learner to use any locally available powered surgical drill for bicortical drilling skills training
  • simplify the bicortical drilling skills training steps of our self-assessed module
  • prevent the development of learner dependence on augmented feedback to minimize plunge ("anti-skills"), and
  • improve long-term learning and clinical outcomes for bicortical drilling.

We will still be including a clay backstop to permit the learner to measure plunge depth values which will provide targeted feedback to the learner during bicortical drilling skills training.

Our user testing in Nigeria showed that the transparent cellophane will permit the learner to visually inspect and confirm that the self-drilling Schanz screws did not perforate the far cortex of the Tibial Shaft Transverse Fracture Simulator for the self-assessment framework.

Based on our user testing in Nigeria, we opted not to require the use of Far Cortex Breakthrough Detection and chose not to include the Plunge Depth Measurement for the Tibial Shaft Transverse Fracture Simulator. The rationale for these design choices is because:

  • the likelihood of exiting the far cortex and plunging is very low with the manual advancement of the Schanz screw into the far cortex
  • the transparent cellophane allows the learner to visually inspect and confirm that the self-drilling Schanz screws did not perforate the far cortex
  • plunge detection has not been shown to confer long-term learning benefits in reducing plunge
  • we want to avoid fostering learner dependence on augmented feedback ("anti-skills") since the learner will not have augmented feedback during the real procedure, and
  • this increases simulator fidelity, reduces simulator costs, simplifies the simulator build, and minimizes simulator assembly time for the learner.[19][43]

On October 18, 2021, we tested the NASA Task Load Index for Nigerian users of the module but observed that these survey's generic questions did not provide useful, targeted feedback to the learner above and beyond the module's existing self-assessment frameworks, and that learner compliance with completing the forms was poor. We removed the NASA Task Load Index from our self-assessment frameworks because it did not add any additional training value to the learner and this would reduce the administrative burden on the learner.

Design for Extreme Accessibility in Low Resource Settings[edit | edit source]

This module applies user-centered, reproducible, and accessible design choices to maximize adoption in resource-constrained settings.

User-Centered Design[edit | edit source]

Medical officers are fully trained, non-specialist physicians who have not received any exposure to orthopedic surgery outside of their undergraduate medical education. Surgeons who are not orthopedic specialists have received formal advanced training in their surgical specialty but have not been trained to perform external fixation procedures for tibial fracture patients.

The placement of an external fixator is one of the 44 essential surgical procedures identified by the World Bank.[16] This module teaches modular external fixation because this procedure offers the greatest freedom in fracture management and maximum patient safety when performed by practitioners who are not orthopedic specialists in resource-constrained settings. The advantages of training non-orthopedic specialists to perform modular external fixation over uniplanar external fixation are that modular external fixationː

  • is the preferred method for the temporary stabilization of open tibial fractures
  • requires less experience and surgical skill
  • permits the practitioner to freely place pins at suitable sites to avoid nerves, vessels, and traumatized soft tissues
  • does not require intraoperative X-rays and,
  • allows for subsequent definitive fixation.[98]

Although medical officers will have training and clinical experience with performing abdominal surgery, they will not have had experience with making stab incisions to insert external fixation pins. The Tibial Shaft Transverse Fracture Simulator includes a simulated soft tissue-bone interface to give the learner confidence and competence with making stab incisions for placement of Schanz screws for modular external fixation of open tibial shaft fractures.

Medical officers in low-resource settings may not have access to direct fluoroscopy. Modular external fixation of an open tibial fracture is a procedure that can be quickly applied without image intensification and adjusted afterwards.[98]

Practitioners in resource-constrained settings may not have access to orthopedic surgical drills for training. This module recommends a cost-saving ISO 13485 compliant orthopedic surgical drill that is designed for LMICs and permits back-to-back surgeries with a single power drill.[99]

Learners require access to high quality, standardized simulators and training. This module gives surgical practitioners in LMICs access to open-source, affordable, high fidelity, locally reproducible 3D printed bone simulation models for both basic and advanced training that are comparable to state-of-the-art, quality-tested artificial bone products that are available in high income countries.[54][56]

Learners need access to safe simulation training. All of the 3D printed bone models have a vise attachment to allow the user to secure the model inside a standard vise clamp to maximize learner safety during simulation training. Learners will be obtaining vise clamps locally and these devices can vary in size. We increased the height of the vise attachment of the Tibial Shaft Simulator to 6.0 cm in order to maximize compatibility with different sizes of locally available vise clamps.

To maximize safety and minimize the risk of the learner directly touching any conductive material (like the metal Universal Chuck with T-handle used for manual advancement of the Schanz screw) in a live electrical circuit during simulation training:

  • we added an extra insulated alligator clip to minimize the length of non-insulated metal wire for the Far Cortex Breakthrough Detector
  • we revised the simulator build and use instructions to re-emphasize and explain the safety rationale for the mandatory use of gloves during training.

Based on our user testing, we opted not to require the use of Far Cortex Breakthrough Detection and chose not to include the Plunge Depth Measurement for the Tibial Shaft Transverse Fracture Simulator. The rationale for these design choices is becauseː

  • the likelihood of perforating the far cortex and plunging is very low with the manual advancement of the Schanz screw into the far cortex
  • the transparent cellophane allows the learner to visually inspect and confirm that the self-drilling Schanz screws did not perforate the far cortex
  • plunge detection has not been shown to confer long-term learning benefits in reducing plunge
  • we want to avoid fostering dependence on augmented feedback ("anti-skills") since the learner will not have augmented feedback during the actual procedure, and
  • this increases simulator fidelity, reduces simulator costs, simplifies the simulator build, and minimizes simulator assembly time for the learner.[19][43]

Medical officers and surgeons who are not orthopedic specialists in LMICs have busy work schedules and typically do not have a technical background. We tailored the design of the surgical training module prototype to meet their training needs by:

  • Providing high fidelity 3D printed bone models for both basic and advanced simulation training that are designed to substantially simplify the simulator build, minimize the simulator assembly time, and accelerate the learning process for greater convenience for the learner
  • Adding detailed instructions on how to input the customized settings for the 3D printed bone models into a 3D slicing program in case the user was not familiar with using advanced 3D slicer settings, and
  • Designing the Tibial Shaft Simulator and Tibial Shaft Transverse Fracture Simulator to be easy and quick to assemble and not require any tools, specialized equipment, technical expertise, or time-consuming preparation to build, install, operate and maintain these simulators within the intended place of use.

Over 4 billion people do not have access to the Internet.[100] The penetration of high-speed Internet connectivity (broadband, 3G, or better mobile connections) is less than 30% in rural regions.[101] Smartphones only make up 50% of total connections in sub Saharan Africa.[102] In 2021, nearly 711 million people were in extreme poverty, which is defined as living on less than $1.90 per day.[103] To promote adoption of this surgical training module in low resource settings, we:

  • Designed the non-3D printed simulator components to be made using low cost, locally available materials and supplies
  • Switched to using cost-saving modelling clay for the backstop instead of single-use foam material for plunge depth measurement on the Tibial Shaft Simulator because clay is reusable and can be locally obtained in LMICs
  • Developed an Appropedia module which does not require the downloading of a mobile app, creation of an account, inputting of a username and password, or paying journal or other subscription fees to access the training content
  • Provided step-by-step instructions and labelled images (instead of only videos) and published our self-assessment frameworks directly in Appropedia so the module content can be available in multiple languages and exported for offline access
  • Created self-assessment frameworks that only require taking photos and not videos which allows learners to use any cellphone with a camera and not only smartphones.

Reproducible Design[edit | edit source]

3D printing technology empowers the local, reliable, and automated manufacturing of high fidelity bone simulation models to permit high quality, standardized simulation training around the world. All of the module's bone simulation model files and print settings are open-source and available on Appropedia, can be locally reproduced on open-source, open filament desktop 3D printers using low-cost, biorenewable plastic, and are designed to be ready for use right out of the 3D printer.[20][21][35][36][37][38][39][49] These high fidelity 3D printed bone models are designed to substantially simplify the simulator build, minimize the simulator assembly time, and accelerate the learning process for greater convenience for the learner.

On-site access to a 3D printer is not required for the learner. Only one 3D printer is required within a country. The open-source 3D files can be emailed to any 3D printing organization anywhere.[22] The 3D printed simulation models can be picked up by the learner or delivered anywhere across the country by motorcycles, all-terrain vehicles, trucks, or airplanes within 1-2 days.[104]

This module does not require access to teachers, animal bones, artificial bones or human cadaveric bones, and uses locally available hardware and materials, and locally made, high fidelity bone simulation models for bicortical drilling skills and modular external fixation procedure skills training.

When possible, the surgical hardware and equipment are reusable to minimize the use of consumables and maximize their lifespan in the place of use.

The primary risk to reproducibility of this surgical training module is access to affordable orthopedic surgical hardware for training. We have developed local and international partnerships to deliver modular external fixation kits, and surgical drills with autoclavable covers on demand and at minimal cost for up to 39,650 medical officers and surgeons across Nigeria who are not orthopedic specialists.[99][104]

The total cost of Tibial Shaft Simulator consumables per learner is $9.73 USD. The total cost of purchasing reusable supplies in Nigeria for the Tibial Shaft Simulator for Bicortical Drilling Skills Training is $81.60 USD with the Far Cortex Breakthrough Detector and $60.00 USD without the Far Cortex Breakthrough Detector. This Tibial Shaft Simulator cost calculation does not cover shipping, delivery or orthopedic surgical hardware, supplies, and equipment costs.

2021 Learner Costs for Supplies Locally Purchased in Nigeria for the Tibial Shaft Simulator for Bicortical Drilling Skills Training
Item Quantity Purchase Cost in USD Consumable or Resuable
3D Printed Adult Male Tibial Bone Model #1 (manufactured locally by a 3D printing company in Nigeria[22]) 1 $8.90 (includes filament, 3D printing, and staffing costs) Consumable
Vise Clamp 1 G-clamp and 1 vise clamp $54.00 Reusable
Shallow Container 1 Readily available in place of use Reusable
Aluminum Foil 17.0 cm by 3.0 cm strip $0.03 (one 30.0 cm x 10.0 m roll of aluminum foil costs $19.20) Consumable
Ruler 1 Readily available in place of use Reusable
Marker 1 Readily available in place of use Reusable
Scissors 1 Readily available in place of use Reusable
Tape Multiple strips Readily available in place of use Consumable
Optionalː Wire Stripper 1 Not used; estimated cost is $10.67 Reusable
Alligator Clips 4 $21.60 Reusable
Buzzer 1 Covered above Reusable
9 V Battery 1 Covered above Reusable
Small Gauge, Non-Insulated Wire Short length (~12.0 cm or less) Covered above Reusable
Cellophane Two 20.0 cm by 100.0 cm strips $0.80 (one 30.0 cm x 20.0 m roll costs $12.00) Consumable
Modelling Clay 1 block $6.00 Reusable

The total cost of Tibial Shaft Transverse Fracture Simulator consumables per learner is $19.45 USD. The total cost of purchasing the additional reusable supplies in Nigeria for the Tibial Shaft Transverse Fracture Simulator for Modular External Fixation for an Open Tibial Shaft Transverse Fracture Training is $56.40 USD. This Tibial Shaft Transverse Fracture Simulator cost calculation does not cover shipping, delivery or orthopedic surgical hardware, supplies, and equipment costs.

2021 Learner Costs for Supplies Locally Purchased in Nigeria for the Tibial Shaft Transverse Fracture Simulator for Modular External Fixation for an Open Tibial Shaft Transverse Fracture Training
Item Quantity Purchase Cost in USD Consumable or Resuable
3D Printed Adult Male Tibial Bone Model #2 (manufactured locally by a 3D printing company in Nigeria[22]) 1 $9.35 (includes filament, 3D printing, and staffing costs) Consumable but can be reused indefinitely after hardware removal for a planned module on the Management of Non-Displaced Fractures
3D Printed Adult Male Tibial Bone Model #3 (manufactured locally by a 3D printing company in Nigeria[22]) 1 $9.30 (includes filament, 3D printing, and staffing costs) Consumable but can be reused indefinitely after hardware removal for a planned module on the Management of Non-Displaced Fractures
Additional Vise Clamp 1 G-clamp and 1 vise clamp $54.00 Reusable
Cellophane One 40.0 cm by 100.0 cm strip $0.80 Consumable
Protractor 1 $2.40 Reusable
Cellphone Camera 1 Readily available in place of use Reusable

No tools, specialized equipment, technical expertise, or time-consuming preparation is required to build, install, operate and maintain the Tibial Shaft Simulator and Tibial Shaft Transverse Fracture Simulator within the intended place of use.

Our high fidelity simulators offer significant value for money in comparison to existing approaches such as artificial bones and human cadaveric bones.

The costs of the 3D Printed Adult Tibial Bone Models will vary depending on the region's 3D printing organizations, and locally available brands of filament.

In Canada, a 1.0 kg roll of white PLA costs $17.95 CAD which is equal to about 1.4¢ USD per gram.[52] The Tibial Shaft Simulator (3D Printed Adult Female Tibial Bone Model #1) weighs 138.57 grams and the total filament cost in Canada is $1.95 USD. The Tibial Shaft Transverse Fracture Simulator (3D Printed Adult Female Tibial Bone Models # 2 and # 3) weighs 332.86 grams and the total filament cost in Canada is $4.69 USD.

In Nigeria, the 3D printer filament costs for the Tibial Shaft Simulator is $6.88 USD or less and the estimated print time is 6 hours and 2 minutes.[53] The benefits of 3D printing the Tibial Shaft Simulator (3D Printed Adult Female Tibial Bone Models #1) locally in Nigeria for bicortical drilling skills training are that the 3D printer filament costs are 12 times cheaper and the production time is 84 times faster than purchasing a comparable artificial bone cylinder product that is imported from abroad.[54] By obtaining locally made 3D printed bone models for bicortical drilling skills training, the learner also supports the local economy while saving on customs dues, processing fees, and international shipping costs that would be incurred when using artificial bone products that are not made locally.

In Nigeria, the 3D printer filament costs for the Tibial Shaft Transverse Fracture Simulator is $16.53 USD or less and the estimated print time is 15 hours 8 minutes (when the 3D Printed Adult Female Tibial Bone Models #2 and #3 are printed consecutively).[53] The benefits of 3D printing the Tibial Shaft Transverse Fracture Simulator locally in Nigeria for modular external fixation skills training are that the 3D printer filament costs are over 3 times cheaper and the production time is over 33 times faster than purchasing comparable artificial bone products that are imported from abroad, and the 3D printing filament costs are over 9 times cheaper than acquiring a human cadaveric tibia prepared by a local university anatomy lab.[56][57] By obtaining locally made 3D printed bone models for modular external fixation skills training, the learner also supports the local economy while saving on customs dues, processing fees, and international shipping costs that would be incurred when using artificial bone products that are not made locally.

Accessible Design[edit | edit source]

This Appropedia-based module is available in the 6 official languages of the United Nations, Kiswahili, the lingua franca of the East African Community, and other languages to help ensure that surgical practitioners from anywhere in the world will be able to engage with the content without barriers or gatekeeping.

Each 3D printed bone simulation model displays the model number translated in the 6 official languages of the United Nations, and the model gender using internationally recognized ISO 7001 graphical symbols for males and females to assist with model identification.

We provided step-by-step instructions and labelled images (instead of only videos) so the module content can be available in multiple languages and exported for offline access. In the future, we can create line drawings of our graphics to save on color printing costs for learners in LMICs.

We published our self-assessment frameworks directly in the Appropedia module (instead of a downloadable pdf) to provide automatic translations of the Training Logbooks in multiple languages to learners around the world.

We created self-assessment frameworks that only require taking photos and not videos which allows learners to use any cellphone with a camera and not only smartphones.

This module does not require the downloading of a mobile app, creation of an account, inputting of a username and password, or paying journal or other subscription fees to access the training content.

Offline and Off Grid Access[edit | edit source]

Self-directed training is typically only available online or via mobile apps. These traditional approaches have accessibility barriers in low resource settings because:

  • Over 4 billion people do not have access to the Internet
  • The penetration of high-speed Internet connectivity (broadband, 3G, or better mobile connections) is less than 30% in rural regions
  • Smartphones only make up 50% of total connections in sub Saharan Africa, and
  • An estimated 770 million people worldwide lack access to electricity and 600 million of these individuals reside in sub Saharan Africa.[100][101][102][105]

The demand for this module will be greatest in regions with little or no access to the Internet, smartphones, or grid electricity. Our self-assessment frameworks only require taking photos and not videos. This allows learners to use any cellphone with a camera and not only smartphones. When possible, we have provided images (instead of only videos) so the module content can be available in pdf format using Appropedia's export function for offline access.

Over 235 million people require humanitarian assistance and 44.7 million people in conflict zones are unable to access essential surgical care.[106][107] Every day, hospitals, patients, healthcare staff, ambulances, and aid workers come under attack in regions affected by conflict and other emergencies.[108][109] Online platforms and mobile phones are vulnerable to security breaches which can be used to target bombing attacks on hospitals in conflict zones.[110] It is critical that this training module be available offline to remain isolated from any surveillance from an external Internet connection to prevent hackers from targeting healthcare workers and facilities in conflict zones.

Paper-based versions of surgical training modules are sub-optimal because they cannot provide video and multimedia content which is essential for self-assessed surgical skills training. We can use Linux open-source software and an offline (air gapped), energy-efficient, ultraportable Raspberry Pi with integrated 7-inch touchscreen display to make this module safely available to the surgical practitioners serving the 4 billion people who do not have access to the Internet and the millions of the most vulnerable civilians in conflict zones.[111][112]

A 2015 study shows that a Raspberry Pi ($35 USD) with a 10 inch display consumes almost the same amount of energy (21.24 kJ/h) as a smartphone ($400 USD) with 4.7 inch display (18 kJ/h), 4.2 times less energy than a $320 USD tablet (90 kJ/h), and 8.5 times less energy than a $728 USD laptop (180 kJ/h).[113] The advantages of using a Raspberry Pi with an integrated 7-inch display screen over a smartphone or tablet are reduced costs, energy efficiency and a larger screen area to optimize learning.

To minimize the use of offline storage capacity and maximize the number of validated, open-source GSTC Appropedia modules that can be stored and made available offline on a Raspberry Pi, we designed this module to minimize the number of secondary or tertiary links, when possible. Our team will be recruiting volunteer Medical Makers to help make GSTC Appropedia modules available offline to maximize the global impact of the GSTC.

Last Mile Implementation[edit | edit source]

We will be evaluating the concept of setting up a Medical Makerspace in a government hospital in a LMIC to serve as a training, manufacturing, and distribution center that educates local Makers to make high fidelity, 3D printed bone models and offline simulation training modules at the lowest cost for any practitioner across the country.

We are continuing to develop local and international partnerships to deliver 3D printed bone models, modular external fixation kits for simulation training and clinical use, surgical drills with autoclavable covers, and offline training modules on demand and at minimal cost for up to 39,650 medical officers and surgeons across Nigeria who are not orthopedic specialists.[22][99][104][114]

Follow-on[edit | edit source]

(Optional) After completion and practice to competency, the learner may wish to continue study with these courses:

  • Management of Non-Displaced Fractures (coming in the next phase!)
  • Uniplanar External Fixation of Open Fractures (coming in the next phaseǃ)

References[edit | edit source]

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