User:Medical Makers/Management of Non-Displaced Fractures

This module allows traditional bone setters, clinical officers, nurses, nurse practitioners, and medical officers to become confident and competent in performing point-of-care ultrasound diagnostic imaging to rule out the presence of a pediatric distal forearm fracture and distinguish between buckle (torus) fractures and cortical break fractures to make appropriate referrals as part of the management of closed pediatric (≤ 12 years of age) distal forearm fractures in regions without access to X-ray imaging and orthopedic specialist coverage.

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 incidence of fractures of the radius, ulna, or both was 30.7 million cases resulting in an estimated 210,000 years lived with disability (YLD). The distal forearm fracture is the most common childhood fracture (40%) and is routinely treated in every outpatient clinic.^[2] Distal forearm fractures comprise 74% of all pediatric fractures in the upper extremity and the incidence of pediatric distal forearm fractures has been increasing despite global efforts to promote childhood safety.^{[3][4][5][6][7][8][9]}

Access to high-quality orthopedic care in low to middle income countries (LMICs) is limited by a lack of providers, resources, and training programs.^[10] The global standard is a ratio of one orthopedic surgeon to 200,000 people.^[11] In 2008, Uganda reported a ratio of 1 orthopedic surgeon for every 1.3 million people.^[12] In 2020, Nigeria had an estimated population of over 206 million people.^[13] According to the Nigerian Orthopaedic Association, Nigeria's ratio is 1 orthopedic surgeon to approximately 500,000 people.^[11] An estimated 75% of Nigerian orthopedic surgeons are located in 4 major cities which leaves other urban areas and rural regions without coverage.^[14]

The national shortages of orthopedic surgeons in LIMCs leaves patients vulnerable to traditional bone setters whose unsafe practices result in worse outcomes compared to no treatment and commonly lead to malunion, limb shortening, gangrene, limb loss, and death.^{[15][16][17][18][19]} 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.^[15] 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.^[16] Since medical officers do not receive adequate exposure to orthopedic surgery during their undergraduate medical education, they often refer fracture patients to traditional bone setters in regions without orthopedic specialist coverage.

To compound matters, an estimated two-thirds of the world’s population (3.5–4.7 billion people) lacks access to any diagnostic imaging.^[2][20] Handheld ultrasound devices can provide diagnostic imaging at the point-of-care for almost any musculoskeletal injury in resource-constrained settings, particularly where trauma is a primary cause of morbidity and mortality. Any ultrasound device with a linear transducer (from 3.5 to 16 MHz and more) is suitable for fracture sonography.^[2] Nearly almost all commercially available portable ultrasound devices can be used in the musculoskeletal examination of an injured patient.

Ultrasound has been shown to be most effective for the diagnosis of long bone fractures and is capable of detecting fractures as small as 1 mm.^[2] However, sonography cannot be used to evaluate joint fractures. Since intra-articular fractures are uncommon in patients aged 12 or younger, it may not be necessary to X-ray the joint above and below a long bone shaft fracture in these patients with a low-risk injury mechanism.^{[2][21][22][23]}

While fracture sonography offer advantages across all patient populations, it is particularly beneficial for patients aged 12 or younger.^[2] Pediatric fracture lesions always cause alterations to the bone's surface which can be accurately detected on ultrasound.^[2][22] Since up to 80% of X-rays obtained in children are negative for fractures and joint fractures are uncommon in patients aged 12 or younger with a low-risk injury mechanism, sonography offers an alternative, reliable method to diagnose fractures, and minimize the number of X-rays and exposure to ionizing radiation in radiation-sensitive children.^{[2][21][22][23]} Sonography can be performed at the bedside, and thereby, eliminates the need to transport a child for imaging. Ultrasound imaging is very well tolerated in children when copious amounts of ultrasound gel is used with the probe, the sonographer's scanning hand rests on an non-injured area, minimal pressure is applied to the injured region, and the child is permitted to remain in a comfortable position, typically next to or on a parent's lap.

Fracture sonography cannot be used universally, but only when there is high quality evidence demonstrating its effectiveness and safety.^[2] Sonographic diagnosis must be proven independently for each anatomic location and each fracture type. Fracture sonography can replace X-rays for certain indications, but overall, sonography complements radiographs and does not replace them.^[2] If there is any doubt about a sonographic finding, an X-ray image should be obtained. The practitioner must still have access to X-ray imaging on-site or via referral at all times.

An evidence-based clinical guide shows that fracture sonography can or could replace X-rays for specific indications which are outlined in the table below:^[2]

Fracture Category[1]	Global Incidence in 2019[1]	Years Lived with Disability (YLD) in 2019[1]	Ultrasound Application[2]	Evidence Level[2][24]	Special Notes[2]
Fracture of skull	7.59 million cases	213,000 YLD	X-ray-free diagnosis of skullcap (dome) fractures in patients ages 0-18 years	Ia	Several studies showed a sensitivity of 88% and a specificity of 97% for sonography of skull cap fractures.[2]
Fracture of sternum or fracture of one or more ribs, or both	4.11 million cases	191,000 YLD	X-ray-free diagnosis of rib and sternal fractures in patients of any age	Ia	"In general, sonography is superior to conventional X-ray diagnostics for mild and moderate trauma and can therefore generally be used as a primary diagnostic tool."[2]
Fracture of clavicle, scapula, or humerus	19.3 million cases	247,000 YLD	X-ray-free diagnosis of clavicle fractures in newborns	IIa	"Compared to an X-ray, ultrasonography can accurately detect clavicular fractures in newborns, so that the connection between clinical and sonographic diagnostics is sufficient for diagnosis and documentation."[2]
Fracture of radius or ulna, or both	30.7 million cases	210,000 YLD	X-ray-free exclusion of a fracture close to the elbow by diagnosis of the intra-articular effusion in patients ages 0-12 years	IIa	.Use Elbow SAFE Algorithm.[2]
Fracture of hand, wrist, or other distal part of hand	19.0 million cases	301,000 YLD	X-ray-free diagnosis and therapy of distal wrist fractures in patients ages 0-12 years	Ia	Use Wrist SAFE Algorithm.[2] Compared to X-ray imaging, sonography for distal wrist fractures has a sensitivity of 96%, specificity 10%, a positive predictive value of 1, and negative predictive value of 0.88.[22][25]
			Determination of the axis deviation in subcapital metacarpal 5 fractures (boxer fracture) in patients of any age	V	"The indication for sonographic assessment is given in all cases with an unclear surgical indication. Due to the problems of X-ray imaging, the findings should be confirmed sonographically with every decision regarding conservative therapy."[2]
Fracture of hip	14.2 million cases	2.94 million YLD	X-ray-free diagnosis and therapy for injuries to the lower extremity in patients ages 0-8 years	not provided	Use Screening-SAFE Algorithm.[2] "Basically, the ultrasound can be used for primary evaluation as a screening in every toddler who is presented with painful limps. With the sound probe, the entire limb is scanned from the hip joint to the knee to the distal lower leg. If there is a sonographic fracture detection or if there is diagnostic uncertainty, an additional X-ray examination can be arranged. In the case of sonographic fracture exclusion, however, an X-ray examination can be dispensed with for the time being." "Clinical experience shows that the typical bead and toddler fractures of the femur or tibia heal easily and without consequences under conservative therapy (immobilization in the cast association). Basically, the sole ultrasound is also suitable for therapy control in these cases with reliable fracture diagnosis. A confirmatory X-ray examination does not result in any diagnostic added value. However, there are still insufficient comparative studies available. For this reason, a targeted X-ray examination of the corresponding bone section is to be discussed at present with sonographic fracture detection. An additional X-ray imaging should therefore only be dispensed with after extensive clarification and with the consent of the parents."
Fracture of femur, other than femoral neck	14.6 million cases	1.85 million YLD	X-ray-free diagnosis and control of distal femoral torus fractures in patients ages 0-12 years	IV	"The indication for sonographic assessment is possible in children up to the age of 10 and in slim patients up to the age of 12. The diagnosis is made using classic sonographic fracture signs. If the course is uncomplicated, an X-ray diagnosis is not mandatory."[2]
Fracture of patella, tibia or fibula, or ankle	32.7 million cases	15.5 million YLD	Additional diagnostics in the event of clinical suspicion of a proximal tibia torus fracture in patients up to the age of 12	V	"Torus fractures are often only discreet in the X-ray image. There is usually a minimal bulge in the AP picture, while the side picture is completely unremarkable. [F]racture sonography can quickly provide a reliable diagnosis and make the bulge clearly visible. Since there are no randomized studies on this indication, the accompanying X-ray diagnosis is still mandatory. However, it is to be expected that ultrasound can also be used for exclusion diagnosis at this point in the future and will also be used as sole imaging in the case of torus fractures."[2]
Fracture of foot bones except ankle	10.7 million cases	480,000 YLD	Position control, and detection/exclusion of a dislocation in a conservatively treated, radiologically proven MFK 5 base fracture in patients of any age	IIa	"Since no blinded studies have yet been published on this indication, exact information on the safety of the method compared to the X-ray display is not available. However, the good visualization of the structures and the simple technology make it very likely that the display will achieve a comparable or better quality than the conventional X-ray image."[2]
Total:	153 million cases	22 million YLD

The sonographic diagnosis of pediatric distal forearm fractures is the ideal entry-level indication for novices to fracture sonography because of the frequent occurrence of this injury, the rapid (~1 minute) and painless application of this examination, the bone contour and thin soft tissue envelope enables reliable sonographic diagnosis, and the distal wrist can tolerate axis deviations of up to 40° until the patient reaches 12 years of age.^[2] A 2022 Australian study demonstrated that nurse practitioners with no prior sonographic experience achieved a mean diagnostic accuracy of 90% in the sonographic examination of pediatric distal forearm injuries after a 2 hour training course, practical training on each other's upper extremities and simulation models made from animal bones, 3 proctored ultrasound exams on patients, and 15 independent scans on patients.^[26] The high level evidence showing sonography can replace X-rays for the diagnosis of pediatric distal forearm fractures makes this indication suitable for traditional bone setters, nurses, clinical officers, and medical officers who work at community facilities and primary health centers where X-ray equipment is not available on-site but can be accessed via referral.^[2][26][27] As more evidence accumulates for using sonography as the sole imaging modality for other indications (see table above), additional ultrasound skills training modules will be developed for these traditional and orthodox practitioners.^[2][23]

In 2021, nearly 711 million people were in extreme poverty, which is defined as living on less than $1.90 per day.^[28] This module's innovative, open-source, locally reproducible, low-cost, high fidelity, data-driven, gender-specific, labor-saving, eco-friendly, hygienic, and cruelty-free 3D printed bone simulators could empower local 3D printing entrepreneurs in low­ and middle ­income countries to build sustainable livelihoods.^{[21][22][23][2][29]}

The management of non-displaced fractures is one of the 44 essential surgical procedures identified by the World Bank.^[30] This module uses locally made, high-fidelity simulators with targeted feedback to train healthcare providers to perform point-of-care ultrasound diagnostic imaging, safe splinting techniques for pediatric , closed, non-displaced buckle fractures of the distal forearm, and appropriate referrals as part of the management of pediatric distal forearm fractures to prevent disability and limb loss. This module teaches psychomotor skills that are transferable to the performance of other limb-saving procedures that require point-of-care diagnostic imaging, and splint immobilization. These skills can be used to prevent needless suffering, disability, and deaths for the estimated 153 million patients who experience 22 million years lived with disability (YLD) from sustaining axial and appendicular skeletal fractures globally every year.^[1]

Open-source 3D printing technology supports the local and automated reproduction of the highest fidelity bone simulation models at the lowest cost.

Open-source, open filament and user-friendly desktop 3D printers are currently in use at small to medium enterprises, Makerspaces, start-up incubators, universities, and hospitals worldwide.^{[31][32][33][34][2][21][35][36][37][23][22][29][38]} 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, *physeal width, and fracture subtypes for both genders at ultrasound scanning sites for pediatric distal forearm fractures.^{[39][40][41][42][43][1][44][45][46][47]}

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.^{[48][49][50][51][52]} According to one filament manufacturer, 3D printed PLA at 100% infill has a Shore Hardness D value of 83D and 84D while independently measured Shore Hardness D values of 3D printed PLA samples range from 80D to 88D (n=12).^[42][43][53] 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.^[1]

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.^{[42][43][1][48][54][55]} *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.^{[56][57][44][45][46][47]}

The user's learnings on high fidelity 3D printed bone simulation models will translate into the clinical performance of Ultrasound Diagnosis of a Pediatric Distal Forearm Fractures.

*The psychomotor skills that will be acquired are:

1. Using portable ultrasonography to capture a suspected long bone fracture in six planes
2. Using point-of-care ultrasound to compare findings with the contralateral extremity to identify any cortical discontinuities and confirm or rule out the diagnosis of a buckle or cortical breach fracture of the distal forearm
3. Applying proper padding to prevent skin breakdown, and
4. Avoiding the application of splints that are too tight.^{[42][11][58][59][60][61][62][63][64]}

Open-source 3D printing technology supports the local manufacturing of reusable and frugal fracture simulation training models. The Pediatric Forearm Simulators are composed of 3D printed fracture models that mimic bone sonographically and are housed within a gelatin base solution that simulates soft tissue.^[11]

Before the learner starts this module:

1. • Go to this link.
2. Download, print out, and complete the pre-learning clinical confidence assessment for this training module.
3. Photograph the completed assessment on your cellphone as a backup and file the assessment in your training records.

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

Anatomy of the distal forearm

• Epiphysis, physis, metaphysis, diaphysis
• Radius
  • Proximal, middle, distal 1/3
• Ulna
  • Styloid

Classification of Children's Fractures

#	Fracture Type	Fracture Description	Reference Images	Prognosis
1	Buckle (Torus)	Bone is deformed but both cortices are intact[65][66][67]	Figure 1A: Buckle Fracture	Stable[67]
2	Greenstick	Bone is deformed and one cortex is disrupted [65][67]	Figure 1B: Greenstick Fracture	Unstable[67]
3	Complete	Bone is broken and both cortices are disrupted[67]	Figure 1C: Complete Fracture	Highly unstable[67]
4	Physeal	Fracture of the growth plate (physis)[67]	Figure 1D: Physeal Fracture	Might lead to growth disturbances (rare)[67]

Salter-Harris (Physeal) Fractures^[68]

Fracture SubType	Fracture Description	Reference Images
Salter-Harris Type I		Figure E: SH Type 1
Salter-Harris Type II		Figure F: SH Type 2
Salter-Harris Type IIa
Salter-Harris Type III		Figure G: SH Type 3
Salter-Harris Type IV		Figure H: SH Type 4

AO Distal Metaphyseal Fracture of Radius, Ulna, or Both

• Age
• Hand preference
• Injured extremity
• Mechanism of injury
• Time of injury
• Previous forearm injury

• Neurovascular Exam

• Isolated, clinically non-angulated distal forearm injury in patient aged 12 or younger ^[26][2] or between 5 to 15 years (up to 15 years and 364 days)^[69]

If one or more of these symptoms are present, the pediatric patient with a distal forearm injury must be referred for X-ray imaging:

• Patient > 12 years of age^[2] or patient ≥ 16 years or older^[69]
• Obvious angulation/deformity (soft tissue swelling allowed)^[69]
• Injury > 1 week old ^[26] / Injury > 48 h old ^[69]
• External imaging performed^[26][69]
• Bone disease (e.g. osteogenesis imperfecta)^[26][69]
• Suspicion of non-accidental injury^[26][69]
• Congenital forearm malformation (e.g. radius hypoplasia)^[26][69]
• Compound/open fracture (including concern for foreign body)^[26][69]
• Neurovascular compromise^[26][69]
• Distracting injury^[26]
• Suspicion for other fracture (i.e., scaphoid or elbow fracture)^[26][69]
• Inability to assess child^[69]

Obtain Consent

1. "Place the arm to be examined on an arm table in a pronated position.
2. Apply transducer gel to the distal forearm.
3. With the ultrasound transducer in contact with the gel but not the underlying skin, examine the radius and ulna in 6 standardized planes using a linear probe, as shown."^[70]

copious amounts of ultrasound gel is used with the probe, the sonographer's scanning hand rests on an non-injured area, minimal pressure is applied to the injured region, and the child is permitted to remain in a comfortable position, typically next to or on a parent's lap.

"Examination: longitudinal section in six planes: radius^[71] from dorsal, radial and volar, ulna from dorsal, ulnar and volar." / Ultrasound examination in 6 planes

• "Examine the radius in all three planes (dorsal, radial, volar) and then the ulna in all three planes (volar, ulnar, dorsal)."
• "After showing the bone, which is shown as a bright, sharp line, the transducer is first aligned parallel to the longitudinal axis. This can be seen from the fact that the bone is shown across the entire width of the image section."
• Then the epiphyseal plate is shown. The correct setting has now been reached.
• The process is repeated in principle on all six levels, but experience has shown that this is very easy after the first setting"
• Therefore, the greatest axis deviation can be set by swiveling and moving the transducer and this can be measured as true deformation [look up ref]

1. Fanning the iQ
2. Sliding the iQ
3. Rotating the iQ
4. Proper Hand Positioning
5. Choosing the Right Preset
6. Adjusting the Overall Gain

Sonographic Signs of Pediatric Distal Forearm Fracture Subtypes

#	Fracture Subtype	Sonographic Signs	Reference Images
1	No Fracture	Intact bone cortex appears as a bright, sharp white (echogenic) line with black shadowing underneath (posterior acoustic shadowing)[72][73] The open growth plates (physes) in children can be mistaken for fractures. Physes will appear as smooth, downward-sloping white curves while fractures have abrupt step-offs.[74] Comparing ultrasound findings to the opposite uninjured forearm can help distinguish between a normal open physis and a fracture.[72]	Figure 1 (top image): no fracture (arrow pointing to physis) Figure of Normal Cortex (Crosby et al. 2014) Fig 1. Ultrasound of the normal open physis (arrow) of a skeletally immature patient Figure of Normal Open Tibial Physis (Crosby et. al. 2014)
2	Buckle (Torus) Fracture	Asymmetric (compared with uninjured forearm) inward or outward deformation or angulation of bone cortex without any breach or disruption[69][70][72][73][75][76]	Figure 1 (middle image): buckle fracture (*) Figure 2(b) Ultrasound Image of a Distal Radius Buckle Fracture (arrow) Figure 5: a buckle fracture of the distal radius (a*) Fig 9. Ultrasound demonstrating angling of the periosteum (arrow) in a patient with a buckle fracture Figure 4 Case 3: Right distal radius buckle fracture. POCUS images: buckle fracture(arrow) on lateral (A) and volar (B) aspects. Right (C) and left (D) PQ thickness measurements (0.3 mm difference) with no hematoma formation.
3	Cortical Breach Fracture	Primary Sign: Break, step or gap in bone cortex[69][70][72][73] which appears as a black (hypoechoic) zone[73][75] Secondary Signs: Buckle fracture angulation greater than ~ 5 degrees (visually angulated)[69] Buckle fracture < 1 cm from physis[69] Physis widened or narrowed[69] Periosteal hematoma[69][70] Pronator quadratus hematoma present (i.e. positive fat pad sign)[69][77][78]	Figure 1 (bottom image): cortical breach fracture (#) Figure 5: a cortical breach of a different distal radius (b*) Fig 10. (a) Placement of the ultrasound transducer longitudinally on the distal radius. Ultrasound demonstrating a distal radius fracture (b, arrow). Figure 5.Case 12: Left distal radius non-displaced greenstick fracture. POCUS images: cortical breaches (arrow) visualized on dorsal (A) and lateral (B) aspects, with associated small periosteal hematoma (*). Left PQ (C) with both increased thickness (5.9 mm difference) and disrupted muscle echotexture (hematoma formation), indicating a positive PQH sign, compared with a normal right PQ (D). Figures 6. Case 21: Right distal radius non-displaced complete (transverse) fracture. POCUS images: cortical breaches (arrows) visualized on dorsal (A) and volar (B) views, with a prominence of the PQ hematoma in this region (*).Right PQ (C) with both increased thickness (5.0 mm difference) and disrupted muscle echotexture (hematoma formation), indicating a positive PQH sign, compared with a normal left PQ (D). Figure 7. Case 28: Right distal radius non-displaced Salter-Harris II fracture. POCUS images:Subtle cortical breaches (arrows) visualized on dorsal (A) and lateral (B) views. Right PQ (C) with both increased thickness (8.2 mm difference) and disrupted muscle echotexture (hematoma formation), indicating a positive PQH sign, compared with a normal left PQ (D). Figure 8.Case 30: Right distal ulna complete (transverse) fracture with mild dorsal angulation. POCUS images: cortical breaches (arrows) visualized on dorsal (A) and volar (B) views, with mild dorsal angulation. Right PQ (C) with both increased thickness (8.4 mm difference) and disrupted muscle echotexture (hematoma formation), indicating a positive PQH sign, compared with a normal left PQ (D).

• Point-of-care ultrasound in the diagnosis of upper extremity fracture-dislocation. A pictorial essay. - Figures 9 and 1
• Sonographic images of normal bones and different fracture types^[26]

Principles of nonoperative treatment of children’s fractures

If any of these sonographic signs or clinical findings are present, the pediatric patient with a distal forearm injury must be referred for X-ray imaging:

• Cortical breach fracture (apart from an isolated ulna styloid fracture or non-displaced, non-angulated ulna metaphyseal fracture)^[69]
• Buckle fracture >  5 degrees angulation (visually angulated)^[69]
• Buckle fracture < 1 cm from physis^[69]
• Physis widened or narrowed^[69]
• Periosteal hematoma^[69]
• Pronator quadratus hematoma (i.e. positive fat pad sign)^{[26][69][77][78]}
• Clinical suspicion e.g. ‘pain out of proportion’ despite normal sonographic findings^[69]

Management of Fracture Categories^[69]

#	Fracture Category	Category Definition	Management
1	No fracture	No fracture of the radius or ulna	Conservative management with follow-up visit in 1 week[69]
2	Buckle (torus) fracture	Buckle fracture of the distal 1/3 of the radius, with or without: Ulnar styloid fracture Ulnar metaphysis non-displaced/non-angulated buckle or cortical breach fracture Isolated buckle fracture of the distal 1/3 of the ulna	Apply removeable[26][79] forearm splint with follow-up visit in 1 week[69][65][73][75][65]
3	Other	Cortical breach fracture of the distal 1/3 of the radius (including greenstick, complete or physeal), with or without any ulnar fracture type Any isolated displaced/angulated cortical breach fracture of the ulnar metaphysis Fractures at other locations, e.g. proximal radius, scaphoid[26][69] Bowing fractures of the radius and/or ulna with or without any other fracture type	Referral for X-ray imaging and fracture management with manipulation, reduction, and/or surgery and immobilization in a plaster cast or equivalent as required[65]

• Splinting of pediatric buckle (torus) fractures of the distal forearm
• General introduction to nonoperative fracture care (1:01:56 minute video)
• Overview of cast, splint, orthosis and bandage techniques (English pdf only)
• Palmar short arm splint using synthetics (7:30 minute video)
• Compartment Syndrome
• Healing times
• Physical Rehabilitation

• Physical Rehabilitation
• Functional Assessment with Pediatric Upper Extremity Short Patient-Reported Outcomes Measurement Information System (PROMIS) Tool

• 3D Printed Pediatric Female Forearm Bone Models

In a 2022 Danish study on 4,316 patients, the incidence of pediatric distal forearm fractures in females was 44% and in males was 56% and with a slighter higher incidence observed on left (57%) versus right (42%) extremities.^[9] The incidence of pediatric distal forearm fractures peaks in girls between the ages of 9 to 11 years, with the highest incidence at age 10 years and peaks in boys between the ages 11 to 13 years with the second highest incidence at age 12 years. Thus, radial lengths corresponding to the mean radial diaphyseal length of healthy Caucasian girls ages 10 years (185.39 mm) and boys ages 12 years (208.59 mm) was used in the design of our gender-specific pediatric forearm simulators.^[80]

The most common pediatric distal forearm fractures are greenstick or buckle (torus) fractures to the radius (48% of all fractures), a Salter Harris type I fracture of the radius (17% of all fractures), greenstick or buckle (torus) fractures of the radius and ulna (12%), radius fracture with no epiphyseal involvement (7%), Salter-Harris type IIa of the radius (7%),and complete radius and ulna fractures (6%).^[9] 98% of pediatric distal forearm fractures are isolated fractures. A greenstick fracture with cortical breach of the volar aspect of distal radius and concurrent buckling of the dorsal radius was the most commonly missed fracture in training Australian POCUS-novice nurse practitioners to diagnose pediatric distal forearm fractures.^[26]

Pediatric Female Distal Forearm Bone Model STL Files

Model Number	Anatomic Region or Simulator Component	Pediatric Forearm Simulator Model Type	File Name	Revision Date	Download File	Comments
1A	Normal Distal Epiphysis of Radius and Ulna	No Fracture of the Radius or Ulna	Model 1A - Female -10-Aug-2022 version.STL	August 10, 2022		Print testing in progress
1B	Normal Distal Metaphysis, Diaphysis and Proximal Metaphysis of Radius and Ulna	No Fracture of the Radius or Ulna	Model 1B - Female -10-Aug-2022 version.STL	August 10, 2022		Print testing in progress
1C	Male Part Connectors for Female Parts of Radius and Ulna	No Fracture of the Radius or Ulna	Model 1C - Female -11-Aug-2022 verison.STL	August 11, 2022		Print testing in progress
2A	Normal Distal Epiphysis of Radius and Ulna	Buckle (Torus) Fracture of the Distal 1/3 of the Radius
2B	Distal Metaphysis, Diaphysis and Proximal Metaphysis of Radius and Ulna with Buckle/Torus Fracture of the Distal 1/3 of the Radius	Buckle (Torus) Fracture of the Distal 1/3 of the Radius
2C	Male Part Connectors for Female Parts of Radius and Ulna	Buckle (Torus) Fracture of the Distal 1/3 of the Radius
3A	Normal Distal Epiphysis of Radius and Ulna	Greenstick Fracture of the Distal 1/3 of the Radius
3B	Distal Metaphysis, Diaphysis and Proximal Metaphysis of Radius and Ulna with Greenstick Fracture of the Distal 1/3 of the Radius	Greenstick Fracture of the Distal 1/3 of the Radius
3C	Male Part Connectors for Female Parts of Radius and Ulna	Greenstick Fracture of the Distal 1/3 of the Radius

• Pediatric Forearm Simulators
  • Materials and Equipment
    • 3D Printed Pediatric Forearm Bone Models
    • 3D Printed Forearm Soft Tissue Moulds
    • Miscellaneous Supplies
      • Cellophane
      • Scissors
      • Tape
      • Cardboard box or tube longer than the 3D Printed Pediatric Forearm Bone Models
      • Measuring cups and spoons that can measure 450 mL, 50 mL, and 15 mL
      • Pot
      • Stove
      • Red, blue, and yellow food colouring
      • Spoon
      • Knox Gelatin
      • Refrigerator
      • Optional: plate
  • Assembly of the Pediatric Forearm Simulators
    1. Insert male connectors into bone models.
    2. Place 3D Printed Pediatric Forearm Bone Models inside an open face mould (3D printed or constructed from cardboard, and tape) lined with cellophane.
    3. Pour 450 mL of water into a pot.
    4. Place the pot on the stove to boil.
    5. Pour 50 mL of water into a glass container.
    6. Add equal amounts of red, blue, and yellow food colouring (about 15 drops for each colour).
    7. Stir water so it becomes a dark brown ("deepest almond") colour.^[57]
    8. Add 15 mL of Knox Gelatin to the coloured water.
    9. Add the 450 mL of boiling water to the coloured water with Knox Gelatin.
    10. Stir well for 2 minutes until all the Knox Gelatin is dissolved.
    11. If required, add more equal amounts of red, blue, and yellow food colouring to ensure that the water is a dark brown colour.^[57]
    12. Pour solution into mould.
    13. Place mould in refrigerator for 4-6 hours to allow the Knox Gelatin to set.
    14. Use to remove Pediatric Forearm Simulator from the mould.
• Butterfly iQ Ultrasound

1. Initial training on each other's arms
2. Basic training on 10 unblinded and 10 blinded simulated models
3. Advanced training on 10 blinded simulated models
4. Minimum of 20 scans on blinded simulation models completed and logged in training logbook

Basic Fracture Sonography Training with Unblinded and Blinded Models

#	Pediatric Forearm Simulator Model Type	Sonographic Signs
1	No Fracture of the Radius or Ulna	Intact cortex Physes appears as smooth, downward-sloping curves and is similar to opposite, uninjured side
2	Buckle (Torus) Fracture of the Distal 1/3 of the Radius	Deformed cortex without breach *Type A and Type B
3	Greenstick Fracture of the Distal 1/3 of the Radius	A greenstick fracture with cortical breach of the volar aspect of distal radius and concurrent buckling of the dorsal radius was the most commonly missed fracture in training Australian POCUS-novice nurse practitioners to diagnose pediatric distal forearm fractures.[26] "Minor fractures may be more difficult to detect, and visualization of a hematoma or surrounding soft tissue swelling may help localize a fracture, particularly in greenstick fractures."[72]
4	Salter-Harris (Physeal) Fracture Type 1 of the Distal 1/3 of the Radius	Physis narrowing[69]
5	Buckle (Torus) Fracture of the Distal 1/3 of the Radius and Ulna
6	Greenstick Fracture of the Distal 1/3 of the Radius and Ulna
7	Complete Fracture of the Distal 1/3 of the Radius	Pronator Quadratus Hematoma Sign[78] Pronator Quadratus Delta Thicknesses ≧ 2.1 mm
8	Salter-Harris (Physeal) Fracture Type 2a of the Distal 1/3 of the Radius	Physis widening[69]
9	Complete Radius and Ulna Fracture
10	Proximal Radius Fracture

Advanced Fracture Sonography Training with Blinded Models

#	Pediatric Forearm Simulator Model Type	Training Type	Sonographic Signs
1	No Fracture of the Radius or Ulna	Unblinded	Normal physis
2A	Buckle (Torus) Fracture of the Distal 1/3 of the Radius	Unblinded
2B	Buckle (Torus) Fracture of the Distal 1/3 of the Radius
2C	Buckle (Torus) Fracture of the Distal 1/3 of the Radius with a Ulnar Metaphysis Non-Displaced/Non-Angulated Buckle Fracture
2D	Buckle (Torus) Fracture of the Distal 1/3 of the Radius with an Ulnar Cortical Breach Fracture
2E	Isolated Buckle Fracture of the Distal 1/3 of the Ulna	Unblinded
3A	Greenstick Fracture of the Distal 1/3 of the Radius	Unblinded
3B	Greenstick Fracture of the Distal 1/3 of the Radius with a Ulnar Styloid Fracture
3C	Greenstick Fracture of the Distal 1/3 of the Radius with a Ulnar Metaphysis Non-Displaced/Non-Angulated Buckle Fracture
3D	Greenstick Fracture of the Distal 1/3 of the Radius with an Ulnar Cortical Breach Fracture
4A	Complete Fracture of the Distal 1/3 of the Radius	Unblinded	Pronator Quadratus Hematoma Sign[78]Pronator Quadratus Delta Thicknesses ≧ 2.1 mm
4B	Complete Fracture of the Distal 1/3 of the Radius with a Ulnar Styloid Fracture
4C	Complete Fracture of the Distal 1/3 of the Radius with a Ulnar Metaphysis Non-Displaced/Non-Angulated Buckle Fracture
4D	Complete Fracture of the Distal 1/3 of the Radius with an Ulnar Cortical Breach Fracture
5A	Salter-Harris (Physeal) Fracture Type 1 of the Distal 1/3 of the Radius	Unblinded
5B	Salter-Harris (Physeal) Fracture Type 1 of the Distal 1/3 of the Radius with a Ulnar Styloid Fracture
5C	Salter-Harris (Physeal) Fracture Type 1 of the Distal 1/3 of the Radius with a Ulnar Metaphysis Non-Displaced/Non-Angulated Buckle Fracture
5D	Salter-Harris (Physeal) Fracture Type 1 of the Distal 1/3 of the Radius with an Ulnar Cortical Breach Fracture
6A	Salter-Harris (Physeal) Fracture Type 2 of the Distal 1/3 of the Radius	Unblinded
6B	Salter-Harris (Physeal) Fracture Type 2 of the Distal 1/3 of the Radius with a Ulnar Styloid Fracture
6C	Salter-Harris (Physeal) Fracture Type 2 of the Distal 1/3 of the Radius with a Ulnar Metaphysis Non-Displaced/Non-Angulated Buckle Fracture
6D	Salter-Harris (Physeal) Fracture Type 2 of the Distal 1/3 of the Radius with an Ulnar Cortical Breach Fracture
7A	Salter-Harris (Physeal) Fracture Type 3 of the Distal 1/3 of the Radius	Unblinded
7B	Salter-Harris (Physeal) Fracture Type 3 of the Distal 1/3 of the Radius with a Ulnar Styloid Fracture
7C	Salter-Harris (Physeal) Fracture Type 3 of the Distal 1/3 of the Radius with a Ulnar Metaphysis Non-Displaced/Non-Angulated Buckle Fracture
7D	Salter-Harris (Physeal) Fracture Type 3 of the Distal 1/3 of the Radius with an Ulnar Cortical Breach Fracture
8A	Salter-Harris (Physeal) Fracture Type 4 of the Distal 1/3 of the Radius	Unblinded
8B	Salter-Harris (Physeal) Fracture Type 4 of the Distal 1/3 of the Radius with a Ulnar Styloid Fracture
8C	Salter-Harris (Physeal) Fracture Type 4 of the Distal 1/3 of the Radius with a Ulnar Metaphysis Non-Displaced/Non-Angulated Buckle Fracture
8D	Salter-Harris (Physeal) Fracture Type 4 of the Distal 1/3 of the Radius with an Ulnar Cortical Breach Fracture
9A	Ulnar Styloid Fracture	Unblinded
9B	Non-Displaced/Non-Angulated Buckle Fracture of the Ulnar Metaphysis	Unblinded
9C	Non-Displaced/Non-Angulated Cortical Breach Fracture of the Ulnar Metaphysis	Unblinded
9D	Isolated Displaced/Angulated Cortical Breach Fracture of the Ulnar Metaphysis	Unblinded
9E	Complete Ulna Fracture	Unblinded
10A	Complete Radius and Ulna Fracture
11	Proximal Radius Fracture	Unblinded
	*Bowing fractures of the radius and/or ulna with or without any other fracture type		Buckle fracture with visible curvature

The module’s simulators are 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 Training Logbook - Point-of-Care Ultrasound Diagnosis of Extremity Shaft Fractures includes procedure step-by-step checklists and image review to allow the user to:

• capture a suspected fracture in two? perpendicular planes
• compare sonographic findings of suspected fracture with the contralateral extremity
• identify any cortical discontinuities, and
• confirm or rule out the diagnosis of no fracture, a buckle fracture, or a cortical breach in a pediatric distal forearm injury.

The Pediatric Forearm Simulators contain 3D printed bone models housed within semi-opaque and opaque gelatin base solutions for unblinded and blinded training, respectively.

Fifteen fracture patterns for each distal forearm will be provided:

Training Logbook^[26]

Scan #	Model Numbers	Distal Forearm Injury Diagnosis	Labelled Ultrasound Final Image to Document Diagnosis	Patient Care Plan
1		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:__________________________
2		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
3		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
4		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
5		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
6		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
7		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
8		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
9		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
10		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
11		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
12		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
13		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
14		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:___________________________
15		🔲 No Fracture 🔲 Buckle Fracture 🔲 Other Fracture	🔲 No Fracture with Normal Physis 🔲 Buckle Fracture 🔲 Cortical Breach Fracture	🔲 Clinical Observation Only 🔲 Application of Removeable Wrist Splint[26][79] 🔲 Referral for X-Ray Imaging 🔲 Other:____________________________

*The Extremity Simulator with Compartment Pressure Feedback uses a water pressure column made from oxygen tubing to provide targeted feedback to the learner if the splint is applying pressure in excess of 30 mm Hg to the extremity.^[56]

*The Training Logbooks provide a scoring structure and metrics that permit the learner to self-assess their clinical competence and confidence.

After the learner completes this module:

1. • Go to this link.
2. Download, print out, and complete the post-learning clinical confidence assessment for this training module.
3. Photograph the completed assessment on your cellphone as a backup and file the assessment in your training records.

If the learner does not feel confident in performing this procedure in real clinical scenarios, the learner can repeat this module and practice the skills training as many times as they feel necessary to gain the confidence to perform this procedure on patients.

This module provides easy to print, environmentally friendly, reusable, cost-savings, and cruelty-free bone simulation models that can be locally manufactured for high fidelity simulation training for our target learners in LMICs.

The Point-of-Care Ultrasound Extremity Fracture Simulators use 3D printed bone models which provide a higher fidelity, reproducible, ready-to-use, hygienic, reusable, and humane training alternative to using animal bones which require the slaughtering of sentient beings and additional preparation to simulate fractures. The innovative design of the 3D printed models permits specific and consistent cortical displacement for each fracture model.

2022 Comparison of Pediatric Forearm Simulator Locally Made in Nigeria to an Animal Model and a Commercially Available Product

	Pediatric Female Forearm Simulator (3D Printed Pediatric Female Forearm Bone Models #1 and #2)	Animal Bone Model	Human Cadaveric Tibia (Prepared by an University Anatomy Lab in Nigeria)
Bone Simulator Features and Materials	3D printed, biorenewable plastic anatomic bone models are made with a rigid plastic shell and housed within semi-opaque and opaque gelatin base solutions for unblinded and blinded training, respectively.	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 buckle, greenstick, complete, physeal distal fractures of the radius and ulna and proximal forearm fractures for comprehensive fracture sonography training.	Requires time consuming (1-2 day) preparation by user to simulate a buckle fracture.[73]	.Simulates greenstick fracture only
Reusable Bone Models	Yes	No	Yes
Provides Unblinded and Blinded Training	Yes	Yes	No (only blinded training provided)
Sonographic Features	Proximal, Mid-Shaft, and Distal Forearm Cortex Physis (Growth Plate) Pronator Quadratus Hematoma	Distal Forearm Cortex	Cortex
Simulates Epiphysis and Represent Salter–Harris Fracture Subtypes	Yes	No	No
Bone Simulator Dimensions	Forearms with overall lengths of 185.39 mm and 208.59 mm to anatomically represent the radius of a 10-year old female radius and 12-year old male radius	Forearms with overall lengths of 100 and 170 mm to anatomically represent the radius of a 2-year old's radius and 8 year old's radius[73]	Varies.
Unit Cost	$18.65 USD	$53.50 USD	$150.00 USD
Production Time	17 hours 33 minutes (when Adult Male Tibial Bone Models #1 and #2 are printed consecutively).	Ready to ship in 21 days or more.	Depends on local availability of cadaver specimens which is difficult to predict.

*Note: A product comparison was not made with the:

• Sawbones Tibia, Solid Foam, Large ($16.00 USD) because this model simulates the intramedullary canal but not cancellous bone, and 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.^[81][21]

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

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

Traditional bonesetters acquire their skills informally through apprenticeship from relatives.^[82] A 2020 Nigerian feasibility study found that traditional bonesetters recognize their need for formal skills training, are willing to undertake training, and seek formal recognition by the government.

Nurses, clinical officers, and medical officers are formally trained healthcare practitioners who have not received any exposure to diagnostic imaging or orthopedic surgery outside of their undergraduate education.

This module will address user needs by providing competency-based and microcredential training to orthodox and traditional fracture caregivers on fracture diagnosis and safe methods of fracture treatment to improve fracture outcomes in LMICs.

Over 4 billion people do not have access to the Internet.^[83] The penetration of high-speed Internet connectivity (broadband, 3G, or better mobile connections) is less than 30% in rural regions.^[84] Smartphones only make up 50% of total connections in sub Saharan Africa.^[85] 44% of the world's population lives in remote or rural regions.^[86] Over half of Nigeria's population of 206 million people live in rural areas but only 15% of the road networks are paved.^[87]

To promote adoption of this training module in resource-constrained settings, we recommend using a mobile tablet device with the following user-centered design features:

• Wi-fi and cellular connectivity to maximize the ability to receive software updates to the Butterfly App and ensure the Butterfly iQ+ probe is the most up-to-date version
• ruggedized cover to withstand rough handling during transport to and from a rural community,
• tablet stand to permit hands-free use, and
• larger screen area and extended battery life to optimize learning.

This module does not require access to teachers, animal bones, artificial bones or fracture patients, and uses locally available materials and supplies, and locally made, high-fidelity, 3D printed bone simulation models for point-of-care ultrasound diagnostic, and proper splinting techniques skills training.

All of the module's bone simulation models are open-source, can be digitally manufactured 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.

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. 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.

We will publish our self-assessment framework 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.

The demand for this module will be greatest in regions with little or no access to the Internet, smartphones, or grid electricity. When possible, we will make as much of the module content (including step-by-step simulator build, simulator use, and self-assessment framework instructions with photos instead of only videos) available in pdf format using Appropedia's export function for offline access.

The primary risk to reproducibility of this module is access to affordable point-of-care ultrasound devices ($2,399 USD) for training and clinical use.^[88] We will be developing local and international private-public partnerships to provide point-of-care ultrasound devices at the lowest cost for traditional bone setters, nurses, midwives, clinical officers, and medical officers in LMICs.

Another risk to reproducibility is that the 3D printed simulators are often locally made from imported plastic filament. If the learner wants to order a large volume of 3D printed models, they should notify their local 3D printing supplier in advance to stock adequate filament.

No tools, specialized equipment, or technical expertise is required to build, install, operate and maintain the simulators within the intended place of use.^[11][89][48]

The reusable components required for the Extremity Fracture Simulators include:

• 3D Printed Bone Models ($18.65 USD/extremity)
• Vise Clamps ($108 USD/pair)
• Towel
• Scissors
• 50 mL Irrigation Syringe ($1.44 USD/syringe), and
• Gauze (not reused if honey is applied).

The consumables include:

• Bubble wrap
• Tape
• Water, and
• Honey (can be simulated).

The anticipated simulator cost in Nigeria is around $128.09 USD per extremity. However, these simulators can be re-used indefinitely by multiple learners which makes their per use cost very low.

The reusable components required for the Point-of-Care Ultrasound Extremity Fracture Simulators include:

• 3D Printed Fracture Models ($18.65 USD/extremity)
• Shallow Container

The consumables are:

• Black food colouring ($5.68/unit)
• Cooking grade gelatin ($5.63 USD/extremity)
• Gauze strip to simulate skin and prolong the longevity of the simulator for re-use, and
• Water.

The equipment required includes:

• Stove and pot for boiling water, and
• Refrigerator for cooling with freezer for long-term storage for simulator re-use.

The anticipated simulator cost is $29.96 USD. These simulators can be re-used for 5 weeks or longer by multiple learners which makes their per use cost very low.^[48]

The reusable materials required for the Extremity Simulators with Compartment Pressure Feedback include:

• Hot Water Bottle
• Pressure Monitoring Gauge from a Non-Electronic Blood Pressure Cuff
• Oxygen Tubing (any available clear plastic tubing of known diameter), and
• 3D Printed Custom Connectors

The anticipated simulator cost is less than $1 USD.

Our high-fidelity, reusable simulators offer significant value for money in comparison to existing approaches such as costly, reusable, commercial ultrasound phantoms and single-use animal cadaveric bones.^[11][43]

The benefits of making the Point-of-Care Ultrasound Extremity Fracture Simulator locally in Nigeria are the filament and supplies costs are over 35 times cheaper than purchasing a comparable, patented, U.S.-made ultrasound phantom that costs $1,034.80 USD.^[43] By obtaining locally made simulators, the learner also saves on customs dues, processing fees, and international shipping costs that are incurred when using a product that is not made locally.

This module uses simulators built from 3D printed models and connectors locally manufactured from locally produced or imported filament plus readily available materials, supplies, and equipment. These include: vise clamps, towels, bubble wrap, tape, towels, scissors, irrigation syringe, honey, gauze, shallow containers, food colouring, cooking grade gelatin, water, stove, pot, refrigerator with freezer, hot water bottle, pressure monitoring gauge from a non-electronic blood pressure cuff, and clear plastic (oxygen) tubing.

We propose training orthodox and traditional practitioners to use clinical examination and point-of-care ultrasound to diagnose long bone fractures because fracture patients often cannot afford or access X-ray imaging services in LMICs.

When possible, the simulator components are reusable to minimize the use of consumables and maximize their lifespan in the place of use.

Traditional bone setters may not be literate in the languages available on the Appropedia platform.^[42] The global community of Medical Makers are fluent in at least 20 in-country and cross-border languages. Our team plans to translate this module into local regional languages in Nigeria.

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.^{[90][91][92][93]}

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 274 million people require humanitarian assistance and 44.7 million people in conflict zones are unable to access essential surgical care.^[94][95] Every day, hospitals, patients, healthcare staff, ambulances, and aid workers come under attack in regions affected by conflict and other emergencies.^[96][97] Online platforms and mobile phones are vulnerable to security breaches which can be used to target bombing attacks on hospitals in conflict zones.^[98] 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.^[99][100]

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).^[101] 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.

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, handheld ultrasound probes and accessories for simulation training and clinical use, and offline training modules on demand and at minimal cost for traditional bone setters, nurses, clinical officers and up to 39,650 medical officers and surgeons across Nigeria who are not orthopedic specialists.^{[102][103][104]}

(Optional) After completion of the module, the learner may wish to learn more about 3D printing technology:

• Original Prusa i3 MK3S+ 3D Printer
• Ultimaker S5 3D Printer

(Optional) After completion of the module, the learner may wish to learn more about this module:

• *Innovative Design
• *Evaluation
• *Design for Extreme Accessibility in Low Resource Settings

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

• Tibial Fracture Fixation
• Humeral Fracture Fixation
• Bicortical Drilling

This work is funded by a grant from the Intuitive Foundation. Any research, findings, conclusions, or recommendations expressed in this work are those of the author(s), and not of the Intuitive Foundation.