Fracture sonography – Literature review and current recommendations

Abstract

Purpose Over the course of more than two years, an expert group of 9 professional societies has created the S2e guidelines for fracture sonography. This publication summarizes the key points regarding the individual indications.

Materials and Methods A systematic literature search was performed in PubMed, Google Scholar, and the Cochrane Database of Systematic Reviews from 2000 to March 2021 with evaluation of the literature lists. Randomized controlled clinical trials, observational clinical trials, meta-analyses, and systematic reviews were included. Guidelines, conferences, reviews, case reports, and expert opinions were excluded. Evidence was graded using the SIGN grading system 1999–2012, and the SIGN tables were then presented to the expert group. These were used to develop specific recommendations for the use of fracture sonography. All recommendations were discussed in detail and finally unanimously agreed upon.

Results Of the 520 primary literature sources found, 182 sources (146 clinical studies and 36 meta-analyses and systematic reviews) were evaluated after screening and content assessment. 21 indications that allow reasonable application of fracture sonography were identified.

Conclusion Ultrasound is a sensible, easy-to-use diagnostic method that is feasible for a large number of indications.

Zusammenfassung

Einleitung In über 2-jähriger Arbeit hat eine Expertengruppe von 9 Fachgesellschaften die S2e-Leitlinie „Fraktursonografie“ erstellt. Die vorliegende Publikation fasst die zentralen Punkte zu den einzelnen Indikationen zusammen.

Methodik Es erfolgte eine systematische Literaturrecherche in PubMed, Google Scholar und der Cochrane Database of Systematic Reviews aus den Jahren 2000 bis zum März 2021 mit Auswertung der Literaturlisten. Es wurden randomisierte, kontrollierte klinische Tests, klinische Beobachtungsstudien, Meta-Analysen und systematische Reviews eingeschlossen. Ausgeschlossen wurden Leitlinien, Konferenzen, Reviews, Fallberichte und Expertenmeinungen. Die Evidenzbewertung erfolgte nach dem SIGN-Grading-System 1999–2012. Die so erhaltenen SIGN-Tabellen wurden dann der Expertengruppe vorgelegt, die hieraus konkrete Empfehlungen für die Anwendung der Fraktursonografie erarbeitete. Sämtliche Empfehlungen wurden ausführlich diskutiert und zuletzt einstimmig konsentiert.

Ergebnisse Von primär 520 gefundenen Literaturquellen konnten nach Sichtung und inhaltlicher Bewertung 182 Quellen (146 klinische Studien sowie 36 Meta-Analysen und systematische Reviews) ausgewertet werden. Es wurden 21 Indikationen identifiziert, die eine sinnvolle Anwendung der Fraktursonografie erlauben.

Schlussfolgerung Fraktursonografie ist eine sinnvolle Diagnostikmethode bei einer Vielzahl an Indikation.

Keywords

Sonography - METHODS & TECHNIQUES - ultrasound - fracture - bone - diagnosis

Introduction

After the first description of fracture sonography of the wrist by Saphoznikov [1], this method had no importance in daily practice for a long time. Due to the rapid development of ultrasound equipment and based on recent structured research results, fracture sonography has become increasingly important in the last 15 years, resulting in an increasing number of publications and meta-analyses investigating the safety and efficiency of the method [2] [3] [4] [5]. The literature describes some preferred indications both in the growing skeleton and the adult skeleton. Conclusions can then be drawn about the types of injury that may become part of the spectrum of indications in the future.

In a systematic literature review, the current state of research on fracture ultrasonography was investigated and based on this, recommendations for the use of the technique were made in a group of experts. This paper summarizes the recommendations of the expert group.

Methodology

The 9 participating professional societies (supplementary file “participating professional associations”) each sent a delegate to the expert group, which developed concrete recommendations based on the results of the literature search.

Initially in 3/2021, a systematic literature search was conducted in PubMed, Google Scholar, and the Cochrane Database of Systematic Reviews from 2000 to March 2021. The search terms are listed in a supplementary file. In addition, relevant publications were extracted from the literature lists of reviews if they were not already covered by the search grids. The search covered randomized controlled clinical trials, observational clinical trials, meta-analyses, and systematic reviews. Guidelines, professional conferences, case reports, and expert opinions were excluded.

The search was based on PICO criteria (Population, Intervention, Comparison and Outcome) with the selected keywords being approved by the expert group.

Irrelevant papers were excluded from the publications identified in this manner by assessing the abstracts. The remaining publications were subjected to a more detailed analysis based on the full texts. Evidence grading was performed according to the SIGN grading system 1999–2012 (SIGN 50: a guideline developer's handbook; revised edition 2019). The SIGN tables were then presented to the expert group. Based on this, specific recommendations for the use of fracture sonography were developed. All recommendations were discussed in detail and finally unanimously approved.

Results

Of the 520 identified literature sources, 182 sources (146 clinical studies and 36 meta-analyses and systematic reviews) could be evaluated after screening and content assessment. The list of anatomic regions is shown in [Table 1].

Table 1 Anatomical regions.

Anatomical regions
1. skull fracture
2. clavicle fracture
3. AC joint dislocation
4. SC joint dislocation
5. proximal humerus fracture
6. elbow fracture
7. distal forearm fracture
8. scaphoid fracture
9. triquetrum fracture
10. subcapital 5th metacarpal fracture
11. palmar plate avulsion
12. rib fracture
13. sternal fractures
14. femoral bead fractures
15. lower leg fractures
16. toddler’s fracture
17. metatarsal fractures
18. stress fractures
19. fracture dislocation
20. callus presentation
21. pseudarthrosis

Skull fracture [2] [3]

Fractures of the bony skull can also be inadequately visualized on radiographic overviews. In the absence of neurological symptoms, functional symptom-oriented conservative therapy is used. As the course of the sutures is known, ultrasound imaging of skull fractures is possible. By 18 months of age, intracranial injury can also be visualized ([Fig. 1]), but this is reserved for specialists.

Fig. 1 Skull fracture; arrow: cortical step-off.

Therefore, if there are no clinical symptoms that indicate a cross-sectional examination (MRI or CT), a skull fracture should be diagnosed sonographically at an age of up to 18 months. If there is suspicion of child abuse, radiological diagnosis is indicated for forensic reasons.

If child abuse is suspected, X-rays should be taken.

Clavicle fracture [4]

Clavicle fractures in childhood are treated conservatively. Surgical indication is limited to open fractures and concomitant vascular nerve damage, which are very rare. If the clinical examination is not sufficient, the clavicle fracture should be diagnosed sonographically ([Fig. 2]). In the case of complications (vascular/nerve injury), X-ray is mandatory.

Fig. 2 Clavicle fracture arrow: fracture gap.

AC joint dislocation [5]

If there is suspicion of AC joint dislocation, the initial diagnosis can be made sonographically, since dislocated AC joint dislocations can be easily visualized ([Fig. 3]) with a sensitivity of 100% and a specificity of 84%. This recommendation is valid from the age of 15 years. For younger patients, no valid data are available. In the case of doubt or suspicion of additional fractures, an X-ray should be performed.

Fig. 3 Left X-ray, right ultrasound image; yellow marking: clavicle; green: acromion.

SC joint dislocation

Dislocation in the sternoclavicular joint cannot be adequately depicted in conventional radiology, so that a sectional image examination is necessary here. In an emergency, CT is usually preferred due to availability and time constraints, but this is associated with relevant radiation exposure. Ultrasound can substantiate the indication for cross-sectional imaging by showing a differential finding of the SC joint in the meantime ([Fig. 4]). This recommendation was approved as an expert opinion. Meaningful studies are not yet available.

Fig. 4 SC dislocation right; green: normal SC joint; yellow: sternum; opposite side: no SC joint vivid.

Proximal humerus fracture [6] [7]

A major problem regarding the diagnosis of proximal humerus fracture is that it is difficult to obtain radiographs in two perpendicular planes. Because of significant pain, an axial image cannot be obtained, and in the Y-image there is superimposition by the scapula. On the basis of the images, the correct imaging technique of two perpendicular planes cannot be checked in many cases, so that uncertainties remain. The proximal humerus can be reliably visualized sonographically on 4 planes, thus facilitating the determination of the axial deviation. If there is evidence of a fracture, a radiograph must be taken to exclude a pathologic fracture, as it cannot be reliably visualized sonographically. If the sonographic findings are inconspicuous, it is initially possible to wait. If symptoms persist for more than 5 days, an X-ray check is performed. Fracture sonography can be used up to the age of 12.

Diagnosis follows the shoulder-SAFE algorithm ([Fig. 5]).

Fig. 5 Shoulder SAFE.

Fractures of the elbow [8] [9]

In the diagnosis of fractures near the elbow in children up to 12 years of age, sonography is used as the primary imaging method to detect joint effusion, known from radiography as the fat-pad sign. If the findings are inconspicuous, conservative pain-oriented therapy can be used initially. If effusion is detected, X-ray diagnosis on 2 planes is obligatory. Sonography is used to exclude a fracture. The actual differentiated fracture presentation is performed radiologically.

Elbows-SAFE is used as the algorithm ([Fig. 6]).

Fig. 6 Elbow SAFE.

Distal forearm fracture [10] [11]

In distal forearm fractures, sonography is used as a standard diagnostic method until 12 years of age. If the fracture is uncomplicated, X-ray imaging is not required and is only used in cases of uncertainty or if surgical treatment is planned. Imaging is performed in 6 longitudinal sections, three each for the radius and ulna. Diagnosis follows the Wrist-SAFE algorithm ([Fig. 7]).

Fig. 7 Wrist SAFE.

Scaphoid fracture [12] [13]

Because of the potential complications, the use of fracture sonography in scaphoid fracture requires adequate expertise. If a scaphoid fracture is clinically suspected and radiographs are unremarkable, sonography is used for further screening. If the results are positive for fracture, CT is performed, which offers advantages in visualizing cortical fractures. If the results are negative, MRI is performed, which is superior in trabecular injuries.

Triquetral flake fracture [14]

If there is pain over the triquetrum after dorsal extension trauma and radiographic findings are unremarkable, a triquetral flake fracture can be ruled out before performing cross-sectional imaging. Thus, unnecessary cross-sectional imaging indications can be avoided.

Subcapital metacarpal-5 fractures [15] [16]

In subcapital MHK 5 fractures, the surgical indication depends on the dislocation of the metacarpal head. As an alternative to strictly lateral radiography, which is often compromised by superimposition of the other metacarpals, sonographic determination of axial dislocation can be performed in a volar plane, or in a side-to-side comparison in the case of uncertainty.

Bony avulsion of the palmar plate [17] [18]

Avulsions of the palmar plate may escape radiography but can be effectively visualized sonographically ([Fig. 8]). Therefore, if the symptoms fit and the radiograph is unremarkable, further sonographic imaging should be performed.

Fig. 8 Bony avulsion palmar plate; arrow: fragment.

Rib fractures [19] [20]

Detection of rib fractures is more sensitive with ultrasound than radiography (97% versus 77%). Therefore, after clinical delineation of the region of interest (ROI), sonographic diagnosis should be given preference ([Fig. 9]). If radiographic imaging has already been performed and the findings are unclear, sonography can be used on a supplementary basis.

Fig. 9 rib fracture; green: axial buckling, red: hematoma.

Sternal fractures [19]

If a sternal fracture is suspected, fracture ultrasonography is appropriate as a screening method ([Fig. 10]). If a fracture is confirmed, further imaging should be performed. In the context of shock room care of trauma patients, sonography should not delay the procedure.

Fig. 10 Left CT image of a sternal fracture, right ultrasound findings; red: axial buckling.

Distal femoral and proximal tibial bead fractures

There are currently no studies on the sonographic evaluation of distal knee joint compression fractures in growing children. However, since bulge fractures can be very well visualized sonographically ([Fig. 11]) and have high potential for correction at this site, it is expected that this injury entity will become a domain of fracture sonography in the future.

Fig. 11 left X-ray of a tibial medial bulge fracture, right ultrasound image; red: bulge fracture.

Toddler’s fracture [21]

Toddler's fracture occurs when children are learning to walk and leads to the patient's refusal to bear weight. It often causes problems in the delimitation of the ROI (region of interest), so that in this case, with clear symptoms, an extended X-ray diagnosis is often performed as a search radiograph, resulting in the ionizing exposure of the toddler being disproportionate to the diagnostic findings. In this case, sonography can primarily exclude a bone lesion requiring intervention. If a fracture is visualized ([Fig. 12]), a specific X-ray diagnosis can follow. In the absence of evidence, immobilization and re-examination is performed after 5–7 days. In this way, unnecessary radiographs can be avoided.

Fig. 12 Left X-ray, right ultrasound findings of a distal tibia fracture; red: fracture.

Midfoot fractures [22] [23]

With a sensitivity of 80–97%, sonography should be used as a first-line diagnostic tool in patients 14 years of age and older when a midfoot fracture is suspected. Dislocations in the course can also be visualized well. Here, the 1st and 5th rays are visualized from 3 directions each (dorsal, lateral, plantar), and the 2nd–4th rays from 2 directions (dorsal and plantar). 45° oblique planes can be added if there is uncertainty.

Stress fracture [24]

Early radiographic diagnosis of stress or fatigue fractures reveals pathology in only 15–20% of cases. Sonography can be used to visualize early signs (cortical disruption, bulge, small extra fragment, thickening, reverberation artifacts, [Fig. 13]) in these cases, thus substantiating the indication for MRI.

Fig. 13 Fatigue fracture midfoot; arrow: incipient callus.

Callus detection [25] [26]

Callus formation can be detected much earlier sonographically than radiologically (in 97% of cases with sonography after 3 weeks, and in 42% with radiology) and is thus well suited for monitoring the healing process. In the case of suspicion of delayed bone healing or infection, an X-ray should be performed.

Pseudarthrosis [27] [28]

If sufficient expertise and logistics allow, contrast-enhanced ultrasound (CEUS) can be used in pseudarthrosis to diagnose and monitor the progress of an underlying infection. The method is able to reliably distinguish infected from aseptic pseudarthroses.

Summary

Fracture sonography is suitable for several indications to complement or replace conventional radiography and to guide further imaging. While some indications are already well established, there is still a need for research in other areas of application.

Conflict of Interest

The authors declare that they have no conflict of interest.

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Publication History

Received: 27 May 2023

Accepted after revision: 08 December 2023

Article published online:
23 February 2024