The Queen Silvia Children’s Hospital (DSBUS) is the only regional hospital for pediatric trauma in the western region of Sweden. On a normal day the orthopedist on call takes care of between 10 and 40 patients. All follow-ups were made at the same hospital’s orthopedic out-patient department.
Six physicians ranging from junior doctors to consultants participated in the inclusion of patients, all without previous experience of US diagnostics.
They attended a 1.5 h intensive course designed by a pediatric radiologist and an orthopedic surgeon (both authors). The course focused only on the diagnosis of suspected wrist fractures in children. The study physicians performed one examination each on a patient with a fracture to verify that they were acquainted with the method. A fracture was diagnosed only if a cortical gap, torus formation, or displacement was seen (Figs. 1, 2). Indirect signs like subperiosteal hematoma was not used since these signs are deemed more subtle and difficult to learn and interpret for an US novice.
When present at the ED during the study period between February and September 2015, study physicians included all patients eligible. The US equipment used was only available for this time period and was only used for the purpose of this study. Inclusion criteria were all patients between 3 and 16 years with wrist pain after recent (last 3 days) trauma. Patients were excluded if there was an uncertain clinical finding (i.e., pain from proximal forearm or hand), an open fracture, or if the parents did not have the language skills to understand the information material.
Distal radial fractures in children can be categorized in a variety of ways such as buckle (or torus) fractures, greenstick fractures, complete fractures, and fractures involving the physis (classified according to the Salter–Harris classification [13]). For the purpose of this study the exact radiological classification was of less importance since the focus was on the effects of the treatment.
At our department the vast majorities of cases are treated with only a splint or closed reduction followed by a splint [2]. The treatment guidelines for the ED doctors at the hospital can, in a simplified manner, be divided into four groups:
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1.
No fracture.
Advised treatment: No splint or immobilization.
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2.
A buckle or greenstick fracture with acceptable angulation.
Advised treatment: A dorsal forearm plaster of Paris splint for 3 weeks that is removed by the parents. No follow-up is needed.
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3.
A buckle or greenstick fracture with borderline angulation or complete fracture with minor angulation or displacement.
Advised treatment: A dorsal forearm splint for 3–4 weeks with a radiographic control of the fracture position after 5–7 days.
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4.
A buckle or greenstick fracture with unacceptable angulation or complete fractures with little angulation or displacement.
Advised treatment: Closed reduction with or without surgical intervention.
The term “acceptable angulation” is relative since, as noted above, indications for intervention or follow-up depends on the age of the child and other factors. It is therefore up to the ED physician to make a qualified decision with all factors taken into account.
A radiographic follow-up is thus, according to the guidelines for ED doctors, needed if (a) the angulation or displacement is such that any further angulation is unacceptable or (b) the fracture is potentially unstable. The latter is the case for many complete fractures with even minor displacement (Fig. 3). Rare fractures involving the actual joint (Salter–Harris type 3 or 4) generally require a follow-up radiograph or surgery. No such fractures were found in the present study.
Each patient had a physical examination of the wrist and US of the wrist was performed with a Fujifilm SonoSite, Inc. Edge® using a linear 15–6 MHz probe. The US examination took 5–10 min to perform and consisted of longitudinal images in the sagittal plane of the distal 10 cm of the radius with special focus on painful areas. Dorsal, radial, and volar aspects of the distal radius were visualized. Imaging of the radial portion of the wrist in the sagittal plane on US visualized the same plane as a lateral view on radiographs. The decision of the study physician was stored in a coded closed envelope in order to blind the result from the results of the radiograph. The patient was asked if he or she found the examination painful.
The possible outcomes of the US examination correspond to the treatment groups 1–4 described above. The study physician first grouped each patient based only on the US interpretation. The alternative “uncertain finding” was used when the study physician was not able make a decision based on the US findings alone or could not achieve adequate images.
After the US examination standard radiographs of the wrist, using AP and lateral views, were performed in all patients. The same four outcomes were used. The study physician interpreted the images and stored the results in a second envelope.
To validate the accuracy of the radiographic readings by the study physicians the radiographs were also, at a later time, inspected by an independent senior radiologists blinded to the US and radiograph interpretation of the study physician. The radiologist did not sort the fractures according to the four groups used by the study physicians, since the radiologist were not involved in the decision making of the treatment, and the interpretation was used only to analyze the specific fractures where the two diagnostic modalities did not agree. The senior radiologist did no interpret the US images.
To obtain a gold standard for treatment, two senior consultants in pediatric orthopedic surgery, specialized in fractures, analyzed all the radiographs and decided on the most appropriate treatment. This second look was blinded to all other results and interpretations. The consultants were asked “what is the optimal treatment for a patient of this age with this injury based on the radiograph” with the treatment groups corresponding to numbers 1–4 presented above. The consultants established a joint consensus and there were no cases of dispute. This method was used in order to evaluate the clinical relevance of the results and not limit the study to if the US and radiological findings correlated perfectly.
Ethics, consent, and permissions
Participation was voluntary but all patients who met the inclusion criteria approved of participation and subsequent publishing of obtained material. Ethical approval was obtained from the Human Ethics Committee at the Medical Faculty, Gothenburg University (DNR 956-14).
Statistics
To reach the desired level of evidence based on pre-study power analysis, a study group of 130 patients was desirable. The sample size was depending on 80% power and p < 0.05 together with normal distribution, estimating that using US 75% of the fractures would be detected. The very conservative 75% sensitivity estimate was chosen based on the lowest sensitivity that was found in relevant studies [14]. However, only 117 cases were included due to the limited time the ultrasound equipment was available. As mentioned in the result section the sensitivity was shown to be clearly higher than the conservative estimate used to estimate power.