Abstract
Background
Lateral ankle sprain (LAS) is the most common traumatic injury, yet its diagnosis and management remain suboptimal. This contributes to a high prevalence of residual symptoms, negatively impacting patient quality of life and increasing healthcare costs. We hypothesized that routine ultrasonography (US) following LAS could significantly modify the treatment strategy established by a specialist. Additionally, we hypothesized that US is an efficient tool for identifying osseous injuries and associated ligamentous injuries.
Methods
Fifty-one ankles with lateral instability diagnosed in the emergency department (ED) were retrospectively included. A second evaluation by an orthopedic surgeon was conducted within the first ten days to establish the “initial treatment”. All patients underwent US and MRI within the first three weeks after the initial ED assessment and were reevaluated to establish the “post-US treatment”. We determined concordance between initial and post-US treatment. Additionally, we assessed the diagnostic accuracy of US for identifying osseous and associated ligament injuries, including the anteroinferior talofibular ligament (AITFL), deltoid ligament, spring ligament, calcaneocuboid ligament (CCL), dorsal talonavicular ligament (DTNL), and bifurcate ligament, MRI serving as the reference standard for assessing ligamentous and osseous injuries.
Results
Treatment for LAS was modified for 16 ankles (31.3 %) following US examination (W=97, p < 0.05). US demonstrated excellent sensitivity (0.73) and specificity (0.95) for identifying osseous injuries. Additionally, US detected injuries to the AITFL in 6 ankles (11.8 %), deltoid ligament in 16 (31.3 %), spring ligament in 1 (2 %), CCL in 1 (2 %), DTNL in 1 (2 %), and bifurcate ligament in 2 (3.9 %).
Conclusion
US examination following LAS was significantly associated with treatment modifications. It also proved high accuracy for detecting osseous injuries missed by plain X-rays and diagnosing associated ligament injuries. Given these findings, it appears relevant to update the current diagnostic algorithm for LAS, including US.
Highlights
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Routine ultrasonography within 3 weeks of lateral ankle sprain altered initial treatment in 31.4 % of ankles.
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Routine ultrasonography detected deltoid ligament lesions in 31.3 % and AITFL lesions in 11.8 % of ankles.
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Ultrasonography demonstrated a sensitivity of 73 % and a specificity of 95 % for identifying osseous lesions.
1
Introduction
Lateral ankle sprain (LAS) is the most common musculoskeletal injury with over 2 million annual consultations for ankle sprains in France, averaging 6500 per day . Despite this, severity is often underestimated . Less than half of patients experiencing ankle sprains seek medical consultation, and among those who do, less than 15 % are directed towards rehabilitation professionals during the acute phase . This is particularly notable considering that pathologies affecting the ankle and foot region manifest the highest rates of diagnostic inaccuracies principally because of the substantial variability of lesions that may be encountered within a small anatomical region , .
Between 30 % and 70 % of patients report remnant symptoms at 7 years . Forty percent of patients exhibit chronic instability over time, and up to 20 % will develop post-traumatic ankle osteo-arthritis , . This can be explained in part by a non-optimal initial diagnosis and therefore, a non-optimal management leading to an elevated risk of chronic complications. Additionally, the socio-economic impact of ankle sprains is significant, with an estimated cost of between $350 and $3000 per patient largely due to the disabling nature of the condition and the delays in returning to work , .
Currently, the initial management of a patient presenting to the emergency department (ED) with LAS is based on a clinical examination in accordance with the Ottawa criteria . In the event of a positive criteria, ankle X-rays are obtained to exclude fractures which occur in 15 % of cases following LAS . A second evaluation should be carried out within a week enabling treatment to be adapted based on a more accurate ligament and bone examination. Dynamic ultrasonography (US) imaging or cross-sectional imaging as MRI can be performed at this time in complement to the conventional X-rays ,, . Most of the time, this reassessment is not conducted due to several factors, including the commonplace perception of the condition as trivial, both among patients and physicians . Diagnosis is therefore delayed until the lesions are already considered chronic, with a consequent impact on the final prognosis. US has already demonstrated high efficiency and accuracy in diagnosing ankle ligament injuries, particularly tears of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL). However, to date, no study has specifically evaluated its impact on the therapeutic management of LAS. Additionally, the literature remains limited regarding the value of US in assessing osseus injuries . The primary objective of our study is to determine if routine ultrasonography after LAS modifies the treatment of ankle trauma. Secondary objectives included evaluating the diagnostic accuracy of US in detecting osseous injuries, by comparing its findings to those obtained through MRI.
Our hypothesis is that routine ultrasonography after ankle trauma would modify the treatment of ankle sprain.
2
Materials and methods
2.1
Inclusion
This retrospective study was carried out by using the clinical data of patients presenting to the ED of Saint-Etienne University Hospital Centre from January 1st, 2021 to April 1st 2024.
The purpose and procedures of the study were explained to all participants, who provided written informed consent prior to their inclusion in the study. The study was conducted in accordance with the principles of the Declaration of Helsinki and received approval from “Terre d’éthique” (protocol numberIRBN642024/CHUSTE).
Participants were eligible if they met the following conditions: clinical diagnosis of an ankle sprain with normal findings on X-ray imaging. Participants were excluded if they presented with an initial fracture or dislocation, had undergone surgical intervention for chronic ankle instability, or if their medical records were incomplete.
2.2
Study protocol
We included patients diagnosed with a LAS in ED. After the initial examination in ED, a second assessment by a single senior specialist (orthopaedic surgeon) independent to the study was performed within ten days to determine the treatment strategy. An US and an MRI were systematically performed as part of their diagnostic evaluation within the three-week following the initial injury.
US examinations were conducted by an experienced musculoskeletal radiologist using a General Electric Logic E10 system equipped with an L6–24-D high-frequency sonographic probe. Ligament integrity, joint effusions, and traumatic osseous injuries were assessed.
MRI examinations were performed by a musculoskeletal radiologist with 12 years of experience and reviewed independently by a second radiologist. Imaging protocols included Proton Density sequences with Fat Saturation and T1-weighted sequences in all three planes. Ligament integrity, joint effusions, and traumatic osseous injuries were assessed. MRI was considered as the reference standard for ligament and osseous assessment in our article .
Ligament injuries were classified into three grades based on imaging findings from both US and magnetic resonance imaging (MRI). Grade I (mild) injuries correspond to ligamentous stretching without macroscopic fiber disruption. On US, the ligament appears thickened and mildly hypoechoic, but remains continuous and homogeneous, with no abnormal laxity observed during dynamic stress testing. MRI findings include a continuous ligament with low signal intensity on T1-weighted images and mild high signal intensity on T2-weighted or STIR sequences, reflecting intraligamentous edema without fiber disruption. Grade II (moderate) injuries indicate a partial rupture of the ligament. US typically reveals a heterogeneous echotexture with partial fiber discontinuity and increased hypoechogenicity, and dynamic testing may demonstrate moderate laxity. On MRI, there is partial interruption of ligament continuity, with intermediate to marked hyperintensity on T2-weighted or STIR sequences, often associated with periligamentous edema or hemorrhage. Grade III (severe) injuries represent complete ligament rupture. The ligament appears completely discontinuous on US, with retraction of the torn ends and potential presence of a hyperechoic hematoma within the gap. Dynamic testing reveals significant laxity. MRI shows a complete disruption of the ligament with a marked hyperintense signal on T2-weighted or STIR images, frequently accompanied by surrounding soft tissue edema and hemorrhage ( Fig. 1 ).
Illustration of different stages of severity for ATFL injuries visualized on MRI and ultrasonography (US).A complete rupture of the ATFL (grade III) is shown on ultrasonography in image A (longitudinal to the ligament plane) and on MRI in image B (axial view). The red star indicates the rupture site, and the ligament is outlined by white arrowheads.A partial rupture of the ATFL (grade II) is shown on ultrasonography (longitudinal to the ligament plane) in image C and on MRI in image D (axial view). Red stars indicate intraligamentous hematomas; the white dashed arrow shows ligament widening, and the ligament contour is marked by white arrowheads. T: Talus; F: Fibula .
2.3
Assessment of LAS treatment modification based on routine ankle US
The treatment initiated by the orthopedic surgeon, prior to any MRI or ultrasonography assessment, was recorded and considered as the “initial treatment”. Initial treatments were categorized into five progressive classes, numbered from Class 0 to Class 4. The classification was as follows: functional treatment without immobilization (Class 0), use of an ankle brace (Class 1), application of a walking boot (Class 2), immobilization with a plaster cast (Class 3), and surgery (Class 4).
All patients in the study underwent early rehabilitation after a one-week rest period aimed at pain relief, except for those requiring immobilization with a plaster cast , . The treatment was then reassessed by the same orthopedic surgeon following the US examination and was recorded as “post-US treatment”. The treatment could be intensified or reduced based on the US findings. We then determined the number of patients who required treatment modification.
2.4
US diagnostic accuracy in detecting osseous injuries
To assess US diagnostic accuracy in detecting osseous injuries, we compared the osseous injuries detected by US with those identified on MRI ( Fig. 2 ).
Illustration of the value of ultrasonography (US) and MRI in the management of lateral ankle sprains, highlighting the detection of associated osseous injuries that may be missed on standard radiographs.2 A: Anteroposterior plain radiograph of the ankle taken on day 1 post-trauma for suspected sprain, showing peri-diaphyseal fibular oedema.2B: Ultrasonography of the fibular diaphysis (perpendicular to the ligament plane) at 1-week post-trauma, revealing cortical rupture with moderate diastasis and perilesional hematoma.2 C: Coronal T1 MRI of the fibular diaphysis at 1-week post-trauma, showing cortical rupture with moderate diastasis, bone oedema, and perilesional infiltration.Arrow: Cortical fibular fracture. Star: Hematic soft tissue oedema. MRI: Magnetic resonance imaging; US: Ultrasonography.
2.5
US and MRI ligament injury assessment
We analysed ligament lesions detected after systematic MRI and US analysis of the ankle following LAS. The following ligaments were evaluated: Anterior Talofibular Ligament (ATFL), Calcaneofibular Ligament (CFL), Anterior Inferior Talofibular Ligament (AITFL), deltoid ligament, spring ligament, Calcaneocuboid Ligament (CCL), Dorsal Talo-navicular Ligament (DTNL), and the bifurcate ligament. Severity of ATFL tear was detailed.
2.6
Statistical analysis
Statistical analyses were performed using Medistica, with pvalue.io serving as a graphical user interface to the R statistical analysis software. A p-value< 0.05 was considered as statistically significant. Assessment of LAS treatment modification based on routine ankle US was performed using the Wilcoxon signed-rank test for paired samples between the two groups. The sensitivity and specificity of US for diagnosing osseous injuries were determined refering to MRI diagnosis.
3
Results
3.1
Population
A total of 64 ankles were included. Five ankles were excluded for missing their US appointments, and five were excluded for missing their MRI appointments. One patient was ineligible due to incomplete clinical medical records, and two others were excluded because of surgical discussions for a pre-existing chronic ankle instability. This resulted in a final cohort of 51 ankles and 408 ligaments analysed.
The mean age of the examined population was 30.0 ± 11.6 years old. There were 49 % (n = 25) males and 51 % females (n = 26). Average body mass index (BMI) was 23.3 ± 2.7 kg.m – ².
3.2
Assessment of LAS treatment modification based on routine ankle US
Initial treatment has been modified for 16 ankles (31.3 %) after US evaluation (W=97, p < 0.05). Of these, 10 (19.6 %) had their treatment increased and 6 (11.7 %) had it reduced ( Table 1 ).
Table 1
Comparison of treatment strategies (functional treatment, brace, walking boot, plaster cast, or surgery) implemented before and after ultrasonographic assessment.
| Treatment | Before US | After US |
|---|---|---|
| Functional treatment | 2 (4 %) | 2 (4 %) |
| Ankle brace | 32 (63 %) | 26 (51 %) |
| Walking boot | 15 (29 %) | 15 (29 %) |
| Plaster cast | 2 (4 %) | 8 (16 %) |
| Surgery | 0 (0 %) | 0 (0 %) |
3.3
US diagnostic accuracy in detecting osseous injuries
US detected 10 (19.6 %) fractures or fissures that had been missed on initial X-ray and MRI identified 11 (21.6 %). A sensitivity and specificity analysis were performed to assess the ability of US to detect fractures, revealing a sensitivity of 0.73 and a specificity of 0.95. The comparative results of US and MRI for fracture detection are presented in ( Table 2 ).
Table 2
Concordance of osseous injury detection between ultrasonography and MRI in the context of lateral ankle sprains.
| Fracture detected on MRI, n (%) | Absence of fracture on MRI, n (%) | |
|---|---|---|
| Fracture detected on US, n (%) | 8 (80 %) | 2 (20 %) |
| Absence of fracture on US, n (%) | 3 (7 %) | 38 (93 %) |
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