Ankle torque-related fractures and its echo-fast diagnosis protocol

Abstract

Ankle torque is the most frequent injury mechanism encountered in traumatology. It usually develops as an ankle sprain, and often produces an ankle fracture. Signs and symptoms are very unspecific on the differential diagnosis, and conventional radiographs must be obtained to confirm it. This study compares ultrasound and standard X-ray images values found in ankle sprain-related fracture diagnoses. A 3-month prospective study was carried out on 52 patients with ankle torque. First, an ultrasound diagnosis was made by the first researcher at their arrival to the emergency department, usually consisting of a longitudinal section of the fibula, tibia, and V metatarsal. Then, a blinded independent investigator carried out the usual diagnosis protocol using traditional radiographs. When the required number was obtained, a third independent investigator evaluated the results. A Chi-squared test was used to contrast the outcomes between sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) comparing a non-inferiority hypothesis of our protocol against standard X-ray images screening. Echography showed to be at least as good as standard radiographs on the screening of ankle torque-related fractures (p = 0.02). In our series of patients, nearly 8% of fractures are misdiagnosed with plain radiographies, which concurs with the lower limit found in the bibliography. All the false negatives on radiographs were true positives in the first ultrasound assessment. The average time for the ultrasound protocol was 42 s. An ultrasound is at least as effective as conventional X-ray images when used in diagnosing ankle sprain-related fractures, regardless of age or sex and could in fact be better. The use of echography could reduce the number of radiographies performed when diagnosing these kinds of fractures, thereby reducing the amount of radiation exposure and expediting the diagnostic process as well as the "in situ diagnosis".

Level of clinical evidence 2 [prospective cohort (N > 30 patients) study].

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