Ultrasonography for anterior talofibular ligament lesions and ankle joint effusions in acute ankle sprains

SUMMARY Ankle sprains are the most common diagnosis of the ankle injuries in emergency departments (ED). Anterior talofibular ligament (ATFL) is the most common injured ligament of the ankle. The appropiate management of the lesion depends on fast and accurate diagnosis. Long term complications are the instability of the ankle and ongoing pain during exercise. Physical and radiological tests performed in the ED are helpful but not demonstrate objective findings in the assesment of the ligamentous injuries. Artrography and MRI are most valuable methods but they are expensive, time consuming and not cost-effective in the ED. The purpose of this study is to test the ability of low-frequency ultrasound (3.5 mHz with a standoff pad) to detect the ATFL lesion and ankle effusions in patients with acute ankle sprains. In this prospective observational study we examined patients who presented with an acute ankle sprain to Dokuz Eylul University Hospital Emergency Department (ED) between July and December 1998. Inclusion criteria were age over 17 years and an acute ankle sprain (<24 hours old). Patients with fractures of the tibia, fibula, tarsal or metatarsals were excluded. Patients with a clinically suspected lesion of the ATFL were examined with USG and MRI independently by a senior radiololgy resident after evaluation by senior emergency medicine residents in the ED. No further arthroscopic or intraoperational interventions were performed. Data analyses were performed with Pearson and Fisher's exact tests. Eighty-nine patients met inclusion criteria; 17 of them were excluded and 52 of them were lost to follow-up or refused USG or MRI. Twenty patients were examined with USG and MRI. In 13, ATFL lesions were detected by MRI. With MR as the gold standart, an ankle joint effusion was correctly diagnosed by USG in 9 of 13 patients (sensivity %63, specificity %100, PPV %100, NPV %61, p=0,004) and of these nine patients, USG deminstrated the ATFL lesion in 4 (sensivity %30, specifivity %. PPV %100, NPV%43, p>0.05). USG with a low-frequency scanner can allow a correct diagnosis of ankle effusions at the ankle joint. Further studies are needed. 29