The influence of anesthesia-body mass index and chronicity of the injury on the reliability of diagnostic tests for anterior cruciate ligament rupture

This study aimed to analyze the accuracy and interobserver reliability of the four common diagnostic tests for anterior cruciate ligament (ACL) rupture. The effect of anesthesia, chronicity of the injury and patient’s body mass index (BMI) on the reliabilities was also assessed. Patients who underwent arthroscopic knee surgery were examined before the surgery and under anesthesia by three observers categorized based on their experience levels. One hundred two patients were evaluated to determine the accuracy of these tests. Sixty-two patients with ACL rupture were further examined to assess the effect of BMI (≤25 kg/m(2), or >25 kg/m(2)) and chronicity (≤4 or >4 weeks) of the injury on reliabilities with using the Fleiss kappa method. The Lachman test performed under anesthesia had the highest sensitivity (100%, 100%, and 96.7%). In contrast, pivot shift and lever sign tests had the lowest sensitivity both in awake (24.2%, 17.7%, 8.1% and 37.1%, 33.8%, 29%) and anesthetized condition (75.8%, 75.8%, 67.7% and 41.9%, 43.5%, 40.3%). Specificities of the tests except pivot shift were negatively affected when performed under anesthesia. The reliability of the anterior drawer test was perfect under anesthesia. The lever sign test had the highest reliability in the awake condition in patients with a BMI of >25 kg/m(2). Furthermore, the reliabilities of the anterior drawer, Lachman, and pivot-shift tests in awake condition were found to be increased in patients with a chronic injury. Finally, the examiner’s experience is not important for the physical diagnosis of ACL rupture.