Snapshot A 21-year-old man presents to the emergency department for severe pain in the right knee. A few hours prior to presentation, an opposing football player hits his leg from his right side. Afterwards, he felt a "pop" sound that was followed by severe knee pain and a sensation of knee instability. On physical exam, there is anterior translation of the proximal tibia when pulled as the patient has the knee flexed at 90° and supine. Ice is applied to the knee and ibuprofen is prescribed. Orthopedic surgery is consulted to evaluate if ligamental reconstruction is needed. Introduction Clinical definition login to view 1 more bullet Associated conditions login to view 4 more bullets Prognosis The majority of athletes are able to return to their sports activities with ACL reconstruction Epidemiology Incidence login to view 1 more bullet Demographics login to view 1 more bullet Risk factors login to view 2 more bullets ETIOLOGY Pathoanatomy login to view 14 more bullets Presentation Symptoms login to view 3 more bullets Physical exam login to view 6 more bullets Imaging Magnetic resonance imaging (MRI) login to view 3 more bullets Studies Making the diagnosis login to view 2 more bullets Differential Meniscal tear login to view 5 more bullets Posterior collateral ligament (PCL) injury login to view 2 more bullets Treatment Conservative login to view 4 more bullets Operative login to view 6 more bullets Complications Osteoarthritis Arthrosis Sports disability