Overview Snapshot A 27-year-old woman presents to the emergency department for severe pain in the right knee. A few hours prior to presentation, an opposing soccer player strikes her leg from her right side while her foot was planted to the ground. Afterwards, she felt a "pop" sound that was followed by severe knee pain and swelling. After the swelling improved, she feels that her right knee is unstable. On physical exam, the patient has a positive Lachman test. The patient is asked to rest, place ice and compress the knee, and elevate the affected leg. Given her sport demands, a conversation is made on the necessity of surgical reconstruction of the anterior cruciate ligament. Introduction Clinical definition login to view 1 more bullet Epidemiology login to view 7 more bullets Pathoanatomy login to view 14 more bullets Associated conditions login to view 4 more bullets Prognosis login to view 1 more bullet 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 6 more bullets Treatment Conservative login to view 4 more bullets Operative login to view 6 more bullets Complications Osteoarthritis Arthrosis Sports disability