EMRad: Can’t Miss Adult Knee Injuries

Figure 1: Normal AP knee x-ray. Case courtesy of Dr Andrew Dixon, Radiopaedia.org, annotations by Stephen Villa MD.
Have you ever been working a shift at 3am and wondered, “Am I missing something? I’ll just splint and instruct the patient to follow up with their PCP in 1 week.” This is a reasonable approach, especially if you’re concerned there could be a fracture. But we can do better. Enter the “Can’t Miss” series: a series organized by body part that will help identify injuries that ideally should not be missed. This list is not meant to be a comprehensive review of each body part, but rather to highlight and improve your sensitivity for these potentially catastrophic injuries. Now: the knee.



Case: A 32-year-old male with a past medical history of diabetes presents with a 1 month history of finger pain after slamming his finger in a car door. 2 weeks after the initial incident he presented to the emergency department for worsening pain and received x-rays that were negative for acute fracture. Today he presents reporting pain radiating up the hand, arm, and into the shoulder, with associated chills. His labs are significant for hyperglycemia, hyponatremia, and an elevated erythrocyte sedimentation rate and c-reactive protein. His x-ray is seen here (figure 1 image courtesy of Daniel Rogan, MD). What is the diagnosis?