Author: Michael Lee, DO Peer-Reviewer: Brandon Godfrey, MD Editor: Alex Tomesch, MD

Author: BuMin Kong, MD; Susie Lee, BA Peer-Reviewer: Mark Hopkins, MD Final Editor:  Alex Tomesch, MD

Author: Diego Riveros, MD Peer-Reviewer: Mark Hopkins, MD Final Editor: Alex Tomesch, MD

Author: R  "Max" Lystrup, MD, CAQSM Peer-reviewer:  M. Terese Whipple, MD Editor: Alex Tomesch, MD 32 year-old male was doing a 425 lbs back squat and felt a painful "pop" in his anterior R knee above the kneecap and dropped to the ground. He has been unable to walk and his knee is extremely swollen.  X-rays are read as normal but he cannot extend his knee on exam. Image 1 : Ultrasound of the R anterior knee.  Robert Lystrup's  images. What is your suspected diagnosis? What is your initial workup in the ED? What imaging confirms the diagnosis? What is your management and disposition? -- see below for answers -- What is your suspected diagnosis? Quad tendon rupture.  Pearl: Quad tendon ruptures are often missed in the ED and are more common in older patients What physical exam maneuver can help confirm your diagnosis? Unassisted straight leg raise: If a patient cannot lift their lower leg off the bed while lying flat there may be a failure of the extensor mechani

Author: Derek Hatfield, MD Peer-reviewer: Brandon Godfrey, MD Final editor: Alex Tomesch, MD

Author: Sydney Cryder, DO Peer-reviewer: Katie Dolbec, MD, CAQ-SM Final editor: Alex Tomesch, MD

Author: Justine Ko, MD Peer-reviewer: Terese Whipple, MD Final editor: Alex Tomesch, MD

Author: Juan Pablo Nieto, MD Peer-reviewer: Brandon Godfrey, MD Final editor: Alex Tomesch, MD

Author: BuMin Kong, MD; Susie Lee, BA Peer-Reviewer and Final Editor: Mark Hopkins, MD