Virginia Via Research Day Book 2026

Medical Student Research Case Reports

36 ARCUATE SIGN: AN INDICATOR FOR KNEE INTERNAL DERANGEMENT

Jessie Lee, Lucas Gmutza, Matthew Weirath DO, Mark Rogers DO Corresponding author: jlee05@vt.vcom.edu

VCOM Virginia, Blacksburg, Virginia Indiana University Health Orthopedics, Bloomington, Indiana

a small avulsion fracture of the proximal fibular head, also known as an arcuate sign. An MRI was ordered, which revealed an ACL tear, a vertical split tendon tear of the PCL, and a possible posterior lateral corner injury. He is currently scheduled for arthroscopic repair at the end of December. The avulsion fracture of the tip of the fibula is of little concern on its own. What it represents is the amount of extension of the knee that would be required to cause this avulsion, which represents a high likelihood of further ligamentous injury to the knee.

This case is an excellent example of why obtaining X-rays ahead of advanced imaging is important. And in this case, with a fairly benign physical exam, a subtle finding on x-ray should direct the clinician to obtain advanced imaging for concern of ligamentous injury.

Context: An arcuate sign is a rarely seen X-ray finding that is indicative of an increased chance of having a significant internal derangement of the knee Case: 21-year-old college student presented to the clinic with a knee injury when playing flag football. He reported hyperextending his knee after landing on his heel, reaching out for a pass. His initial exam was benign except for a slight interarticular effusion. He had full range of motion and only slight asymmetry of his ligamentous testing on exam. His initial imaging showed

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74 Edward Via College of Osteopathic Medicine (VCOM)