Presentation
Twisting injury 1 week ago. Local pain on the medial side of the knee. Unable to extend the knee.
Patient Data
![](https://prod-images-static.radiopaedia.org/images/10268488/c8303d434aeb12109e28b5f3d99f36_big_gallery.jpg)
Subtle cortical avulsion fracture medial femoral condylar epiphysis (arrow) below the expected poistion of the medial collateral ligament origin with overlying soft tissue swelling
![](https://prod-images-static.radiopaedia.org/images/10268529/7de81cb714a7dd96cc30e5a8b2a363_thumb.jpg)
![This study is a stack](/packs/stack-YQKLCKBI.gif)
![](https://prod-images-static.radiopaedia.org/images/10268581/8c1df7353c4a15b2a74a39aaea8538_thumb.jpg)
![This study is a stack](/packs/stack-YQKLCKBI.gif)
![](https://prod-images-static.radiopaedia.org/images/10268563/f3b43beb6747256a447153c7eca545_thumb.jpg)
![This study is a stack](/packs/stack-YQKLCKBI.gif)
![](https://prod-images-static.radiopaedia.org/images/10268529/7de81cb714a7dd96cc30e5a8b2a363_big_gallery.jpg)
Subtle avulsion fracture caudal to the expected position of the superficial fibers of the medial collateral ligament origin. Fluid sits between the superficial MCL and the so-called menisco-femoral extension of the deep MCL fibers.The attachment of this menisco-femoral extension has been avulsed.
Case Discussion
The MCL has superficial and deep portions usually separated by a layer of fat. The deep portion on the femoral side is attached to the medial meniscus. In this case following twisting injury, the cortical attachment of this menisco-femoral extension has avulsed rather than the ligament rupture.