This patient has a Weber C fracture of the distal fibula without dislocation that was treated conservatively with plaster cast. Edema and tenderness in the calf led the physician to request an ultrasound of the deep veins. The ultrasound showed acute thrombosis of the muscular veins of the calf (both mm. gastrocnemii) recognized as dilated non-compressible veins that contained hypoechoic material with no flow.