Fig. (1) (a) Anteroposterior radiograph of the left knee shows a large solitary broad-based osteochondroma arising from the metadiaphysis of the tibia and projecting towards the proximal fibula. (b) Lateral radiograph of the left knee demonstrates abnormal contact between the osteochondroma and the fibula which created a large pressure erosion involving > 50% the width of the fibular metadiaphysis (arrows).