Magnetic resonance imaging of the knee on presentation. Anterior cruciate ligament reconstruction and two microfracture procedures had been performed on the left knee during the course of the last seven years. (a) Sagittal and (b) coronal three-dimensional gradient echo T1 (WATSf; repetition time 20, echo time 5.2, field of view 150, fractional anisotropy 15°, slice thickness 3 mm) left knee magnetic resonance images demonstrate a large cartilage defect on the lateral femoral condyle (arrow). Hypointense metallic artifacts due to the anterior cruciate ligament reconstruction and osteophyte formation (thick arrow) were also observed. (c) An Outerbridge grade 4, Noyes grade 3B 3 cm × 3 cm large chondral defect with a rough surface at the lateral condyle was diagnosed.