This report describes a patient with a 31-month-old previously operated tibial plateau fracture who had frequent giving way of the involved knee. The symptoms and physical examination suggested a meniscus injury, which was finally ruled out by arthroscopy. Magnetic resonance imaging (MRI) in dynamic knee positions was then done, which showed that a bone ridge on the articular surface caused the symptoms by interfering with the lateral meniscus. The ridge was removed arthroscopically, and a satisfactory result was obtained.