A Case of Snapping Knee caused by An Intraarticular Rheumatoid Nodule

Abstract

We experienced a case of snapping knee caused by an intraarticular nodule within the lateral parapatellar capsule. Histologic examination of the nodule showed f ibrinoid necrosis and therefore that it was rheumatoid. Observation from a cadaveric study revealed that the anterolateral portion of the femorotibial articular surface of the lateral femoral condyle has a sharp edge. Accordingly it is speculated that mechanical friction is likely to occur at the lateral parapatellar capsule on knee motion, and that a tumor which appears in this portion could tend to bring about snapping.