Description:
<jats:p> 1. Three patients are reported in whom a sudden acute internal derangement of the knee was caused by torsion of a pedunculated portion of the infrapatellar fat pad. </jats:p><jats:p> 2. The symptoms and signs are described. </jats:p><jats:p> 3. The pathological changes and the pathogenesis are discussed. </jats:p>