PATELLAR SLEEVE FRACTURE - DEMONSTRATION WITH MR-IMAGING

PURPOSE: To demonstrate the magnetic resonance (MR) imaging characteri stics of patellar sleeve fracture, a cartilaginous avulsion from the l ower pole of the patella occurring during forceful contraction of the quadriceps muscle against a partially flexed knee. MATERIALS AND METHO DS: The authors evaluated radiographs and MR images from three childre n with suspected sleeve fractures. RESULTS: Radiographs showed small b one fragments avulsed from the lower patella in two children and no bo ne abnormality in one. MR imaging demonstrated separation of most of t he cartilaginous lower patella in all children, definite intraarticula r extension in one, and possible intraarticular extension in another. CONCLUSION: MR imaging can help determine the need for surgery by depi cting the extent of cartilaginous injury and displacement of fracture fragments.