Avulsion fractures of the knee: imaging findings and clinical significance.

The knee is an intricate joint with numerous tendinous, ligamentous, and meniscal attachments, which make it particularly vulnerable to complex injuries after trauma. A variety of avulsion fractures of the knee can occur, including Segond and reverse Segond fractures; avulsions of the anterior and posterior cruciate ligaments; arcuate complex avulsion; iliotibial band avulsion; avulsions of the biceps femoris, semimembranosus, and quadriceps tendons; Sinding-Larsen-Johansson syndrome; and Osgood-Schlatter disease. These fractures often have a subtle appearance at conventional radiography, which is typically the first imaging modality performed in these cases. Advanced imaging modalities, particularly magnetic resonance imaging, are helpful and can provide valuable additional information for adequately defining the extent of damage. The onus is on the radiologist to identify the pattern of injury and to understand the substantial underlying damage that it frequently represents. Conveying this information to the referring clinician is crucial and represents the first step toward additional evaluation and probable orthopedic referral. By recognizing the significance of these injuries at initial presentation, radiologists can facilitate appropriate patient work-up and prevent the chronic morbidity associated with delayed treatment. (c) RSNA, 2008.