[Acute medial collateral ligament injuries of the knee: diagnostics and therapy].

The medial collateral ligament complex (MCL) is the most commonly damaged ligamentous stabilizer of the human knee. The diagnostic algorithm comprises patient history, clinical examination and magnetic resonance imaging (MRI). It is important to distinguish between incomplete and complete ruptures of the MCL. For adequate treatment the classification and exact knowledge about concomitant injuries are important. A nonoperative treatment of incomplete ruptures (grades I and II) is widely accepted and usually results in a good clinical outcome but the treatment of complete ruptures (grade III) is a subject of controversy. Complete intraligamentous ruptures with a correct approximation of the stumps and intact dorsomedial joint capsule can also be treated nonoperatively with good and excellent results. In contrast, ruptures close to the abutment and bony avulsions tend to heal better through operative treatment. Dehiscence or dislocation of the ligament stumps in MRI is an indication for operative treatment. In the context of a multiligamentous injury or complex instability, the majority of authors suggest an operative stabilization. As the treatment of chronic instability can be challenging, the initial and adequate treatment of acute ruptures is of great importance.