Muscular buttonholing: An unusual cause of irreducible knee dislocation.

In cases of irreducible knee dislocation, all the medial joint structures have been reported to be the obstructing tissue. The case presented, the first in the English-language literature, is buttonholing of the femoral condyle through the vastus medialis muscle. Entrapment of the muscle bundle was diagnosed preoperatively using magnetic resonance imaging scans. The joint could be reduced easily, following sectioning of the muscle bundle.