Irreducible posterolateral dislocation of the knee

Traumatic knee dislocations are relatively rare, often associated with neur ovascular injury, and almost always amenable to closed reduction. However, over the years, several authors have recognized that the rare knee dislocat ion not reducible by closed manipulation usually involves posterolateral di slocation of the tibia and button-holing of the medial femoral condyle thro ugh the medial retinaculum. These cases present with a dimple sign, a chara cteristic invagination of tissues at the medial joint line. Open reduction entails extraction of the soft-tissue collar that becomes incarcerated in t he trochlea and intercondylar notch. We present an interesting case of irre ducible posterolateral knee dislocation and review many of the salient poin ts associated with this entity. Additionally, we include intraoperative vid eo footage available on the Journal Web site to promote a better appreciati on of the dramatic visual presentation and physical examination of this unu sual injury.