Avulsion fracture of the supinator crest as an indication for a sustained posterolateral (sub)luxation of the elbow. A case report, anatomical evaluation and review of the literature

Abstract

The treatment of elbow injuries can be challenging because of the complexity of both anatomy and pathology. We present a rare traumatic avulsion fracture of the supinator crest of the ulna in a 37-year-old patient. Conservative treatment in a long arm cast for four weeks led to satisfactory results. Reproduction of the fracture on a cadaveric elbow clarified that the avulsed fragment holds the insertion of the lateral ulnar collateral ligament (LUCL). The mechanism of trauma that causes this fracture is a posterolateral (sub) luxation of the elbow, which usually causes the LUCL to rupture, but in rare cases the insertion of this ligament can be avulsed. A posterolateral (sub) luxation of the elbow can lead to chronic posterolateral rotational instability and therefore the stability of the elbow should be taken into account in the treatment of patients with such a fracture. A review of the literature concluded that this fracture often is associated with other injuries to the elbow and that it is easily missed on conventional AP and lateral radiographs. CT or MRI imaging and a radial head-capitellum view radiograph can be beneficial. Both conservative and operative treatments have been described with good clinical results.

Keywords: Avulsion fracture; Elbow; Lateral collateral ligament complex; Lateral ulnar collateral ligament; Luxation; Posterolateral rotational instability; Supinator crest; Ulna; Ulnar.