Coronal shear fractures of the distal end of the humerus.

We identified a shear fracture of the distal articular surface of the humerus, with anterior and proximal displacement of the capitellum and a portion of the trochlea, in six patients (five female and one male). The average age of the patients was thirty-eight years (range, ten to sixty-three years). Each fracture was the result of a fall from a standing height. A characteristic radiographic abnormality, which we have termed the double-arc sign, was seen on the lateral radiograph of each patient and represented the subchondral bone of the displaced capitellum and the lateral trochlear ridge. All patients were managed with open reduction, internal fixation, and early motion of the elbow. The average duration of follow-up was twenty-two months (range, eighteen to twenty-six months). The fracture united in all patients at an average of six weeks (range, four to nine weeks), without radiographic evidence of osteonecrosis of the fracture fragment. Flexion of the elbow averaged 141 degrees (range, 130 to 150 degrees), with an average flexion contracture of 15 degrees (range, 0 to 40 degrees). Pronation of the forearm averaged 83 degrees, and supination averaged 84 degrees. All patients had a good or excellent functional result, according to the elbow-rating scale of Broberg and Morrey.