Locked Elbow Joint Due to a Cartilage Flap Caused by Osteonecrosis of the Humeral Trochlea: A Case Report.

Abstract

Although osteonecrosis of the humeral trochlea is a well-known complication of supracondylar humeral fractures in childhood, its frequency is relatively rare1. We report a case of a young boy with a locked elbow joint due to a cartilage flap caused by osteonecrosis of the humeral trochlea. Osteonecrosis was confirmed by follow-up radiographic examinations. The patient’s mother was informed that data concerning the case would be submitted for publication, and she provided consent. A ten-year-old boy was referred to our hospital with the symptom of locking during left elbow extension, which was accompanied with pain. The locking occurred suddenly when he turned a doorknob with the left hand. The medical history included a left supracondylar humeral fracture when he was five years old, which was treated conservatively by a local physician (Fig. 1). Fig. 1 Nondisplaced supracondylar fracture of the left elbow (arrow) when the patient was five years old. On the initial examination, no swelling or tenderness was observed in the left elbow. Although the active elbow flexion range was up to 137°, the active and passive extension loss was 75°, with painful locking. Passive extension induced pain on the posterolateral side of the lateral humeral condyle. The range of forearm motion was 90° for pronation and 80° for supination without limitation. Radiographs revealed an irregularly contoured ossification of the epiphysis in the lateral humeral condyle (Fig. 2-A), and computed tomography (CT) revealed irregular ossification of the medial trochlea (Fig. 2-B). Magnetic resonance imaging (MRI) revealed an abnormal low-intensity shadow on the T2-weighted …