The progress of the HO on X-ray or Three dimensional computed tomography (3DCT) images of the left elbow. (a). (9 weeks after the injury) The border of HO (yellow arrow) was irregular. (b). (14 weeks after the injury, immediately after the operation) The HO was all resected. (c). (17 weeks after the injury, 3 weeks postoperatively) The HO recurred (yellow arrow). (d). (21 weeks after the injury, 7 weeks postoperatively) The recurrent HO was resolving spontaneously. (e). (30 weeks after the injury, 16 weeks postoperatively) Recurrent HO was absent. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)