Bilateral trochlear avascular necrosis
An overweight (BMI of 27) previously healthy medically and surgically, not on any medication, 11-year-old boy presented to the emergency department with a history of trauma to the right elbow 2 h prior to his presentation. His friend fell on his outstretched right arm. The patient was seen and assessed by the orthopedic on-call team. He was vitally stable and had no previous traumatic history, motion limitation, pain, locking, nor prior infection in either elbow. Local examination of his elbow revealed a right elbow swelling without deformity or instability. Tenderness was noted over the lateral condyle. Range of motion (ROM) was 0–90 of elbow flexion extension and he was able to do full pronation and supination. Distal neurovascular status was intact. His left elbow exam was negative for swelling, tenderness, deformity, as well as instability. He had a full left elbow ROM. His initial right elbow X-ray showed a posterior fat pad sign, with no clear fracture line, but an abnormally appearing trochlea was evident. Afterward, X-rays of the contralateral elbow showed a similar abnormal appearance of the trochlea.

Carrying angles were 9 and 5° in valgus, for right and left elbows, respectively. The trochlear notch angles were 123 and 112°, for right and left elbows, respectively. He had no complaints from his left elbow, therefore, he was discharged on an above-elbow cast for the right arm with a close follow-up and analgesia. The parents were in agreement with our assessment and treatment plan. During his follow-up, he was found to have an undisplaced supracondylar fracture in addition to the diagnosis of bilateral Hegemann's disease. A repeat history was found to be negative for preceding trauma. After cast removal (at 6 weeks), ROM exercises at home were advised to improve his range of motion. Following the readings of his carrying angles and trochlear notch, angles were not possible due to the inappropriate X-ray views that were done in the clinic. He is scheduled for new X-rays in his next clinic visit. During his latest follow-up (12-week visit), his right elbow showed no tenderness, and ROM was 30–110 and was referred for physical therapy to improve his ROM. During all his visits, his left elbow revealed no deformity and he had a full painless ROM. The patient is still being seen in our clinic for motion arc assessments as well as possible improvement of his bilateral trochlear avascular necrosis (AVN).