Review Question - QID 219366

There is likely an incarcerated medial epicondyle fragment in the ulnohumeral joint which is not yet ossified given the patient's age.

Pediatric medial epicondyle fractures are common and most frequently occur in adolescent boys aged 9-14. They are also often associated with elbow dislocations. In this age group, the fracture is usually identified radiographically and provided there is no incarceration of the fragment, conservative treatment with casting vs. open reduction internal fixation (ORIF) is indicated based on the displacement. In younger patients, it is important to consider the order of ossification of the elbow (Illustration A). The medial epicondyle typically ossifies around age 5, which means that elbow injury prior to this age may be radiographically occult. A high index of suspicion must exist for these injuries. In elbow dislocations where it is difficult to achieve a concentric reduction, incarceration of the medial epicondyle must be considered. Ultimately, ORIF is required to reduce this fragment and restore joint mechanics.

Vuillermin et al. looked at risk factors associated with morbidity in incarcerated medial epicondyle fractures. They note that typically these injuries occur in older adolescents (average age = 13) after elbow dislocation. All subjects in the study underwent ORIF of the fragment with 16 reporting excellent outcomes, 13 with good outcomes, 3 with fair outcomes, and 0 with poor outcomes. They did not find a relationship between poorer outcomes and a longer duration prior to surgical intervention.

Tarallo et al. looked at pediatric medial epicondyle fractures which became incarcerated, noting that this occurs in 5-18% of these fractures and requires fixation. Their procedure of choice was 1-2 4.0mm cannulated screws and they noted excellent outcome scores in all patients. There were complications in 4/13 patients, with most related to hardware prominence.

Pezzutti et al. published a systematic review highlighting the management of pediatric medial epicondyle fractures. They discuss in the article that an incarcerated medial epicondyle fragment should always be ruled out but in cases where this is not present, there is still no true consensus on treating medial epicondyle fractures operatively vs. conservatively. This said, operative treatment had a higher rate of union and a higher rate of ulnar neuropraxia resolution.

Illustration A highlights the ossification centers of the elbow and their respective timeline. Illustrations B and C are sagittal and axial MRI slices depicting an incarcerated medial epicondyle fragment.

Incorrect Answers:
Answers 1 & 2: The capitellum and radial head ossify at 1 and 3 years, respectively. This means that if there were a fracture of either of these structures that was preventing reduction it would have likely been identified on initial radiographs.
Answer 4: There is no sign of nerve injury on examination, despite the fact that ulnar nerve injury can occur concomitantly with medial epicondyle fracture in ~10% of cases.
Answer 5: The ulnar collateral ligament (UCL) can be injured in the setting of an elbow dislocation but injury is uncommon with a posterolateral dislocation. Additionally, injury to the UCL would not typically prevent concentric reduction.