Purpose: The treatment of extension type II pediatric supracondylar humerus fractures remains controversial. Some argue that closed reduction and cast immobilization is sufficient to treat these fractures, while others advocate closed reduction and pinning. The purpose of this radiographic outcomes study was to determine whether closed reduction and cast immobilization could successfully obtain and maintain appropriate position of extension type II supracondylar humerus fractures.

Method: The radiographs of 1017 pediatric patients treated for supracondylar fractures between 1987 and 2007 were retrospectively reviewed. Pre-reduction, immediate post-reduction, and final radiographs of 155 extension type II fractures were measured in order to assess the position and alignment of the fracture fragments. Measurements included the anterior humeral line, humeral-capitellar angle, Baumann’s angle, the Gordon index, and the Griffet index. The latter two indices calculate the rotational instability of the fracture, which can be predictive of reduction loss. Patients were excluded if insufficient radiographs failed to allow complete assessment of the measurement parameters, or if open reduction was required.

Results: The average age of the subjects was 5.3 years (range 1–13 years) and had a mean follow-up of 5.3 months. Analysis of the final radiographs demonstrated that in 80% of subjects, the anterior humeral line remained anterior to the mid third segment of the capitellum (radiographic extension deformity), the mean humeral-capitellar angle was 23.8° (range – 11°–50°), the mean Baumann’s angle was 79.4° (range 62°–97°), the mean Gordon index was 4.59%, and 44% of subjects had a Griffet index between 1–3 (potentially indicative of unstable reduction due to malrotation of the fragments, which can allow the development of a cubitus varus deformity).

Conclusion: From this radiographic review, a significant proportion of fractures treated with closed reduction and cast immobilization failed to achieve anatomic position and alignment on final x-rays. However, the clinical significance of these results and the potential for long-term re-modeling of these fractures remains unknown.