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Extension-type supracondylar humerus (SCH) fracture is a common injury in children.1–3 The Wilkins modification of the Gartland classification of SCH fractures is commonly used: type 1 is posteriorly hinged and minimally displaced, with the anterior humeral line (AHL) (Figure) intersecting the anterior or middle one-third of the capitellum; type 2 is posteriorly hinged and anteriorly gapped, but with the posterior cortex in continuity; and type 3 is completely displaced.1–3 It is well accepted that type 1 fractures can be successfully treated in a cast, whereas type 3 fractures require surgery, most frequently with closed reduction and percutaneous pinning (CRPP). Type 2 fractures, however, represent the middling range of injury. Several centers have sought to differentiate which type 2 fractures can be successfully managed with nonoperative treatment and which can be operatively treated like a mild type 3 SCH fracture.4–13
Barton et al14 found that the Gartland classification system for SCH fractures had substantial (kappa=0.74) interobserver and excellent (kappa=0.84) intraobserver reliability. However, the observer changed the fracture classification 10% of the time on repeat reviews, most of the time between type 1 and type 2. Heal et al15 found poor interobserver agreement for type 1 fractures, only fair to moderate agreement for type 2 fractures, and good agreement for type 3 fractures. The lateral capitellar humeral angle, which measures extension at the SCH fracture site, has been reported to have fair reliability, whereas Baumann's angle, measuring anteroposterior varus/valgus, has excellent interobserver reliability.16 The AHL has been shown to have moderate to substantial reliability and to pass through the middle one-third of the capitellum in children older than 5 years and through the anterior or middle one-third in most children younger than 5 years.17,18 Fitzgibbons et al13 outlined the AHL index used in this study, finding that of the fractures that were AHL0 (AHL anterior to the capitellum) at the time of injury, 38% would be considered nonoperative treatment failures.
This study assessed the reliability of the AHL index compared with the Gartland classification, particularly regarding posteriorly hinged SCH fractures, and the consistency of treatment recommendations based on the classifications.
Materials and Methods
On institutional review board approval, the anteroposterior and lateral radiographs of 50 consecutive patients 18 months to 15 years old with extension-type...