Prophylactic fixation or surveillance: predicting subsequent displacement of lateral condyle of humeral fractures based on soft tissue swelling.

Background: Nondisplaced or minimally displaced fractures (≤2 mm) of the lateral condyle of the humerus (LCH) could undergo subsequent displacement (>2 mm), which would be a potential surgical indication. We describe a new method to quantify soft tissue swelling in LCH fractures and to identify a threshold value to predict subsequent displacement of LCH fractures. We hypothesized that the larger the soft tissue swelling, the more likely a subsequent displacement would occur.

Methods: Elbow x-ray images (anteroposterior view) at initial presentation in 87 patients with subsequent displacement and in 87 patients with no subsequent displacement were compared. All fractures were initially nondisplaced or minimally displaced. The lateral elbow swelling-to-humeral shaft diameter (LES-H) ratio was measured. A threshold value for diagnosing a subsequent displacement was identified from the receiver operating characteristic curve analysis.

Results: Both groups had similar age (subsequent displacement: 5.1 ± 2.3 years vs. no subsequent displacement: 5.7 ± 3.2 years; P = .459). The LES-H ratio was significantly larger in the subsequent displacement group (1.8 ± 0.4 vs. 1.4 ± 0.4, P < .001). The area under the receiver operating characteristic curve was 0.728, which was moderately accurate in predicting subsequent displacement. A threshold LES-H ratio of 1.90 had a sensitivity of 41.4% and specificity of 90.8% in diagnosing subsequent displacement. The odds ratio of having subsequent displacement with LES-H ratio of ≥1.90 was 6.1 (95% confidence interval, 2.7-13.8; P < .001).

Conclusion: The LES-H ratio could be used to objectively quantify soft tissue swelling in LCH fractures. An LES-H ratio of ≥1.90 was used as threshold value to predict subsequent displacement.