Correlation between iatrogenic ulnar nerve injury and angular insertion of the medial pin in supracondylar humerus fractures

The aim of this study was to assess the correlation between the occurrence of iatrogenic ulnar nerve injury and frontal and saggital angular insertion of the medial pin in type 3 pediatric supracondylar humerus fractures treated by closed reduction and percutaneous fixation using a cross-pin configuration. Radiographs of 90 children were retrospectively reviewed and two radiographic parameters were measured. The frontal humerus-pin angle was formed between the long axis of the humerus shaft and the axis of the medial pin on an anteroposterior radiograph. The saggital humerus-pin angle was formed between the long axis of the humerus shaft and the axis of the medial pin on a lateral radiograph and expressed as positive and negative values if the insertion direction of the pin was anterior to posterior or posterior to anterior, respectively. There was a significant difference between the mean saggital humerus-pin angle values of ulnar nerve injury and no neurological complication groups (12.1 degrees versus 1.6 degrees , respectively; P=0.001). It was concluded that, anteroposterior insertion of the medial pin in the saggital plane, while the elbow was in hyperflexion, correlated with the occurrence of iatrogenic ulnar nerve injury.