Development of a Novel Intra-Operative Evaluation Method for the Directions and Degrees of Malrotation in Supracondylar Humerus Fractures

Abstract Introduction : The malrotation of supracondylar humerus fractures (SCHF) often occurred, prolonging the reduction time during operation. An effective method should be established to achieve accurate reduction rapidly. Methods Three dimensional (3D) printed humerus models were used to obtain the linear correlation equation between the width and projection degrees. Then, transverse fracture was performed in the peak of the humeral olecranon fossa of 3D printed models, which was examined by C-arm in the lateral 45° oblique position. Then, ten images in models and five cases in clinics with internal or external rotation within 90° were selected, as their rotation direction and degrees were evaluated by five orthopedic surgeons. Finally, the intraclass correlation coefficient (ICC) and Kappa statistic were used to analyze the accuracy of this novel method. Results After linear regression analysis, the equation was obtained to show the correlation between the distal fracture line width and the rotation degrees. With the application of this method, the observers correctly predicted the rotation direction in 96% and correctly predicted the rotation degrees in 86% of models with a superior ICC value. Especially in the rotation range from − 45° to 45°, the accuracy of rotation direction and degrees could reach to 100% and 93.3%. Also, it has an equally accuracy (24/30) in five clinical cases. Conclusions This method provided a simple and efficient method for correcting intraoperative rotational displacement in patients with SCHF. By using this method, it can rapidly correct the malrotation displacement during operation, in order to distinctly shorten operation time, reduce bleeding volume and potential skeletal muscle injuries.