A Simulation Study On The Loss Of Elbow Flexion With The Extension Type Gartland ⅡA Humeral Supracondylar Fractures In Children

Objective:To assess the immediate loss of elbow flexion after Gartland ⅡA humeral supracondylar fractures according to the relationship between the anterior margin line of the humerus and the capitellum in the lateral view.Methods:Standard lateral radiographs of the elbows of sixty-six children between 1and 14 years old were collected from the PAC(Picture Archiving and Communications)system of Shengjing Hospital.Adobe Photoshop 14.0 was used to simulate Gartland ⅡA supracondylar fractures with different degrees of angulation and rotation in the sagittal plane based on the images.A mathematical model was constructed according to the linear transformation and vector product theory in advanced mathematics to conjecture the relationship between the loss of elbow flexion and age,as well as the angulations of the fractures.All the data was grouped at an age interval of three years.Results:When the distal fragment was rotated backward so that the anterior humeral line(AHL)went tangent to the anterior margin of the capitellum ossification center,the loss of elbow flexion would be about 11-30 degrees,with an average of 19 degrees.The average loss angle of elbow flexion was 14.3±4.2、18.4±3.6、20.6±3.6、20.7±4.0、24.0±4.8 degrees in 1-3、4-6、7-9、10-12、13-14 years groups,respectively.Except for the difference between 7-9 years old and 10-12 years old groups,there was significant difference in elbow flexion loss angle among the other groups(P< 0.05).And in the same age group,the angle of elbow flexion loss decreases with the increase of the sagittal tilt of the fracture line.Within the same age group,the elbow flexion loss would be the greatest when the fracture line was perpendicular to the humeral shaft.Within the same fracture line,the elbow flexion loss would increase with age.Positive correlation existed between age and elbow flexion loss,while negative correlation existed between elbow flexion loss and the angulation of fracture.Conclusion : The loss in elbow flexion immediately after Gartland Ⅱ A humeral supracondylar fracture would increase with age and decrease with the angulation of the fracture line in the sagittal plane.When the anterior margin of the humerus goes tangent to the anterior margin of the ossification center of the capitellum,there will be a loss of 19° in elbow flexion on average.