Diagnostic accuracy of the shaft-condylar angle for an incomplete supracondylar fracture of elbow in children.

Objective: The incomplete supracondylar fracture of distal humerus poses difficulty for diagnosis. A shaft-condylar angle and a lateral capitellohumeral angle, which can be measured from a routine lateral view of plain film of the injured elbow, may be a clue to assist in the diagnosis. Nevertheless, no literature explains about the accuracy of these angles for diagnosis. Our goal is to investigate the accuracy, sensitivity, specificity, positive predictive value and negative predictive value of the shaft-condylar angle and the lateral capitellohumeral angle for diagnosis of the incomplete supracondylar fracture.

Methods: The retrospective study in tertiary care hospital was performed from January, 2014, to January, 2018. The patients aged below 15 years with elbow injury were recruited. The patients with complete fracture were excluded. The rest of the patients were divided into four groups which consisted of incomplete fracture and non-fracture group. With the shaft-condylar angle at 40° and the lateral capitellohumeral angle at 50°, the diagnostic accuracy of both angles were calculated.

Results: A total number of patients were 53. For the SCA, the accuracy was 92%, the sensitivity was 76%, the specificity was 93%, the positive predictive value was 92% and the negative predictive value was 93%. For the LCHA, the accuracy was 70%, the sensitivity was 55%, the specificity was 72%, the positive predictive value was 67% and a negative predictive value was 72%.

Conclusion: The shaft-condylar angle less than 40° in lateral elbow film might be a useful tool for diagnosis of the incomplete supracondylar fracture in pediatric patients with elbow injury.