Classification of femur trochanteric fracture: Evaluating the reliability of Tang classification

Given the drawbacks of a femoral intertrochanteric fracture classification based on 2-dimensional radiographic imaging, an artificial intelligence-based classification system- the Tang classification system-which uses 3-dimensional image analysis, has previously been developed. This study explored the reliability of the Tang classification by comparing the consistency of this classification with the conventional 2-dimensional femoral intertrochanteric fracture classification systems.

X-ray and computed tomography (CT) data of 258 patients with femoral intertrochanteric fractures were classified by 6 orthopedic surgeons using the Evans, Jensen, AO/OTA, and Tang classification systems on 2 separate occasions, 1 month apart. Kappa statistics were used to evaluate the inter- and intraobserver differences in classifications.

When the interobserver reliability was based on X-ray image analysis, the Kappa values for the Evans, Jensen, AO/OTA, and Tang classifications were 0.54 ± 0.03 (moderate agreement), 0.53 ± 0.02 (moderate agreement), 0.46 ± 0.02 (moderate agreement), and 0.63 ± 0.02 (substantial agreement), respectively. When the interobserver reliability was based on CT images, the Kappa values of the Evans, Jensen, AO/OTA, and Tang classifications were 0.49 ± 0.03 (moderate agreement), 0.49 ± 0.03 (moderate agreement), 0.44 ± 0.03 (moderate agreement), 0.64 ± 0.02 (substantial agreement), respectively. For X-ray images, the intraobserver Kappa values for the Evans, Jensen, AO/OTA, and Tang classification were 0.53 ± 0.02 (moderate agreement), 0.54 ± 0.03 (moderate agreement), 0.45 ± 0.03 (moderate agreement), and 0.65 ± 0.03 (substantial agreement), respectively. When intraobserver reliability was based on CT images, the Kappa values for the Evans, Jensen, AO/OTA, and Tang classification were 0.52 ± 0.03 (moderate agreement), 0.52 ± 0.02 (moderate agreement), 0.41 ± 0.02 (moderate agreement), and 0.63 ± 0.03(substantial agreement), respectively.

The current study suggests that the Tang classification system is more reliable than the Evans, Jensen, and AO/OTA classification systems for measuring intertrochanteric fractures of the proximal femur.