Preoperative classification assessment reliability and influence on the length of intertrochanteric fracture operations

Abstract

Purpose: The accuracy of intertrochanteric fracture classification is important; indeed, the patient outcomes are dependent on their classification. The aim of this study was to use the AO classification system to evaluate the variation in classification between X-ray and computed tomography (CT)/3D CT images. Then, differences in the length of surgery were evaluated based on two examinations.

Methods: Intertrochanteric fractures were reviewed and surgeons were interviewed. The rates of correct discrimination and misclassification (overestimates and underestimates) probabilities were determined. The impact of misclassification on length of surgery was also evaluated.

Results: In total, 370 patents and four surgeons were included in the study. All patients had X-ray images and 210 patients had CT/3D CT images. Of them, 214 and 156 patients were treated by intramedullary and extramedullary fixation systems, respectively. The mean length of surgery was 62.1 ± 17.7 min. The overall rate of correct discrimination was 83.8 % and in the classification of A1, A2 and A3 were 80.0, 85.7 and 82.4 %, respectively. The rate of misclassification showed no significant difference between stable and unstable fractures (21.3 vs 13.1 %, P = 0.173). The overall rates of overestimates and underestimates were significantly different (5 vs 11.25 %, P = 0.041). Subtracting the rate of overestimates from underestimates had a positive correlation with prolonged surgery and showed a significant difference with intramedullary fixation (P < 0.001).

Conclusions: Classification based on the AO system was good in terms of consistency. CT/3D CT examination was more reliable and more helpful for preoperative assessment, especially for performance of an intramedullary fixation.

Fig. 1

Flowsheet of this study

Fig. 2

Classification data B1 and data B2. a and b show data B1 based on X-ray images. c and d show data B2 based on CT/3D CT images. a and c show the number of patients in classification between Drs. Tang and Tao, Drs. Tang and Zhang, Drs. Liang and Tao, Drs. Liang and Zhang. b and d show the number of patients in classification between Drs. Tang and Liang, Drs. Tao and Zhang. Black square frames are the number of patients in agreement between two surgeons

Fig. 3

Correlation between differences of length of surgery and subtracted rate of overestimates from underestimates in the same classification. EM extramedullary fixation (blue triangles and linear fitting line). IM intramedullary fixation (red dots and linear fitting line). Total difference between group 3 and group 4 (black squares and linear fitting line)