Fracture morphology of AO/OTA 31-A trochanteric fractures: A 3D CT study with an emphasis on coronal fragments

Abstract

Aims: This study was designed to assess the incidence and morphology of coronal plane fragments in AO/OTA 31-A trochanteric fractures.

Patients and methods: 156 cases of AO/OTA 31-A trochanteric fractures were retrospectively evaluated. Lateral radiographs were analyzed for the presence of coronal plane fragments followed by analysis of 3D CT reconstructions in these fractures. The incidence of coronal fragments identified on the lateral radiograph and 3D CT reconstructions were both calculated. Coronal fragment morphology was described based upon the origin and exit points of fracture lines and the number of fragments.

Results and conclusion: On plain radiographs, a coronal plane fracture was identified in 59 cases, an incidence of 37.8% (59/156). In comparison, 3D CT reconstructions identified coronal plane fractures in 138 cases for an incidence of 88.4% (138/156). 3D CT reconstructions identified coronal fracture fragments in 81.9% (50/61) of AO/OTA 31-A1 cases, 94.5% (69/73) of 31-A2 cases, and 86.3% (19/22) of 31-A3 cases. Incidence of coronal fractures identified on plain radiographs of 3 AO/OTA 31-A1,A2,A3 groups was lower when compared to the incidence of coronal fractures identified on 3D CT. Of the 138 cases that had coronal plane fracture, 82 cases (59.4%) had a single coronal fragment (GT fragment 35 cases, GLT fragment 19 cases, GLPC fragment 28 cases). The remaining 56 cases (40.5%) had two coronal fragments. There is a high incidence of coronal fragments in intertrochanteric femur fractures when analyzed with 3D CT reconstructions. Our study suggests that these coronal fragments are difficult to identify on plain radiographs. Knowledge of the incidence and morphology of coronal fragments helps to avoid potential intraoperative pitfalls.

Keywords: 3D CT; Coronal fragment; Fracture morphology; Intertrochanteric fracture.