Unstable AO/OTA type 31-A1.2 intertrochanteric femur fracture: An unusual case report

Abstract

AO/OTA type 31-A1.2 intertrochanteric femoral fractures generally are considered stable intertrochanteric fractures. We report a case of an unstable AO/OTA type 31-A1.2 intertrochanteric femoral fracture. Primary internal fixation was performed with a long cephalomedullary nail taking instability into account. Postoperative X-rays showed an acceptable reduction with a slight fracture gap in extension on the lateral trochanteric side. However, additional salvage surgery was required because the long cephalomedullary nail broke as a result of the instability caused by non-union and varus deformity of the proximal femur. More attention should be directed to strategies of primary internal fixation including choice of fixation instrumentation in terms of mechanical stability because this type of fracture can be remarkably unstable despite radiographic diagnosis of a usually stable AO/OTA classification type 31-A1.2 fracture.

Keywords: 95o–angled blade plate; AO/OTA type 31-A1.2; Cephalomedullary nail; Fixation instability; Intertrochanteric femoral fracture.

Fig. 1

Preoperative (a) anteroposterior and (b) lateral radiograph. Preoperative (c) anteroposterior and (d) lateral three-dimensional computed tomography. Anteroposterior radiograph shows radiological sign of reverse epsilon ‘3’. The distance between the innominate tubercle of the greater trochanter and the reference point is 3.0 cm as shown by the double-ended white arrow. Lateral wall thickness between the reference point and the fracture line is 27 mm as shown by the double-ended black arrow.

Fig. 2

Postoperative (a) anteroposterior and (b) lateral radiographs.

Fig. 3

Five months after surgery, anteroposterior (a) radiograph and (b) computed tomography.

Fig. 4

Intraoperative view of the long cephalomedullary nail and screws after removal.

Fig. 5

(a) Anteroposterior and lateral radiographs after re-fixation. (b) Anteroposterior and lateral radiographs one year after re-fixation.

Fig. 6

Comparison between (a) anteroposterior radiographs before re-fixation and (b) anteroposterior radiographs after re-fixation. The femoral neck angle before and after re-fixation was 120° and 138°, respectively.

Fig. 7

Drawing of anatomical structures around the fracture line. Modified with permission from the Atlas of Human Anatomy, illustrated by Frank H. Netter, MD. All rights reserved.