ISOLATED GREATER TROCHANTER FRACTURES: CAN WE PREDICT INTERTROCHANTERIC EXTENSION?

Abstract

Introduction: Isolated greater trochanter fractures gained clinical importance because of the possibility of their inter-trochanteric extension.

Aim: To assess whether the direction and the extent of the fracture measured on plain radiographs could be used to predict the inter-trochanteric extension.

Materials and Methods: We reviewed plain radiographs and MRI scans of 24 patients who sustained isolated greater trochanter fractures between year 2003 and 2006. We considered two parameters

1. extent of fracture in percentage along the intertrochanteric line

2. angle of the fracture line.

Both these parameters were measured on a plain anteroposterior radiograph. To measure the length of fracture we have drawn a straight line along the medial border of femoral shaft extending proximally in to the pelvis. Then we measured the distance between the most superior point of the fracture line on the lateral cortex and the midpoint of lesser trochanter on the first line. Then we measured the length of the fracture starting from the most superior point on the lateral cortex. We estimated the percentage of this fracture length in relation to line.

To estimate the angle, again we have drawn a straight line along the medial border of femoral shaft extending proximally in to the pelvis. We have drawn another line in the direction of fracture staring from most superior point of fracture on the lateral cortex joining the first line. We measured the angle between these two lines (Fig 2). We used our Hospital PACS system to measure the angles and the length of the fracture.

Results: Out of 24 isolated greater trochanteric fractures as diagnosed by plain radiographs, MRI scans revealed intertrochanteric extension in nine (37.5%). On the plain anteroposterior radiograph, the mean angle of the fracture in those with MRI proven intertrochanteric extension was 34º (range 20º–45º). In those with no intertrochanteric extension on MRI scan, the mean angle was 55º (Range 25º–125º). The mean percentage of length of fracture across the intertrochanteric line was 62% (47%–73%) and 40% (27%–62%) respectively. All the fractures with MRI proven intertrochanteric extension had a fracture angle of < 45º and the percentage of fracture length of > 40%. All the 15 fractures with fracture angle more than 45º did not show intertrochanteric extension on MRI scan

Conclusions: We conclude that those isolated greater trochanteric fractures, with fracture angle of more than 45 º are unlikely to have an intertrochanteric extension. These patients could be mobilised without further MRI scans. Those fractures which fulfil the plain radiographic criteria of extension of more than 40% and fracture angle between 20º–40º are likely to show inter trochanteric extension. These patients need further clinical assessment and MRI scans to confirm the intertrochanteric extension.