We wanted to compare the insufficiency stress fractures of the femoral neck (group I) with the traumatic femoral neck fractures (group II) in patients who were 70 years of age and older.

Between January 2000 and October 2006, we evaluated 10 insufficiency stress fractures among 191 femoral neck fractures in patients who were 70 years of age and older. We compared these fractures with the traumatic femoral neck fractures by using the bone mineral density (BMD), neck-shaft angle, the hip axis length (HAL) and the ratio of the HAL to the femoral neck width.

The incidence of insufficiency stress fracture was 5.2%. There were 6 cases of displaced fractures and 4 cases of non-displaced fractures. All of non-displaced fractures revealed the tension (transverse) type. The mean neck-shaft angle was 130.45 degrees in group I and this was 131.94 degrees in group II. The mean HAL was 117.6 mm in group I and 115.3 mm in group II, and the ratio of the HAL to the femoral neck width was 0.30 in each group. The BMD (T-score) was -3.73 in group I and -3.4 in group II.

The BMD of the insufficiency fracture group was significantly lower than that of the traumatic femoral neck fracture group. However, there were no significant differences in the neck-shaft angle, the HAL and the ratio of the HAL to femoral the neck width between the 2 groups.