Purpose: This study analyzed the treatment results of highly unstable trochanteric fractures and made treatment guidelines.
Materials and Methods: Among three hundred six cases of trochanteric fractures from October 2001 to February 2006, the patients were divided into group 1(highly unstable trochanteric fracture, 69 cases) and group 2(age and gender-matched control group, 70 cases). The two groups were compared clinically and radiologically. A highly unstable trochanteric was defined as a fracture with a neck-shaft angle < 100° and anterior angulation. The mean follow-up duration in groups 1 and 2 was 13.2 and 15.5 months, respectively. The mean neck-shaft angle in groups 1 and 2 was 92.1° and 118.9°, respectively. The mean anterior angulation in groups 1 and 2 was 23.0° and 4.6°.
Results: In group 1, 39 cases were treated with a dynamic hip screw (DHS), 22 cases were treated with a proximal femoral nail (PFN), and 8 cases(11.6%) were treated with primary bipolar hemiarthroplasty. The average amount of sliding of the lag screw in groups 1 and 2 was 10.5 mm and 3.7 mm, respectively (p<0.05). The average change in the neck-shaft angle in groups 1 and 2 was 7.0° 1 and 2.1°, respectively (p<0.05). There were 7 complications in group 1, including 5 cutting-out, 1 back-out and 1 Z-effect, and 2 cases of cutting-out in group 2.
Conclusion: A highly unstable trochanteric fracture has a high risk of the need for additional surgery. Therefore, considerable care should be taken to treat it with a consideration of the possible need for arthroplasty.

Keywords: Trochanteric fracture, Highly unstable, Neck-shaft angle, Anterior angulation