Intramedullary nailing of subtrochanteric fractures--does malreduction matter?

INTRODUCTION: Subtrochanteric femur fractures remain challenging injuries to treat. Historically, varus malreduction has been linked to the development of nonunion; however, there is a paucity of literature evaluating the impact of sagittal plane malreduction. The purpose of this study was to evaluate the influence of coronal and sagittal plane malreductions on time to union of subtrochanteric femur fractures treated with an intramedullary device. METHODS: A retrospective study was performed of all sub-trochanteric fractures (AO/OTA type 32) treated at a single institution. Inclusion criteria consisted of: 1. 18 or more years of age, and 2. fracture stabilization using an intramedullary device. All patients included were followed to union or revision surgery. Radiographic evidence of healing was defined as bridging callus on three of four cortices on AP and lateral views. Delayed union was defined as lack of radiographic healing by 4 months postoperatively and nonunion as lack of healing by 6 months. The definition of malreduction was coronal or sagittal plane deformity greater than 10° at the fracture site. RESULTS: Thirty-five patients met inclusion criteria; 20 men and 15 women with an average age of 55 years (range 19 to 100 years). Mean clinical follow up was 7 months (range 3 to 18 months). Thirty-four of 35 fractures (97%) healed without need for additional surgery. Twenty-one of the 35 fractures (60%) healed within 4 months of surgery. Thirteen fractures (37%) had delayed union, and 1 (2.9%) developed nonunion requiring reoperation. Seven of 35 fractures (20.0%) had a malreduction of greater than 10°, defined as varus (2 fractures), flexion (4 fractures), or both (1 fracture). Of the seven fractures with a malreduction, all (100%) developed a delayed (6) or nonunion (1). Of the 28 fractures without malreduction, 21 (75%) healed within 4 months, 7 (25%) had a delayed union, and none had a nonunion. The presence of a malreduction greater than 10° in any plane resulted in a significantly higher rate of delayed or nonunion (p = 0.0005). CONCLUSION: For patients with subtrochanteric fractures treated with an intramedullary device, malreduction in any plane of greater than 10° resulted in a significantly increased rate of delayed or nonunion or both.