Analysis of the Changes in Femoral Varus Bowing and the Factors Affecting Nonunion for the Treatment of Femoral Shaft Fractures over 60 Years Old Using Piriformis Fossa Insertion Intramedullary Nailing

Abstract

Financial support: None. Conflict of interests: None. Purpose: This study examined the bony morphological changes to analyze the factors affecting bony union in the treatment of elderly femoral shaft fractures with varus bowing using piriformis fossa insertion intramedullary nailing. Materials and Methods: This study included 26 patients over 60 years of age, who were admitted for femoral shaft fractures between January 2005 and December 2014 and treated with piriformis fossa insertion intramedullary nailing. Age, sex, height, weight, bone mineral density, injury mechanism, fracture type, diameter and length of the nail, postoperative lengthening of the femur, postoperative change in varus angle, contact between the lateral and anterior cortex, and the gap between the fracture line and the bony union were checked. The patients were divided into a varus group and nonvarus group, as well as a bone union group and nonunion group. Logistic regression analysis was performed to analyze the factors affecting nonunion. Results: The patients were classified into 11 in the varus group and 15 in the non-varus group and 24 in the union group and 2 in the nonunion group. The varus group showed a larger increase in leg length and varus angle reduction than the non-varus group (p<0.05). The union group had more contact with the lateral cortical bone than that of the nonunion group (p<0.05). The factor affecting bone union in regression analysis was contact of the lateral cortical bone (p<0.05). Conclusion: Treatment of a femoral shaft fracture in elderly patients with a varus deformity of the femur using piriformis fossa insertion intramedullary nail increases the length of the femur and decreases the varus deformity. For bony union, the most important thing during surgery is contact of the lateral cortical bone with the fracture site.