Proximal femoral nail antirotation for Evans-Jensen III intertrochanter fracture without fixation of the femoral lesser trochanterlc fragment: a finite element analysis and clinical study

Abstract

Objective To analyse the biomechanical stability of Evans-Jensen Ⅲ intertrochanteric fracture fixed by proximal femoral nail antirotation (PFNA) without fixation of the femoral lesser trochanteric fragment through the finite element and clinical effects of this method. Methods Three three-dimensional finite element models of the Evans-Jensen Ⅲ intertrochanteric fracture fixed with PFNA with or without fixation of the femoral lesser trochanteric fragment was established. Von Mises stress distribution of points was observed to analyze the biomechanical stability.115 patients with Evans-Jensen Ⅲ intertrochanteric fracture were treated by PFNA without fixation of the femoral lesser trochanterlc fragment, Fractures heal and internal fixations were evaluated by radiograph postoperatively and hip joint function were done by Harris criteria. Results Whether femoral lesser trochanterlc fragment fixed, the maximum Von Mises stress of femur is located on distal and meidal femur and that of inter fixation on main screw or medial connection. But peak von Mises stress of No fixed femoral lesser trochanterlc fragment was lower than that of fixed. The mean follow-up was 32 months for 115 cases, Fracture union occurred in all patients with a mean healing time of 3 months, Two cases were found with varus deformity of hip because of early weight. The hip function was rated as excellent in 91, good in 15, fare in 7 and poor in 2 case according to Harris functional evaluation system. Conclusion PFNA fixation for Evans-Jensen Ⅲ intertrochanteric fracture without fixation of the femoral lesser trochanteric fragment can effectively maintain the stability of the fractures and seems simple, safe and also can achieve satisfactory clinical effect. Key words: Intertrochanteric fracture; Lesser trochanteric fragment; Proximal femoral nail antirotation; Finite element; Clinical effect