Biomechanical comparison of three different cephalomedullary nail systems in an Evans–Jensen type 2 intertrochanteric femur fracture model

Intertrochanteric femur fractures are common injuries in the elderly population and are frequently associated with osteoporosis. Cephalomedullary nailing is widely preferred for surgical fixation due to its biomechanical advantages; however, different proximal fixation designs may demonstrate variable mechanical performance. This study aimed to biomechanically compare three different cephalomedullary nail systems under axial loading conditions using a standardized intertrochanteric fracture model. An Evans–Jensen type 2 intertrochanteric fracture model was created on synthetic composite femurs. Fifteen identical fourth-generation composite femur models (Sawbones, Pacific Research Laboratories, Vashon, WA, USA), medium-sized right femurs with a 15 mm canal diameter and foam cortical structure, were divided into three groups (n = 5 per group). All specimens were fixed using one of the following systems: a double lag screw cephalomedullary nail (PROFIN), an antirotational proximal femoral nail (A-PFN), and a blade–screw integrated nail system (INTERTAN), all with a standard length of 200 mm and diameter of 10 mm. The canal diameter (15 mm) and nail diameter (10 mm) were kept constant across all groups to ensure standardized testing conditions and minimize bias related to implant fit. All specimens were subjected to axial compression testing at a displacement rate of 1 mm/min until mechanical failure. Maximum load to failure and displacement at maximum load were recorded. Group comparisons were performed using the Kruskal–Wallis test and Dunn–Bonferroni post-hoc analysis, with p < 0.05 considered statistically significant. The mean maximum failure load was highest in the PROFIN group (1701.24 ± 80.9 N), followed by the A-PFN group (1302.43 ± 201 N), and the INTERTAN group (1071.62 ± 106.48 N). The mean displacement at maximum load was 17.38 ± 3.78 mm for PROFIN, 27.59 ± 4.08 mm for A-PFN, and 14.07 ± 1.27 mm for INTERTAN. Statistical analysis demonstrated a significant difference in axial load resistance among the three fixation systems ( p < 0.05). In this synthetic Evans–Jensen type 2 intertrochanteric fracture model, the double lag screw cephalomedullary nail demonstrated superior axial load resistance compared with antirotational and blade–screw designs. These findings suggest that proximal fixation configuration may influence biomechanical stability; however, their clinical relevance should be interpreted with caution due to the limitations of in vitro testing.