Biomechanical comparison of PFNA combined with the modified candy-package wiring technique versus PFNA alone in complex unstable intertrochanteric femoral fractures: A biomechanical model study.

Proximal femoral nail antirotation (PFNA) may not provide sufficient control of unstable fracture fragments in complex intertrochanteric fractures. The modified candy-package wiring technique may supplement PFNA by improving resistance to rotational and shear displacement. This biomechanical model study compared PFNA combined with modified candy-package wiring with PFNA alone in an Evans type III intertrochanteric fracture model. Ten standardized femoral fracture models were randomly allocated to a PFNA group (n = 5) or a PFNA plus modified candy-package wiring group (PFNA + MCW group; n = 5). Torsional and axial compression tests were performed. Three repeated loading cycles were conducted for each specimen as conditioning cycles; the prespecified third cycle was used for analysis. Torsional stiffness was calculated as the change in torque divided by the corresponding change in angular displacement (Kt = ΔT/Δθ). The mean torsional angle was significantly lower in the PFNA + MCW group than in the PFNA group (2.09 ± 0.24° vs 2.90 ± 0.18°; P = .0007). Torsional stiffness was also significantly lower in the PFNA + MCW group than in the PFNA group (0.48 ± 0.0529 vs 0.59 ± 0.0850 N·m/°; P = .045). The maximum failure load was numerically higher in the PFNA + MCW group than in the PFNA group (571.26 ± 92.75 N vs 510.34 ± 76.59 N), although the difference was not statistically significant (P = .291). In this small biomechanical model study, PFNA combined with modified candy-package wiring reduced torsional displacement and showed favorable trends in axial load-bearing performance compared with PFNA alone. Because several outcomes were not statistically significant and only 5 models were included per group, these findings should be interpreted as preliminary biomechanical evidence rather than proof of superiority. Larger biomechanical studies and clinical validation are required.