A biomechanical investigation of a novel intramedullary nail used to salvage failed internal fixations in intertrochanteric fractures

A Novel Internal Fixation Design for the Treatment of AO/OTA-31A3.3 Intertrochanteric Fractures: Finite Element Analysis

OBJECTIVE

AO/OTA 31-A3.3 intertrochanteric fracture is the most unstable type of intertrochanteric fracture, with a high rate of postoperative complications and implant failure. We have designed a new intramedullary fixation, proximal femoral totally bionic nail (PFTBN), for the treatment of A3.3 intertrochanteric fracture. To test its biomechanical performance, we adopted the method of finite element analysis and compared PFTBN with proximal femoral nail antirotation (PFNA) and proximal femoral bionic nail (PFBN, another internal fixation we previously designed for stable intertrochanteric fractures).

METHODS

Mimics, 3-matic, ANSYS, and other software were used to construct a highly precise and realistic 3D digital model of the human femur. An AO/OTA 31-A3.3 intertrochanteric fracture of the femur was constructed according to the 2018 classification of AO/OTA, and then assembled with PFNA, PFBN and PFTBN models, respectively. The stress distribution and displacement distribution of the three groups of constructs were tested under three times the body weight load and one-foot standing configuration.

RESULTS

In terms of maximum stress and maximum displacement, the PFTBN group outperforms the PFBN group, and the PFBN group, in turn, surpasses the PFNA group. The maximum stress of PFTBN group was 408.5 Mpa, that of PFBN group was 525.4 MPa, and that of PFNA group was 764.3 Mpa. Comparatively, the maximum stress in the PFTBN group was reduced by 46.6% when contrasted with the PFNA group. Moreover, the stress dispersion within the PFTBN group was more evenly distributed than PFNA group. Regarding maximum displacement, the PFTBN group displayed the least displacement at 5.15 mm, followed by the PFBN group at 7.32 mm, and the PFNA group at 7.73 mm. Notably, the maximum displacement of the PFTBN group was 33.4% less than that observed in the PFNA group. Additionally, the relative displacement between the fragment and implant at the tip of pressure screw or helical blade was 0.22 mm in the PFTBN group, 0.34 mm in the PFBN group, and substantially higher 0.51 mm in the PFNA group.

CONCLUSION

The "lever-reconstruction-balance" theory provides a new perspective for us to understand the mechanical conduction of the proximal femur. Compared with PFNA, in treating A3.3 intertrochanteric fractures PFTBN can better reconstruct the function of lateral wall, restore physiological mechanical conduction, increase postoperative stability, and finally reduce the risk of postoperative cut-out and implant failure. It might be a better alternative for the treatment of A3.3 intertrochanteric fracture.

Nomogram based on high-density lipoprotein cholesterol for the occurrence of preoperative deep vein thrombosis in patients with intertrochanteric femur fracture: a retrospective study

BACKGROUND

This study aims to develop a nomogram and forecast the incidence of DVT in individuals suffering from an intertrochanteric femur fracture.

METHOD

This work created a nomogram using the R programming language and employed logistic regression to determine independent predicting features. An external validation dataset was used to validate the nomogram.

RESULT

The findings demonstrated the independence of LYM (0.02[0.01-0.09], p < 0.001), ALB (0.83[0.74, 0.94], p = 0.002), and HDL-C (0.18[0.04, 0.71], p = 0.014). Good prediction performance with modest errors was shown by the nomogram in both the training and validation groups.

CONCLUSION

In conclusion, the nomogram that was created using HDL-C, ALB, and LYM can assist medical professionals in determining the likelihood that DVT will occur.