A pilot biomechanical study comparing a novel, intramedullary Nail/Plate construct to standard Dual-Plate fixation of intra-articular C2.3 distal humerus fractures

A novel configuration for the fixation of intra-articular C2.3 distal humerus fractures with the potential for minimally invasive surgery: a biomechanical evaluation and finite element analysis

BACKGROUND

Distal humerus fractures are a challenge to treat, and the current standard of care, open reduction internal fixation with a double-plate, has a high rate of complications. We proposed a novel internal fixation configuration, lateral intramedullary nail and medial plate (LINMP) and verified its rigidity through biomechanical tests and finite element analysis.

METHODS

The study involved biomechanical testing of 30 synthetic humerus models to compare 2 different fixation systems for an AO 13C-2.3 type fracture. The orthogonal double-plate (ODP) group and the LINMP group were compared through biomechanical testing to measure stiffness and failure load fewer than 3 working conditions. Based on the results, we optimized the intramedullary nail by eliminating the holes at the distal end of the nail and incorporating a 2-hole external locking plate. The Finite element analysis was also conducted to further compare the modified LINMP configuration with the previous 2 fixation configurations.

RESULTS

In biomechanical tests, the ODP group exhibited lower stiffness under bending and compression forces compared to the LINMP group, but higher stiffness and failure loads under torsion force. In finite element analysis, the modified LINMP reduces the maximum stress of the fixation structure without significantly reducing the stiffness under bending stress and axial compression conditions. In torsion stress conditions, the modified LINMP enhances both the maximum stress and the stiffness, although it remains marginally inferior to the ODP structure.

CONCLUSION

Our study demonstrates that the innovative LINMP presents comparable or slightly superior concerning bending and axial loading compared to orthogonal double-plate osteosynthesis for distal humeral intra-articular fractures, which might become a minimally invasive option for these fractures.

Biomechanical analysis of different osteosynthesis configurations in the pin and plate fixation method for distal humerus fractures

Distal humerus fractures commonly occur in adults with low bone mineral density causing major technical challenges for orthopedic surgeons. Persian fixation method was introduced as a novel technique to stabilize small fragments in comminuted distal humerus fractures using a set of K-wires and a reconstruction plate. The present study aims to measure this technique's stiffness and stability of this technique and analyze the effect of influential parameters with numerical simulation and biomechanical testing on a cadaveric specimen. Validation of the finite element (FE) model was conducted based on results of experiments. The results indicated that Delta configuration mainly led to a higher stiffness in the case of axial loading and anterior bending compared to L configuration. Analyzing the influential factors of this technique suggests that changes in diameter and number of K-wires have a similarly significant effect on the construct stiffness while the height of plate had a slight influence. Also, the diameter of wires was the most effective parameter for implant failure, particularly in the 3-pin construct, which caused a reduction in failure risk by about 60%. The results revealed that the Persian fixation method would achieve suitable stability compared to the dual-plating technique.

Technical Trick: Supplemental Medial Column Screw Fixation of Distal Femur Fractures Treated With a Laterally Based Locked Plate

SUMMARY

Given known failure rates after lateral plating of distal femur fractures, there is an increasing interest in augmenting fixation to improve outcomes. The addition of medial plates or intramedullary nails have been described with promising results, decreasing nonunion and varus collapse rates. However, the use of dual implants increases implant costs, adds surgical complexity, and requires a second surgical approach that may increase morbidity. A supplemental, percutaneously placed, medial column screw may provide a less invasive means of improving stability and achieving fracture union compared with lateral plating alone.