Finite Element Analysis of Six Transcortical Pin Parameters and Their Effect on Bone-Pin Interface Stresses in the Equine Third Metacarpal Bone.

This study aimed to validate a computer-generated model that simulates the stresses on the Metacarpal bone of a horse’s lower limb due to the application of pins in a medical procedure, and identify how changes in six parameters of these pins affect the strain on the bone.

Study Overview

• This research revolves around understanding the impact of different parameters of transfixation pins on the creation of stress in the bone-pin interface (BPI) area of an equine animal’s third metacarpal bone. A transfixation cast finite element model was developed based on a CT scan of the third metacarpal bone. This model was validated by comparing experimentally obtained strain around a 6.3-mm transfixation pin in the third metacarpal bone.

Methods and Techniques Used

• The primary method used in this research was the finite element analysis; a numerical method for solving problems of engineering and mathematical physics, which is used here to analyze the stress on a horse’s bone.
• The model was then tested using different versions which took into account six pin variables: diameter, number, location, spacing, orientation, and material. Each variable was altered while keeping the other parameters constant to conclude the impact of each parameter on BPI stress.

Results and Findings

• The findings of the study revealed that the diameter and number parameters of the transfixation pins have a significant impact on the stress on BPI. Increasing the diameter and number of pins resulted in lower BPI stress.
• It was observed that using pins at the diaphyseal bone location and employing stainless-steel pins caused lesser stress than those at the metaphyseal location and titanium alloy pins respectively.
• It was found that the offset pin orientation and spacing of the pins had a minimal effect on BPI stress during axial loading.

Conclusions and Recommendations

• The research suggests that the diameter and number are the vital pin parameters influencing the BPI stress in an equine distal limb transfixation cast. Therefore, modifying the pin size and number could help in minimizing the risk of pin-related complications and reduce BPI stress.
• However, the researchers also pointed out the need for further refinement in these models to optimize pin configurations considering pin hole size and its impact on the overall bone’s strength.