Finite element analysis of a novel pin-sleeve system for external fixation of distal limb fractures in horses.

The research article is based on introducing and testing a novel technique, the pin sleeve cast system (PSC), to treat horses with distal limb fractures. It is being compared to a traditional method known as transfixation pin cast (TPC) and the finite element models of bone substitutes were used for evaluating the performance of both techniques.

Objective of the Research

• The research intends to address the problem of implant loosening which is often associated with the traditional transfixation pin cast (TPC). This problem increases the risk of treatment failure when treating distal limb fractures in horses.
• To alleviate this problem, a pin sleeve cast system (PSC) was designed and tested. The performance of this novel technique was compared with that of the TPC using finite element models of bone substitutes.

Master Design of Pin Sleeve Cast System (PSC)

• The PSC system consists of a pin-sleeve unit that is inserted into the bone of the horse. Each pin in the setup runs through a sleeve placed within the bone.
• The design is such that each pin makes contact at two fixed points within the sleeve. Finally, each pin is also attached to a ring that is embedded in a resin cast.

Comparative Analysis

• Using finite element models of bone substitutes, the researchers compared the mechanical performance of the traditional TPC and the novel PSC.
• It was found that the PSC was successful in significantly reducing the peak strain magnitude around the pins, and it also resulted in a more uniform distribution of strain across the bone cortex.
• In terms of proximal fragment displacement, both the TPC and the PSC showed similar results. Similar stress concentration around bone defects was observed during the process of implant removal.

Conclusion

• The findings show that the PSC’s load transfer mechanism is effective even in complex structures such as equine bones, offering promising solutions to the persistent issues with the traditional TPC method.