Comparison of insertion characteristics of tapered and cylindrical transfixation pins in third metacarpal bones of equine cadavers.

This research sought to evaluate the difference in heat production and bone damage between tapered and cylindrical transfixation pins used in the third metacarpal bones of horses, and determined that tapered pins generate less heat but cause more bone damage than cylindrical pins.

Methodology

The study utilized 16 pairs of equine third metacarpal bones from cadavers. Two different procedures were undertaken for the insertion of pins:

• For the cylindrical pin insertion – a 6.2-mm hole was drilled and tapped with a cylindrical tap, then a standard 6.3-mm pin was inserted.
• For tapered pin insertion – a 6-mm hole was drilled, reamed with a tapered reamer, and tapped with a tapered tap, and then a 6.3-mm tapered pin was inserted.

Paired t tests and 1-way ANOVAs were used to compare the heat generation and bone damage associated with each type of pin.

Results

It was determined that the insertion of a tapered pin resulted in less heat production but more bone damage than the insertion of a cylindrical pin when these pins were inserted with the same torque. Moreover, when tapered pins were inserted with various torques, higher torque resulted in an increase in both heat generation and bone damage.

Conclusions and Clinical Relevance

The study suggests that the tapered pin could be a better choice than the cylindrical pin for insertion in equine cortical bone due to its lower heat production. However, the tapered pin also resulted in greater bone damage, which the researchers attribute to the differences in the design of the cylindrical and tapered taps.

This research concludes that while the tapered pin is more favorable in terms of reduced heat generation during insertion, there is a need for improvements in tap design that could potentially reduce the level of bone damage during the process.