Related Experiment Video
Updated: Jun 10, 2026
An Intramedullary Locking Nail for Standardized Fixation of Femur Osteotomies to Analyze Normal and Defective Bone Healing in Mice
Published on: November 13, 2016
In vitro comparison of two centrally threaded, positive-profile transfixation pin designs for use in third metacarpal
Kirstin A Bubeck1, José M García-Lopez, Thomas M Jenei
1Orthopedic Research Laboratory, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA. kirstin.bubeck@tufts.edu
Objective:
To compare heat generation during insertion, pullout strength, and associated microdamage between a self-tapping positive profile transfixation pin (STTP) and nontapping positive profile transfixation pin (NTTP).
Sample Population:
30 pairs of third metacarpal bones (MC3s) from adult equine cadavers.
Procedures:
One MC3 of each pair was assigned to the STTP group; the other was assigned to the NTTP group. The assigned pin was inserted into the diaphysis in a lateral to medial direction. Bone temperature increase during pilot-hole drilling and pin insertion was recorded at 1 mm from the final thread position with wire thermocouples at cis and trans cortices. Resistance to axial extraction before and after cyclic loading was measured in a material testing device, and microstructural damage caused by transfixation pin insertion was assessed with scanning electron microscopy.
Results:
The STTP group developed a significant increase in bone temperature, compared with the NTTP group. No significant difference was found between the mean maximal pullout strength of the STTP and the NTTP in both non-cyclic-loaded and cyclic-loaded groups. Microdamage to the bone-pin interface was lower when the STTP versus the NTTP was used, but more bone debris was apparent after inserting the STTP.
Conclusion And Clinical Relevance:
Because of the significant increase in temperature generation and debris accumulation despite similar pullout strengths and lesser microfracture formation, the STTP likely poses a higher risk of bone necrosis and potential loosening than the NTTP. This might be corrected by redesign of the tapping aspect of the STTP.
