In Vitro Mechanical Evaluation of a Novel Pin-Sleeve System for External Fixation of Distal Limb Fractures in Horses: A Proof of Concept Study

Abstract

The PSC system has the potential to reduce the risk of pin loosening in horses.

Comparative Biomechanical Evaluation of a Pin‐Sleeve Transfixation System in Cadaveric Calf Metacarpal Bones

“…The PSC prototype was numerically scaled down to the dimensions of 4‐ to 6‐week‐old calf metacarpal bones . The boundary conditions considered during development of the new implants were an average animal weight of 500 N and the creation of a circular defect in the bone with a similar diameter to that created by the transfixation pin thread.…”

“…Use of TPC can be often associated in both species with pin loosening, a complication at the bone‐implant interface that limits effectiveness potentially resulting in treatment failure . A novel pin‐sleeve cast (PSC) transfixation system (US patent application number: 20100125273) was developed to address high strain at the bone‐implant interface as one major causal mechanism for pin loosening. This system transfers the load applied to the injured limb to the ground by means of a pin‐sleeve unit inserted into the bone and firmly connected to an external ring embedded, at the moment, in a cast .…”

“…A novel pin‐sleeve cast (PSC) transfixation system (US patent application number: 20100125273) was developed to address high strain at the bone‐implant interface as one major causal mechanism for pin loosening. This system transfers the load applied to the injured limb to the ground by means of a pin‐sleeve unit inserted into the bone and firmly connected to an external ring embedded, at the moment, in a cast . The PSC aims to reduce strain at the bone‐implant interface avoiding contact between the part of the compound implant mostly subjected to bending and the bone tissue (Fig ).…”

“…This system transfers the load applied to the injured limb to the ground by means of a pin‐sleeve unit inserted into the bone and firmly connected to an external ring embedded, at the moment, in a cast . The PSC aims to reduce strain at the bone‐implant interface avoiding contact between the part of the compound implant mostly subjected to bending and the bone tissue (Fig ).…”

“…This study is part of a multistep investigation testing the efficacy of the new system by comparative studies between equivalent PSC and TPC systems. In an initial study on simple bone models, the loading mechanism concept was validated by showing that the PSC reduces the peri‐implant strain at the model surface and provides at the same time an axial displacement comparable to the one observed with TPC. Using a computational method it has been shown in a second study that the strain magnitude decrease in bone substitutes instrumented with the PSC is not limited to the external bone surface but is characteristic of all the material around the PSC.…”