In vitro mechanical evaluation of a novel pin-sleeve system for external fixation of distal limb fractures in horses: a proof of concept study.
OBJECTIVE
To evaluate the efficacy of a novel pin-sleeve cast (PSC) system for external fixation of distal limb fractures in horses and to compare it with the transfixation pin cast (TPC) system.


METHODS
Experimental.


METHODS
One bone substitute each was used for the TPC and PSC systems. The PSC was tested in 4 configurations characterized by different pin preloads.


METHODS
Specimens were loaded in axial compression in the elastic range. Variables compared statistically were: bone substitute axial displacement and axial strain measured above implants with strain gauges. Pin preload was correlated with the variables investigated. Load to failure and a fatigue tests supplemented the investigation.


RESULTS
The PSC configuration with the highest pin preload showed a significantly lower axial displacement compared with the TPC. No significant differences were observed between all other PSC configurations and the TPC. All PSC systems had a significant decrease in recorded strain compared with the TPC system. Pin axial preload inversely correlated with axial displacement but had no effect on axial strain. In the failure test, the PSC encountered plastic deformation earlier than the TPC. In the fatigue test, the PSC ran >200,000 cycles.


CONCLUSIONS
Preliminary in vitro tests showed that the PSC system significantly reduced peri-implant strain while concurrently having comparable axial displacement to the TPC system.


CONCLUSIONS
The PSC system has the potential to reduce the risk of pin loosening in horses.
Brianza
Stefano
S
AO Research Institute, 7270 Davos Platz, Switzerland. stefano.brianza@aofoundation.org
Brighenti
Vittoria
V
Boure
Ludovic
L
Sprenger
Victor
V
Pearce
Simon
S
Schwieger
Karsten
K
D000818:Animals; D001696:Biomechanical Phenomena; D001858:Bone Nails / Q000662:veterinary*; D016267:External Fixators / Q000662:veterinary*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary; D006734:Horse Diseases / Q000601:surgery; D006736:Horses / Q000601:surgery*; D066298:In Vitro Techniques; D013314:Stress, Mechanical; D016474:Weight-Bearing