In vitro biomechanical comparison of a newly designed interlocking nail system to a standard DCP

Summary

Objective: To describe a newly designed interlocking nail system (Targon® Vet System, TVS) tested in a model of diaphyseal femoral fractures in cats. Material and methods: Introduction of the TVS and presentation of the system components. Evaluation of application range and biomechanical testing of the TVS in cadaver bones under cyclic loading until fatigue failure occurred. The first two test groups compared the influence of implantation and immediate removal of the TVS locking bolts and six holes created by 2.0 mm cortical screws on the stability of feline femora. In the third group the two fixation systems were compared to each other with implants in place in an osteotomy gap model. The failure mode was statistically compared for each group (p < 0.05). Results: Femora after implantation and removal of the bolts of the TVS were significantly stiffer than after implantation and removal of the six 2.0 mm cortical screws. In the osteotomy gap model, femora with the TVS in place failed somewhat later, but not statistically significant, than the opposite femur of the same cat with the 2.0 8-hole DCP in place. Conclusion and clinical relevance: Using this testing method, stability of the TVS seems to be biomechanically comparable to conventional osteosynthesis plate systems. Therefore the TVS may be an encouraging alternative to conventional osteosynthesis systems in diaphyseal fractures, offering several advantages without the need for extensive specialized equipment.

Zusammenfassung

Gegenstand und Ziel: Beschreibung eines neuartigen Verriege-lungs nagel-Systems (Targon® Vet System, TVS) und Testung dieses Systems in einem In-vitro-Modell an Katzenfemora mit diaphysären Frakturen. Material und Methode: Beschreibung des Systems und der einzelnen Systemkomponenten. Ermittlung der Mindestgröße für die Anwendung des TVS und biomechanische Testung des TVS in Kadaverknochen unter zyklischer Belastung bis zum Eintreten einer Ermüdungsfraktur. In den ersten beiden Testgruppen wurde vergleichend untersucht, wie sich die Implantation und anschließende Entfernung eines TVS-Verriegelungsbolzens bzw. sechs 2,0-mm-Kortikalschrauben auf die Stabilität von Katzenfemora auswirkt. In der dritten Testgruppe erfolgte ein Vergleich beider Implantatsysteme in einem “Osteotomiespalt-Modell”. Das Versagen des jeweiligen Knochens bzw. Implantat-Knochen-Konstrukts wurde zwischen den Gruppen statistisch verglichen (p < 0,05). Ergebnisse: Die Femora nach Implantation und Entfernung der Verriegelungsbolzen waren signifikant stabiler als diejenigen nach Implantation und Entfernung von sechs 2,0-mm-Kortikalschrauben. Im „Osteotomiespalt-Modell” erwiesen sich die Femora mit dem implantierten TVS als geringfügig stabiler im Vergleich zum jeweils kontralateralen, mit einer 2,0 DCP und sechs Kortikalschrauben fixierten Femur, doch war der Unterschied statistisch nicht signifikant. Schlussfolgerung und klinische Relevanz: Die Stabilität des TVS ist unter diesen Testbedingungen biomechanisch vergleichbar zu der konventioneller Plattensysteme für die Osteosynthese. Das TVS könnte bei diaphysären Frakturen eine vielversprechende Alternative zu konventionellen Osteosynthesesystemen darstellen und bietet verschiedene Vorteile, ohne den Bedarf für ein umfangreiches spezielles Equipment.

Key words

Interlocking nail - cat - femur - diaphyseal fractures

Schlüsselwörter

Verriegelungsnagel - Katze - Femur - diaphysäre Frakturen

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