Effect of bending direction on the mechanical behaviour of interlocking nail systems

L. M. Déjardin; R. P. Guillou; D. Ting; M. T. Sinnott; E. Meyer; R. C. Haut

doi:10.3415/VCOT-08-08-0075

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2009; 22(04): 264-269
DOI: 10.3415/VCOT-08-08-0075

Original Research

Schattauer GmbH

Effect of bending direction on the mechanical behaviour of interlocking nail systems

Authors

L. M. Déjardin

¹Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
R. P. Guillou

¹Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
D. Ting

¹Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
M. T. Sinnott

²The Orthopaedic Biomechanics Laboratories, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
E. Meyer

²The Orthopaedic Biomechanics Laboratories, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
R. C. Haut

²The Orthopaedic Biomechanics Laboratories, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA

Abstract

Summary

Objectives: To compare the mechanical properties of various interlocking nail constructs in medio-lateral (ML) and cranio-caudal (CC) bending. Methods: Synthetic bone models simulating a severely comminuted tibial fracture were treated with either screwed or bolted, 6 or 8 mm standard interlocking nails (ILN), or an angle-stable ILN (AS-ILN), after which they were then sequentially tested in ML and CC bending. Construct compliance, maximum angular deformation (MaxDef) and slack were statistically compared (p<0.05).

Results: The compliance of all constructs was significantly greater in CC than in ML bending. However, due to the presence of a greater slack in the ML plane, standard ILN constructs sustained significantly more deformation in that plane. Maximum deformation of the novel AS-ILN constructs was the smallest of all constructs and consistently occurred without slack regardless of bending direction. Clinical significance: This study suggested that standard ILN construct overall deformation and acute instability (slack) may be more critical in ML than in CC bending. Conversely, the small MaxDef and the absence of slack in both bending planes seen in novel angle-stable AS-ILN may provide optimal construct stability and in turn may be more conducive to bone healing.

Keywords

Interlocking nail - bending - angle-stable implant

Full Text

References

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